New Perspectives on Computer Concepts 2018 - Introductory 2017934814, 9781305951518, 9781337388542

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NEW PERSPECTIVES

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Computer Concepts 2018

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TABLE OF CONTENTS

PREFACE

STUDENT RESOURCES

2

The Digital Revolution

4

Data Processing

6

Personal Computing

8

Network Computing

10

xlv

2

INSTRUCTOR RESOURCES

INTRODUCTION

16

MODULE 1: DIGITAL CONTENT

82

MODULE 2: DIGITAL DEVICES

158

MODULE 3; NETWORKS

240

MODULE 4: THE WEB

310

MODULE 5: SOCIAL MEDIA

376

MODULE 6: SOFTWARE

452

MODULE 7: DIGITAL SECURITY

520

MODULE PY: CODING WITH PYTHON

584

GLOSSARY

602

INDEX

616

ANSWERS

INTRODUCTIQN

3

Cloud Computing

13

Ubiquitous Computing

15

QUICKQUIZ

16

DIGITAL CONTENT

82

DIGITAL DEVICES

18

SECTION A: DIGITAL BASICS

84

SECTION A: DEVICE BASICS

19

Data Representation Basics

85

Computers

21

Representing Numbers

87

Circuits and Chips

22

RepresenlingTexl

89

Components

25

Bits and Bytes

91

Maintenance

26

Compressiort

94

29

SECTION B; DIGITAL SOUND

30

Digital Audio Basics

SECTION B: DEVICE OPTIONS

95

Enterprise Computers

96

Personal Computers

32

Digital Audio File Formats

98

Niche Devices

34

MIDI

99

Choosing a Digital Device

36

Digitized Speech

104

SECTIONC:PROCESSORSANDMEMORY

105

Microprocessors

39

Bitmap Basics

107

How Processors Work

42

Bitmap Data Representation

110

Performance

44

Image Compression

113

Random Access Memory

38

SECTION C: BITMAP GRAPHICS

46

Modifying Bitmap Images

114

48

Panoramic and 360 Images

116

49

Stereoscopy

117

Read-only Memory SECTION D; STORAGE

Storage Basics

119

Magnetic StorageTechnology

52

Vector Graphics Basics

121

Optical StorageTechnology

55

Vector Tools

122

Solid State StorageTechnology

56

3D Graphics

123

Cloud Storage

58

Vectors andVirtual Reality

125

Backup

51

60

SECTION D:VECTOR GRAPHICS

SECTION E: DIGITALVIDEO

129

SECTION E: INPUT AND OUTPUT

61

Digital Video Basics

130

Add-on Gadgets

65

Video Compression

131

Expansion Ports

66

Video File Formats

134

Bluetooth

68

DigitalVideo Variations

135

Device Drivers

70

ISSUE:WHATISFAIRUSE7

136

Display Devices

72

INFORMATION TOOLS;PHOTO FORENSICS

140

Printers

74

TECHNOLOGY IN CONTEXT: FILM

142

Things

76

MODULE ACTIVITIES

144

AutonomousVehicies

81

LAB:THE DIGITALWORLDWITH EYES SHUT

146

ISSUE: WHERE DOES ALLTHE EWASTEGO?

148

INFORMATIONTOOLS: FINDINGTHE RIGHT STUFF

150

TECHNOLOGY IN CONTEXT: MILITARY

152

MODULE ACTIVITIES

157

LAB: WHAT'S GOING ON INTHERE7

158

NETWORKS

240

THE WEB

160

SECTION A: NETWORK BASICS

242

161

Communication Systems

243

Web Overview

162

Communication Channels

244

Evolution

166

Network Topology

246

Web Sites

168

Network Nodes

247

Hypertext Links

170

Communication Protocols

249

URLs

172

SECTION B;THE INTERNET

264

SECTION A:WEB BASICS

SECTION B: BROWSERS

173

Background

255

Browser Basics

175

internet Infrastructure

258

Customization

176

Packets

262

Browser Cache

179

Internet Addresses

266

SECTION C: HTML

182

Domain Names

267

HTML Basics

269

HTML EditingTools

186

SECTION C:INTERNET ACCESS

187

Connection Basics

272

CSS

192

Cable Internet Service

274

Dynamic Web Pages

193

Telephone Network Internet Service

276

Site Creation

195

Satellite Internet Service

278

SECTION D: HTTP

196

Mobile Broadband Service

279

HTTP Basics

198

Wi-Fi Hotspots

281

Cookies

200

SECTION D: LOCAL AREA NETWORKS

284

HTTPS

201

LAN Basics

286

203

Ethernet

287

Search Engine Basics

205

Wi-Fi

292

Formulating Searches

207

Set UpYour Own Network

295

Search Privacy

211

Network Monitoring

296

Using Web-based Source Material

212

lot Networks

298

ISSUE: WHO ISTRACKINGYOU?

214

300

INFORMATIONTOOLS: CITATIONS

215

File Sharing Basics

302

TECHNOLOGY IN CONTEXT: FASHION

216

Accessing LAN Files

304

MODULE ACTIVITIES

219

Sharing Your Files

309

LAB: DESIGNYOUR HOME PAGE

222

Internet-based Sharing

224

SECTION E; FILE SHARING

SECTION E: SEARCH ENGINES

Torrents

226

ISSUE; WHO WILL CONTROL THE INTERNET?

228

INFORMATIONTOOLS: FACT CHECKING

230

TECHNOLOGY IN CONTEXT: EDUCATION

232

MODULE ACTIVITIES

237

UB; HACKYOUR NET

310

SOCIAL MEDIA

376

SOFTWARE

312

SECTION A:SOCIAL NETWORKING

378

SECTION A:SOFTWARE BASICS

313

The Social Media Mix

379

Essentials

316

Social Networking Evolution

382

Distribution

317

Social Networking Basics

384

Software Licenses

319

Geosocial Networking

389

Fake and Pirated Software

321

Social Network Analytics

390

SECTION 8;OPERATING SYSTEMS

391

Operating System Basics

325

Evolution

395

Microsoft Windows

327

Media Content Communities

398

macOS

329

Intellectual Property

400

iOS

Creative Commons

401

Android

402

Chrome OS

403

Linux

324

331

334

335

SECTION B: CONTENT COMMUNITIES

SECTION C:8L0GSAND MORE

Blogs

338

Microblogs

404

340

Wikis

405

344

SECTION 0:ONLINE COMMUNICATION

Virtual Machines

SECTION C:APPS AND APPLICATIONS

406

WebApps Mobile Apps

345

Communication Matrix

408

346

Email

409

Local Applicatiorts

351

Online Chat

413

Uninstalling Software

Voice andVideo over IP

414

352

354

355

SECTION E;SOCIAL MEDIA VALUES

Identity

SECTION D: PRODUCTIVITY SOnWARE

415

Office Suite Basics

416

Word Processing

357

Reputation

419

Spreadsheets

360

Privacy

423

Databases Presentations

364

ISSUE: WHEN DO ONLINE AVATARS DIE?

425

366

INFORMATION TOOLS: MEDIA ATTRIBUTION

426

368

TECHNOLOGY IN CONTEXT: JOURNALISM

427

File Basics

370

MODULE ACTIVITIES

430

File Management Tools

375

LAB: MY SOCIAL NETWORK

435

Application-based File Management

436

Physical File Storage

SECTION E: FILE MANAGEMENT UTILITIES

438

ISSUE: HOW SERIOUS IS SOFTWARE PIRACY?

440

INFORMATION TOOLS: DOCUMENTATION LITERACY

442

TECHNOLOGY IN CONTEXT: ARCHITECTURE AND CONSTRUCTION

444

MODULE ACTIVITIES

449

LAB: PUTYOUR FILE DUCKS IN A ROW

452 454

DIGITAL SECURITY

520 CODING WITH PYTHON

SECTION A: BASIC SECURITY

522

SECTIONA: "HELLOWORLD!"-PYTHON STYLE

455

Encryption

523 Coding Basics

456

Authentication

523 Introduction to Python

460

Passwords

524 Let's Start Coding

464

Password Managers

527 WorkingWith Strings

466

SECTION B: MALWARE

528

Using Python Keywords

467

MalwareThreats

529 Debugging

468

Computer Viruses

531

SECTION B:THEWACKVWORD GAME

470

ComputerWorms

532

Using Variables

471

Trojans

536

Objects and Classes

472

Antlvirus Software

538

Input

478

SECTION C: ONUNE INTRUSIONS

539 Wacky Word Game

479

IntruslonThreats

540 SharingYour Programs

483

Zero-day Attacks

541

SECTION C: BUILD YOUR OWN CALCULATOR

484

Netstat

542

Calculations

546

Selection Structures

485 488

489

Firewalls SECTION D: INTERCEPTION

Interception Basics

548 Comparison and Logical Operators 550 Comparing Strings

490

EvilTwins

552 SECTION DtASKTHE FORTUNETELLER

491

Address Spoofing

553 Repetition Control Structures

492

Digital Certificate Hacks

559

Lists

IMS! Catchers

563

SECTION E: DOGS AND CATS

564

Functions

569

Methods

494 496

SECTION E: SOCIAL ENGINEERING

497

Social Engineering Basics

499

Spam

575

MODULE ACTIVITIES

503

Phishing

579

LAB:ADVENTURE GAME

504

Pharming

506

Rogue Antivirus

507

PUAs

584 GLOSSARY

508

ISSUE: HOW SECURE IS DEMOCRACY?

602 INDEX 616

510

INFORMATIONTOOLS; YOUR OWN WORDS

512

TECHNOLOGY IN CONTEXT: LAW ENFORCEMENT

514

MODULEACTIVITIES

519

LAB: CHROME LOCKOOWN

ANSWERS

VI I I

NP2018

New Perspectives on Computer Concepts 2018 Preface

L O M0I V I T T

COLLEGE GRADUATES OF THE 21ST CENTURY

Computer Concepts 20i8

are expected to have a broad base of knowledge to intelligently address social, political, economic, and legal issues associated with rapidly evolving digital technology.

Today's students have a patchwork of knowledge, acquired from using various digital devices. New Perspectives on Computer Concepts (NP2018) helps students build a cohesive framework that organizes this acquired knowl edge and serves as a foundation for assimilating new

concepts essential to careers and lifestyles in our digital world.

FULLY REVISED. NP2018 has been newly revised and updated to increase learning effec tiveness and to reflect the wide scope of digital devices in use today, with an enhanced focus on the connectivity that pervades modern life and the security necessary to protect it.

TARGETED LEARNING SUPPORT. This award-winning textbook contains layers of targeted learning support for active learning that keeps students engaged and helps them succeed. Using the mindtap digital platform, students benefit from interactive feedback and new col laborative opportunities.

READING IN THE DISCIPLINE. Short paragraphs and a clear narrative style help students grasp concepts and learn how to read technical material.

RETENTION. What's the most effective study technique: Taking notes? Reviewing? According to researchers, students study most effectively by simply trying to recall the material they've read, seen, or heard. That's why NP2018 offers continuous assessment, Embedded QuickChecks on just about every page help students recall key concepts while reading and later while reviewing. QuickQuizzes and end-of-module reinforcement promote successful learning outcomes.

HANDS-ON. NP2018 contains plenty of practical information about how to use apps, manage files, create content, configure security software, and more. Try Itl activities throughout the book show students how to immediately apply concepts in real-world contexts.

FLIPPED CLASSROOMS. Flipping a course is easy with NP2018, which includes flipped class projects for critical thinking, cyberclassroom exploration, collaborative group work, multimedia integration, career building, and globalization. End-of-module features, such as Issues and Information Tools, offer additional topics for hands-on in-class activities.

PREFACE

IX

EXTENDED INTRO MODULE.The Introduction module puts technology into context with in-depth coverage of the multi-phased digital revolution. For NP2018. this introduction has been expanded to include virtual reality, augmented reality, and autonomous vehicles.

A FRESH APPROACH TO SOCIAL MEDIA.Sure, students use social media, but are they familiar with underlying concepts, such as the social media honeycomb, geolocation,and sociocrams? Are they up to speed with Creative Commons and intellectual properly concepts? Do they recognize fake news? And do they understand the relevance of online identity, PRIVACY, AND REPUTATION MANAGEMENT? Module 5 o^ers 3 fresh approach to social media that delves into concepts while also providing practical how-to tips.

NEW IMAGING TECHNOLOGIES. in an increasingly visual world, graphical imaging is becoming ever more sophisticated. Module 1 is packed with new information about 360-degree video, stereoscopic graphics, and spherical imaging popularized by copro cameras, youtube 360, POKEMON GO, AND GOOGLE CARDBOARD.

NEW SECURITY ISSUE, tvlodule 7 contains a new Issue, how secure is democracy?, that explores the challenges required to secure voting machines, voter registration data, cam paign Web sites, campaign email messages, fund-raising bank accounts, lists of campaign workers, and donor databases.

THE LATEST TECHNOLOGY. Digital technology evolves at a fast pace. NP2018 keeps stu dents up to bate with raspberry pi, 3D printers, smart appliances, lightning ports, USB-C, accelerometers, gyro sensors, magnetometers, macOS, windows io, virtual reality headsets, Microsoft Edge, hypervisors, two-factor authentication, Locky ransomware, and more!

HANDS-ON PROGRAMMING MODULE.Programming with Python provides highly inter active programming activities that introduce students to the world of programming without requiring any prior experience. Python is an easy-to-learn language that supports proce dural and object-oriented programs.

INFOGRAPHIC ILLUSTRATIONS. Illustrations based on popular infographic visuals are carefully integrated into the learning path to provide visual scaffolding that is so important to understanding technical concepts. INFOGRAPHIC-STYLE ILLUSTRATIONS

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Back up hard

Back up hard disk

Back up handheld

Back up hand-

Back up cloud

disk to cloud

to external drive

to hard disk

held to cloud

to hard disk

jn

7

NP2018

Student Resources: The Book

WHETHER YOU USE THE PRINTED BOOK OR DIGITAL VERSIONS, NP201S GIVES YOU THE STRAIGHT STORY ON TODAY'S TECHNOLOGY.

EASY TO READ. Each module is divided into five sections, beginning with a CONCEPT MAP that provides a visual overview of topics, faqs answer commonly asked questions about technology and help you follow the flow of the presentation.

KEEPS YOU ON TRACK. As you read each page, watch for quickchecks. They'll help you gauge if you comprehend key concepts. And take some time to complete the try iti activities. They bring concepts to the real world and help you hone your digital skills, quickquizzes at the end of each section provide a chance to find out if you remember the most important concepts, end-of-module REVIEW activities such as Key Terms, Interactive Situation Questions, and Interactive Summary Questions are great for test prep.

HELPS YOU EXPLORE. The ISSUE section in each module highlights contro versial aspects of technology. In the technology in context section, you'll discover how technology plays a role in careers such as film-making, architecture, banking, and fashion design. The information tools section helps you sharpen your digital research techniques. Check out the labs at the end of each module for

some step-by-step exploration Into your digital devices.

FAQs break down concepts Into manageable chunks of Information.

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ia What about the Web? When historians look back on the digitai revolution, they are certain to identify the Web as a major transformative infiuence. The Web (short for World Wide Web) is a coliection of iinked documents, graphics, and audio that can be accessed over the internet. A key aspect of the Web is that it adds content and substance to the intemet.

Without the Web, the internet wouid be iike a iibrary without any books or a raiiroad without any trains. Online storefronts, auction sites, news, sports,

travei reservations, and music downioads made the Web a compeiiing digi tai technoiogy for just about everyone.

► So what was computing like during this phase? From 1995 to 2010, computing was characterized by the increasing use of laptops (Figure 8} and the foiiowing elements:

QUICKCHECK The Web and the Internet are

not the same. Why? a. The Internet is a

communication network, but the Web consists of content

that is distributed by the internet.

b. The internet consists of sites

such as Twitter and Facebook, whereas the Web links devices such as iPods and

Sophisticated software. The network computing phase may have been the peak for productivity software. Computer owners amassed large collec tions of software, purchased in boxes containing multiple distribution CDs. Software such as Microsoft Office, Norton's Internet Security suite, and Corel Digitai Studio required local installation and provided more features than most people had any desire to use. This trend reverses during the next phase of the digital revolution, when applications become simpler and more focused on specific tasks.

computers.

Stationary Internet access. Even as laptop computers began to dis place desktop models, connecting to the internet required a cable that effectively tethered computers to a nearby phone jack or cable outlet, in the next phase of the digitai revolution, internet access breaks free from cables and goes mobile. Online communication. Email was the first widespread technology used to communicate over the internet. Online services such as CompuServe and AOL pioneered chat rooms, which were primitive versions of Google Hangouts. Early forums and message boards were similar to Facebook

timelines. A technology called Voice over IP allowed participants to bypass the telephone company to make phone calls over the internet. That technoi ogy eventually developed into Skype and similar video chat services. Muitiplayer games. Sophisticated computer games reached a peak dur ing the network phase of the digitai revolution. Audio and visual hardware components improved to support video-realistic game environments, arti ficial intelligence opponents, and multiple players logging in remotely and chatting with other players over headsets, in the next phase, mobile devices become popular gaming platforms, but hardware limitations restrict the feature set.

Music downloads. During the network computing phase, an online

business called Napster pioneered the concept of sharing and down loading music. Subscribers exchanged millions of music files, which they played through the speakers of their computers. The music was protected by copyright, however, making sharing and distribution illegal. This type of file sharing activity and rampant software piracy became one of the defining problems associated with the network phase of the digitai revolution. ITunes and other services for legally downloading music soon appeared, along with dedicated playback devices, such as the IPod. Video distribution over the internet lagged behind until con nection speeds increased in the next phase of the digitai revolution.

FIGURE 8: LAPTOPS

Laptop computers were the

primary devices for accessing

the Internet prior to 2010. User interfaces evolved to

include color, graphics, and mice.

10

INTRODUCTION

CLOUD COMPUTING Around 2010, the Information Age eased into a new phase called cloud computing, which provided access to information, applications, communi cations, and storage over the Internet.

t What did cloud computing change? Before cloud computing, most computers ran software based locally. For example, to use a word processor, you might fire up the latest edition of Microsoft Word, which you'd installed on your computer's hard disk. Prior to the cloud, you stored data locally, too. Email, documents, photos, and music all resided on your computer's hard disk or flash drive. With cloud computing, all that changed. In the cloud, you can use your browser to access word processing applications that run from the Internet instead of software that you have installed on your local hard disk. You can use online applications to manage your email, create floor plans, produce presentations, and carry out a host of other activities. You can store your data in the cloud, too, making it available on any of your digital devices that connect to the Internet.

The cloud gets its name from diagrams like the one in Figure 9, which shows Internet-based applications, storage, and other services outlined by a cloud-like shape designed to help you visualize the idea that cloud ser vices are "out there" somewhere on the Internet. FIGURE 9:THE CLOUD HOSTS APPLICATIONS,CONTENT, AND SERVICES

Data F las

Webmaii Ecommerce Movim Social Media Mufiic

Information

I Wait, this sounds familiar! If cloud computing sounds a bit like cen tralized computing, you're paying attention. The concept of applications and data residing somewhere other than on a local device is common to both centralized and cloud computing. The cloud concept reawakens the idea of monolithic computing facilities, as opposed to distributed architectures of the network era. The fact that your cloud-based data is not stored on devices under your direct control is a potential privacy and security con cern, which is a topic for later modules.

QUICKCHECK Which characteristic of cloud

computing most sets it apart from network computing? a. Internet access

b. Sophisticated software c. The migration of applications and data off of local devices

d. File sharing

11

THE DIGITAL REVOLUTION

I Are smartphones the signature device of the cloud comput ing era? The cloud itself is populated by commercial-grade high-speed computers and high-capacity storage devices. The consumer side is dominated by smartphones (Figure 10)and their dose cousins, tablet com puters. These handheld devices—a product of convergence—were the driving force for many cloud innovations.

FIGURE 10: SMARTPHONES

Cloud computing caters to smartphones and other mobile devices that are a product of convergence. They access and share data from the cloud

using apps.

^ What is convergence? The expansion of cloud computing Is due in part to convergence, a process by which several technologies with distinct functionalities evolve to form a single product. Convergence was important to the digital revolution because it created sophisticated mobile devices whose owners demanded access to the same services available from a full-

size desktop computer. Those services became available in the cloud.

Your computer plays movies. Your ceil phone has a camera. Your dock has a radio. Your watch functions as a communications device. You can store

data on your iPod Touch. Ail these are examples of technological conver gence.

Convergence worked its magic on ceil phones, computers, portable media players, televisions, digital cameras, GPSs, watches, and ebook readers. Now you get features from ail of them by purchasing a single digital device, such as a smartphone or tablet computer (Figure 11).

6) Q fa

FIGURE 11: SMARTPHONES ARE A PRIME EXAMPLE OF CONVERGENCE

Phone

Television

CO G.tmc console

Record player

Dictaphone

QUICKCHECK Camera

Clock

Fitness tracker

^ Why do these devices need the cloud? Smartphones are porta

Which of the following instigated the move to cloud computing?

ble. Compared to desktop and laptop computers, smartphones have small screens, lack a proper keyboard, and have limited space for storing apps and data. The cloud offers a convenient place to store data and applications.

a. Social media

Think of the cloud as a repository for streaming videos, music, photos, and

c. Touchscreens

apps. With that concept in mind, you will begin to understand the cloud's importance to today's consumers.

d. Music downloads

b. Mobile devices

INTRODUCTION

12

I Did the cloud kill the Web? A 2010 Wired magazine cover announced "The Web Is Dead." That pronouncement was premature. The cloud consumed the Web but did not kill it. As a legacy technology from the networking era, the Web continues to be a global marketplace where Amazon, Alibaba, and other retailers sell directly to consumers. That said, Facebook, Twitter, and Google Apps sent the Web in new direc tions. Once a collection of storefronts run exclusively by businesses and

corporations, the Web expanded into a global hub where content was cre ated by individuals, shared on social media sites, and uploaded to content sharing platforms. This grassroots Web of user-created content is some

TRY III In 20H,the United Nations declared that the Internet "is an

indispensable tool for realizing a range of human rights...." Visit the Internet World Stats site to

find out what percentage of the world's population has Internet access.

times referred to as Web 2.0.

i What role do social media play in the cloud era? Facebook. Twitter, and other social media turned the worry of social isolation on its

head; instead of computers decreasing human interaction, social media

encourage interpersonal communications and relationships. Social media are digitally mediated applications designed for communication, social inter action, and consumer-generated content.

Many factors influenced the popularity of these sites, but one important factor is their ease of use. Initially offered as Web sites, there was no soft ware to install and no updates to worry about. Getting started was as simple

as registering your name and creating a password. Now, access to social media is also available from mobile apps, which can be installed on a smartphone or tablet with a single touch. The connections that social media offer come at a price, and that price is

not just monetary. Today's digital citizens surrender a substantial amount of privacy, exposing information that can be used by predators. Privacy, or the lack of it, may be the defining challenge of cloud computing. Another challenge is the growing pervasive ness of advertising. Where social media was once a platform for exchanging infor mation between friends and colleagues,

FIGURE 12: THE UBER APP

.•vVifuon ITI

lltlDAH

UQER

intrusive advertising is now found on virtu ally every Web page, Facebook timeline,

JOSV/H.I'fjSSf

and Twitter stream.

I Cloud-enabled apps? A key char acteristic of the cloud computing era is globe-spanning sharing services. Cloudbased services such as Uber, Airbnb, and

Etsy are part of the sharing economy in which consumers offer goods and services to other consumers through a shared digital

0

c»

■ A..- ■

(,0. SET PICKUP LOCATION (7) C4'hecr»:cJ'.'

platform.

These sharing services use the cloud to communicate and process data. The apps

used by consumers may look simple {Figure 12), but behind the scenes an amazing amount of computer power handies the necessary data and logistics.

TO glc O KHCOUUAftiK

13

THE DIGITAL REVOLUTION

UBIQUITOUS COMPUTING As 2020 nears. a new phase of the digital revolution is taking shape. Ubiquitous computing is characterized by a focus on manipulating realworld objects instead of data. Earlier computing technologies used data to represent things in the real world. Photos represented people, fvlaps showed the location of places. Videos gave us a glimpse of events. Screenbased fantasy worlds and characters entertained us. But all of this was

conjured from data. None of it was tangible reality.

Virtual reality, augmented reality, the Internet of Things, and automated vehicles are shaping a new digital era in which technologies bring comput ing beyond the screen and into the world of tangible objects.

Terminology Ubiguicous computing is sometimes referred to as

pervasive computing. The

idea Is not new. In the 1990s, Mark Welser predicted that computers will "weave themselves into the fabric of

everyday life until they are indistinguishable from it."

► What is virtual reality? In the SfarTre/cseries, the starship Enterprise had a recreational facility called the holodeck. It was actually an empty room, but fictional "hard light" projectors created touchable and temporar ily solid objects to replicate indoor and outdoor spaces. The holodeck is a

futuristic version of virtual reality, the use of technology to create a simu lated three-dimensional world.

Today's virtual reality is far from a holodeck, but donning a virtual reality headset can give you the impression that you are in the middle of a three-

dimensional environment. You can look up and down and swivel your head to see your surroundings {Figure 13). FIGURE 13: VIRTUAL REALITY SIMULATES THE REAL WORLD

> How is augmented reality different than

virtual reality? Instead of creating a simulated world, augmented reality superimposes data over

the real world. Pok6mon GO popularized aug mented reality and provides a great example of how it works.

The reality of Pok6mon GO is the real world in

r

your vicinity. It can be shown on your smartphone screen as a map or as a pass-through image from the camera. Pokemon characters are superim posed on the landscape and can be seen through the camera lens. The characters are the augmen tation {Figure 14).

FIGURE 14: POK£MON GO IS AUGMENTED

REAL TV

INTRODUCTION

14

> What is the Internet of Things? The internet of Things (loT) con nects sensors embedded in machines, clothing, and other objects to the Internet, where they can report data and receive commands, it provides a

clear example of digital technology controlling objects In the real world. On a basic level, an loT device can report to a smartphone. Nest Protect is a smoke and carbon monoxide alarm that not only contains sensors but also contains circuitry that connects to a home Wi-Fi network. That WI-FI network can establish communication with a smartphone to report Its status

and accept commands. For example. If Nest Protect senses smoke when

you are away from home, it sends an alarm to your phone. The phone can be used to silence a false alarm—such as when your roommate burns a bagel In the toaster.

But the Internet of Things also connects multiple devices so that they can communicate with each other. The Nest Thermostat Is designed to control

a home's heating and cooling systems. These systems, when faulty, may

output dangerous carbon monoxide. Suppose the Nest Protect detects a high level of carbon monoxide. It can send a message to the thermostat to turn off the furnace (Figure 15). FIGURE 1S: THE INTERNET OF THINGS LINKS DEVICES WITH EMBEDDED SENSORS

Smoke detectors and thermostats send

signals to each other and connect to a

smartphone through a home network and the Internet.

I What about autonomous vehicles? Self-driving cars and robots are related to the Intemet of Things because they require sensor-equipped

FIGURE 16: AUTONOMOUS VEHICLES

EXEMPLIFY UBIQUITOUS COMPUTING

parts to communicate with each other. Autonomous vehicles, for example,

navigate without human Intervention using sensors to detect the surround ing environment, physical location, speed, and other parameters. They send data and receive commands from an onboard computer running sophisti cated artificial Intelligence software. Autonomous vehicles are clear examples of ubiquitous computing—the

use of digital technology to manipulate objects In the real world. Instead of abstract data. You'll delve Into some of these ubiquitous technologies In

future chapters. For now, try to guess the year In which you take your first ride in a self-driving car (Figure 16).

No

hands!

15

THE DIGITAL REVOLUTION

I Are there more changes to come? If we can learn one thing from the evolving information Age, it is this: Change is inevitable. Today, your favorite social media platform is Facebook; in the future, Facebook may go the way of CompuServe. Figure 17 summarizes changes through each era of the digital revolution. FIGURE 17: THE INFORMATION AGE EVOLVES

EXPIRED

TIRED

Data processing Big corporate and government computers

UNINSPIRED

Network computing

Cloud computing

Desktop computers

Laptop computers

Smartphones and

Autonomous

tablets

vehicles

applications

Cable and satellite

4G and Wi-Fi

Internet access

Internet access

ARPANET

AOL and CompuServe

The Web and email

Social media

Arcade games

20 action games

30 multiplayer

Touchscreen

games

microgames

Mouse

Touchscreen

Keyboard

Embedded apps

cloud-based apps

Dial-up Internet

Printer

Ubiquitous

Mobile apps and

Software suites

access

CB radios

ADMIRED

Personal computing

Standalone

Custom applications

DESIRED

• So what's the point? Learning about digital technology is not just about circuits and electronics, nor is it only about digital gadgets, such as computers and portable music players. Digital technology permeates the very core of modern life.

Internet of Things

Augmented reality

Virtual reality

Voice

QUICKCHECK According to Figure 17, AOL and CompuServe were popular when

Understanding how this technology works and thinking about its potential can help you comprehend many issues related to privacy, security,freedom of speech, and intellectual properly, it will help you become a better con

a. data processing was the main

sumer and give you insights into local and world events.

b. most people had dial-up

As you continue to read this textbook, don't lose sight of the big picture. On one level, you might be simply learning about how to use a computer and software in this course. On a more profound level, however, you are accumulating knowledge about how digital technology applies to broader cultural and legal issues that are certain to affect your life far into the future.

digital technology Internet access and used

desktop computers c. smartphones and tablets were introduced

d. people stopped using cioud computing

fNTRODUCTION

QUICKQUIZ 1.

2.

Data processing Is based on an

4.

Two major technologies that defined the network

-processing-output cycle.

computing era were the

In the personal computing phase of the digital

the Web.

revolution, data and software were stored on

devices, such as hard drives. 3. The idea that several technologies evolve into a

single device is called

5.

and

computing provides access

to information, applications, communications, and storage over the Internet.

Digital Content

Module Contents

I

SECTION A;

DIGITAL BASICS

Data Representation Basics Representing Numbers RepresentingText Bits and Bytes Compression SECTION B:

DIGITAL SOUND

Digital Audio Basics Digital Audio File Formats MIDI

So many aspects of life today are digital: music, photos, movies, news, and communications. How can all this

diverse "stuff" be accessed through one device, such as a laptop or an (Phone? It's all about digitization.

Digitized Speech SECTION C:

TRY IT! Apply what you learn.

BITMAP GRAPHICS

Bitmap Basics Bitmap Data Representation Image Compression Modifying Bitmap Images Panoramic and 360 images Stereoscopv

• Compress files containing various types of data, including text, photos, music, and videos. • Record audio files.

• Select an audio sampling rate and file format for high-

quality sound In files that won't use up all your storage space.

SECTION D:

• Convert audio files from one format to another.

VECTOR GRAPHICS

Vector Graphics Basics

• Use voice commands to control your digital devices.

Vector Tools

• Select the best file format for digital Images, such as

3D Graphics Vectors and Virtual Reality SECTION E:

DIGITAL VIDEO

Digital Video Basics Video Compression Video File Formats

Digital Video Variations

photos and scans, taking into account which formats reduce Image quality with lossy compression. • Convert a paper document into a digital file that can be edited using word processing software. • Work with RGB colors in decimal, hexadecimal, or binary notation.

• Use resolution to gauge the maximum size for an image.

• Use "photoshopping" techniques to enhance, colorize, ISSUE:

WHAT IS FAIR USE?

INFORMATION TOOLS:

clone, inpaint, clip, and merge photo Images.

• Capture 360-degree images on your smartphone. • Draw vector images for logos and infographics.

PHOTO FORENSICS

• Convert vector images into bitmaps. TECHNOLOGY IN CONTEXT: FILM

MODULEACTIVITIES LAB:

THE DIGITAL WORLD WITH EYES SHUT

• Render a 3D image from a wireframe. • Use video editing software to combine video footage with a soundtrack.

• Select output settings for a video,including aspect ratio, resolution, bit rate, compression level, and file format. • Transcode a video from one file format to another. • View vector and bitmap images in a VR headset.

16

Digital Content

C PRE-CHECK

Gauge your level of expertise. The answers are in the module.

6

((®))

How do you write it in binary?

A sound wave is digitized by

makes files smaller without

How do you write it in ASCII?

— its height thou sands of times per second.

any data loss?

§' Which type of compression

LOSSY LOSSLESS

List

FIVE

#EE82EE

bitmap

graphics formats: is the hexadecimal number for what color? BLACK

GREEN

What is the basic unit of sound

in speech synthesis?

VIOLET WHITE

\' /

f Bike.svg

List two popular video codecs:

Adding light and shadows is part of what process that creates an image from a wire

Bitmap or vector?

frame?

17

SECTION A, MODULE 1

Compression/ Extraction

Data Representation

Numenc

SECTION

Bits/Bytes

DIGITAL BASICS

TEXT, NUMBERS, MUSIC, VIDEOS,

Terminology

images, and speech; all of this "stuff" Is digital content. The amazing aspect of digital technol ogy is that it distills such diverse content into Os

data data representation digital data

and 1s and stores them as pulses of electricity. Understanding the data representation concepts

File file name extension file format

presented in Section A will help you grasp the essence of the digital world and get a handle on all the jargon pertaining to bits, bytes, megahertz,and gigabytes.

analog data binary digitization bit numeric data binary number system character data ASCII Extended ASCII Unicode UTF-8 ASCII text delimiter

OCR byte kilobit kilobyte megabit

megabyte gigabit gigabyte data compression lossless compression lossy compression

Objectives > List three technologies that digital devices use to physically store or transmit Is and Os. I Write the numbers 1 through 10 in binary.

t Decipher ASCII text. t Demonstrate how to use the terms bit, byte, megabyte, megabit, and gigabyte in the context of data storage and digital devices.

I Distinguish between data that would be

represented by binary numbers and data that would be represented by ASCII or Unicode.

I Explain how OCR relates to ASCII and Unicode. k Describe the difference between lossy and

lossless compression. I Demonstrate how to compress a file.

19

DIGITAL CONTENT

DATA REPRESENTATION BASICS Digital content, such as ebooks, documents, images, music, and video, is a compilation of data. Data refers to the symbols that represent people, events, things, and ideas. Data can be a name, a number, the colors In a

photograph, or the notes in a musical composition. ^ Is there a difference between data and information? In

everyday conversation, people use the terms data and information interchangeably. However, some technology professionals make a distinction between the two terms. They define data as the symbols that represent people, events, things, and ideas. Data becomes information when it is presented in a format that people can understand and use. As a general rule, remember that {technically speaking) data Is used by machines, such as computers; information is used by humans.

Terminology The word data can be correctly treated either as a plural noun or as an abstract mass noun, so the phrases "The data are being processed" and "The data

is being processed" are both correct usage, in this textbook,

I What is data representation? Data representation refers to the

the word data Is paired with

form in which data Is stored, processed, and transmitted. Devices such as smartphones, IPods, and computers store data in digital formats that can be handled by electronic circuitry. Today, digital data representation has

singular verbs and modifiers.

replaced the analog methods previously used for storing and transmitting photos, videos, and text.

> What's the difference between analog and digital? Digital data is text, numbers, graphics, sound, and video that have been con verted into discrete digits such as Os and 1s. In contrast, analog data is represented using an infinite scale of values. For a simple illustration of the difference between analog and digital, consider the way you can control the lights in a room using a traditional light switch or a dimmer switch. A dimmer switch has a rotating dial that controls a continuous range of brightness, it is, therefore, analog. A traditional light switch, on the other hand, has two discrete states: on and off. There are no in-between states, so this type of light switch is digital. A traditional light switch is also binary because there are only two possible slates. Technically, a digital device could represent data using more than

two states. Some of the earliest computers represented numbers using the decimal system. Today, however, most digital devices represent numbers and other data using the binary system.

QUiCKCHECK Which of the devices on the

left iifustrate analog data representation?

a. The speedometer and Vinyl record

YouTube

YouTube

b. The television and the vinyl

Television

record

c. All but the speedometer d. All but YouTube and the clock

LED ciock

Speedometer Film camera

SECTION A, MODULE 1

20

I How does digital data work? The process of converting informa tion, such as text, numbers, photos, or music, into digitai data that can be manipulated by eiectronic devices is called digitization.

imagine that you want to send a message by flashing a light. Your light switch offers two states: on and off. You can use sequences of ons and offs to represent various letters of the alphabet. To write down the representa tion for each letter, you can use Os and 1s. The Os represent the off slate of your light switch; the Is indicate the on state. For example, the sequence on on off off would be written as 1100, and you might decide that sequence represents the letter A. The Os and Is used to represent digital data are referred to as binary digits. It is from this term that we get the word b/f—binary digit. A bit is a 0 or 1 used in the digital representation of data.

Digital devices are electronic and so you can envision bits flowing within these devices as pulses of light. But digitai signals can take many forms, as shown in Figure 1-1. FIGURE 1-1: MANy WAYS TO REPRESENT DIGITAL DATA

ASCII codes

0

represent data as Os and 1s

1

110100010101010000

Circuit boards

carry data as pulses of current -2V0LTS

+5 +5 -.2 +5 -.2 -.2 -.2 +5 -.2 +5 -.2 +5 -.2 +5

CDs and DVDs store data as dark

and light spots

Disk drives store

data as magnetized particles

I How is digital data stored? Digital data is typically stored in files. A digital file, usually referred to simply as a file, is a named coilection of data that exists on a storage medium, such as a hard disk. CD. DVD, or flash drive. A file can contain data for a term paper. Web page, email message,or video, for example.

Every file has a unique name,such as Thriiler.mp3. Afile name extension,

such as .mp3, can be appended to the end of the file name after a period. This extension indicates the file format; the type of data in the file and the way it is encoded. Let's take a look at how numbers, text, images, sound, and video are encoded into digital formats that become computer files.

QUICKCHECK Digital devices work with bits in

all of the following ways except; a. voltage variations b. light and dark spots c. analog values d. orientation of magnetized particles

21

DIGITAL CONTENT

REPRESENTING NUMBERS Numeric data consists of numbers that can be used in arithmetic opera tions. For example, your annual income is numeric data, as is your age.That concept seems obvious, but some data that looks numeric is represented differently. Social Security numbers, telephone numbers, street numbers, and similar data are not represented by numeric data. These "numerals" are not considered numeric data because they are never used in mathemati cal calculations. This numeric quirk is a key concept in the digital world and turns up when you work with spreadsheets, databases, and computer pro gramming.

QUICKCHECK Which one of the following is considered numeric data?

a. Passport number 47756902231

b. Telephone number 906-222-3450

The S28.99S.00 cost of a car

> How do digital devices represent numbers? Digital devices rep

c.

resent numeric data using the binary number system, also called base 2. The binary number system has only two digits: 0 and 1. No numeral like 2 exists in this system, so the number "two" is represented in binary as 10 (pronounced "one zero"). You'll understand why if you think about what happens when you're counting from 1 to 10 in the familiar decimal system. After reaching 9, you run out of digits. For ten, you have to use the digits 10—zero is a placeholder and the 1 indicates one group of tens.

d. The address 22 E. Main Street

In binary, you just run out of digits sooner—right after you count to 1. To get to the next number, you use 0 as a placeholder and 1 indicates one group of twos. In binary, then, you count 0(zero), 1 (one), 10(one zero), instead of counting 0, 1, 2 in decimal. If you need to brush up on binary numbers, refer to Figure 1-2. FIGURE 1-2: BINARY EQUIVALENT OF DECIMAL NUMBERS

DECIMAL(BASE 10)

BINARY (BASE 2)

0

0

1

1

2

10

3

11

4

100

5

101

6

110

7

ill

8

1000

9

1001

10

1010

11

1011

1000

1111101000

The important point to understand is that the binary number system allows digital devices to represent virtually any number simply by using Os and Is. Digital devices can then perform calculations using these numbers. The

ability to perform rapid and accurate calculations was the key feature of the first computers, and it now provides the foundation for online banking, ecommerce, and many other number-crunching applications.

QUICKCHECK Figure 1-2 shows the binary equivalent for numbers 0 through 11 and 1000. What is the binary equivalent for the number 12? a.

10111

b. 1100 c.

10000

d. nil

SECTION A, MODULE 1

22

REPRESENTING TEXT Character data is composed of letters, symbols, and numerals that are not used in calcuiations. Examples of character data include your name, address, and hair color. Character data is commonly referred to as "text."

QUICKCHECK

I How do digital devices represent text? Digital devices employ

Write out Hi! in Extended ASCII

several types of codes to represent character data, including ASCII, Unicode, and their variants. ASCII(American Standard Code for Information Interchange, pronounced "ASK ee") requires seven bits for each charac ter, For example, the ASCII code for an uppercase A is 1000001. ASCII provides codes for 128 characters, including uppercase letters, lowercase letters, punctuation symbols, and numerals.

code.(Hint: Use an uppercase

H, but a lowercase /.)

H

Extended ASCII is a superset of ASCII that uses eight bits for each char acter. For example. Extended ASCII represents the uppercase letter A as 01000001. Using eight bits instead of seven bits ailows Extended ASCII to provide codes for 256 characters. The additional Extended ASCII charac ters include boxes and other graphical symbols. Unicode (pronounced "YOU ni code") uses sixteen bits and provides codes for 65,000 characters—a real bonus for representing the alphabets of mul tiple languages.

UTF-8 is a variable-length coding scheme that uses seven bits for common ASCII characters, but uses 16-blt Unicode as necessary.

Take a lookat the ASCII codes in Figure 1-3. Notice there is a code for the

space character in addition to codes for symbols, numerals, uppercase let ters, and lowercase letters. FIGURE1-3: ASCII CODES 00100000

Space

00110011

3

01000110

F

01011001

Y

01101100

00100001

I

00110100

4

01000111

c

01011010

z

01101101

m

00100010

"

00110101

5

01001000

H

01011011

(

01101110

n

00100011

n

00110110

6

01001001

1

01011100

\

01101111

0

00100100

$

00110111

7

01001010

J

01011101

)

01110000

p

A

01110001

q

01110010

r

01110011

s

00100101

%

00111000

8

01001011

K

01011110

00100110

&

00111001

9

01001100

L

01011111

t

00111010

00101000

(

00111011

00101001

)

00101010

•

00101011 00101100

'

01001101

M

01100000

t

01001110

N

01100001

a

01110100

t

00111100




01010001

Q

01100100

d

01110111

w

00111111

?

01010010

R

01100101

e

01111000

X

/

00101101

01000000

@

01010011

s

01100110

f

01111001

y

00101110

01000001

A

01010100

T

01100111

s

01111010

z

01000010

B

01010101

u

01101000

h

01111011

{

01000011

c

01010110

V

01101001

1

01111100

1 }

00100111

00101111

/

00110000 00110001

1

01000100

D

01010111

w

01101010

i

01111101

00110010

2

01000101

E

01011000

X

01101011

k

01111110

-

23

DIGITAL CONTENT

• Why are there ASCII codes for numbers? While glancing al the table of ASCII codes in Figure 1-3, you might have wondered why the table contains codes for 0, 1, 2. 3. and so on. Aren't these numbers represented

by the binary number system? Yes, the binary number system is used for representing numeric data, but these ASCii codes are used for numerais,

such as Sociai Security numbers and phone numbers that are not used for caiculations. For example, 475-6677 is a phone number; it is not a formula

QUICKCHECK If your address Is 10 B Street, what are the first three bytes in ASCII?

that means subtract 6677 from 475. a.

00110001 OOllOOOO 01000010

> Where is digital text used? Digital text is everywhere. It is the foun dation for ail kinds of digital documents, Web sites, social media sites, games, and email. It Is also the basis for ebooks designed for Kindies and

b- 00110001 OOllOOOO 00100000 c.

OOllOOOl 00110111 00100000

other ebook readers.

Documents produced on a digital device are stored as a string of Is and Os encoded as ASCII, Unicode, or UTF-8. Some kinds of documents stmpiy contain this piain text, whereas other documents contain formatting codes to produce boid fonts, columns, and other effects.

► What is plain text? Piain. unformatted text is sometimes caiied ASCII text and is stored in a so-cailed "text fiie" with a name ending in .txt. On Appie devices, these flies are labeled "Plain Text." In Windows, these files are labeled "Text Document," like this;

RollerCoasters.txt

Text Document

2 KB

ASCII text files can be created with text editors, such as TextEdit and

Notepad. They are typically used for writing computer programs because

executable program code cannot include formatting such as underlining and special fonts. They can also be used for creating Web pages. Text files can usually be opened by any word processing software regard less of the type of device, in that sense, they are universal. Figure 1-4 illustrates an ASCII text file and the actual binary code that is stored for it. FIGURE 1-4; ASCII TEXT FILES CONTAIN NO FORMATTING CODES 01010010 01101111 01101100 01101100 01100101 01110010 OOlOOOOO

OlC^Oll 01101111 01100001 01110011 01110100 01100101 01110010 oiimSff WTTOWft^lOlOlll

01101000 01101111 OOlOOOOO 01110111

01100001 01101110

1110100 01110011 OOlOOOOO 01110100 oiionii

00100000 01110011

1100001 01110110 01100101 OOlOOOOO 01100001

01101110 OOlOOOOO

iioini 01101100 01100100 ooiooooo oinooio

OllCllll 01101100

iioiio,ojijpoioi.oii.iooip.ogiooo.eojU2Qp.u

01101111 01100001

1110' .■? umiiiefl - No»Ma

00100000 01001100

1100

01101000 OllOOIOl

n^^oller Coasters Uho wants to save an old roller

-

□

X

Edrf Foimft Vim hHp

QUICKCHECK

00100000

01101001011101 coaster? Leap-the-Oips is the world's oldest

00100000

01110111 01101'""Oiler coaster and, according to a spokesperson

What ii tlie seventh byte in the

00100111

01110011 OOlOO'

Roller Coasters file?

01110011

01110100 OOlOOC®"®

01100101

01110010 OOIOOF^" "-eap-the-Dips is "the sole survivor of 01100101 OiiiQr® technology that was represented in OOlOOOOO onoo.""^® ithe early years of the amusement industry.

01110100 00101100

01100100 01101001 OllOl;

Leap-the-Dips Preservation Foundation,

historically significant. Built

a. Uppercase C (01000011) b. Lowercase c (01100011) c. Space (OOlOOOOO) d. Carriage return (OOOOllOl)

r

SECTION A, MODULE 1

24

> How does formatting get added to documents? ASCII text files contain no formatting. They have no bold, italics, underlining, or font colors. There are no margins, columns, bullets, headers, or page numbers.

Suppose you want the title of the Roller Coasters document to be centered and shown in a large, bold font, like this: y

• O 4* > twun

T

«:ds ra wciS

«'Mit LAnrc'T

u.ciii«^/S

» -

n

X

cjv.rw

Roller Coasters Who ¥fOf>ts to savo on oW rofltr eooittr? Le«p-th«*Oips is the world's oldest roitef eoister srtd,

accerdiOB to a spokesperson for the Leap-the-Dips Preservation foundation^ one of the most historically

signiflcarTt. SuHt In 1902. Leap*the*Dlps Is 'the sole survivor of a style and technolo|v that was represented in more then 2S0 parks In North America slone In the early years of the amusement industry.'

To create documents with styles and formats, formatting codes have to be embedded in the text. There are many techniques for doing so, and each

one produces a unique file format. These formats can be opened by the software that produced them. Opening those files with other kinds of soft ware requires conversion.

Microsoft Word produces formatted text and creates documents in DOCX format, whereas Apple Pages produces documents in PAGES format. Adobe Acrobat produces documents in PDF format- The HTML markup lan

guage used for Web pages produces documents in HTML format. Ebooks

Terminology

are created using the EPUB format.

A delimiter is a special character

Formatting codes can be added to documents directly within the text

used to separate commands or formatting characters from the

stream, using some sort of delimiter to signal the beginning and end of the formatting command. When the document is displayed, the formatting

rest of the text in a file. Slashes

codes are hidden. What do those hidden codes look like? Figure 1-5 gives

// and angle brackets < > are commonly used delimiters.

you a behind-the-scenes look at the Roller Coasters document with all the embedded formatting codes revealed. FIGURE 1-5: FORMATTING COOES WITHIN A DOCUMENT

Here is the document

Coasters.DOCX

title. The formatting codes that make it bold

xmlns;wps-'http://s are delimited by < and

fice/word/2010/wordprocessingShape" mc:lgnorable="w14

w15 wp14"> angle brackets.

49" w:rsidRPr="003E2449" w;rsldRDefault="003

E2449">Who wants to save an old roller coaster? Leap-

the-Dlps is the world's oldest roller coaster and. according to a spokesperson for the Leap-the-Dips Preservation Foundation, one of the most historically significant. Built in 1902, Leap-the-Dips is "the sole survivor of a style and technology that was represented in more than 250 parks in North America alone in the earty years of the amusement industry."

25

DIGITAL CONTENT

I What happens when I scan a document? When using a scanner to digitize a document, you may have a choice between graphics formats and OCR- Graphics formats, presented later in the module, essentially cap ture a photo of the document. Individual letters and punctuation marks are not encoded as ASCII. A document scanned into a graphics format cannot be edited using a word processor.

OCR (optical character recognition) is a process that interprets individual characters during or after a scan. It assigns the appropriate ASCII code to each letter and outputs the document in a format that can be edited using word processing software. OCR software is available for most scanners and is handy when you have a printed copy of a document that you want to

modify, but would prefer not to retype.

QUICKCHECK Which one of the following would most likely require OCR?

a. A two-page bibliography of award-winning books from 1945 that you would like to annotate

b. An excerpt from a magazine article that you want to

include in a term paper c. A football poster containing the home game schedule

BITS AND BYTES

All of the data stored and transmitted by digital devices is encoded as bits. Terminology related to bits and bytes is extensively used to describe stor age capacity and network access speed. As a digital-goods consumer, you'll want to have this terminology handy.

d. A page from a handwritten diary that you want to include in a historical

biography

• What is the difference between bits and bytes? Even though the word bit is an abbreviation for binary digit, it can be further abbreviated,

usualiy as a lowercase b. A group of eight bits is called a byte and is usually TRY IT!

abbreviated as an uppercase 6. Transmission speeds are expressed in bits, whereas storage space is expressed in bytes. For example,a cable Internet connection might transfer

data from the Internet to your computer at 50 megabits per second. In an iPad ad, you might notice that it can store up to 60 gigabytes of music and video.

Scan a one-page document using a scanner or a multifunction

printer. The default format for

the scan is probably a JPEG or

PNG graphic. Try using your scanner's OCR feature or a free

• What do the prefixes kilo-, mega-, giga-, and tera- mean?

online OCR service to convert

When reading about digital devices, you'll frequently encounter references such as 90 kilobits per second, 1.44 megabytes, 2.4 gigahertz, and 2 tera

the scan into a document

bytes. Kilo, mega, giga, tera, and similar terms are used to quantify digital

that can be edited using word processing software.

data as shown in Figure 1-6. FIGURE 1-6: DIGITAL QUANTITIES Bit

One binary digit

Gigabit

Byte

8 bits

Gigabyte 2^0 bytes

Kilobit

1,024 or 2^0 bits

Terabyte 2^0 bytes

Kilobyte

1,024 or 2^f bytes

Petabyte 2^0 bytes

Megabit

1,048,576 or 220 bits

Exabyte

2^0 bits

2®0 bytes

Megabyte 1,048,576 or 2^'^ bytes

Terminology What's a kibibytel Some computer scientists have

proposed alternative terminology to dispel the ambiguity in terms such as kilo that can mean 1,000 or 1,024. They suggest the

I Why such odd numbers? In common usage, kilo, abbreviated as K,

following prefixes:

means a thousand. For example. $50K means $50,000. In the context of

Kibi = 1,024

computers, however, 50K means 51,200. Why the difference? In the deci mal number system we use on a daily basis, the number 1,000 is 10 to the

Mebi = 1,048,576

third power, or 10^. For digital devices where base 2 is the norm, a kilo is precisely 1,024, or 2^^. Mega is derived from 22" and giga from 23°.

Gibi = 1,073,741,824

26

SECTION A, MODULE 1

I When do I use bits and when do I use bytes? As a general rule, use bits for data rates, such as Internet connection speeds and movie

download speeds. Use bytes for file sizes and storage capacities. Figure 1-7 provides some examples. FIGURE 1-7: BITS OR BYTES?

ZT"

c II

104 KB

50 Mbps

Kilobit {Kb or Kbit) can

56 Kbps

Kilobyte (KB or Kbyte)

Megabit(Mb or Mbit)

be used for slow data

is often used when

is used for faster

rates, such as a 56 Kbps (kilobits per second)

referring to the size of small computer files.

data rates, such as a 50 Mbps (megabits

per second) Internet

dial-up connection.

connection.

QUICKCHECK My iPhone has 8.

of

storage space; i uploaded

a high-resolution 8graphic; and I am going to download a small 8 file. a. GB, MB, Mbps 100 Gbit

16GB

Gigabit (Gb or Gbit) is used for really fast network speeds.

Gigabyte(GB or GByte)

3.2 MB

Megabyte (MB or MByte) is typically used when referring to the size of files containing

is commonly used to refer to storage capacity.

b. MB, GB, KB c. GB, MB, KB d. Mbps, MB, G8

photos and videos.

COMPRESSION All those 1s and Os can quickly expand the size of digital files. Whereas

an "A" is simply one character in a printed document, it requires seven bits when represented as ASCII and sixteen bits when represented as Unicode. That "1" in "1st place" seems like it could be represented by a simple 1 bit, but it requires multiple bits when encoded- Numeric data also requires lots of bits. The number 10 is 1010 in binary and requires four bits. To reduce file size and transmission times, digital data can be compressed.

Data compression refers to any technique that recedes the data in a file so that it contains fewer bits. Compression is commonly referred to as "zip

ping." Many compression techniques exist. They can be divided into two categories; lossless and iossy.

> What is the difference between lossless and lossy compression? Lossless compression provides a way to compress data and reconsti

tute it into its original state. Character data and numeric data in documents and spreadsheets are compressed using lossless techniques so that the uncompressed data is exactly the same as the original data.

Lossy compression throws away some of the original data during the

compression process. After the data is uncompressed, it is not exactly the same as the original. This type of compression is lypicaliy used for music,

images, and videos because the human ear or eye cannot discern minor changes. Later in the module, you'll learn more about the compression techniques used to shrink the size of music, image, and video files.

QUICKCHECK Which one of the following

requires lossless compression? a. A very large document that

you intend to send as an email attachment

b. A photo of your class reunion that you intend to

post on your Facefaook page c. An ITunes track saved to

your iPod that you want to back up on your computer

27

DIGITAL CONTENT

I How do I compress data? The software for compressing data is sometimes referred to as a compression utility or a zip tool. Most computers

include software for compressing data, but tablets and smartphones may require a third-party app for working with compressed data. On laptops and desktop computers, the compression utility is accessed from the same screen used to manage files. You can compress the data in a single file or you can combine multiple fifes to create a single zipped file that is reconstituted to the original files when unzipped (Figure 1-8).

TRY IT!

Experiment with compressing files to see how much they

shrink. Try compressing a document, then try a graphic.

FIGURE 1-e: COMPRESSING FILES I • nn««r

IM

Edi

V>r-

Cd

fooer wii

2. Select one or

$*»

more files, then

right-click

K2*5

5* 8ooLMuS< *»


a single small file

^ 0 fiJuetcxiCh devue ' I Ccfltgmaa aiopgg

b. enlarge a file to increase its resolution

lA Oocunvnci

c. zip a single file to decrease Its

M^reoeM

4^ 05 CO lO'lems

isia

■ Omie^ (crMTF meivut)

« Oo«tVO«K

A

iLV'st o

f *< g sc«.

ft Oetiisee

> MiAie

Compression uiiiiues can be

3. Select th ese options

R«5ejrcn mc90

''."f—

size

{0}

PE4pcn>n gn IS

d. extract a file to Its original size and content

Compressing files using File Explorer on a PC

SECTION A, MODUIE 1

> How do 1 return files to their uncompressed state? The process of reconstituting files is called extracting or unzipping. As with compression, most laptops and desktop computers include extraction and unzipping soft ware; tablets and smarlphones may require a third-party app. Compressed files usually have .zip at the end of the file name and are rep resented with specialty icons. Compressed files may also end with .gz, .pkg, or .tar.gz. These files have to be extracted or unzipped before you can

view the data they contain. The process is easy. To extract a file on a Mac, simply double-click the zipped folder. With Windows (Figure 1-9), use the Compressed Folder Tools or Extract All option. FIGURE 1-9; EXTRACTING FILES IN WINDOWS »c™tr»n«3 »CIj Which audio formats are most popular? Digital audio is stored in a variety of file formats. The table in Figure 1-12 provides an overview of the most popular digital audio formats, which Include AAC, MRS, Ogg

Make a short audio recording

using your favorite digital device. What are the default

file format and sampling

rate? if you record at a higher sampling rate, can you tell the difference in sound quality?

Vorbis, WAV, Fl-AC, and WflflA. FIGURE 1-12; POPULAR AUDIO FILE FORMATS

AUDIO FORMAT

EXTENSION

AAC (Advanced Audio Coding)

,aac, .m4p, or

.mp4

MP3 (also called MPEG-1 Layers)

.mp3

Ogg Vorbis

-ogg

ADVANTAGES

DISADVANTAGES

Very good sound quality based on

Files can be copy protected

MPEG-4; lossy compression; used

so that use Is limited to

for itunes music

approved devices

Good sound quality; lossy compres

Might require a standalone player or browser plugln

sion; can be streamed over the Web Free, open standard; lossy compres sion; supported by some browsers

Slow to catch on as a

popular standard; part of Google's WebM format Audio data is stored In raw,

WAV

,wav

Good sound quality; supported in browsers without a plugln

FLAG (Free Lossless Audio Compression)

.flac

Excellent sound quality; lossless compression

Open source format sup ported by many devices

WMA (Windows Media Audio)

Lossy or lossless compression; very

Files can be copy protected;

.wma

good sound quality; used on several

requires an add-on player

music download sites

for some devices

noncompressed format, so files are very large

33

DIGITAL CONTENT

> What are the best sources for digital music? There are several options for obtaining audio content,such as music, soundtracks, narrations, and sound effects.

TRY iTl

Live recording is an option for obtaining digitai sound fiies from concerts or lectures. For casual recording. Voice Memos and similar apps work well. Professional recordings require more sophisticated software and hardware tools. A device called an audio interface accepts input from a standalone microphone and feeds it into a computer. Ripping CD tracks is handy for someone who inherits a stack of old CDs and wants to convert the music into a format that plays on a smartphone or other mobile device. Ripping is a siang term that refers to the process of importing tracks from a CD or DVD to your computer's hard disk. The tech nical term for ripping music tracks is digital audio extraction.

find the names of two live

streaming music services and the names of two on-demand

streaming services.

QUiCKCHECK You've selected a music track

Downloading is popular for saving audio fiies on local devices. A down load copies a file from a private network or Internet server to a local device. The file is transferred as an unit and cannot be played until the entire file

on your smartphone, but there is a pause before it begins. This pause is associated with

has arrived.

Streaming offers yet another way of obtaining audio content. Unlike some

digitai content, such as photos, that must be accessed as a whole piece, audio content plays back over a period of time. Audio files can be acquired as a live stream or on-demand stream In addition to downloads (Figure

a. downloading audio tracks b. live streaming audio

c. on-demand streaming

1-13). FIGURE 1-13: DOWNLOADING AND STREAMING

0

Live stream A live stream sends media from a

Download A download transfers an audio file

from a server to your local device. You can play back the file even

server to your local device, where

4'V On-demand stream

it is played, but not stored.

An on-demand stream sends the

This method is also known as

media to your local device, where it is stored temporarily, or "buffered,"

Webcasting.

until there is enough data to begin

when your device is not online.

You have to be online while listen

The file can be played with any

ing.

compatible software or player.

The content stream cannot be

You can fast-forward to any point in the stream without waiting for the

paused, stored, or rewound.

entire file to download.

playback.

34

SECTION 6, MODULE 1

I What type of software is required to work with digital audio files? To play a digital audio file, you must use some type of audio software. Whether you can use general-purpose audio software, a speciai-purpose player, or a browser plugin depends on the source and type of audio. Audio piayers. An audio piayer is a smaii standalone software appiication or mobile app that offers loois for iistening to digitai audio and managing

QUICKCHECK The term lifjping epplfes to: a. converting CD tracks to formats such as MP3 and AAC

playlists. but may not provide toois for making your own recordings. Audio

piayers might be inciuded with your computer's operating system, pack

b. downioading MP3 files

aged with your sound card, instaiied in a handheld device, or available as a download.

Audio piugins. An audio plugin is software that works in conjunction with your computer's browser to manage and play audio that you are

illegally from the Internet

c. compressing AAC files with digitai audio extraction

accessing from a Web page. Each audio plugin tends to work with only

one audio format, so multiple piugins are necessary when you have audio files in several formats.

Audio software. General-purpose audio software and apps provide toois

for recording, playing, and modifying audio files. Popular audio software includes ITunes, Windows Media Piayer, and Audacity (Figure 1-14). FIGURE M4:AUDACITY AUDIO SOFTWARE A

W

Wrw

Ttanaport

Ttacn

AjWjtt

Wieoow

Hito

Srafifrnltfi Q ft -5

J

•'>

0-4»II

o

j2_' ® A CtntM 044 •M

.n

0

'o

'

^

BuO-n MkmC 0 2 iSMiWl U

W

44

IM

1.11

0

U0 14$ im

HM

Clip out sec tions of a track to remix

Tools for record

ing and playback.

X4I iM

Work with more than one track for stereo and

mixing

fUl

w« What's the difference between speech synthesis and speech recognition? Speech synthesis is the process by which machines pro duce sound that resembles spoken words. Speech recognition (or voice

recognition) refers to the ability of a machine to understand spoken words.

> How does speech synthesis work? A basic sound unit, such as "reh' or "gay," is called a phoneme. Most speech synthesizers string together phonemes to form words. For example, the phonemes "reh" and "gay" produce the word "reggae." Phonemes are usually derived from recordings of human voices reading specially prepared passages of text. Text-to-speech software analyzes the words in a section of text, finds corresponding phonemes, and combines them into sentences for output.

QUICKCHECK Which one of the follovwing requires digitnl-to-nnnlog conversion?

a. Speech synthesis b. Speech recognition

c. Entering a Google Voice command

d. Voice dialing

I How does speech recognition work? On a personal computer or smartphone, a speech recognition system collects words spoken into a microphone that's connected to sound processing circuitry. This circuitry's analog-to-digital converter transforms the analog sound of your voice into digital data. This data is then processed by speech recognition software. Speech recognition software analyzes the sounds of your voice and con verts each word into groups of phonemes. Next, the software compares the groups of phonemes to the words in a digital dictionary that lists pho neme combinations along with their corresponding English (or French, Spanish, and so on) words. When a match is found, the software can dis play the word on the screen or use it to carry out a command. Most digital devices offer a way to use spoken commands (Figure 1-16). FIGURE 1-16: MICROSOFT CORTANA SPEECH RECOGNITION

TRY IT!

1. Open the Windows Speech Recognition application. Mst mjtch

U

windCMsSpMchRMogmtion

if vou have a laptop with Windows 10, it includes 2. After following the setup instructions, the Listening Mode con trol appears. Ctrl+the Windows key turns it

a comprehensive speech recognition system called

on. Saying "stop listen

apps, navigate menus, and dictate text for email messages

Ing" turns it off. Snipping Tool

0 Sellir>gs Q Sicyp« vi^ □ Store

O SpCNU Settings Web

Cortana. Try it out. Vou can

speak commands to launch

and documents.

37

DIGITAL CONTENT

I How does Siri work? Devices of the Speak & Spell generation had robotic voices and were not responsive to a wide variety of commartds and queries. What makes modem technologies like Siri so much more versatile and lifelike? Figure 1-17 provides an overview. FIGURE 1-17: HOW SIRI WORKS

TRY IT

Are you wondering what a Speak 6c Spell is? Go to YouTube and search for "Speak & Spell" to see a demonstration.

-It is located near a busy street

•«|

located

"one two buckle , , my shoe" ittches

The voices of Siri were created by live actors, but they couldn't record every possible response to user queries.

Instead they recorded the words and sentences from a script. Although the script may appear nonsensical, the sen tences are rich in phonemes.

When the recordings are complete, a team of linguists analyzes and tags various speech components and loads them into a database. The process Is called concatenative speech synthesis.

Where is ttie nearest Starbucks?

Q.

3. Search algorithms look for an answer to the query, then 1. Queries are encoded

s£

into digital audio, relayed to a nearby cell tower, and

access the speech database to assemble a response.

forwarded to an Apple

2. Apple's voice recognition

server.

•=1)0101

►«c|HO)I 001100^

system identifies words and

located

T

looks for patterns similar to common queries.

SECTION B

QUICKQUIZ 1.

2.

3.

rate refers to the number

4.

files store a series of

of times per second that a sound is measured

instructions that specify which notes to play,

during the recording process.

their duration, and their volume.

Audio formats such as fvlPS, Ogg Vorbis, and

5.

The audio components for Siri and similar ser

AAC have good sound quality even though

vices are obtained by recording real voices

they use

and then applying 1

compression.

The process of ripping tracks from an audio CD to a digital format such as MP3 is called digital audio

synthesis.

I speech

38

SECTION C, MODULE 1

Bitmap Graphics Digitize

Image Compression

Color Models

WEQgS

SECTION

BITMAP GRAPHICS iT^rai^'^TP

IMAGES ARE EVERYWHERE.Photos

Terminology

plaster Pinterest boards like so many posters on a Paris kiosk. Facebook feeds offer a continu

ous stream of vacation pics. Colorful icons dot the screens of every digital device. Infographlcs use images to convey information, and Web sites would be much less interesting if not for the col

orful graphics they display. Section C explains the technology that powers this polnt-and-shoot world to help you harness the power of digital graphics.

cuinputer grnphlcs still images motion graphics

bitmap graphic pixel scanner CCD

photosites BMP RAW TIFF JPEG GIF PNG RGB color model color depth TrueColor

image resolution resolutloD dependent pixelation pixel interpolation image compression

run-length encoding Image histogram

cloning Inpalnting digital compositing clipping path alpha blending image stitching stereoscopic imaging stereo pair stereogram anaglyph

Objectives I Describe the differences between bitmap and vector graphics file formats.

I Describe how cameras and scanners produce

I Explain how pixel color is represented in

I Explain how 3D images are created.

decimal, hexadecimal, and binary. I Calculate the size of a bitmap file given its resolution.

t Decide which graphics format to use for school,

digital Images.

t Describe the RGB and CMYK color models.

I Explain what a color histogram represents and how to use one.

I Provide examples of image stitching.

work,or personal projects. I Describe two types of stereoscopic imaging. i List six popular bitmap file formats.

39

DIGITAL CONTENT

BITMAP BASICS As digital devices gained the ability to display images, two types of com puter graphics evolved: bitmap and vector. These graphics can produce still Images, such as photographs and diagrams, or motion graphics,

Terminology The term 3D is used today to

refer to a variety of commercial products that should be called stereoscopic. For example, those so-called "30" glasses

such as videos and animations.

Computer graphics can produce two-dimensional flat images and stereo scopic images with visual depth that makes close-up objects appear near

with blue and red lenses are

enough to grasp.

technically stereoscopic, not 3D.

Despite their similarities, bitmap and vector images are quite different. Bitmap graphics may be the most common, but they are less flexible than vector graphics and cannot be used to model three-dimensional objects. To find out why, let's take a look at the characteristics of bitmaps.

As you continue in this module, pay attention to the difference

between 3D and stereoscopic.

I What is a bitmap graphic? A bitmap graphic, also called a ras ter graphic or simply a bitmap, is composed of a grid of tiny rectangular cells. Each cell is a picture element, commonly called a pixel. Each pixel is assigned a color, which is stored as a binary number. Figure 1-18 illustrates these basic characteristics of a bitmap graphic. FIGURE 1-18: BITrvlAP GRAPHICS ARE PIXEL BASED

One gray pixel stored as lOOlOllOlOOlOllOlOOlOllO

r ■ ■■■■IBM

Bu--csaBBBaa

»mmumc"r ■■■■■■ •■BaiLj

BBBBBIBB BBBBBBB^n rmmmmum-a rBBBBBB i LBBIBB. . I■■IBBU

> Where would I encounter bitmap graphics? Bitmap graph ics are used to create realistic images, such as photographs. You might also encounter bitmaps in the form of cartoons, images that appear in computer games, the desktop images displayed by your computer or smartphone, and photorealistic images derived from 3D graphical

QUICKCHECK Bitmap graphics are based on: a. codecs

objects.

When you use a digital camera or camera-enabled ceil phone, your pho tos are stored as bitmaps. A scanner also produces bitmaps. The photos you send or receive as email attachments are bitmaps, as are most Web page graphics.

b. pixels c.

rasters

d. vectors

40

SECTION C, MODULE

I How do I create bitmap images? You can create a bitmap graphic from scratch using the tools provided by graphics software—specifically a category of graphics software referred to as paint software. You might be familiar with paint software such as Adobe Photoshop, Apple Photos {included with Apple computers), and Microsoft Paint (included with Windows). Other alternatives, such as AutoDesk Pixir, are available online and as downloads for smartphones and laptops.

• How do I convert a printed image into a bitmap? When you have a printed image, such as a photograph, a page from a magazine, or a picture from a book, you can use a scanner to convert the printed image into a bitmap graphic.

TRY IT!

Check the features of the photo

app on your smartphone. Which of the following does it provide? Retouch

Crop Special effects

Exposure adjustment

A scanner essentially divides an image into a fine grid of cells and assigns a digital value for the color of each cell. As the scan progresses, these values are transferred to your digital device and stored as a bitmap graphics file. Scanners, such as the one pictured in Figure 1-19, are inexpensive and easy to use. FIGURE 1-19; SCAN IMAGES

To scan an image, turn on the scanner and start your scanner software. Place the image face down on the scanner

glass, then use the scanner software to initiate the scan. The scanned image

is saved in memory and can then be

saved on your computer's hard disk or in another storage location.

> How does a digital camera capture bitmap images? The lens

FIGURE 1-20: CAMERA CAPTURE

camera, the lens focuses light from the image onto a small image sensor

A digital camera's CCD converts the image captured by the camera lens into a grid of col ored pixels, which are stored

called a CCD (charge-coupled device). This technology is used in stand

as bits.

of a film camera captures the light from an image onto a light-sensitive roll of film, which is developed to produce a photographic print. In a digital

alone digital cameras and smartphone cameras. A CCD contains a grid of liny light-sensitive diodes called photosites. The number of photosites depends on the size of the CCD. A one-half-inch square CCD can contain more than 500,000 photosites. Each photosite detects the brightness and color for its tiny piece of the image (Figure 1-20). A CCD's photosites correspond to pixels. The more pixels used to capture an image, the higher its resolution, and the better the resulting picture. Cameras with larger CCDs produce higher quality images. Some cam eras contain multiple CCDs, which enhance the color quality of a camera's output.

TTfi

fviiNausv.

i .]

/'

41

DIGITAL CONTENT

► What are the most common bitmap file formats? Cameras, scanners, and graphics software may offer a choice of bitmap formats, such

as BMP, RAW, TiFF, JPEG, GIF, and PNG. Seiecting the best graphics file format to use depends on what you intend to do with the image. Figure 1-21 summarizes popuiar bitmap formats and their uses. FIGURE 1-21: BITMAP FORMATS

BITMAP FORMAT

BMP. pronounced "bee-em-pee" or "bump," is the native bitmap graphics file format of the Microsoft Windows environment- Microsoft Paint, Included as part of Microsoft Windows, creates BMP graphics files. The BMP format supports True Color and can be used for a wide variety of graphics applications, such as photographs, illustrations, and graphs. BMP files are often too large for email attach ments. BMP graphics are not supported by most browsers, so they are not used on the Web. RAW Image formats contain the unprocessed pixel data

Graphical elements, such as buttons and other controls for

graphical user inter faces

generated directly by a digital camera's sensor. Up to

Photographic images before they are stored

12 bits of data can be storedfor eachof the red, blue,

in other formats

and green values for a pixel, so RAW files are very large. Cameras that offer a RAW format also supply proprietary software to convert RAW data to JPEG or TIFF.

TIFF (Tagged Image File Format), or TIF, is a flexible and

platform-Independent graphics file format supported by most photoediting software packages. Scanners and digital cameras commonly store bitmaps in TIFF format because ft supports True Color and can be easily converted Into other graphics file formats.

JPEG (pronounced "JAY-peg"). which stands for Joint Photographic Experts Group, is a graphics format with built-in compression that stores True Color bitmap data very efficiently In a small file. The JPEG format Is popular for Web graphics, smartphone photos, and for photos

Desktop publishing and any projects that require highresolution graphics; not supported by browsers

General use, such as desktop publishing or Web pages, where flexibility In file size Is Important

attached to email messages. When creating a JPEG or con verting an Image to JPEG format, you can control the level

of compression and the resulting file size. The compression

process eliminates some image data, however, so highly compressed fries suffer some quality deterioration. GIF (Graphics Interchange Format), pronounced "gif" or "jiff," was specifically designed to create Images that can be

Web graphics and simple animations

displayed on multiple platforms, such as PCs and Macs. GIF

graphics are limited to 256 colors, but the format supports simple animations. Once a popular format for Web pages, GIF is being replaced by JPEG and PNG. PNG (Portable Network Graphics), pronounced "ping," is a graphics format designed to Improve on the GIF format. A

PNG graphic can display up to 48-blt True Color (trillions of colors). Unlike JPEG, PNG compresses bitmap files without losing any data, so compressed Images retain the same high quality as the originals. PNG was developed as a public domain format without any restrictions on its use.

Web graphics and other general uses

42

SECTION C. MODULE 1

BITMAP DATA REPRESENTATION

The fad that bitmap images are formed by a grid of pixels controls not only how those images are stored, but also how they can be modified. Color and resolution are key elements in bitmap data representation.

> How does each pixel get a color number? Today's color display devices represent color using the RGB color model. The color displayed for a pixel Is based on the Intensity of red, green, and blue signals received by the screen's color elements. Each red. green, and blue signal is assigned a value ranging from 0 to 255: 0 represents the absence of color, and 255 represents the highest intensity level for that color. A pixel appears while if the red, green, and blue signals are set to maximum intensity. If red, green, and blue signals are equal but at a lower intensity, the pixel displays a shade of gray. A pixel appears violet if it receives high red and blue signals andjust a bit of green (Figure 1-22).

Terminology The CMYK color mode! defines

four color values: cyan, magenta, yellow, and black. It is a subtractive system, whereas RGB is an additive system. In

CMYK, white is 00000000; but in RGB, 11111111 is white.

CMYK is typically used for

projects that require color printing.

FIGURE 1-22: RGB COLOR

White Red Green Blue 255

255

255

Violet Red 238

Green Blue 130

238

#FFFFFF

#EE82EE

111111111111111111111111

111011101000001011101110

Look at the center where the circles intersect to see the color that is gen erated. Color numbers are shown in decimal, hexadecimal, and binary.

I How are colors specified? Color values can be specified in decimal

(base 10), hexadecimal (base 16), or binary (base 2). Even artists need to know their way around number systems! Decimal notation tends to be used

QUICKCHECK

within graphics software, and hexadecimal(hex) notation is common on the

To represent the color violet In

Web. Whichever notation is used, however, color data is ultimately repre

sented as binary digits when it is stored and transmitted.

Figure 1-22, the decimal value for green is 130. What are the

In decimal, a pixel color is specified with values such as Red 238, Green

equivalent hexadecimal and binary values for green?

130, and Blue 238. In hexadecimal, each pair of digits refers to a color value. For example, the hexadecimal number for violet is #EE82EE. That

a, 82 and 10000010

means Ee(hex)= 238 Red,82(hex)= 130 Green, and EE(hex)= 238 Blue. You can find lists of colors and their hexadecimal triplets on the Web. In

binary, eight bits are used to represent the red value, another eight bits are used for the green value, and eight more bits are used for blue.

i How much data is required for each pixel color? With eight bits used to represent each color value, one pixel requires 24 bits. Because each R, G, and B can have 256 values, the number of possible colors is

16.7 million (256 x 256 x 256). The number of colors available in a graphic is referred to as color depth, images that use 24 bits for each pixel have a color depth of 24. 24-bit coior depth is also called True Color.

b, 255 and 11111111 c, EE and 11101110

43

DIGITAL CONTENT

The dimensions of the grid that forms a bitmap graphic are referred to as image resolution. The resolution of a bitmap is usually expressed as the number of horizontal and vertical pixels it contains. For example, a small FIGURE 1-23: PIXELATION

graphic for a Web page might have a resolution of 150 x 100 pixels—150

The enlargement of this bal loon appears pixelated because it was a small part of a photo that had few pixels.

pixels across and 100 pixels high.

I How does resolution relate to image quality? High-resolution graphics contain more data than low-resolution graphics. With more data,

it is possible to display and print high-quality images that are sharper and clearer than images produced using less data.

► Can I shrink and enlarge bitmaps? Bitmap graphics are resolution dependent because each element is a discrete pixel. Imagine that a bitmap image and its grid come on a surface that you can stretch or shrink. As you stretch the surface, the grid maintains the same number of horizontal and vertical cells, but each cell becomes larger, the grid becomes more visible, and the image develops an undesirable jagged appearance referred to as

pixelation. Simply stretching a bitmap to enlarge it doesn't produce highquality results (Figure 1-23).

► Can I change a bitmap's resolution? Graphics software offers options for changing the resolution of bitmap images. Suppose you reduce the resolution from 2160 x 1440 to 1080 x 720. The image grid becomes a quarter of its original size, but every fourth pixel was removed from the image, which typically reduces image quality.

If you attempt to enlarge a bitmap by increasing its resolution, your com puter must somehow add pixels because no additional picture data exists.

But what colors should these additional pixels become? Most graphics soft ware uses a process called pixel interpolation to create new pixels by averaging the colors of nearby pixels.

For some images, pixel interpolation produces an enlargement that appears

very similar to the original. Other images—particularly those with strong

TRY IT

curved or diagonal lines—may appear pixelated.

Open an image with Photoshop or similar graphics software.

I So how much resolution does a bitmap need to be printed

Check its size and its ppi. At 300

as a poster? Graphics software, such as Adobe Photoshop, can help you gauge how large an image can be printed before the quality begins to dete

ppi, how large can the image be printed before its quality begins

riorate. The minimum resolution for printed output is 72 pixels per inch (ppi).

to deteriorate?

Suppose that a photo taken with a smartphone has a resolution of 1936 x 2592.

At 72 ppi. the photo can be printed up to a size of 26" x 36".

To print the same photo but with a better resolution of 150 ppi, the poster would be

Pixel Dimensions: 14.4M' Width: 1936

pixels

Height: 2S92

pixels

much smaller: about 12" x 17" as shown

in Figure 1-24.

Auto... — Document Size: Width:

12.907

Height: 117.28 Resolulion:|150 FIGURE 1-24: IMAGE SIZE

Check these specifications to determine maximum

print size.

Cancel

inches Inches

pixels/inch

]'

V Scale Styles Resampling an Image requires pixel interpolation and may O Resample Image: decrease the image quality. To I Bicubic (best for smc maintain quality, do not resample. Constrain Proportions

44

SECTION C. MODULE

IMAGE COMPRESSION Bitmap files are big. An image with a resolution of 1936 x 2592 contains 5,018,112 pixels. Each pixel requires 24 bits, so the RAW image file could be as large as 120,434,688 bits (12,434,696 bytes or 12 megabytes). By any measure, that's a lot of data to store and move. Various image com pression techniques can be used to shrink bitmap files.

i What is image compression? Image compression refers to any technique that recedes the data in an image file so that it contains fewer bits. Many bitmap file formats automatically apply compression to an image

QUICKCHECK Run-length encoding is a typo of . a. bitmap digitization

b. RLE graphics format

when it is saved.

I Which formats apply lossless compression? TIFF, PNG,and GIF graphics formats offer lossless compression. Images stored in these for mats do not lose any quality when compressed.

c. lossless compression d. pixelation

I How does lossless compression shrink a file without throw ing away data? Various techniques exist for lossless image compression. As a simple example, consider a type of lossless compression called run-

length encoding. Run-length encoding (RLE)replaces a series of similarly colored pixels with a binary code that indicates the number of pixels and their colors.

Suppose that a section of a picture has 167 consecutive white pixels, and each pixel is described by three bytes of data. RLE compresses this series of 167 bytes into as few as four bytes, as shown in Figure 1-25. FIGURE 1-25; RUN-LENGTH ENCODING

The data for the first 167 white

pixels can be compressed as

NUMBER

NUMBER

OF PIXELS

OF PIXELS

(DECIMAL)

(BINARY)

PIXEL PIXEL

COLOR

COLOR

(BINARY)

White

llllllll 1111111111111111

00000101

Biack

00000000 00000000 00000000

QOQIIOIO

While

111111111111111111111111

1

OOOOOOOl

Black

00000000 00000000 00000000

5

00000101

Yeilow

llllllll llllllll 00000000

00000000 OOOOOOOQ 00000000

167

lOlOOlll

11111111. The first byte is the binary representation of 167. The next three bytes are the

5 26

code for white.

10100111 11111111 11111111

1

OOOOOOOl

Black

23

00010111

White

llllllllllllllllllllllll

2

00000010

Black

OOOOOOOQ 00000000 00000000

7

00000111

Yellow

111111111111111100000000

18

OOOIOOlO

Biack

00000000 00000000 00000000

5

00000101

White

llllllll 1111111111111111

1

OOOOOOOl

Biack

00000000 00000000 00000000

25

00011001

Yeilow

llllllll 1111111100000000

1

OOOOOOOl

Biack

OOOOOOOQ OOOOOOOO 00000000

1

OOOOOOOl

White

llllllllllllllllllllllll

OOOOOOOl 11111111 11111111 00000000

QUICKCHECK

00000011 11111111 11111111 11111111 Is this the correct RLE for the OOOOOOOl 00000000 00000000 00000000

row shown below?

00011001 11111111 11111111 00000000 OOOOOOOl 00000000 00000000 00000000

a. Yes

OOOOOOOl 11111111 11111111 00000000

b. No

□:

1 1 1 1 1 1 1 1 1 1 1 1 1

rr

45

DIGITAL CONTENT

► Which formats apply lossless compression? JPEG files are com pressed using lossy compression, so some quality is lost when the file is saved. When saving an image as a JPEG, you may be able to select a com pression level. Take care with lossy compression to ensure that your image is not further compressed every time you save it (Figure 1-26). FIGURE 1-26: JPEG COMPRESSION

Matte:

Selected com

None

pression level

— image uptions -

«

Quality; f? smzl) fi k

| 1 Medium

;'

1

OK

[

Cancel

i The original file was 14 MB.

0 Preview

With Medium

compression, the

U/ge ftit 7S9.8X

size shrinks to 759.8 KB.

> What happens during lossy compression? Lossy compression techniques discard some data from an image to shrink its file size. JPEG is

a lossy version of run-length encoding that can be applied to images, such as photographs, that don't have large areas of solid color.

TRY IT!

A True Color photograph might not have any adjoining pixels of the same

color. Applying RLE to such a photo would not result in any compression whatsoever. JPEG preprocesses an image by tweaking the colors in adjoin ing pixels so that they are the same color whenever possible. After this preprocessing is complete, run-length encoding can be applied with more success.

For many images, lossy compression results in only a minor reduction in the sharpness of the image. The reduction in quality can be unnoticeable in many circumstances. Figure 1-27 illustrates a section of a noncompressed

image and a section of that same image after JPEG compression has been

Open a JPEij image, use the

Save As command or Duplicate command to make a copy of the image with a name different from the original. As you save the copy, apply as much compression as possible. Close both files and then

reopen them. Is there a visible

difference in quality?

applied. Can you see any difference? FIGURE 1-27: COMPRESSED IMAGE QUALITY

Noncompressed JPEG imugc

JPEG iinu

I Can 1 compress images using general compression tools? The same compression tools used to shrink text and numeric data can be used

with bitmaps. Images stored in file formats such as JPEG and PNG, which are automatically compressed, may not shrink much, whereas RAW files,

BMPs, and noncompressed TlFFs may shrink quite a bit.

v.iiii jSLo comprusiiuit

46

SECTION C, MODULE 1

MODIFYING BITMAP IMAGES

"Photoshopping" has become an everyday term for fixing up photos that are underexposed, are marred by red eye effects, or display an awkward object in the background. Photoshop software and a host of iocal and online apps make it easy to modify digital images.

I What characteristics of a bitmap can I modify? Because bit map graphics are coded as a series of bits that represent pixels, you can use graphics software to modify or edit this type of graphic by changing the

QUICKCHECK When modifying a JPEG image, which of the following is true?

a. It Is stored in a compressed format b. It cannot be modified until

you unzip it

color of pixels.

In the early days of digital Imaging, primitive photoediting was limited to

c. You can no longer edit

changing the color of individual pixels, or roughly cropping out objects to

individual pixels in the

delete them or paste them elsewhere.

image

Today, photoediting software includes sophisticated tools based on graph ics algorithms that produce amazing transformations of digital images. Knowing how to use the available toolset can improve the images you pro duce. Understanding the extent to which photos can be edited also builds awareness of the "tricks" that can be used to alter images in news stories and other information sources.

Noise reduction. In an image,"noise" refers to artifacts such as spots, dust, and scratches that may be produced when old photos are scanned.

TRY IT

Some Images have undesirable speckles resulting from low light conditions.

Histograms can perform miracles! Open a photo using

Noise reduction tools can remove these noisy artifacts.

software such as Photoshop,

Image enhancement.A mediocre photo can benefit from image enhance ment techniques that correct brightness, improve color saturation, and

sharpen the focus. Beyond one-click enhancement tools, image editors provide an image histogram that can be used to adjust the brightness val

Apple Photos, or Photo Galiery. Locate the histogram control and experiment to see what you can reveal In the shadows.

ues for various ranges of dark, mid-range, or light pixels (Figure 1 -28). FIGURE 1-28: HOW IMAGE HISTOGRAMS WORK

A Levels

Dark

Mid-range

& Lcvc

100111

Light

The histogram for the original photo shows lots of dark pixels (the buildings) and a few light ones (the sunset).

Dark

Mid-range

Light

By sliding the Levels bar, more pixels become mid-range and the details of the buildings begin to emerge.

47

DIGITAL CONTENT

Selective color change. The mannequin at an online store displays a red dress, which is also available in other colors. How would it look In blue?

The photographer did not have to take a photo of the dress In every color. Photoediling software can outline the dress in the original photo and then apply the new color. Similar algorithms are used to colorize black-and-white photos.

Correcting image distortion. The human eye compensates for per spective, but the camera does not. When a rectangular object in a photo appears distorted, reconstructing the straight edges is easy with photo edit ing software (Figure 1-29). FIGURE 1-29; CORRECTING IMAGE DISTORTION

Lens distortion makes the

computer unit appear angled.

Correcting image distortion straightens the sides.

Cloning. Cloning employs algorithms that pull pixels from one area of an image and then apply them to another area. Cloning can be used to remove small blemishes as shown In Figure 1-30. FIGURE 1-30: ERASING ARTIFACTS WITH CLONING

Cloning works well to remove natural blemishes

and photo artifacts, such as the white spot under

the subject's eye.

I

r

1

inpainting. Reconstructing lost, unwanted, or deteriorated areas In a

photo is called inpainting. Using information from nearby pixels, and tak

ing into account the overall structure of the image, Inpainting algorithms essentially scrub out designated areas and miraculously replace the miss ing pixels with a background or an object that fits with the rest of the image (Figure 1-31). FIGURE 1-31: INPAINTING WITH CONTENT-AWARE FILL

~r-..

The original photo Includes a man in the foreground.

Photoshop's Content-Aware Tiil algorithm creates a

Removing the man leaves a blank area.

background to fill the blank area.

SECTION C. MODULE 1

48

Digital compositing. Have you seen the photo of a great white shark attacking a U.S. Air Force helicopter? That image and many more bizarre

photos are a product of digital compositing, which assembles several images into one. Compositing is achieved using two tools: clipping paths and alpha blending.

A clipping path essentially cuts an object out of an image and knocks out the background to make it transparent. This object can then be superim posed on a background. Alpha blending alters the pixel colors where the edges of the object and the background meet, so that the object appears to

TRY IT!

You can see digital compositing

in action by going to YouTube and searching for ConfenrAware Fill. If you have access to Photoshop, open a few of your own photos and see what kind of crazy composite you can create.

merge with the background (Figure 1-32). FIGURE 1-32: DIGITAL COMPOSITING

The object is straightened and resized before

A clipping path cuts out an

object from the background.

being merged into the photo.

PANORAMIC AND 360 IMAGES

Photos are no longer limited to flat rectangles. They've gone beyond the box to become panoramic views, 360-degree images, and immersive

photo spheres. These image formats are made possible by a technology called image stitching.

I What is image stitching? Image stitching (or photo stitching) cre ates a panoramic image by combining two or more separate photographs that have overlapping edges. The photos are captured from a fixed loca tion. The photographer stands in one place and may rotate, but cannot

QUICKCHECK Image stitching knits photos into panoramic, cylindrical,

and spherical images, but what technique is used to insert

parts of one Image into another

step forward, back, or to the sides.

image?

i What kinds of images does stitching produce? Stitching uses photos in standard bitmap formats, such as JPEG and PNG.The stitching process is based on sophisticated algorithms that match pixels near the edges of each image to determine how they fit together. Stitching con nects the photos and produces various kinds of images called projections (Figure 1-33)that can be viewed on flat screens or with VR headsets.

a. Cloning b. Inpainting

c. Compression d. Compositing

FIGURE 1-33: IMAGE STITCHING

Rectilinear projections are viewed

Cylindrical projections produce

in a two-dimensional plane, typi

a 360-degree image similar to the view from a merry-go-round.

cally 3S a long horizontal photo. These images can be produced

Images are captured from the

using the panoramic feature of a

front, back, and sides, and then

digital camera.

stitched together.

Spherical projections include images from the 360-degree verti cal view as well as the 360-degree horizontal panorama.

49

DIGITAL CONTENT

i Are special software and equipment required to capture photos for stitched images? A series of photos can be manually stitched together using software such as Autopano and AutoStitch, but many digital cameras take care of stitching automatically. Most smartphones include a camera app with a panoramic function for capturing a rectilinear projection. Panoramic functions are also available on most standalone digital cameras.

For producing 360-degree cylindrical projections with a smartphone, a third-party app might be required. Apps, such as Google Street View and Photo Sphere, guide photographers through the rotational process to cap ture a 360-degree view, which is then stitched together into a continuous image.

Special cameras are also available for capturing and stitching photos for cylindrical and spherical projections. These cameras typically use a fisheye lens to capture a half-sphere (think of an upside-down cereal bowl) of images. Two of these fish-eye lenses can be linked to capture a full sphere of images. STEREOSCOPY

Cylindrical and spherical projections can give viewers the sense of being immersed in a scene, but elements within the image remain flat and twodimensional. Computer graphics technology can produce images with the

illusion of depth that make some objects seem close enough to touch. These images are sometimes referred to as 3D, but technically they are stereoscopic.

► What is stereoscopic imaging? Stereoscopic imaging (or stereoscopy) is a graphical technique used to produce an illusion of spatial depth from flat, two-dimensional images. The technique dates back to the 1800s and the use of simple stereoscopes (Figure 1-34). FIGURE 1-34: STEREOSCOPIC IMAGING

Image

Most cameras capture a photo using only one lens, so the image does not convev spatial depth. Two

Simply looking at two similar pho

Because human eyes are spaced

cameras, or a camera with two

apart, they project two slightly different images onto the reti nas. Those images are processed by the brain, which constructs

front-facing lenses, can produce two photos called a stereo pair that mimic the dual Images captured by human eyes. Two images from

viewed with only one eye. A ste reoscopic viewer, or stereoscope,

an Image of the world that cor responds to a three-dimensional environment with spatial depth.

a stereo pair displayed side by side

away from the eyes and required

are called a stereogram.

a partition between the lenses to

n

Brajn

tographs does not produce a 3D

experience. Each Image must be

provides this differentiation using lenses. Old-fashioned stereoscopic viewers placed images 5-11"

separate overlapping views.

50

SECTION C, MODULE I

► What's the modern version of stereoscopic imaging? Modern stereoscopic imaging uses digital images and viewers. Apps for capturing a stereo pair with a single lens camera are available, but somewhat tricky to use. As more cell phones sport dual front-facing cameras, creating ste

QUICKCHECK Name two techniques for creating stereoscopic images.

reo pairs becomes easier.

a. Anaglyphs and stereograms

A stereoscopic viewer, such as Google Cardboard, displays images gener ated by mobile devices. A smartphone simply slides into the device where

b. Compositing and overlays

an app displays a digital stereogram (Figure 1-35).

c.

Blue and red

d. Steganography and depthing FIGURE 1-35; DIGITAL STEREOSCOPY

Google Cardboard stereoscope

Digital stereogram

I What about those red and blue stereo

FIGURE 1-36; ANAGLYPHIC IMAGE

glasses? An anaglyph Is a graphic composed of two images, one that is tinted red and the other that is tinted blue. The two images are printed on top of each other to produce a stereoscopic effect (Figure 1-36). Viewing anaglyph Images requires red-green or red-blue glasses. Usually, the red lens on the left filters out blue and green, while the blue- or green-colored lens on the right filters out red. As a result each eye sees a slightly different image. The two images are processed in the brain to give the impression of three dimensions.

SECTION C

QUICKQUIZ 1.

A digital camera captures images on the pho-

tosiles of a(n) I

bits for each pixel. 4.

so

Two images from a stereo pair displayed side by side are called a(n)

A characteristic of bitmap graphics Is that they are resolution

Graphics stored in True Color format require

1. (Hint: Use

the acronym.) 2.

3.

5.

The most popular True Color formats for Web

that reducing the resolution also reduces the

graphics include 1

Image quality.

JPEG. (Hint: Use the acronym.)

! and

51

DIGITAL CONTENT

Vector Graphics Charactenstics

Digitize

SECTION

VECTOR GRAPHICS tS-U-

IF YOU'VE PLAYED any computer games

Terminology

recently or watched an animated movie, you've seen computer-generated graphics. This section begins with two-dimensional vector graphics. You'll find out how they differ from bitmaps and

vector vector graphic SVG rasterization

why you might want to use them. After covering the basics for two-dimensional graphics,the sec tion progresses to static 3D graphics and concludes

3D graphics wireframe rendering ray tracing vector animation frame

keyframe pre-rendermg CGI real time rendering game engine

with a look at vector motion graphics for virtual reality videogames and instructional modules.

Objectives I Identify vector graphics used on Web sites and social media.

I Based on the characteristics of vector graphics, determine when they are more suitable for a project than bitmaps.

> Draw simple vector shapes and outlines using drawing software.

I Convert a vector drawing into a bitmap.

I Explain the process of rendering a 3D wireframe into an image.

I Identify the key difference between rendering 3D graphics for computer games and creating special effects for movies.

i Explain how vector graphics relate to augmented reality.

I Describe the type of graphics commonly used for virtual reality.

52

SECTION D, MODULE 1

VECTOR GRAPHICS BASICS

The first graphics that appeared on computer screens were not photos, but simple shapes consisting of lines and curves, each referred to as a vector. This type of graphic evolved in sophistication as the shapes became Tilled, then shaded, and then textured (Figure 1-37). FIGURE 1-37: VECTOR LINES AND SHAPES

Lines

Shape

Filled shape

/ Gradient-filled

3D shape

2D shape

Gradient-filled

3D shape

I What is a vector graphic? A vector graphic consists of a set of instructions for creating a picture. Instead of storing the color value for each pixel, a vector graphics file contains instructions that a computer uses to create the shape, size, position, and color for each object in an image.

QUICKCHECK Vector commands in the

example at left are written using .

Vector drawing instructions are similar to those a drafting teacher might give students: "Draw a line of width 3 beginning at coordinates 20, 20 and

a. Flash

extend the line to coordinates 20, 60. Color the line with #OOBFOO (green)."

b. Basic

The command in "computerese" using an XML script would be:

c. WOOBFOO

d. XML scripts

Vector graphics include standard shapes such as circles and rectangles, so they don't have to be built from scratch. The green square in Figure 1-37 was created by specifying a rectangle beginning at coordinates 100,100 with a width of 400 and a height of 400, filled with #006F0O, like this:

QUICKCHECK What kind of shape would the following vector command create?

What is a computer? Most people can formulate a mental picture of a computer, but computers do so many things and come in such a vari ety of shapes and sizes that it might seem difficult to distill their common characteristics into an all-purpose definition. At its core, a computer is a multipurpose device that accepts input, processes data, stores data, and produces output, ail according to a series of stored instructions.

1940, you might be surprised to find a computer defined as a person who performs calculations. Prior to 1940,

machines designed to perform calculations were usually referred to as calculators and

Input is whatever is typed, submitted, or transmitted to a computer. Output is the result produced by a computer. Input and output can be handled by components contained within the computer or by add-on, such as keyboards and printers, that are attached to the computer with cables or

use of the term computer emerged in the 1940s, when

connected wireiessly.

the first electronic computing

Computers process data by performing calculations, modifying docu ments and pictures, drawing graphs, and sorting lists of words or numbers. Processing is handled by the computer's central processing unit(CPU). The CPU of most modern computers is a microprocessor, which is an electronic component that can be programmed to process data.

devices were developed.

tabulators, not computers. The modern definition and

Computers store data and the software that processes data. Most computers have temporary holding areas called memory in addition to long-term storage housed on hard disks or flash drives. Figure 2-1 illus trates the IPOS (input, process, output, store) activities characteristic of computers. FIGURE 2-1: THE IPOS MODEL DEFINES COMPUTERS

calculate sort

draw

manipulate words generate sound

PROCESS

INPUT

OUTPUT

QUICKCHECK Where does sorting fit into the

words and symbols numbers

dates

photos temperatures

documents

0

locations

audio recordings video footage

music

IPOS model?

graphs images

a. Input

movies

b. Process

schedules

c. Store

maps

STORE data files

software

text messages

d. Output

SECTION A, MODULE 2

86

I What's so significant about a computer's ability to store instructions? The instruclions Lhat tell a digital device how to carry out

processing tasks are referred to as a computer program, or simply a program. These programs form the software that sets up a computer to do a specific task. When a computer "runs" software, it performs the instruc tions to carry out the task.

QUICKCHECK The stored program concept turns computers into

The first computers were "programmed" to perform a specific task by con

necting wire circuitry in a certain way. Changing tasks meant rewiring the

a. calculators

circuits. The term stored program means that a series of instructions for a computing task can be loaded into a computer's memory. These instruc tions can be replaced easily by a different set of instructions when it is time

b. smartphones

for the computer to perform another task. This ability to switch programs

c. multipurpose devices d. software

makes computers multipurpose devices (Figure 2-2). FIGURE 2-2: STORED PROGRAMS MAKE COMPUTERS VERSATILE MACHINES

The stored program concept

allows you to use a computer for one task, such as word process

ing, and then easily switch to a

different type of computing task, such as editing a photo or play ing music. It is the single most Important characteristic that dis

tinguishes computers from other simpler and less versatile digital devices, such as digital clocks, Word processing

Music

software

software

I What kinds of software do comput ers run? Computers run three main types of software: application software, system soft ware, and development tools (Figure 2-3). A

calculators, and cameras.

FIGURE 2-3: SOFTWARE CATEGORIES

computer can be applied to many tasks, such as writing, number crunching, video editing, and online shopping. Application software is a set of computer programs that helps a per

son carry out a task. Application software is sometimes referred to as an app.

Whereas application software is designed to help a person carry out a task, the primary purpose of system software is to help the computer system monitor itself in order to function efficiently. An example of system soft ware is a computer operating system (OS), which is essentially the master controller for all the activities that take place within a computer. Development tools are used for cre ating software applications. Web sites,

operating systems, and utilities. Examples of development tools include computer program

ming languages, such as C++, and scripting languages, such as HTML,

Operating

Programming

systems

languages

Mobile epps

CPU monitor

Scripting languages

Sproadsheet

Device drivers

Word

software

Debugging tools

DIGITAL DEVICES

CIRCUITS AND CHIPS

The first computers were closet-sized devices filled with wires, vacuum tubes, transistors, and other bulky components. As digital electronics evolved, components became smaller and smaller. Open up a digital device. You won't see clumps of wires and gears. Instead, you'll see small circuit

boards and integrated circuits. These tiny components are the essence of

QUICKCHECK In Figure 2-4, the fiery bit

digital electronics.

> What are digital electronics? Digital electronics represent data bits as electrical signals that travel over circuits in much the same way that electricity flows over a wire when you turn on a light switch. To represent data, such as 01101100, high-voltage signals are used for 1 bits, and lowvoltage signals are used for 0 bits. All the calculations performed by digital devices take place in a maze of electronic circuitry (Figure 2-4).

a. represents a 1 b. is heading toward a resistor c. is a low-voltage signal d. represents a 0

FIGURE 2-4: A SIMPLE CIRCUIT

This little circuit is

o

composed of electrical pathways (lines), tran sistors (circles), and resistors (rectangles). The electronics for

digital devices require millions of similar

circuits. Today, this circuitry is condensed into integrated cir cuits.

i What's an integrated circuit? An integrated circuit (IC) Is a set of microscopic electronic components etched onto a thin slice of semi conducting material. The terms computer chip, microchip, and chip are commonly used to refer to integrated circuits. Some integrated circuits are devoted to collecting input, while others might be devoted to processing tasks, output, or storage. The first computer chips contained fewer than 100 miniaturized components, such as resistors and transistors. The chips for today's digital devices contain billions of transistors.

QUICKCHECK There is an abundant supply of materials for fabricating semiconductors because:

Semiconductors, such as silicon and germanium, are substances with properties between those of a conductor (like copper) and an insulator (like wood). To fabricate a chip, the conductive properties of selective parts of the semiconductor can be enhanced to essentially create min iature electronic pathways and components, such as transistors, as shown in Figure 2-5.

a. They are made from purified silicon (sand). b. They are basically insulators made from wood.

FIGURE 2-5: COMPUTER CHIPS ARE MADE FROM SEMICONDUaORS

Blank semiconductor

Chip etched with circuits

Chip ready for packaging

88

SECTION A, MODULE 2

I Aren't chips black? Integrated circuits are packaged in protec tive carriers that vary In shape and size. Figure 2-6 iiiuslrates some chip carriers, including small rectangular DIPs (dual in-iine packages) with caterpiiiar-iike legs protruding from a black, rectangular body, and pincushion-iike LGAs (land-grid arrays). FIGURE 2-6; CHIPS ARE HOUSED IN CERAMIC PACKAGES

TRY IT!

DIPs have two rows of pins that connect the chip to a circuit board.

An LGA is a square chip package, typicaily used for microprocessors, with

The chips on a circuit board have identifying numbers that

pins arranged in concentric squares.

you can look up online. Suppose you've opened the system unit

> How do chips fit together? The electronic components of most digital devices are mounted on a circuit board called a system board, motherboard, or main board. The system board houses all essential chips and provides connecting circuitry between them. Figure 2-7 illustrates the main chips on the front and back sides of a laptop system board.

of a Microsoft Surface tablet and

you're looking at a chip labeled Atme! MXT154E. Can you find out what it does?

FIGURE 2-7: A SYSTEM BOARD HOLDS CHIPS AND OTHER COMPONENTS

Processor

Input and output

From

Control

chips

Audio processing

Rear

Memory |

89

DIGITAL DEVICES

COMPONENTS

When you acquire a new digital device, your first step is to locate the power button and all the other hardware components. The devices we use today

have a fairly predictable collection of features, depending on the device's form factor.

I What is a form factor? in the computer industry, the term form factor refers to the size and dimensions of a device or components, such as circuit boards and system units. The term system unit is tech speak for the part of a digital device that holds the system board, it can apply to the body of a smartphone or laptop, as well as to the tower unit of a desktop computer. Digital devices are available in ail sorts of form factors; some of the most popular include component, ciamsheii, and slate.

► What are the features of a component system?Acom-

QUICKCHECK How many on/off buttons would you expect on a component system like the one in Figure 2-8?

a. One on the system unit

ponent device is composed of various standalone parts, such as a display unit, system unit, and keyboard. Components can be connected

using cables or wireless signals. Most of the first personal computers were component systems. Today, this form factor is much less popular because of the effort required to assemble the components. Figure 2-8 illustrates the hardware features of a typical component system.

b. One for each standalone device

c. One on the system unit and one on the display device

FIGURE 2-8: A TYPICAL COMPONENT SYSTEM

Camera

Display device

Display on/off button

System unit

Hard disk dnve

and system board

(inside system unit)

CD/DVD drive

Computer on/ off button

Keyboard Mouse

90

>

SECTION A, MODULE 2

What are the features of a clamshell device? Clamshell

devices have a keyboard as the base and a screen on the hinged cover. The system unit on these devices contains all of the basic components required for input, processing, storage, and output {Figure 2-9). FIGURE 2-9; A TYPICAL CLAMSHELL DEVICE

MkrophonJ

Camera

QUICKCHECK Display screen How many components are typically housed on the top half of a clamshell device? a. One

System unit

b. Two c. Three

d. Four On/off button

CD/DVD drive

Touchpad

Hard disk drive, battery, artd system board (inside system urtit)

• What are the features of a slate device? Devices config ured in the slate form factor feature a touchscreen that covers most of

the device's surface. The screen can display a virtual keyboard for text and numeric input. An additional control, such as a Home button or a circular control pad, is featured on some slate devices. The system unit also includes controls for commonly used features, such as volume and airplane mode (Figure 2-10).

TRY ITt Chock out the devices thdt

you own. Can you find all of the components listed in the figures?

FIGURE 2-10: A TYPICAL SLATE DEVICE Camera

RIng/sllent switch

CaiicpI

button']

Volume buttons

Battery, antenna,

and system board Display screen

Q

I

Iq w e r Virtual keyboard

(Inside system unit)

iSt ^ & ffw t y u I 0 p

s d f g h j k

1

|0 zxevbnm0 1123 ® Home button

Speaker I

91

DIGITAL DEVICES

MAINTENANCE

Digital devices can be costly. You can extend their life (with a bit of regu lar maintenance. There are four components of digital devices that require

maintenance: the system unit, keyboard, screen, and battery,

i How do I start? Before you undertake any maintenance, turn the device off—that's off, not just asleep—and disconnect any power cables.

Doing so will prevent random screen swipes or key presses from altering your device settings.

► Which cleaning products are safe to use? The products you can use depend on the component you are cleaning. What might work well to scrub out stubborn stains on the system unit case could permanently cloud or scratch your touchscreen. Always follow the manufacturer's advice for cleaning procedures and products (Figure 2-11). FIGURE 2-11: CLEANING GUIDELINES

harsh

Never immerse a device

cleaning products;

Don't

use

in liquid; water and

follow manufacturer

electronics don't mix.

Do not allow cleaning agents to drip on key boards or touchpads.

recommendations.

Do not spray cleaning agents directly on the

device; spray them onto a cleaning cloth.

> What kind of maintenance does the system unit require? Basic system unit maintenance is simple. You want to keep the unit clean, prevent it from overheating, shield it from damage, and protect it from electrical surges (Figure 2-12). FIGURE 2-12: BASIC SYSTEM UNIT MAINTENANCE

Dust with a clean

Use a low vacuum

Use a protective case

Only plug into a surge-

microfiber cloth and

setting to remove

or carrying bag.

protected outlet.

disinfect with anti

dust from fan vents.

bacterial wipes.

i How can I safely clean and disinfect a touchscreen? Touchscreens collect fingerprints and are a breeding ground for bacte

ria, so it is a good idea to clean them periodically. Many touchscreens are made from Gorilla Glass, which Is designed to resist scratching and cracking. Damaged screens can be replaced, but that can cost close to

$100, so a few preventive measures may help you avoid costly repairs. A plastic screen protector is the first line of defense against scratches

QUICKCHECK What is the first step for hardware maintenance?

a. Wipe It with a soft clothb. Remove the screen protector.

and cracks. These films can be cleaned using water and a soft cloth, or a

c.

disinfecting wipe. When the screen protector gets grubby, simply peel it

d. Vacuum the fan vents.

off and replace it with a new one.

Turn the device off.

92

SECTION A. MODULE 2

Without a screen protector, you will have to carefully clean the screen itself. Many touchscreens have an oteophobic coating designed to repel the oils deposited by fingertips. When alcohol is used to clean these screens, each application degrades the coating. Non-alcohol wipes are available, or use eyeglass cleaner.

> What about my keyboard? Keyboards quickly build up grime, gather dust, and collect crumbs. To start the cleaning process, turn the keyboard upside down and shake it gently to dislodge debris. Most manu facturers suggest using an antibacterial wipe to clean key surfaces. Take a moment to test the cleaning product on a small unnoticeable spot just to make sure it will not discolor the keys or leave a residue. Use cotton swabs to clean between the keys.

I What is the best way to clean up spills? Liquids and elec tronics don't mix. If you spill liquid on a device, turn it off immediately. With luck, that step will prevent electrical shorts that would permanently damage circuit boards. Once the device is off, you can assess the dam age. If the spill is water, dry off the device, shake out the moisture, and set it in a warm, dry place where there is good air circulation. A fan or hair dryer set on low can help drive out moisture. Allow the device to dry for at least 72 hours.

Sticky spills are another matter. If the goo has penetrated the interior of the device, it is best to leave the cleanup to a professional. If you think the spill only affected the surface, you can wipe the device with clean water and allow it to dry for 24 hours (Figure 2-13). FIGURE 2-13: DO NOT SET LIQUIDS NEAR A KEYBOARD

QUICKCHECK When liquid spills on a digital device, what should you do? a. Shut off the device

immediately.

b. Back up all your data before turning off the device. c. Rinse the device with clear water.

d. Call *611.

> How do I maintain the battery for a device? You know how it goes. It happens to everyone. The battery on your device dies

just when you really need it. Battery life is the time your device operates before it must be recharged. Battery lifespan is the amount of time a bat tery lasts until it must be replaced. Good maintenance extends the life of your battery and Its lifetime, so your digital devices are ready when you need them.

Most of today's battery-powered digital devices contain a lithium ion (Li-ion) battery. Unlike batteries of the past, Li-ion batteries contain no toxic compounds and operate efficiently, but they are sensitive to heat.

93

DIGITAL DEVICES

Li-ion batteries can occasionally overheat, and in the worst case, they can explode. Most devices today contain circuitry to prevent heat-trig gered damage, but smart consumers don't operate devices that are hot to the touch.

Batteries have a discharge rate at which they lose charge even when not in use. The discharge rate for Li-ion batteries is quite low—about 1.5% per month—so the batteries in your devices basically discharge

i

only as they are used.

Device manufacturers often advertise battery watts per hour (Wh). A 60 Wh battery will last 60 hours if it expends 1 watt per hour. A typical laptop uses about 30 watts per hour, however, so a 60 Wh battery can power the

device for two hours(60 Wh + 30 watts = 2 hours). Some applications require more battery power than others. Locationbased apps that keep track of your whereabouts are constantly using extra power to check cell towers or Wi-Fi networks. Push applications,

such as autoretrieving email, make your device continually check for new messages. To extend battery life, disable these kinds of apps when you are not using them. Figure 2-14 summarizes good practices for charging

and using Li-ion batteries. FIGURE 2-14: EXTEND THE LIFE OF THE BATTERIES IN YOUR DEVICES

QUICKCHECK Charge when the low battery indicator comes on. Suppose your smartphone has a battery rated at 5.2 Wh. When

Avoid totally discharging the battery.

Remove the device from the charger when it's fully charged.

you use map guidance, the phone draws 1.3 watts per hour. How long can you travel before your phone runs out of juice? a. One hour

If your device becomes hot while in use, turn it off. b. Four hours

Disable unused apps that constantly connect to the Internet.

c. Eight hours d. Ten hours

Switch to airplane mode when in an area with no cell coverage.

SECTION A

QUICKQUIZ 1.

A computer is a multipurpose device that accepts

input, processes

4.

I , stores

data, and produces output, all according to the

Three form factors for digital devices are component,

5.

Touchscreens on many digital devices have a(n)

instructions of a stored program. 2.

An operating system is an example of software.

3.

A(n)

circuit is a set of

microscopic electronic components etched onto a thin slice of semiconducting material.

, and slate.

coating that resists finger prints.

94

SECTION B, MODULE 2

Digital Devices Enterprise Computers

\ Personal

Computers

SECTION

« DEVICE OPTIONS

WHEN SHOPPING for a new device, the choices may seem overwhelming. Section B helps

you sort out the devices that are on the market by function and price. It addresses the tricky issue of

Terminology supercomputer mainframe SCrver

personal computer desktop computer

compatibility and other factors important to con

portabio computer laptop computer

sumers.

Chromebook tablet computer slate tabiut 2-in-1 smartphones

PDA wearable computers microcontrollers compatible

Objectives List three types of computers that are commonly used in businesses,serve multiple simultaneous users, and offer very fast processing speeds. Draw a hierarchy chart showing the classifications of personal computers.

List two applications that would tend to require a desktop computer.

List the devices that typically support cellular voice and texting. List devices that can support cellular data plans.

Specify three operating systems that are common in each of the following categories: desktops,laptops, tablets, and smartphones.

95

DIGITAL DEVICES

ENTERPRISE COMPUTERS At one time, it was possible to define three distinct categories of computers. Mainframes were housed in large, closet-sized metal frames. Minicomputers were smaller, less expensive, and less powerful, but they

FIGURE 2-15:"BIG* COMPUTERS

could support multiple users and run business software. Microcomputers were clearly differentiated from computers in other categories because they were dedicated to a single user and their CPUs consisted of a single micro processor chip.

(

Today, microprocessors are no longer a distinction between computer

categories because just about every computer uses one or more micropro

cessors as its CPU.The term minicomputer has fallen into disuse, and the

terms m/crocompuferand mainframe are used with less and less frequency.

t What are the most powerful computers? Today's most power ful computers include supercomputers, mainframes, and servers. These devices are generally used in businesses and government agencies. They have the ability to service many simultaneous users and process data at very fast speeds(Figure 2-15).

Supercomputer

Supercomputers. A computer falls into the supercomputer category if it is, at the time of construction, one of the fastest computers in the world. Because of their speed, supercomputers can tackle complex tasks that just would not be practical for other computers. Typical uses for supercomput ers include breaking codes, modeling worldwide weather systems, and simulating nuclear explosions. Computer manufacturers such as IBM, Cray, and China's NRCPC have in recent years held top honors for the world's fastest computer. Supercomputer speeds are measured in petaflops(PFLOPS). One petaflop is an astounding 1,000,000,000,000,000 (quadrillion) calculations per sec ond. That's about 20,000 times faster than your laptop computer. Mainframes. A mainframe computer (or simply a mainframe) is a large and expensive computer capable of simultaneously processing data for hundreds or thousands of users. Its main processing circuitry is housed in a closet-sized cabinet like the one shown at left; but after large components are added for storage and output, a mainframe installation can fill a goodsized room.

Mainfreme

Mainframes are generally used by businesses and government agencies to provide centralized storage, processing, and management for large amounts of data. For example, banks depend on mainframes as their com puter of choice to ensure reliability, data security, and centralized control. The price of a mainframe computer typically starts at several hundred thou sand dollars and can easily exceed $1 million. Servers. The purpose of a server is to "serve" data to computers con nected to a network. When you search Google or access a Web site, the information you obtain is provided by servers. At ecommerce sites, the store's merchandise information is housed in database servers. Email,

chat, Skype, and online multiplayer games are all operated by servers. Technically, just about any computer can be configured to perform the work of a server. However, computer manufacturers such as IBM and Dell offer devices classified as servers that are especially suited for storing and distributing data on networks. These devices are about the size of a desk Servers

drawer and are often mounted in racks of multiple servers.

SECTION B, MODULE 2

95

PERSONAL COMPUTERS FIGURE 2-16; PERSONAL COMPUTERS

A personal computer is designed to meet the comput ing needs of an individual. These computers were originally referred to as microcomputers. Personal computers provide access to a wide variety of computing appiications, such as word processing, photo editing, email, and Internet access. The term personal computer is sometimes abbreviated as PC. However, PC can also refer to a specific type of personal

computer that descended from the original IBM PC and runs Windows software. In this book, PC refers to IBM PC descen

dants. It is not used as an abbreviation for personal computer.

► What are the options for personal computers? Desktop

Personal computers can be classified as desktop, portable, or mobile devices. The lines that delineate these categories are sometimes a bit blurry, but the general characteristics of each category are described below and common configurations are shown in Figure 2-16.

Desktops. A desktop computer fits on a desk and runs on power from an electrical wall outlet. The keyboard is typically a separate component connected to the main unit by a cable. A desktop computer can be housed in a vertical case or in a horizontal case. In some modern desktops, called all-in-one units, the system board is incorporated into the display device. Desktop computers are popular for offices and schools where portability is not important. Their operating systems include Microsoft Windows, macOS, and Linux. The price of an entrylevel desktop computer starts at S500 or a bit less.

Laptop

Portables. A portable computer runs on battery power. Its screen, keyboard, camera, storage devices, and speakers are fully contained in a single case so that the device can be eas ily transported from one place to another. Portable computers include laptops, tablets, and smartphones.

Slate tablet

Laptops. A laptop computer (also referred to as a note book computer) is a small, lightweight personal computer designed like a clamshell with a keyboard as the base and a screen on the hinged cover. Most laptops use the same oper

ating systems as desktop computers, with the exception of Chromebooks, which use Google's Chrome OS as their oper ating system. A Chromebook is a special category of laptop, designed to be connected to the Internet for most routine computing activi ties. Chromebook owners use Web-based software and store all their data in the cloud rather than on a local hard disk.

Chromebooks use a standard clamshell form factor, so they look very much like a laptop. Their sub-$300 price lags are attractive to consumers who primarily browse the Web and 2-ln-l tablet

use Web-based apps.

97

DIGITAL DEVICES

Tablets. A tablet computer is a portable computing device featuring a touch-sensitive screen that can be used for input as well as for output.

Tablet computers use specialized operating systems, such as iOS and Android, or special operating system modes, such as Windows 10 Tablet mode. Some models support cell phone network data plans but require apps such as Google Voice or Skype for voice calls. A slate tablet configuration is basically a screen in a narrow frame that lacks a physical keyboard (although one can be attached). The Apple IPad and Samsung Galaxy Tab are popular slate tablets. A 2-ln-1 (or convertible

tablet) can be operated using its touch-sensitive screen or with a physical keyboard that can be folded out of the way or removed.

Smartphones are the most commonly used digital device in the world. A smartphone features a small keyboard or touchscreen and is designed to fit into a pocket, run on batteries, and be used while you are holding it in your hands (Figure 2-17). FIGURE 2-17: SMARTPHONES ACCEPT INPUT FROM A TOUCHSCREEN OR MICROPHONE

Sotne things you can ask me:

What

•«

rrd • oed

neWr

r«fM ui

toi

lOT tn>

Mr

e W •' f X V u -f'S9 « % rf r e 1?

V

t ■ < V (> •m **

!«■ I-'»

S

How many digital devices do you own? Which do you use most often? Make a list of

Smartphones. Smartphones are mobile devices that have features simi lar to tablet computers, but also provide telecommunications capabilities over ceil phone networks. They can make voice calls, send text messages, and access the Internet. Unlike a basic mobile phone, smartphones are programmable, so they can download, store, and run software.

t

TRY IT

T «

Smartphones are equipped with built-in speech recognition that allows you to ask questions and control the device using spoken commands. Smartphones also include GPS capability so that apps are able to provide location-based services such as a route navigation map or a list of nearby restaurants.

Smartphones evolved from basic cell phones and PDAs. A PDA (personal digital assistant) was a handheld device used as an electronic appointment book, calculator, and notepad. Modem smartphones include a similar suite of applications, but they also have access to a huge variety of mobile apps that help you calculate tips, play your favorite music, and entertain you with games.

The operating systems for smartphones are similar to those used for tab let computers. IDS is used on the IPad and iPhone. Microsoft Windows

10 Mobile Is used on smartphones that offer a similar user experience as Windows laptops. The Android operating system used on Samsung tab lets is also used for Samsung Galaxy and Motorola Droid smartphones.

your devices and their serial numbers, and tuck it away in a

safe place In case one of your devices is lost or stolen.

98

SECTION B, MODUEE 2

FIGURE 2-18; SPECIALIZED DEVICES

NICHE DEVICES

The list of digital devices is long. Many devices, such as fitness traclcers, cameras, and handheld GPSs, are dedicated to specific tasks. Other devices perform a wider variety of tasks.

I What about other digital devices? Niche devices ail have one thing in common: They contain a microprocessor, Some of these devices, such as smartwatches and fitness trackers, can be classified

as wearable computers. Which of the devices in Figure 2-18 do you Raspberry Pi

own?

Raspberry Pi. A full computer system unit that is just a tad larger than a deck of cards, the Raspberry Pi can be connected to a keyboard and screen for a full computer experience. These little powerhouses cost less than $50 and provide an inexpensive platform for experiment ing with programming, robotics, and just about any creative computer application you can imagine.

Videogame console

Game consoles. Devices for playing computer games include Sony's PiayStation, Nintendo's Wii, and Microsoft's Xbox. They fea ture powerful processing capability and excellent graphics, but they are generally used for dedicated game playing and streaming videos rather than running application software. Portable media players. Media players, such as the iPod Touch, revolutionized the music industry by providing consumers with a handheld device that can store and play thousands of songs. These devices are controlled by touchscreens or simple click-wheel mecha nisms.

Portable media player

Smartwatches. Watches and clocks were some of the first devices

to go digital. Mass produced in the 1970s with a price as low as $10, these watches were limited to time and date functions. In 2013,

Samsung, Google, and Quaicomm introduced a new breed of digital watch. Dubbed smartwatches, these multifunction devices can include

a camera, thermometer, compass, calculator, cell phone, GPS, media player, and fitness tracker. Some smartwatch functions are onboard the device, whereas other functions require access to the Internet or Smartwatch

to the wearer's smartphone. Activity trackers. To monitor activity throughout the day, you can wear a fitness tracker. These devices, worn on the wrist or clipped to a pocket, monitor your steps and heart rate. They can calculate calo ries, graph your fitness achievements, and share information with your Facebook friends.

Titness irncker

Smart appliances. Modern refrigerators, washing machines, and other appliances are controlled by integrated circuits called microcontrollers that combine sensors with processing circuitry. Microcontrollers can monitor energy efficiency, offer programmed start

times, and may be controlled remotely from a smartphone or laptop.

PI

Smart appliances

99

DIGITAL DEVICES

CHOOSING A DIGITAL DEVICE

The process of selecting a digital device is all about choices, and there can be an overwhelming number of them. Do you want a tablet or a laptop? Do you need a super-light device? What size screen? Mac or Windows? Is the most powerful and most expensive processor necessary? Understanding the choices is the key to getting the right device at the right price.

Which tasks tend to require the fastest processor?

I How do ! get started? Whether you are replacing an outdated

b. Social media and Web

device or adding to your digital collection, the following activities can get you started:

QUICKCKECK

a. Email and photo editing

browsing

Consider how you plan to use your device.

c. Desktop publishing and video editing

Choose the type of device.

d. Accounting and budgeting

Decide on a budget and stick to it. Select a platform.

Check out the device's specifications.

> Why is it important to figure out how I'm going to use my new device? Some digital tasks require specific devices, processing power, storage capacity, and connectivity. Therefore, if you consider the usage guidelines in Figure 2-19, you're more likely to buy the right device and not have to purchase expensive upgrades later. FIGURE 2-19: USAGE GUIDELINES

USAGE PLAN

PURCHASE RECOMMENDATION

You plan to use your computer for email

A mid-priced computer with standard features

and Facebook, browsing the Web. playing games, managing finartces, downloading

might meet your needs.

digital music, and writing school papers. You're buying a new computer to replace an

a. €

•

oid one.

If you have a big investment in software, you should select a new computer that's compatible with the old one.

You plan to work on accounting and budget

Consider one of the business systems offered

ing for a small business.

by a local or an online computer vendor.

You spend lots of time playing computer

Buy a computer with the fastest processor and

games.

graphics card you can afford.

You plan to work extensively with video editing or desktop publishing.

lots of hard disk capacity, a large screen, and a

Select a computer system with a fast processor, graphics card loaded with memory.

h-

Someone who will use the computer has special needs.

You plan to use specialized peripheral devices.

Your work at home overlaps your work at

'h school or on the job. You want to work with specific software, such as a 3D graphics tool.

Consider purchasing appropriate adaptive equipment, such as a voice synthesizer or onehanded keyboard. Make sure the computer you purchase can accommodate the devices you plan to use.

Shop for a computer that's compatible with the computers you use at school or work. Select a computer that meets the specifications listed on the software box or Web site.

i

100

SECTION B, MODULE 2

► What are the pros and cons of the most popular consumer devices? The most popular digital devices are desktops, laptops, tablets, and smartphones. Figure 2-20 can help you choose the one that best meets your needs. FIGURE 2-20: CHOOSE THE RIGHT DEVICE

a Desktop- ■ Most power per dollar

Can make repairs and upgrade components yourself (except for all-in-one units) Full-size keyboard with numeric keypad for data entry

Large screen for multiple windows and detail work

Adjustable placement of compo nents means less strain on eyes, back, and wrists

Bottom Hne^ The choice for dedicated

gamers, serious designers, desktop publishers, and video editors

^Laptop All components in one unit Easy to move

Battery powered for portability Energy efficient means low operating cost Connects to WI-FI networks for Internet access

Lightweight models have higher price tags and may not have a

CD/DVD player

Bottom line Adequate for most digital tasks that are not dependent on cellular connections The choice for students and

Small and easy to carry fl attery powered Connects to Wi-Fi networks

Cellular data plans available for mobile Internet access

Convertible units with keyboards

available for writing long docu ments and creating other content Might not use software designed for desktop and laptops

Which device is best if you want to consume and create content

using a device that is portable?

a. Desktop

on-the-go professionals who

b. Laptop

want to create content and

c. Tablet

be productive, in addition to

□ Tablet

QUiCKCHECK

consuming content

D Smartphone Cellular connection for voice and

texting Add a cellular data connection for Internet access

Connects to Wi-Fi networks

Longer battery life than tablets and laptops Larger sizes offer bigger, essier-to-

Small screen limits multitasking

read screens

Bottom line

Bottom linc'^

Great for consuming content,

Great for communications and

such as ebooks, music, and

mobile apps

videos

Adequate for watching occasional

Adequate for browsing the Web and managing social media

videos and for mobile access to social media

Works for some specialized tasks, such as business presentations

Not optimal for creating text-based content, but excellent for voice

calls, texting, and Web browsing

d. Smartphone

101

DIGITAL DEVICES

I How important is compatibility? Suppose that you want to work on some assignments at home using the same software provided by your school lab. Maybe you want to transport data back and forth between your job and home. Or, perhaps your children want to use a computer at home that is similar to those they use at school. Computers that operate In essentially the same way and use the same soft ware are said to be compatible. They can also be described as having the same "platform." To assess whether two computers are compatible, check their operating systems. Computers with the same operating systems can typically use the same software and peripheral devices. Figure 2-21 pro vides an overview of popular platforms. You'll learn more about operating systems In a later module. FIGURE 2-21: COMPATIBILITY IS RELATED TO OPERATING SYSTEMS

Apple microsoft Google nucUS

Wincjows

"Mac'

0

M

QUfCKCHECK Do Apple and Android tablets use the same software and apps as laptops? a. Yes

b. No

VVlM'jl)'. y,

d ► Should I stick to one family of devices? As you can see from

Terminology

Figure 2-21, operating systems and the devices that use them are grouped

Desktops and laptops that

into families. Apple produces macOS and ICS. Microsoft produces Windows and Windows Mobile. The open source community produces Linux for desktops and servers: and with the support of Google, it produces Chrome

run Windows are sometimes

OS and Android.

as Macs.

The operating systems within a family have similarities In the way they look and function. So if you are familiar with macOS on your laptop, then you might find It easier to work with an IPhone rather than an Android phone.

Working within an operating system family can have other benefits. For example. If you are storing your photos, documents, and other data In

Apple's ICIoud, you'll have easier access to them from devices running ICS and macOS than from a device running Windows. Finally, you might find that synching and backing up data between devices Is easier If they have operating systems from the same family.

referred to as PCs. Computers that run macOS are referred to

102

SECTION B, MODULE 2

I What can t expect to pay for a personal device? The price tag for a smartphone is $200-$900, whereas tablet computer prices range from $200 to $1,200. Desktop and laptop computers usually cost a bit more, with price points roughly grouped Into three categories: above $1,200, $500$1,200, and under $500.

Computers priced above $1,200 contain one or more fast processors, a generous amount of RAM, and a copious amount of disk space. These computers contain state-of-the-art components and should not have to be replaced as quickly as less expensive computers. Computer game enthusi asts and anyone planning to work extensively with video editing, graphics, and desktop publishing are likely to require a high-end computer.

TRY IT! Visit the Dell Web site. What is

the price of the least expensive desktop computer?

A majority of buyers select desktops and laptops that retail for between $500 and $1,200. These popular computers lack the flashy specifications of their state-of-the-art cousins but provide ample computing power to meet the needs of an average user. In the computer industry, the equivalent of a compact car is a sub-$500 computer. The technology in these computers is usually a year or two old, and you can expect reduced processor speed, memory capacity, and drive capacity. You might have to replace a budget computer sooner than a more expensive computer, but it should be serviceable for typical applications.

QUICKCHECK The majority of desktop and

laptop buyers spend how much

P What are the factors that have the biggest effect on device

on a computer?

prices? A microprocessor is one of the most expensive components in a digital device, The newest, fastest microprocessor is likely to add several hundred dollars to the price tag.

a. $100-5250

Memory is another factor that affects price. For example, doubling the amount of memory in a smartphone could raise the cost from $199 to $299. Large screens cost more to manufacture and raise the price of digital devices. An iMac—Apple's version of an all-in-one desktop unit—with a 27-inch screen costs $700 more than the 21-inch version.

For laptops, size and weight make a difference in price. Thinner and lighter laptops are priced higher, not necessarily because they cost more to manu facture. but because they are more desirable to consumers. QUICKCHECK Which one of the following statements is correct about computer classifications?

a. The speed of supercomputers is measured in petaflops, which makes them the ideal platform for ecommerce stores that are accessed by millions of people.

b. The fact that features of small tablets overlap with features of large smartphones is an example of how the lines between categories of computers can be a bit blurry.

c. The main distinction between desktop computers and laptops is the inclusion of processing circuitry in the display device. d. Portable computers and laptops have similar characteristics when it comes to accessing cellular voice and data.

b. S250-S500 c. $500-51,200 d. $800-Sl,500

103

DIGITAL DEVICES

I How can I make sense of all the jargon in computer ads? Computer ads are loaded with jargon and acronyms, such as RAM, ROM, GHz, GB, and USB. You're sure to spot lots of this computer lingo in ads

like the one in Figure 2-22. The remaining sections of Module 2 delve into specifications for digital com ponents, You'll see how these components work and how they affect the way you work. By the end of Module 2, you should be able to understand the terminology in computer ads and use your knowledge to evaluate vari ous digital devices. FIGURE 2-22: COMPUTER A[)S ARE FULL OF JARGON

POWERFULLY LIGHT DO EVERYTHING YOU LOVE.

■ 7th Generation Intel Core 17 processor 3.5 GHz 1066 MHz FSB ■ 4 MB cache ■ 8 GB D0R3 1866 MHz RAM ■ 512 GB solid state drive

■ 13" high QHD LCD display screen ■ Intel integrated graphics ■ Integrated speakers ■ Integrated lOSOp megapixel webcam ■ 1 USB 3.0 port

■ 1 USB 3.0 port with PowerShare ■ 1 USB Type C port ■ Thunderbolt 3 port ■ SO card reader

■ Wireless networking 802.11 BGN ■ 52 Wh, 4-cell battery ■ Windows 10 64-bit operating system ■ Home/small business sotlware bundle

■ 2-7 pounds ■ l-year limited warranty

SECTION B

QUICKQUIZ 1.

Google and other Web service providers use

banks of| 2.

3. A(n)|

j 1o process and

I computer is the only

type of personal computer that must remain

manage data.

plugged into an electrical source during opera

Windows is the operating system used on

tion.

desktop and laptop PCs. What is the equiva

are the most popular digital

4.

lent operating system for Apple computers?

devices worldwide. 5.

Compatibility is primarily controlled by a device's

I system.

1 04

SECTION C, MODULE 2

System Board Components

Microprocessors

SECTION C

Memory

PROCESSORS AND MEMORY

ARCHITECTURE•That's how techies

Terminology

refer to the inner workings of digital devices. Sure, you can use a digital device

x86 ARM Instruction set

without understanding its architecture.

programming language machine language ALU

But to intelligently discuss the opportu nities and controversies of your digital world, you need more than a vague notion about microprocessors. Section C will help

registers control unit instruction cycle instruction

^

pointer microprocessor clock gigahertz multi-core processor serial processing pipetine

you keep your head above water when the

processing parallel processing cpu cache WORD SIZE

talk gets technical.

CISC RISC RAM capacitors volatile dynamic RAM

virtual memory rom boot loader

Objectives I Distinguish between the x86 and ARM processor standards.

I List at least three items that would be found in

» Describe the significance of microprocessor

I List three events that occur during the boot

instruction sets.

k Trace an instruction through RAM,the control

unit, and ALU as it Is processed. I List seven factors that affect microprocessor performance. I Use the pizza analogy to explain serial, pipeline,

and parallel processing.

RAM while you are using a digital device.

process.

t Explain why digital devices have ROM in addition to RAM.

I List four reasons for flashing ROM.

105

DIGITAL DEVICES

MICROPROCESSORS A microprocessor is an integrated circuit designed to process instructions.

It is the most important, and usually the most expensive, component of a digital device. The specifications for a microprocessor include the manufac turer's name and the chip model.

¥ Which processors are popular for desktops and laptops? Intel Corporation is the world's largest chipmaker and supplies a sizeable percentage of the microprocessors that power desktops and laptops. In 1971, Intel introduced the world's first microprocessor—the 4004. Intel's 8088 processor powered the original IBM PC, and chips in Intel's 8086 fam ily powered subsequent models of PCs manufactured by IBM and other companies.

The 8086 chip family set the standard for processors used in today's desk top and laptop computers, as well as servers. This standard is sometimes referred to as x86 because it includes chip models that originally ended in 86, such as the 8086, 80286, and 80386.

Modern processors no longer follow Intel's original numbering sequence, but x86 is still used when referring to the modern descendants of the 8086.

Processors found in today's desktops and laptops are x86 compatible,such as the Intel 13, i5, and 17 microprocessors (Figure 2-23), as well as Athlon and A-series processors manufactured by AMD.

QUICKCHECK What does x86 mean? a. It is the model of an Intel

chip. b. It designates low-power chips suitable for tablets and

smartphones. c. It Is used to refer to a

standard family of processors used in most desktop and laptop computers. d. It means the chip was manufactured by Intel.

FIGURE 2-23; INTEL PROCESSORS FOR DESKTOPS AND LAPTOPS

> Which processors are popular for tablets and smartphones? Whereas processors based on x86 technology are inside just about all

desktop and laptop computers, processors based on ARM technology dominate tablet computers and smartphones. ARM technology was origi nally designed by ARM Holdings, a British technology company founded by Acorn Computers, Apple Inc., and VLSI Technology. Today, ARM proces sors are designed and manufactured by companies that include NVIDIA, Samsung, and Nintendo.

QUICKCHECK Which processor would you be likely to find in an iPhone?

ARM-based processors are energy efficient—an important characteristic for devices that run primarily on battery power. ARM processors are found

a. Intel x86

in Microsoft's Surface tablets, Apple's iPads and iPhones, and Samsung's

b. ARM

lineup of Galaxy phones. The processors go by brand names such as Cortex and Apple A10. For Surface 2-in-1 tablet computers, Microsoft uses

c. Intel Core M3

Core M2 processors specially designed for low-power mobile devices.

d. 8088

SECTION C, MODULE 2

106

I Which microprocessor is best? The microprocessor that's best for you depends on your budget and the type of work and play you plan to do. The microprocessors marketed with the current crop of desktops and laptops can handle most business, educational, and entertainment applica tions. You'll want to consider the fastest processor offerings if you engage In processing-hungry activities, such as 3D animated computer games, desk top publishing, multitrack sound recording, and video editing.

> What microprocessor is in my favorite device? If you know the make and model of a digital device, you can generally find processor specifications by searching online. For example, searching for processor specifications iPhone 7 reveals that the phone contains an A10 chip with 64-bit architecture.

Although phones and tablets require an online search, desktops and lap tops offer an easier way to discover exactly what's inside (Figure 2-24). FIGURE 2-24: FIND THE PROCESSOR SPECIFICATIONS FOR A DESKTOP OR LAPTOP

TRY IT!

Find the processor specifications fcr»»g»

for your favorite desktop computer, laptop, or

Processor 2.13 GHz Intel Core 2 Duo macOS Sierra

smartphorre. How are the specs similar to or different from the

tmmm JU&Qw&anjOA

processor specifications shown

gi Mini NyeuMo-nusMmHt wwibpw caf

in Figure 2-24?

On a Mac desktop or laptop, selecting the Apple icon and then choosing About This Mac displays processor specifications, along with memory capacity.

-

□

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XPS13 9360

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lntel( R} Core(TM) i5-T2007U CPU @ 2

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009 2S 96024- 74 3

Processor

irrteflK) Co What happens inside a compLiter chlp?Amicroprocessorcon tains miles of microscopic circuitry and millions of miniature components divided into different kinds of operational units, such as the ALU and the control unit.

The ALU (arithmetic logic unit) is the part of the microprocessor that performs arithmetic operations, such as addition and subtraction. It also performs logical operations, such as comparing two numbers to see if they are the same. The ALU uses registers to hold data that Is being pro cessed. As an analogy, registers are similar to a mixing bowl you might use to hold the ingredients for a batch of cookies. The microprocessor's control unit fetches each instruction, in the same way you might get ingredients for cookies out of a cupboard or the refrig

QUICKCHECK When the control unit swings into action, which step comes first? a. Perform arithmetic

operations.

erator. Data is loaded Into the ALU's registers, just like you add all the

cookie ingredients to the mixing bowl. Finally, the control unit gives the ALU the green light to begin processing, just the way you flip the switch on your electric mixer to blend the cookie ingredients. Figure 2-26 illus trates a microprocessor control unit and its ALU preparing to add 5 + 4.

b. Load data into the ALU. c. Fetch an instruction. d. Execute the Instruction.

FIGURE 2-26: THE MICROPROCESSOR'S CONTROL UNIT AND ALU

Control Unit

♦►ADD

ADD

The control

unit

loads data into the The control unit

ALU for the addi

fetches the ADD

tion operation.

instruction.

QUICKCHECK Of course, the processor in Figure 2-25 would be using binary for the instruction and data. What is the binary

5"4

machine language instruction for ADD? (Hint; Look back at Figure 2-25.)

Microprocessor

a- 0000 0000

I What happens when a computer executes an instruction? The term instruction cycle refers to the process in which a computer exe cutes a single instruction. Some parts of the instruction cycle are performed by the microprocessor's control unit; other parts of the cycle are performed by the ALU. The steps In this cycle are summarized in Figure 2-27. FIGURE 2-27: THE INSTRUCTION CYCLE

1, Fetch an instruction.

2. Interpret the instruction.

4. Go to the next instruction.

3. Execute the instruction.

b. 0101 0100 c.

11101110

d. 11111111

109

DIGITAL DEVICES

> What role does the control unit play? The machine language instructions for a particular program are held in memory. When the program begins, the memory address of the first instruction is placed in a part of the

microprocessor's control unit called an instruction pointer. Figure 2-28 shows how the control unit can then go to the memory address (A) and fetch the instruction by copying data from that address into its instruction register {B). Next, the control unit interprets the instruction and executes it (C). FIGURE 2-28; PROCESSING AN INSTRUCTION

Memory

Control Unit

ALU QUICKCHECK

M1

i

Load 5 in Register 1

Instruction Pointer ll REG1 »

Ml

II

5

In Figure 2-28, what happens next?

M2

a. The control unit adds 2.

Load 4 in Register 2

Load 5 in Register 1

b. The instruction pointer

changes to M2. c. The processor checks AcGumu ator

M4 Put result in M5

register 2. d. 5 is added to 4.

instruction Register

I When does the ALU swing into action? The ALU is responsible for performing arithmetic and logical operations. As shown in Figure 2-29, the ALU uses registers to hold data that is ready to be processed. When it gets the go-ahead signal from the control unit (A), the ALU processes the data and places the result in an accumulator (B). From the accumulator, the data can be sent to memory or used for further processing. When the com puter completes an instruction, the control unit increments the instruction pointer to the memory address of the next instruction, and the instruction cycle begins again. FIGURE 2-29: THE ALU ADOS, SUBTRACTS, AND COMPARES

Memory Ml

Load 5 in Register 1

Control Unit Instruction Pointer

MS

ALU

■■ REG1

II

QUICKCHECK _

5

When the processor has

completed the instruction In M4,

M2

where is 9?

Load 4 in Register 2

a. In the accumulator

b. In the control unit c. In MS

Accumulator M4

9

Put result In M5

Instruction Register

d. In MS and the accumulator

SECTION C, MODULE 2

1 10

PERFORMANCE Now lhal you have some background on how microprocessors work, you can begin to appreciate what makes some microprocessors perform bet ter than others. A microprocessor's performance is affected by several factors, including ciock speed, number of cores, processing techniques, cache size, word size, and instruction set.

I What does GHz have to do with processor performance? A processor specification, such as 3.4 GHz, indicates the speed of the microprocessor clock—a timing device that sets the pace for executing instructions. Most computer ads specify the speed of a microprocessor in gigahertz. Gigahertz(GHz) means a biliion cycies per second. A specifi cation such as 2.13 GHz means that the microprocessor's ciock operates

at a speed of 2.13 biliion cycies per second. A cycle is the smallest unit of lime in a microprocessor's universe. Every action a processor performs is measured by these cycies. it is customary to equate clock cycles with the number of instructions a processor can execute per second. There is not always a one-to-one correspondence, however. Some instructions are processed within one ciock cycle, but other instructions might require multiple cycies. Some processors can even execute several instructions in a single clock cycle.

QUICKCHECK Which one of the following statements is true?

a. A microprocessor executes

You might expect a computer with a 2.13 GHz processor to perform

one instruction for each ciock

slower than a computer with a 3.4 GHz processor. This is not necessar ily the case. Ciock speed comparisons are only valid when comparing processors within the same chip family. A 2.13 GHz processor could outperform a 3.4 GHz processor. Why? Because factors other than clock speed contribute to the overall performance of a microprocessor.

cycle.

► What's a multi-core processor? The "core" of a microprocessor consists of the control unit and ALU. A microprocessor that contains circuitry for more than one processing unit is called a multi-core processor. Having more cores usually equates to faster performance. The 2.4 GHz Intel i5 pro cessor has two cores, giving it the equivalent of 4.8 GHz performance (2.4 x 2). The 1.6 GHz Intel 17 processor has four cores, giving it the equivalent of 6.4 GHz perfotmance (1.6 x 4). Figure 2-30 illustrates a microscopic view of a processor with multiple cores.

b. A 2.4 GHz Intel 15 processor is faster than a 1.6 GHz Intel 17 processor.

c. Clock speed is the most important factor that affects

processor performance. d. A multi-core processor can outperform a single-core processor that has a faster clock speed.

FIGURE 2-30: FOUR CORES OF AN INTEL FOURTH-GENERATION MICROPROCESSOR

Terminology The thin wafer of silicon and

the microscopic circuitry it contains is called a die.

I, .

vr.l Kr - V>;; —

...

Figure 2-30 Illustrates a microprocessor die with four

!;n ~

-

l| •

I i Core 1

Core 2

Core 3

Core 4

cores.

111

DIGITAL DEVICES

I Can a microprocessor execute more than one Instruction at a time? Some processors execute instructions "serially"—that is. one instruction at a time. With serial processing, the processor must complete all steps in the instruction cycle before it begins to execute the next instruction. To use an analogy, visualize a pizzeria with one small oven. The pizzas are instructions; the oven is the microprocessor. Pizzas (instructions) are processed one at a time.

QUICKCHECK Many of today's digital devices are capable of parallei processing because:

Now, what if the pizzeria rigs up a conveyor-belt through the oven. A pizza (instruction) starts moving along the conveyor belt into the oven; but before it reaches the end, another pizza starts moving along the belt. When a pro cessor begins to execute an instruction before it completes the previous

a. Their processors have

instruction, it is using pipeline processing.

c. They can run more than one program at a time.

A pizzeria might also have large ovens that hold multiple pizzas. Just as these ovens can bake more than one pizza at a time, parallel process ing executes more than one instruction at a time. This efficient processing technology is possible with today's multi-core microprocessors. Pipeline and parallel processing offer better performance than serial pro cessing (Figure 2-31). FIGURE 2-31: SERIAL. PIPELINE. AND PARALLEL PROCESSING

Instruction 3

Instruction 2

Instruction 1

Serial Processing The CXi'CUtiOii LYCle for iresch instruction muit he? completed bt'fcre the ncvi fn'ilructior^ i& ••xecuted.

Instruction 3

Instrud

Pipeline Processing ;.)f.' .ill four

CPU

of the

rxt'cution cycle for Instruction 1 .)tf iiic C?0 begins to

bn 1 ninni kio'Oim

t'xvdJlo Inslfuclion 2.

Instruction 3 oioAtoTpiemiitt

Instruction 4

CPU t:. 'm . I I ►. i r. ^ r'

Parallel Processing The CPU oxucuies multiple instructions at the same time.

oioonooiooioitn

multipie cores.

b. They have pipelining.

d. They have high GHz specifications.

SECTION C, MODULE 2

1 12

I How does cache size affect performance? CPU cache (pronounced "cash") is special high-speed memory thai allows a micropro cessor to access data more rapidly than from memory located elsewhere on the system board. A large cache can increase processing performanceCPU cache is structured Into several levels. Level 1 cache (LI) Is the fast est, whereas Level 2(L2)and Level 3(L3)are slightly slower but still faster than accessing main memory or disk storage. Cache capacity Is usually measured in megabytes,

I What impact does word size have on performance? Word size refers to the number of bits that a microprocessor can manipulate at one time. It corresponds to the size of the registers used by the control unit and ALU. A processor with a 64-blt word size, for example, has regis ters that can process 64 bits at a time. Word size controls the amount of memory that the processor can access. Processors with a 32-blt word size can access a maximum of 4 GB of

memory, whereas processors with a 64-blt word size can potentially access many terabytes of memory. A large word size gives processors the ability to handle more data dur ing each processing cycle—a factor that leads to Increased performance. Today's digital devices typically contain 32-blt processors or 64-blt pro cessors. In a computer with a 32-blt word size, registers that hold data and those that hold Instructions all have capacity for 32 bits(Figure 2-32).

TRY IT! Take another look at the

processor specifications for your favorite desktop or laptop

computer. Can you tell if its processor has a 32-blt or 64-bit word size?

FIGURE 2-32: A REGISTER HOLDS A 32-BIT WORD

Oil

101100100101111

The bits in this 32-bit register could be an instruction or an Item of data that Is waiting to be processed.

I How does an instruction set affect performance? As chip designers developed various Instruction sets for microprocessors, they added Increasingly complex instructions, each requiring severai clock cycles for execution. A microprocessor with such an instruction set uses

QUICKCHECK x86 processors use

CiSC (complex Instruction set computer)technology. A microprocessor with a limited set of simple instructions uses RISC (reduced instruction set com puter) technology.

A RISC processor performs most instructions faster than a CISC processor. It might, however, require more of these simple Instructions to complete a task than a CISC processor requires for the same task. Most processors In today's desktop and laptop computers use CISC tech nology. Many processors In handheld devices, such as smarlphones and tablets, use ARM (Advanced RISC Machine)technology.

a. RISC technology b. CISC technology c. ARM technology

113

DIGITAL DEVICES

RANDOM ACCESS MEMORY

RAM (random access memory) is a temporary holding area for data, application program instructions, and the operating system, RAM can be packaged in a chip carrier that is wired to the system board or it can be located on small circuit boards that plug into the system board.

I How much RAM does a device need? When purchasing a digi tal device, you may have a choice of RAM capacity. Higher RAM capacity adds to the expense of a device. RAM capacity is expressed in gigabytes. Today's desktop and laptop computers typically feature 2-8 GB of RAM. Handheld devices usually have 1-3 GB of RAM.

TRY IT! Find out how much RAM is in

your favorite digital device. If you're working with a laptop or desktop, you can access RAM

specs the same way you found the processor specifications.

> But my smartphone has 64 GB, right? Your smartphone has RAM, but not 64 GB. The specifications for smartphones that describe "memory" capacity are not referring to RAM, but to another kind of storage that is more permanent. You'll learn more about this type of storage in the next section. For now, let's focus on RAM and why it is such an essential

component of your favorite digital devices.

► Why is RAM so important? RAM is the "waiting room" for the microprocessor. It holds raw data waiting to be processed as well as the program instructions for processing that data. RAM also holds the results of processing until they can be moved to a more permanent location such as an internal drive, flash drive, or cloud storage. In addition to data and application software instructions, RAM also holds operating system instructions that control the basic functions of a com puter system. These instructions are loaded into RAM every time you turn on a digital device, and they remain there until you turn off the device (Figure 2-33). FIGURE 2-33: RAM HOLDS THE ELEMENTS FOR CURRENT TASKS

WORD Operating SYSTEM

ProrcsstnfJ Software

ALDIO Software

J tic ijtikV jimipi'il ttio

du:'

Kilty iVm Koai

O

I How does RAM work? In RAM. microscopic electronic parts called capacitors hold the bits that represent data. You can visualize the capaci tors as microscopic lights that can be turned on or off. A charged capacitor is "turned on" and represents a "1" bit. Adischarged capacitor is "turned off' and represents a "0" bit. A RAM address on each bank helps the computer

locate data, as needed, for processing.

QUICKCHECK

The programs and data in RAM disappear when .

Unlike disk storage, most RAM is volatile, which means it requires electri cal power to hold data. If the device is turned off, if the battery runs out of juice, or If a desktop computer is accidentally unplugged or experiences a power failure, all data stored in RAM instantly and permanently disappears.

a. the device goes to sleep

This type of RAM is technically classified as dynamic RAM (DRAM), but it is commonly referred to simply as f3AM.

d. all of the above

b. the device is turned off

c. you close a program

1 14

SECTIOf^ C, MODULE 2

► Can a device run out of memory? Suppose that you want to work with several programs and large graphics at the same time. Will your device eventually run out of memory? The answer Is probably not. If a program exceeds its allocated space, the operating system uses an area of the hard disk or other storage medium as virtual memory to store parts of programs or data files until they are needed. By selectively exchanging the data in RAM with the data in virtual mem

ory, your computer effectively gains almost unlimited memory capacity. Too much dependence on virtual memory can decrease performance, however, especially if virtual memory is located on a relatively slow mechanical device, such as a hard disk drive.

READ-ONLY MEMORY ROM (read-only memory) is a type of memory circuitry that is housed in a single Integrated circuit on the system board. Whereas RAM is tempo rary and volatile, ROM is more permanent and non-volatile. The contents of ROM remain in place even when the device is turned off.

I Why do digital devices have ROM? When you switch on a digi tal device, there is a waiting period while the device gets ready for use. While you are waiting, ROM is performing its role to "boot" the device. The boot process varies from one kind of device to another; but in gen eral. it begins when you press the power button and ends when the

Terminology A ROM chip, along with its instructions, Is commonly referred to as firmware because it is a combination of hardware and software.

device is ready to useROM contains a small set of instructions and data called the boot loader.

The boot loader instructions tell a digital device how to start. Typically, the boot loader performs self-tests to find out if the hardware is operating properly and may also verify that essential programs have not been cor rupted. It then loads the operating system into RAM.

I Why isn't the boot loader stored in RAM? RAM requires power to hold data. When a device is off, RAM Is empty. When you turn on the device, RAM is still empty and doesn't contain any instructions for the microprocessor to execute. ROM, on the other hand, holds data even when the power is off. As Figure 2-34 shows, when you press the power button (A), your device can immediately access the instructions in ROM and proceed with the startup routine (B). Only when the startup is com plete can you access apps and data (C).

QUICKCHECK While you are waiting for a digital device to boot, all of the following occur except:

a. The microprocessor fetches data from the ALU.

b. The boot loader checks hardware functions.

FIGURE 2-34: WHY THE WAIT?

c. Instructions in ROM verify

E>(!) 0

RAM

that essential programs have

When you power

not been corrupted.

on a device, you

d. The operating system is

have to wait for

loaded into RAM.

the boot loader program.

Operating system

ROM Ready!

Boot Loader Check hardware

Verify software Load the operating system

1 15

DIGITAL DEVICES

> Can I change the contents of ROM? The process of changing the contents of ROM is sometimes called "flashing" because it is similar to the way a camera flash helps the camera capture an image. There are sev eral reasons that you might want to change the contents of ROM and boot loader instructions.

Repair. Electrical surges and other hardware problems might corrupt the contents of ROM, which would prevent the device from powering on prop erly. Flashing the ROM to restore the boot loader instructions might correct the problem.

Terminology There are many types of nonvoiatile memory, such as EEPROM and NAND, but for convenience the term ROM Is

used for all of them. Technically, the contents of ROM cannot

User modification. The boot loader may limit the programs that can be

be changed. The EEPROM and

downloaded and run on a device. Flashing the ROM with a modified boot loader can bypass these limitations. The process is sometimes called "jail-

NANO chips that hold the boot loader programs for modern

breaking" on iOS devices and "rooting" on Android devices. These ROM modifications may cause more problems than they solve and may void the

flashing.

computers can be changed by

device's warranty.

Forensics. Tricky criminals may hide incriminating data in ROM, or they may alter the boot loader so that it deletes incriminating files when the device is powered on by an unauthorized person, investigators may want to

examine the BIOS for hidden data, and they may have to flash the BIOS to restore it to a non-destructive state.

Updates. Device manufacturers offer updates to the boot loader as neces sary to patch security weaknesses. Such updates are performed by running a program supplied by the manufacturer. Be sure to back up your device before flashing, and carefully follow instructions for this procedure. If the flash fails, your device will not start until you get the ROM chip replaced. After a successful update (Figure 2-35), your device should boot normally.

TRY IT!

What does Apple have to say about jailbreaking iPhones

and iPads? You can find out by conducting an online search for

support apple jailbreak.

FIGURE 2-3S: ROM UPDATE

Soot Instructions v 2.0

The ROM chip con taining the boot

The process of flashing

loader is located on

of ROM and replaces

the system board.

it with a new set of

erases the contents

instructions.

SECTION C

QUiCKQUiZ 1.

A laptop with an Intel Core i7 microprocessor

operates at a speed of 3.4|

.

(Hint: Use the abbreviation.) 2.

3.

4.

Because RAM is

, it cannot

retain data in a device that is turned off.

g

The instructions for loading the operating system

8088, i7, and Athlon A6 are

into RAM when a device is Rrst turned on are

compatible microprocessors.

stored in

The two main parts of a microprocessor include

acronym.

the

and the control unit.

. (Hint: Use the

1 16

SECTION D, MODULE 2

Cloud

Storage Options Magnetic

Optical

Solid State

SECTION

STORAGE

HARD DRIVES, CDS,dvds,flash drives, memory cards. What's the point of having so many storage options? As it turns out, none of today's storage tech nologies are perfect. In this section, you'll find guidelines that can make you a smart storage technology buyer and owner.The storage technologies you'll learn about are used in a variety of devices —from

digital cameras to player pianos —so an understanding of storage technology can be useful even outside the boundaries of

Terminology local storage magnetic storage hard disk drive hard disk platter read-write head head crash access time data transfer rate

optical storage read-only recordable rewritable solid state storage non-volatlle

memory card card reader solid state drive

USB flash drive remote storage cloud storage BACKUP recovery drive file synchronization disk Image

personal computing.

Objectives t List five criteria for comparing storage options. t Describe the relationship between storage and memory.

t Identify the technology used for hard disk

I Explain the significance of ROM,R,and RW for optical storage. ¥ Evaluate whether to use local or cloud storage for various projects.

drives, DVDs, USB drives, and other storage

I List at least four common backup pairings.

accessories.

I List four backup tools available to Windows

I Inteipret the storage specifications given for digital devices. I State the advantages and disadvantages of devices that use magnetic storage technology.

t fMame three types of optical storage media.

users.

I Explain the process of restoring a Windows

computer after a hard drive failure. I Describe the backup options for macOS and iOS devices.

DIGITAL DEVICES

117

STORAGE BASICS

Storage is the term used for the components of a digital device designed to hold data permanently. Unlike RAM, storage is non-voiatile and retains data even when the device is powered down. Storage is used to save doc uments, photos, and piayiists. it also houses software and the operating system.

Today's digital devices may use local storage and remote storage, but they are not interchangeable. To find out what gets stored where, let's look at local storage first, then expand into remote storage.

t Which local storage technology is best? Local storage refers to storage devices and media that can be directly attached to a computer, smartphone, or appliance. Local storage options include hard drives, CDs, DVDs,flash drives, solid state drives, and memory cards. Most digital devices have some type of local storage that is permanently available as you use the device. Built-in storage can be supplemented by removable storage, such as flash drives and memory cards. Each of these local storage options has its advantages and disadvantages,

if one storage system were perfect, we wouldn't need so many storage devices connected to our digital devices! To compare local storage options, it is useful to review their durability, dependability, speed, capacity, and cost (Figure 2-36). FIGURE 2-36: EVALUATING STORAGE OPTIONS

Durability Resistance to damage from handling and

environmental factors such as dust, humidity, heat, and cold. Can be measured in lifespan or in write cycles [the number of times data can be written and revised).

Dependability Available when needed; not subject to breakdown,

malfunction, network outages, or service interruptions. Can be measured by mean time between failures(MTBF is the time a device is

expected to function before failing). Cloud storage service dependability can be measured by uptime

(the percent of time the service is accessible).

Speed The rate at which data can be stored or accessed.

Faster is better. Can be measured by data transfer rate (the number of megabytes per second that are read or written by the storage device).

Capacity The amount of data that can be stored,

usually measured in gigabytes(GB)or terabytes (TB).

Cost The price of the storage device and media,

usually expressed per gigabyte(GB).

A

SECTION D, MODULE 2

1 18

I How much Storage do I have? The amount of local storage avail able on a digital devices depends on the capacity of each storage device and the amount of data that is currenliy stored. Avaiiabie storage space is sometimes referred to as "free space." The process of finding the amount of

free space depends on the device. Figure 2-37 can get you started. FIGURE 2-37: ARE YOU RUNNING OUT OF STORAGE SPACE?

macOS(Macs)

Windows(PCs)

1. Right-click the

HQ®

Macintosh HD icon.

1. Enter storage in the Windows Start menu, then

select the Storage option.

B«st mauh

CS

2. Select Get Info. SflRin9s

■S Slonge Space

Open

^ Default save locations

Get Info i Manage Stonge Spaces

Rename

Manage Storage... Duplicate

2. Select a storage device,

Make Alias

Quick Look "Macintosh HD"

such as C;.

® Storage Storage Otfow a

Macintosh HO Info

TRY IT!

ft MacfntQahHD

.1 of 2J5GB

How close are you to running

Hov 6.201B.9:10 AM

Owige

yCMf afpi. OetufBCMv muffe piduPM wid ^Ueos

▼ Genwak HnS: Ve 1

V»raiMi- 10171

:OS Extendeo I

'CVMitv: 250.14 CO Avai!aei«: 65.23 GB(846J MB p(?eesble) used: 164,906,050,077 Bytes 1184.91 GB on disk)

out of storage space on your favorite digital device? Check now to find out. For laptops and desktops, follow the steps In Figure 2-37. For IDS

tablets and phones, select Settings->General->About. For Android devices, select Settings-^More-^Storage.

"SUIEUIlMf

• How do storage technologies work? You can think of your computer's storage devices as having a direct pipeline to RAM. Data gets copied from a storage device into RAM, where it waits to be processed. After data is processed, it is held temporarily in RAM, but it is usually copied to a storage medium for more permanent safekeeping. As you know, a computer's processor works with data that has been coded into bits that can be represented by Is and Os. When data is stored, these Is and Os must be converted into some kind of signal or mark that's fairly permanent but can be changed when necessary.

Obviously, the data is not literally written as "1"or"0." Instead, the Is and Os must be transformed into something that can remain on a storage medium. Exactly how this transformation happens depends on the storage technol ogy. For example, hard disks store data in a different way than CDs. Three types of storage technologies are commonly used for personal computers: magnetic, optical, and solid state.

Terminology The process of storing data is often referred to as writing data

or saving a file because the storage device writes the data on the storage medium to save It for later use.

The process of retrieving data

Is often referred to as reading data, loading data, or opening a file.

1 19

DIGITAL DEVICES

MAGNETIC STORAGE TECHNOLOGY Those big reels of tape that you see on computers in classic science fic tion movies are an example of magnetic storage technology used on data processing era mainframe computers. The first personal computers used cassette (apes for storage, though floppy disk storage was soon available. Today, magnetic storage technology is the foundation for the hard disk drives in desktop computers, laptops, and enterprise servers.

► What is magnetic storage technology? Magnetic storage represents data by magnetizing microscopic particles on a disk or tape surface. The particles retain their magnetic orientation until that orienta tion is changed, providing permanent but modifiable storage for data. Data stored magnetically can be easily changed or deleted simply by changing the magnetic orientation of particles on the disk surface. This feature of magnetic storage provides lots of fiexibility for editing data and reusing areas of a storage medium containing unneeded data. •

How does a hard disk drive work? A hard disk drive contains

one or more platters and their associated read-write heads. A hard disk platter is a fiat, rigid disk made of aluminum or glass and coated with mag netic iron oxide particles.

Terminology You might hear the term fixed disk used to refer to hard disks. You often see the terms hard disk and hard disk drive

used interchangeably, though technically hard disk refers to the platters sealed inside the hard disk drive.

The platters rotate as a unit on a spindle, making thousands of rotations per minute. Each platter has a read-write head that hovers just a few microinches above the surface. A read-write head mechanism in the disk drive

magnetizes particles to write data, and senses the particles' polarities to read data (Figure 2-38).

FIGURE 2-38; ORIENTING PARTICLES ON A HARD DISK

QUICKCHECK Disk surface

What is the purpose of a readwrite head?

Read-wnte head

a. It puiis particles up as data is read.

Magnetized particles

b. It etches a track on the disk surface.

Randomly scattered

particles

c. It orients partides north or south depending on If they represent Os or Is.

Before data Is stored on a hard disk, particles on the disk surface are scattered in random patterns. The disk drive's read-write head orients them in a positive (north) or negative (south) direction to represent 0 and 1 bits, respectively.

I What are the advantages of hard disk drives? Hard disk drives can be installed inside a device or attached externally for additional stor age capacity or backup. Hard disk technology has three advantages. First, it provides lots of storage, with capacities ranging from 40 GB to 8 TB. Second, it provides fast access to files. Third, hard disk drives are economi

cal. The cost of storing 1 gigabyte of data is about two cents.

1 20

SECTION D, MODULE 2

> What's the downside of hard disk storage? Data stored on magnetic media can be unintentionally altered by magnetic fields, dust, mold, smoke particles, heat, and mechanical problems with a storage device. Over time, magnetic media gradually lose their magnetic charge. Some experts estimate that the reliable lifespan of data stored on magnetic media is about three years. They recommend that you refresh your data every two years by recopying it. The read-write heads in a hard disk drive hover a microscopic distance above each platter. If a read-write head comes into contact with the platter, the head crash is likely to damage the platter and corrupt the data con

tained on it. The causes of a head crash are explained in Figure 2-39. FIGURE 2-39: WHAT CAUSES A HEAD CRASH?

Dropping a device may cause the read-write head to bounce off the surface of the platter, scraping off particles tiial represent data.

dust particles or other contaminants

seep into the drive case, they may come to rest on a platter where the read-write head will crash into them.

I What should I know about hard disk drive specifications? Computer ads commonly specify (he capacity, access time, and speed of a hard disk drive. For example,"2 TB 8 ms 7200 RPM HDD" means a hard

disk drive with a 2 terabyte capacity, an access time of8 milliseconds, and a speed of 7,200 revolutions per minute.

QUICKCHECK if you see an ad for a computer with a 6 ms hard drive, you can assume that 6 ms refers to the

drive's

.

Access time is the average time it takes a computer to locate data on the

storage medium and read it. Hard disk access times of 6 to 11 ms are not

a. access time

uncommon. Hard disk drives have much faster access times than CDs,

b. capacity

which take about 500 ms to spin up to speed and find data.

c. rotational speed

Hard disk drive speed is sometimes measured in revolutions per minute (rpm). The faster a drive spins, the more rapidly it can position the readwrite head over specific data. For example, a 7,200 rpm drive is able to access data faster than a 5,400 rpm drive.

d. data transfer rate

When comparing hard disk drives to other storage technologies, data trans fer rates can be useful. Data transfer rate is the amount of data a storage device can move per second from the storage medium to RAM. Higher

numbers indicate faster transfer rates. The average data transfer rate for a hard disk drive is about 57,000 KBps (also expressed as 57 MBps or MB/s).

TRY IT! Check online. What's the

average price for a 2 TB hard drive?

121

DIGITAL DEVICES

OPTICAL STORAGE TECHNOLOGY Devices that store data on CDs, DVDs, and Bio-ray discs may seem out

dated, yet optical technologies remain useful for archival storage because they can provide a permanent home for collections of documents, music,

QUICKCHECK

and photos that you might not trust to less robust storage technologies.

Optical storage devices read and record data using ..

I How does optical technology work? CD, DVD. and Biu-ray(BD)

a. a read-write head

technologies are classified as optical storage, which represents data as microscopic light and dark spots on the disc surface. An optical drive con tains a laser that directs a beam of light toward the underside of the disc. Reflected light is collected by a lens and converted into Os and Is that rep

b. a laser lens

c. dark and light spots d. electron microscopes

resent data.

ft How do CD, DVD, and B!u-ray technologies differ? A single optical drive typically handles CDs, DVDs, and Biu-ray discs, but the costs and capacities of these discs vary (Figure 2-40). FIGURE 2-40; OPTICAL STORAGE OPTIONS

CD

DVD

Blu-ray

650 MB 15e

4.7 GB 25(1;

25 GB 504;

CD (compact disc): Designed

DVD (digital video disc or digital versatile disc): Designed with the

Biu-ray (BD): Designed to hold

to hold 74 minutes of recorded

high-definition lOSOp video by offering 25 GB storage capacity. the blue-violet colored laser used

to 80 minutes of music or 700 MB

capacity to hold a feature-length film. A single-sided DVD offers 4.7 GB (4,700 MB) of data storage. A double-layer DVD has two record able layers on the same side and

of data.

can store 8.5 GB of data.

near Infrared laser.

music, then adapted for computer

storage with capacity for 650 MB of data. Later improvements iri CO standards increased the capacity

The name Biu-ray is derived from to read data. DVD technology uses

a red laser; CD technology uses a

ft What's the significance of ROM, R, and RW? Optical technolo

Terminology

gies are grouped into three categories;

Writing data on a CD, DVD,or BD is often called burning because the laser essentially burns a pit

Read-only (ROM). CD-ROMs and DVD-ROMs are mass produced. Their contents cannot be changed; their lifespan is estimated to be 100 years.

in the disc.

Recordable (R). Data can be written on a recordable disc by consumer devices, but once written, the data cannot be changed. Lifespan: 100 years. Rewritable (RW). Data can be written on the disc and later changed. The estimated lifespan of data is about 30 years.

ft How durable are optical discs? Optical discs are not disrupted by humidity, fingerprints, dust, magnets, or spilled soft drinks. Some optical discs have an estimated lifespan of at least 30 years, while other types of optical discs can probably hold data securely for up to 100 years. When using optical technology for archival purposes, the archive should include an optical drive as well as the media containing data. The drive that recorded the data will have the best chance of reading it as the years go by.

QUICKCHECK Which cplical technology

performs most similarly to a hard disk drive? a. RAM

b. ROM c. R

d. RW

122

SECTION D. MODULE 2

SOLID STATE STORAGE TECHNOLOGY If you're a typical digital device owner, you use solid state storage every day. You carry a flash drive and you might swap memory cards in a camera or tablet. The main storage for your smartphone is also based on solid state technology, as is the storage for many of today's laptops.

I What is solid state storage? Solid state storage (sometimes called flash memory) stores data in erasable, rewritable circuitry, rather than on spinning disks or streaming tape. Each data bit is held in a gate-like circuit that can be open or shut. Very little power is required to open or close the gates, which makes solid

state storage ideal for battery-operated devices, such as digital cameras and media players. Once the data is stored, it is non-volatile—the circuits retain data without the need for an external power source. Solid state storage provides fast access to data because it includes no QUICKCHECK

moving parts. This storage technology is very durable—it is virtually imper vious to vibration, magnetic fields, or extreme temperature fluctuations. It Is also dependable. With no mechanical parts, it is less likely to fail than a

and RAM similar?

hard disk drive.

a. They are volatile.

I When should I use memory cards? A memory card is a flat, solid

b. They are non-volatile.

state storage medium commonly used to transfer files from digital cameras and media players to computers. The term memory card might lead you to believe that it is similar to random access memory (RAM). However, these cards are non-volatile, so they retain data even when they are disconnected from computers and other devices. The formats for memory cards include CompactFlash, MultlMediaCard,

In what way are memory cards

c. They are for temporary storage. d. They are solid state.

TRY IT!

Secure Digital (SD), and SmartMedia. A card reader is a device that reads and writes data on solid state storage. Sometimes referred to as 5-in-1,

Check the device you are currently using. Does it have a

7-in-1, or all-in-one card readers, these combination devices work with mul

built-in card reader?

tiple types of memory oards (Figure 2-41),

FIGURE 2-41: SOLID STATE MEMORY CARDS

card roader

Memory cards are available in

Many difjital devices are equipped with a card reader for

several formats and capacities.

transferring data to and from solid state memory cards.

123

DIGITAL DEVICES

I Do I need a solid state drive? Asolid state drive(SSD)is a pack

age of flash memory that can be used as a substitute for a hard disk drive. An SSD is instaiied inside the system unit and is not meant to be removed except for servicing. Some soiid state drives are about the same size as

a microprocessor chip; others are about the size of a smali deck of cards (Figure 2-42). FIGURE 2-42: SOLID STATE DRIVES

35 What is cloud storage? Storage that is built into a digital device or that can be plugged directly into a device is classified as local storage. In contrast, remote storage is housed on an external device that can be accessed from a network. Remote storage may be available on a home, school, or work network. It can also be available as an Internet service, in

which case it is called cloud storage. Cloud storage is provided to individuals by services such as Apple iCIoud, Microsoft OneDrive, Google Drive, and Dropbox. The basic concept is that files can be stored in a subscriber's cloud-based storage area and accessed by logging in from any device. In a simple implementation, cloud storage functions just like a local drive (Figure 2-43). FIGURE 2-43: DROPBOX IS IN THE CLOUD BUT ACCESSED LIKE A LOCAL DRIVE to Orvba

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QUICKCHECK Which of the following is a good substitute for a hard disk drive? a. An SSD

b. A memory card c. A USB flash drive d. ADVD-RW

124

SECTION D, MODULE 2

Some cloud implementations offer a synchronization feature that automati cally dupiicates fiies stored on a local device by aiso saving them in the cioud (Figure 2-44), FIGURE 2-44: CLOUD SYNCHRONIZATION

Motocross.docx •••••••••

Files stored while offline are added to

Fina Scores.x sx

the cloud the next

time you go online.

When you're offline, files are

files are saved on

saved on a local

a local drive and to

drive.

the cloud-

When you're online,

•Motocross.docx

FinalScores.xisx

I What shouitJ I know about cloud storage? The term c/oud storage refers to a set of technologies for transporting, synchronizing, and managing data stored on banks of high-performance hard disk drives housed in the service provider's data center.

Most cloud services offer a generous amount of free storage space, so the price is right. If you regularly use several digital devices and want to access

your files from all of them, then cloud storage is an exceiient soiution. Also, if you procrastinate about backing up your devices, files stored in the cioud remain there even if a iocai device maifunctions. That being said, cloud storage has several drawbacks. Security and privacy risks. The more places your data is stored and the more networks on which it traveis, the more susceptible it becomes to inter

cepts from hackers and government spying agencies. Carefuliy consider what you store in the cloud. QUICKCHECK

Service outages. When a cloud storage site has an outage, aii the data stored there becomes temporariiy inaccessibie. if you have a term paper due in two days, it wouid be best not to trust the only copy to cioud storage

Cioud services generally use

where a two-day outage couid make your files inaccessible until after the

a. Magnetic

what type of storage devices?

due date.

b. Optical

Discontinuation of service. Some cioud storage providers have shut

tered their storage services with little warning to customers. Cloud storage may offer a convenient option for backing up your fiies, but don't depend on it as the oniy backup.

c. Flash d. Cloud circuits

125

DIGITAL DEVICES

BACKUP

TRY IT!

Storage devices fail. Cloud storage services go dark. When they do, the data they contain might not be recoverable. To protect your data, you need backups. Do you have them? Do they contain the files you'll need to resume work without a hitch?

How many GB of data would be stored in a backup of the entire contents of your desktop or

more files that Is made in case the originals become damaged. Although

laptop computer? (Hint; Figure 2-37 showed you how to check the amount of space that is used

the best practice might seem to be "back up everything," that is not always

on a local hard disk.)

► What do I really need to back up? A backup Is a copy of one or

practical. Your files are often scattered—some on a local hard disk, others on USB

drives, some on your phone, and even others on cloud storage. Simply copying all of your files from one device to another or to the cloud requires lots of space and lots of time. Plus, there are some sticky technical Issues that make It difficult to actually get a complete backup. To understand the problem, consider what a typical hard disk contains (Figure 2-45). FIGURE 2-45; WHAT CAN YOU AFFORD TO LOSE?

.«os

ACOS

Operating system: The operating system Is required to start your device, but a backup copy might not run if It Is unauthorized.

Software: Most devices are populated with prelnstalled software, and you've probably downloaded and

Installed many additional apps. If these are wiped out when a storage device fails, the process of downloading and reinstalling them can be time consuming.

A—I A—I A—I Data files: Your documents, photos, music, videos—all

r=: f^= r^= the goodies that you've created and gathered—can be I ^^1 I ^^1 difficult or impossible to reconstruct from scratch.

ooo ooo

Settings, accounts, and profiles: How much time did you spend customizing your home screen, entering con

tacts, choosing passwords, and setting preferences for your favorite apps? No one wants to have to do that all over again!

• Then what should I do? The best advice is this: Know what's Impor tant and ensure that current versions exist on more than one storage device. The easiest pairings of devices for backups are illustrated In Figure 2-46.

FIGURE 2-46: BACKUP PAIRINGS

Back up hard

Back up hard disk

Back up handheld

1

Back up handheld

Back up cloud

disk to cloud

to external drive

to hard disk

to cloud

to hard disk

■7

1^

1 26

SECTION D, MODULE 2

I What tools do I need for backups? The lools you'll need depend on what you are backing up and where you are putting the backups. If you are a typical consumer with a laptop and a smartphone, you will need a cloud storage account, an external hard disk drive, synchronization soft ware, a blank USB flash drive, and backup or disk imaging software.

I I've got a Windows PC, What should I do? Windows users have access to several backup tools and will need to use more than one of them. Recovery drive. A recovery drive (or system repair disc) contains parts of the operating system necessary to boot your computer and diagnose system problems after a hard drive faiiure or software malfunction. Files

for creating a recovery drive are usually preinstalled on the hard disk drive, but they won't do you any good there when the hard disk fails. Follow the

manufacturer's instructions to move the recovery files to a blank USB flash drive, which you can store until it is needed. Copy command. As you are working on important projects, make cop ies of essentiai files. You can store the copies on the same device as the originals using versioning techniques, such as adding 'mT and "vS" to the file names of versions. And for safety, periodically copy a version to a USB drive or to cioud storage. You can manualiy create copies of your data files

using the Copy option in Windows File Explorer. File History. Data file backup can be automated using File History, which is included with Windows 8.0 and subsequent versions. File History uses file synchronization to make copies of files from your Documents, Music, Pictures, and Videos foiders, aiong with any files that were created or mod ified whiie OneDrive was offline. File History is useful if a data file goes missing, but it requires the System image Backup option for system files, software, and settings. File History is easy to set up (Figure 2-47). FIGURE 2-47: ACTIVATE FILE HISTORY

9File Klfloiy

-

V O

- T e" Smw" i"*! Setuflty'FileHistoiy

□

X

Search Coriirol - P

Control Panel Home

Keep a history of your files

Restore personal files

File History saves copies of your liles so you can gel them back If ihe/te lost or damaged.

Select drive

Lzdude folders

1. To activate File History,

V File History is ofl

connect an external drive and then click the Turn

Advanced settings Copy rues from:

on button.

Utxaries. t

Removable Disk (W SaOGBIreeofS&aOB

Tun on

See also

Recovery ' System Image Sactup

2. Select the System Image Backup option, then follow the

prompts to select a location.

File History can be configured to store backups on an external hard drive, a high-capacity USB flash drive, or a cloud storage service. The system image requires more space than is available on most USB flash drives.

QUiCKCHECK Which backup tool can be used to boot a Windows computer after a hard drive maifunction?

a. A recovery drive

b. The Copy command c. File History d. A cloud drive

127

DIGITAL DEVICES

System image, A disk image is a bit-for-bit copy of the data from all sec tors of a hard disk. Windows includes a disk imaging option called System

Image that creates an exact clone of the original disk, including the oper ating system, your software, and all your settings. Be sure to select the System Image Backup option In the File History window to activate it.

I If my computer's hard drive fails, how do I proceed? First, a new hard drive has to be installed. Then, as shown in Figure 2-48,(A) use

the recovery drive to boot the computer. Then,(B) attach the backup drive containing your system image. Respond to the prompts displayed on the

screen to copy the system image to the new hard disk. After the system image is installed, recover your files by using the File History utility. FIGURE 2-48: RESTORING WINDOWS AFTER A HARD DISK CRASH

QUICKCHECK in Figure 2-48, what is stored on the USB flash drive? a. All the files that the user has

backed up b. Parts of the operating system

needed to boot the computer Recovery drive

c. A system Image

Backup drive

I I have a Mac. What's my best backup option? MacOS offers a comprehensive file synchronization utility called Time Machine, which backs up the entire hard disk, including system files, applications, accounts, preferences, email messages, music, photos, movies, and docu ments. Make sure that Time Machine is set to run in the background at all times while your computer is turned on. If you need to restore a single file, you can open Time Machine, choose a file, and then select the Restore option. To restore an entire backup, make

sure the backup drive is connected and hold down the Command and R keys as the computer starts. Figure 2-49 illustrates the Time Machine. FIGURE 2-49: TIME MACHINE BACKUPS

Each window rep

You can select a day or

resents an hourly update of files.

time to view files as they existed on that date.

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128

SECTION 0, MODULE 2

I What about backing up my smartphone and tablet? Many Android devices include backup software, which is usually accessible from the Settings icon. Generally, backups from Android devices are stored in the cloud on Google servers. If your Android device accepts SD cards, you may also be able to make backups of individual Hies. Owners of ICS devices can back up to a local computer using iTunes or to iCIoud. The process is usually referred to as synchronization because it updates the files on the backup device with newer versions of files found on the smartphone or tablet. To activate iCfoud backup, you can access Settings for your iOS device, tap iCIoud. and then select Backup. Slide the iCIoud Backup button to On. To sync to a local drive using iTunes, simply connect the device to a desktop or laptop using a USB cable. Make sure iTunes is open. Choose File, select Devices, and then select Backup (Figure 2-50). FIGURE 2-50: SYNC YOUR iPHONE OR iPAD TO BACK IT UP i fTm— F*» tan viri CaNroli

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To back up files to a local storage device, choose This Computer from the list of options.

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Synching is usually initiated by tethering your handheld device to a desktop or laptop computer using a USB cable.

SECTION D

QUICKQUIZ 1.

A magnetic storage device uses a readhead to magnetize particles that represent data.

2.

3.

4. A(n) I

age technology as a USB flash drive but is not designed to be removable. (Hint; Use the acro

I storage technology,

nym.)

such as CDs and DVDs, is used for archiving

5. A disk

Today,

I uses the same stor

i is a bil-for-bit copy

data.

of the contents of a hard disk, created as a

Cloud storage, such as OneOrlve and iCioud,

backup in case of a hard drive failure.

is classified as | opposed to local storage.

1 storage as

129

DIGITAL DEVICES

Expansion Devices

Ports

Bluetooth

SECTION E

INPUT AND OUTPUT M

GADGETS.Those fitness trackers, VR

Terminology

headsets,credit card readers,and other gad gets are basically input and output devices. Section E focuses on the technology that

peripheral device expansion ports data bus

makes it possible to expand a host device

by connecting input and output devices, such as displays and printers.The section winds up with a look at the amazing array

hot-plugging USB hub BiuetOOth

device driver LCD LED response rate dot pitch screen resolution touchscreen

virtual keyboard resistive technology

of sensors that collect data for the Intemet

capacitive technology integrated graphics

of Things and self-driving vehicles

dedicated graphics graphics processing unit

ink jet printer laser printer additive manufacturing smart sensors sense-plan-act algorithms accelerometer

gyro sensor magnetometer lldar

Objectives I Categorize devices as input, output, or mixed.

Explain the purpose of a device driver and why

i Diagram the path of data from external devices

one might have to be installed or updated manually.

to the CPU.

I Identify common expansion ports and connectors, such as USB,VGA, HDMI, DVI, DisplayPort.Thunderbolt, and Ethernet.

> State which types of devices should not be unplugged without notification.

I List at least three examples of devices that might be connected using Bluetooth.

List four factors that affect display quality. Explain the role of a GPU and list the applications for which one is most useful.

Explain how resolution settings affect the size of objects and text on the screen.

List five types of sensors that provide Input to autonomous vehicles.

130

SECTION E, MODULE 2

ADD-ON GADGETS

If you have a basic smartphone, tablet, laptop, or desktop, then you know there is a tempting list of add-on gadgets to accompany these devices: for example, that fine set of Beats by Dr. Dre wireless headphones, a Nike FuelBand, an external optical drive, or an Oculus Rift VR headset. There

are lots of options.

> What should I know about add-on gadgets? You'll want to know what a gadget does and how well it works. You can discover relevant information from product reviews and customer ratings. You'll also want to

QUICKCHECK

find out if the gadget will work with your devices, and you'll need to know how to connect the gadget and get it working. A little general background about peripheral devices will smooth the way to successful gadget use.

Which of the following are not considered peripheral devices?

I What is a peripheral device? The term peripheral device Is tech-

a. RAM and CPU

speak for devices such as printers, display devices, storage devices, mice, and headsets that are connected to the system unit of a computer. Although the term is falling out of use. It still pops up here and there, so it is worth knowing. Some modern nontechnical terms for peripheral devices include gadgets, add-ons, and accessories. Peripheral devices are classified as input, output, or mixed devices, as shown In Figure 2-51. FIGURE 2-51: PERIPHERAL DEVICES

© © ® Keyboards

Fitness trackers

Printers

Mice

Touchscreens

Headphones

Touchpads

Home security systems

Speakers

Game controllers

MIDI instruments

Projectors

Scanners

Home control systems

Monitors

Microphones

Audio headsets

Robots

Credit card scanners

VR headsets

Barcode readers

Haptic gloves

Biometric scanners

I m iiii

I

I What can 1 connect to my devices? Many gadgets, such as earbuds, work with a wide variety of devices, including smartphones, smartwatches, tablets, laptops, and desktops. Other gadgets are designed to

work only with IPhones, for example. When shopping for gadgets, read the specifications and make sure they include your device. k What about connections? Add-on gadgets can connect to laptops, desktops, and handhelds using a cable or a wireless connection. Let's take a look at commonly used connectors so that you can identify them on your devices.

b. Speakers and headsets c. Hard disk drive and memory cards

d. Touchscreen and keyboard

131

DIGITAL DEVICES

EXPANSION PORTS

Like an ocean liner's portholes, many digital devices have ports in the sys tem unit for connecting cables and various add-ons. Because these ports expand the options for input, output, and storage, they are commonly called expansion ports. When you plug in a USB flash drive or insert a memory card, you are using an expansion port.

> How do expansion ports relate to the rest of the circuitry in a device? Ail of the components on the system board are connected by circuitry. The main circuits that carry data are called the data bus. These circuits carry data at lightning speeds as pulses of electrical voltages. The part of the data bus that runs between the microprocessor and RAIvl is called the local bus or internal bus. This is the fastest part of the data bus because it has to keep up with the data demands of the microprocessor.

The part of the data bus that stretches from RAM to various expansion ports is called the expansion bus. This part of the bus has several branches to accommodate data traveling to and from various ports (Figure 2-52). FIGURE 2-52: THE EXPANSION BUS

QUICKCHECK How does data flow from an

external storage device to the processor? a. Data first travels on the The local bus carries data

expansion bus, and then

at high speeds between the processor and RAM.

switches to the data bus.

b. Data begins on the internal

The expansion bus carries data between RAM and

bus, and then ends up on the

external devices that are

local bus.

connected to ports on

c. Data from the expansion bus

the system unit.

reaches RAM, and then it is transferred to the processor. d. Data starts on the network

bus, is processed in the CPU, and then is sent to RAM.

Internal storage Display devices

(Tik Audio gear

•t

• i"

□C

Memory cards

USB devices TTTTTIT'TTr I I I I I I I I I I IT

Networks

External storage

132

SECTION E, MODULE 2

I What should I know about expansion ports? When making a connection between a peripherai device and a computer, the cable must connect to the proper expansion port. Ports are sometimes marked by tiny symbois that are difficult to see. You'ii want to be able to identify ports by their size and shape.

From Section D, you are already familiar with the storage ports used for memory cards. You'ii also want to be able to identify general-purpose, video, audio, and network ports (Figure 2-53).

TRY IT Take a look at your laptop or desktop computer. Can you

make a list of ai! Its ports?

FIGURE 2-53: EXPANSION PORTS

Thunderbolt

USB

Mini USB

USB 3.0

USB-C

Lightning FIreWire

General-purpose ports are used to connect a variety of gadgets. Small devices, such as smartphones, might use a single Lightning connector that does double duty as a recharging cable and a connector for peripheral

devices. The Lightning port resembles a USB-C port, but their cables are

Terminology

not interchangeabfe.

An adapter converts one type of connector to another. For

example, a projector might

VGA

DVi

HDMi

Mini DisplayPort

have a DVI connector; but if your laptop has only a Mini DisplayPort, you can use an

adapter to change the DVi plug

Some display devices, such as external display screens and projection devices, are designed to connect to USB ports, but other display devices

to a Mini DisplayPort plug.

use specialized video ports, such as HDMi. DVI, VGA,and DisplayPort. Using

a specialized video port leaves USB ports free for other gadgets.

O QUICKCHECK Which port would be the first choice for connecting a display Ethernet Audio in

Audio Out

Wireless antenna

Most devices have at least one

An Ethernet port handles wired

Audio Out port for a headset or earbuds. There may be an

work connections are usually built

additional Audio In port for connecting a microphone.

In, but an antenna can be inserted In a USB port.

network connections. Wireless net

device? a. DVi b. USB

c. Thunderbolt d. Etherr^et

133

DIGITAL DEVICES

• What is hot-plugging? When a peripheral device is connected or disconnected while the host device Is operating, it is called hot-plugging. Although it is unnecessary to turn devices off before disconnecting them, some devices should not be disconnected while In the middle of data trans

QUICKCHECK When you're ready to put your laptop In your backpack, which

fers. Before unplugging a device, such as a USB flash drive, your computer

of the following do you need to

might require notification. Figure 2-54 shows how to safely remove a USB

eject?

a. A printer that's connected

drive.

with a USB cable FIGURE 2-S4: HOW 70 SAFELY EJECT USB FLASH DRIVES

b. A USB flash drive

1

With Windows, use the File Explorer folder Icon to view the flash drive icon. Rightclick it. then select Eject. You can remove

> I# Network

i

the flash drive when the "Safe to Remove

> *4 Homegroup

• ;

> 'i.OS(C) > ^ USB DRIVE {Od

c. The mouse d. All of the above

Hardware" message appears.

V

.

Safe To Remove Hardware

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DEVICES

^ Mac

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Wifvlows lioM |i;nc[*,s [Kimdll32)

With macOS, use

TRY IT!

Finder to view the flash drive icon. Select the

round Eject icon. It is safe to remove the

Do you have any devices connected to your computer that require notification before they are removed? {Hint: Use

flash drive when its

one of the methods in Figure

listing disappears.

2-54 to find out.)

• What if I run out of USB ports? If you wanf to conned more devices than the available number of USB ports, you can use a USB hub. A USB hub is an inexpensive device that turns one USB port into multi ple ports. It also saves wear and tear on USB ports caused by repeatedly inserting and removing USB devices (Figure 2-55). FIGURE 2-55:A USB HUB IS HANDY FOR CONNECTING LOTS OF GADGETS

USB hub

134

SECTION E, MODULE 2

BLUETOOTH

Increasingly, gadgets are going wireless, instead of exchanging data through a cabie, devices can send signals through the air—no cable required. A common wireless technology for connecting peripherals is Bluetooth.

► What kinds of devices use Bluetooth? You'll find Biuetooth options for connecting wireless keyboards and mice to iaptops and desk tops. Nintendo and Wii game controliers aiso use Biuetooth.

Bluetooth is a low-power technology, so it is ideal for mobile devices that don't have big batteries. Bluetooth is used to connect wireless headsets to

smartphones. And if you're Into fitness, then your armband or smartshoes may transmit data to your phone or computer using Biuetooth technology.

QUICKCHECK Which of the following would be least likely to connect through a Bluetooth port? a. A wireless headset

I What are the range and speed of Bluetooth? Bluetooth devices

b. An external hard drive

must be within 30 feet of each other. The peak data transmission rate is 3 Mbps, which is suitable for sending small bursts of data rather than large

c. A keyboard

files. Compared to wired connections, Biuetooth is quite slow {Figure 2-56).

d. A game controller

FIGURE 2-56: DATA TRANSFER RATES OF POPULAR CONNECTIONS

Thunderbolt 10 Gbps

|USB3.0 5Gbps FireWire 800 Mbps USB 2.0 480 Mbps

Bluetooth 3 Mbps

► Can I tell if a device is equipped with Bluetooth? Bluetooth is

TRY IT!

built into many smartphones, tablets, laptops, and desktops, but there is no corresponding physical port on the system unit. Look for the Bluetooth logo

Does your favorite device

on the Windows taskbar or the Mac menu bar (Figure 2-57). For handheld devices, check Settings. If a device is not equipped with Biuetooth, you can

for the Bluetooth icon or

piug a Biuetooth antenna into a USB port. FIGURE 2-S7: DOES THIS DEVICE HAVE BLUETOOTH?

^ 0 Wll © 0

^

Jane

Q i

Bluetooth Icon on Mac menu bar

O

Q

]

have Bluetooth? Look

settings to find out.

135

DIGITAL DEVICES

DEVICE DRIVERS Many gadgets have associated software. For example, there's an iPhone app for your fitness wristband that graphs your progress and shares it with

your training buddies. These applications help you get the most out of your gadgets. In addition to application software, devices also require a type of software called a device driver.

I What's a device driver? A device driver is software that helps a peripheral device establish communication with its host device. For exam

ple, the device driver for an HP printer sets up data streams from RAM to the printer and makes sure that the data is formatted in a way that the printer can work with.

► When do I have to install device drivers? Operating systems include built-in drivers for standard expansion ports. This feature, some

times called Plug and Play, makes it easy to connect devices without manually installing device drivers. When you connect a new peripheral device, the operating system looks for an appropriate driver. If the device is unable to use a standard driver, you'll be prompted to install the device

QUICKCHECK Suppose you just got an

operating system update and now your printer has stopped

working. What can you do to

driver supplied by the peripheral device manufacturer.

solve the problem?

• Where do I get device drivers? Device drivers, updates, and

a. Go online and check for a

instructions for installing them can also be downloaded from the manufac

printer driver update.

turer's Web site.

> When do I need a device driver update? Device drivers work directly with the host device's operating system. A printer or other con nected gadgets might work perfectly—until the operating system gets an update. Then some device drivers might stop working correctly and the devices they control could malfunction.

In addition to checking cables, trying a different port, and rebooting, one of the first steps in troubleshooting a malfunctioning peripheral device is to access the manufacturer's Web site and look for a driver update. Updated driver downloads are usually available from the Support link (Figure 2-58). FIGURE 2-58: DEVICE DRIVER UPDATES ARE AVAILABLE ONLINE S

Wwt

Fm*

Efiif

v:»a

hkIos

Far««rt

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Drivers & Downloads

Drivers a Downloads

LCijj Troubleshooting

Find my product

Support Forums

Detect my product U
What factors affect image quality? Image quality is a factor of screen size, response rate, dot pitch, and screen resolution. Screen size. Screen size is the measurement in inches from one corner

of the screen diagonally across to the opposite corner. Screen sizes range from 1" for smartwatches to 60" or more for home entertainment systems. Response rate. Response rate is the time it takes for one pixel to change from black to white then back to black. Dispiay devices with fast response rates display a crisp image with minimal blurring or "ghosting" of moving

objects. Response rate is measured in milliseconds (ms). For gaming sys tems, a response rate of 5 ms or less is desirable.

is

137

DIGITAL DEVICES

Dot pitch. The LEDs that form an image on the screen are spaced In a grid. Dot pitch (dp) is the distance in millimeters between like-colored LEDs (Figure 2-60),

QUICKCHECK Which of these 4-inch

smartphone displays would produce the sharpest image quality?

FIGURE 2-60: DOT PITCH

a. Di =.26 mm, ppi = 200 b. Di =.50 mm, ppi = 500

0.26 mm Dot pitch is the dis tance between two

c. Di =.08 mm, ppi = 326 d. Di =.06 mm, ppi = 200

LEDs of the same color.

Screen resolution. The number of horizontal and vertical pixels that a device displays on the screen is referred to as screen resolution. The

iPhone 7, for example, features a resolution of 750 x 1334. Another way to express resolution is pixels per inch (ppi). The 4.7-inch screen on an

iPhone 7 with Apple's Retina display technology has a resolution of 326 ppi.

I Should I set my computer on its highest resolution? Most dis plays have a recommended resolulion at which images are clearest and

text is crispest. On laptops and desktops, however, you can change the resolution, in Windows, you can use the Control Panel or right-click the desktop and select Screen Resolution. In macOS, use the Apple icon to

TRY IT!

What is the current setting for the resolution on your laptop or desktop? Is it the highest possible resolution?

open System Preferences and choose Displays.

At higher resolutions, text and objects may appear smaller, but the desk

top appears more spacious. The two screens in Figure 2-61 help you compare the same display set at two different resolutions. FIGURE 2-61: SCREEN RESOLUTION AND WINDOW SIZE

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What is a GPU? Display devices require graphics circuitry to gener ate and transport the signals for displaying an image on the screen. One type of graphics circuitry, referred to as Integrated graphics, is built into a computer's system board. A second option, caiied dedicated graphics, is graphics circuitry mounted on a small circuit board called a graphics card (or video card)iike the one in Figure 2-63. FIGURE 2-63; GRAPHICS CARD The GPU Is a micro

processor that may generate enough heat to require a cooling fan.

A graphics card plugs Into the system board Inside the case of a

desktop computer.

The video port protrudes from the back of

the system unit so that the port is accessible for plugging in a display device.

A graphics card contains a graphics processing unit(GPU)and special video memory, which stores screen images as they are processed but before they are displayed, A fast GPU and lots of video memory are the keys to iightning-fast screen updating for fast action games, 3D modei-

ing, and graphics-intensive desktop publishing (Figure 2-64). FIGURE 2-64: CPU VS. GPU

tn a device with integrated graphics, image data is processed by the main CPU,

then sent to the graphics circuits that stream the

image to the display device.

r

o

in a device with a GPU,image data is processed by the GPU, freeing the CPU for other tasks.

SECTION E, MODULE 2

140

PRINTERS

The importance of printers has declined as digital distribution becomes more prevalent and cloud-based print services become more popular. Yet a printer can come in handy for creating printed documents, handouts,

posters, and photos. Today's best-selling multifunction printers use ink jet or laser technology and can also serve as scanners, copiers, and fax machines.

i How does an ink jet printer work? An ink jet printer has a nozzle-like print head that sprays ink onto paper to form characters and

graphics. The print head in a color ink jet printer consists of a series of nozzles, each with its own ink cartridge (Figure 2-65). FIGURE 2-65: INK JET CMYK CARTRIDGES

B ack

cartridges

Most ink jet printers use CMYK color, which requires only cyan (blue), maeenta (pink), yellow, and black Inks to create a printout that appears to contain thousands of colors.

Ink jet printers outsell all other types of printers because they are inexpen sive and produce both color and black-and-white printouts. They work well for most home and small business applications. Inkjet technology also pow

ers many photo printers, which are optimized to print high-quality images

QUICKCHECK

Which type of printer is slower but less expensive to operate?

produced by digital cameras and scanners.

a. Laser printer

» How do laser printers compare to ink jet printers? A laser

b. Ink jet printer

printer like the one shown in Figure 2-66 uses the same technology as a photocopier to paint dots of light on a light-sensitive drum. Electrostatically charged ink is applied to the drum and then transferred to paper. A laser printer

prints faster than an ink jet printer, but laser technology is more complex than ink jet technology, which accounts for the higher price of laser printers. A basic laser printer produces only blackand-white printouts. Color laser printers are available, but they are somewhat more costly than basic black-and-white mod els. Laser printers are often the choice for business printers, particularly for applica tions that produce a high volume of printed material.

Toner cartridge

FIGURE 2-66: LASER PRINTER

DIGITAL DEVICES

141

t What about 3D printers? The technology that deposits ink on paper is the foundation for 3D printers that deposit layers of plastic, resin, or metal that build into a three-dimensional object. 3D printing is technically called additive manufacturing.

Consumers can use 3D printers to produce small toys, ornaments, and even simple electronic devices. These printers have been used to create wear able items, such as shoes, and replacement parts for household appliances. An important industrial use for 3D printers is prototyping new products, such as automobile headlights, smartphone cases, firearms, and even full-scale bicycles.

Additive manufacturing is used to produce hearing aids and other medical devices that are custom fit or in other ways unique. Dental laboratories use 3D printing to produce crowns, bridges, and other dental appliances.

> How do 3D printers work? There are several additive manufactur ing technologies, but most consumer-grade 3D printers use a technology called filament deposit modeling (FDM) that melts a coiled filament and

deposits it in layers that harden and form an object(Figure 2-67). FIGURE 2-67:3D PRINTING

A coil of filament is

melted and depos

ited by the printer's extrusion nozzle.

I What are the filaments made from? Several types of filament are available. Poiylactic acid (PLA)filament is versatile, and biodegradable

because it is made from com starch. Acrylonitrile butadiene styrene (ABS)

filament is more durable and heat-resistant, making it suitable for printing objects that need to withstand some wear and tear. Polycarbonate (PC) filament is even sturdier and is used primarily for items that will be used in

high-impact situations. Filaments cost about $10 per pound.

t What controls the printout? A 3D printed object is based on a 3D model that is essentially a 3D vector graphic. The model can be created

using graphics software or it can be derived from a 3D scan of a real object. Modules are often stored in the STL file format. Several Web sites offer col

lections of STL files for 3D printing.

i

SECTION E, MODULE 2

142

THINGS

The Utopian vision for the Internet of Things (loT) is a busy hive of smart sensors that work behind the scenes to collect data and use it to

improve—welt—just about everything. All types of "things" equipped with smart sensors can monitor our homes, cars, and workplaces. They can also monitor our habits and physical fitness and communicate with each other while doing so.

I What are the basic features required for loT devices? loT devices require some way to communicate with other sensors and devices. That communication is handled by network technology, which is covered in the next module.

loT devices may include a microprocessor and memory if the device must

process data, make decisions, or Initiate an activity. A basic loT circuit board contains one or more sensors, a power source, a transmitter, and an antenna (Figure 2-68). FIGURE 2-68: ANATOMY OF AN lOT THING

Transmitter Antenna

Batteries (connected to the back of the

circuit board)

I What types of smart sensors are available? The most popular loT sensors send alerts based on data they collect(Figure 2-69). FIGURE 2-69: SENSORS

Your basement floor seems to be wet."

'A window on your house just broke."

Your swimming pool needs more chlorine."

Your dog is barking." The club is busy (noisy)." Sound

"Your dog is out of your yard."

©

"Your car is not in your driveway." "You hiked a 2.5-mile circuit."

"Your front door isn't locked."

©

"Your doorbell just rang,"

"Your child just got home from school."

Contact

GPS

"A person or animal approached your cabin last night." "Your cat is at the litter box."

"You've walked 10,000 steps today."

(D

I "The baggage handlers just dropped your suitcase."

Accelerometer

Motion

"It's 10 pm; your porch light isn't on." "Do you want to dim the lights?" "Your UV exposure has reached the limit." Light

Your plant needs water." Water

"Your oven Is on."

©

"Your apartment Is unusually hot." "It's below zero; remote start your car."

Temperature

DIGITAL DEVICES

143

> What are the most popular sensors? Many smartphones, VR

^

headsets, and automobile internal navigation systems incorporate three sensors: an acceieronneter, a gyroscope, and a magnetometer. Figure 2-70 illustrates an IMU (inertial measurement unit) that packages these sensors into a single unit. FIGURE 2-70: IMU SENSORS

An accelerometer measures the rate at which a device

accelerates. It can sense.

For example, if a laptop computer is dropped or if a

vehicle brakes suddenly.

A gyro sensor gauges angu lar velocity: the change in

rotational angle, it can help a drone remain level in the

air and helps a VR headset track head movements.

A magnetometer measures magnetic

fields and can be used as a compass to determine orientation relative to mag netic north. Magnetometers provide data about the direction of travel for vehicles and handheld devices.

I Where can I get loT devices? Smart sensors are available In elec tronics stores, hardware stores, and online, Sensors can be purchased

individually or in packages. Popular home monitoring packages, such as Apple's HomeKit, include cameras, thermostats, light bulbs, water sensors, door locks, and VOC air quality sensors.

I Do sensors have security risks? Sensors themselves are not generally a security risk, but the data they collect can be used for unauthor ized purposes.

A smart thermostat can be used legitimately by a homeowner to remotely track and adjust the temperature of a house or apartment. With approval, data from the thermostat might even be collected by the local power com pany and used to gauge usage levels.

QUICKCHECK Which one of the following aspects of smart sensors on the

loT would be the least likely to

Because the thermostat communicates using a wireless network, the signal

pose a security risk?

is subject to interception. An unauthorized person might monitor the signal to determine when a homeowner leaves the house (heat is turned down),

3. Anonymlzed data

arrives home (heat is turned up), or goes on vacation (heat remains down

b. Data transmitted without encryption

for several days). When considering smart sensors, take care to understand where their data can be stored, who can access the data, and who can control the device. To

maximize security, select sensors that store data locally or on a secure site. In addition, confirm that all data is encrypted before it is transmitted and stored, and ensure it can be controlled only by you.

c. Data stored on 3 Web site

d. Temperature sensors supplied by your electric service provider

SECTION E, MODULE 2

144

AUTONOMOUS VEHICLES There are drones in the sky, Roombas crisscrossing the floor, and cars

speeding down the highway in Supercruise mode. The technology that allows these vehicles to operate autonomously or semi-autonomously requires an array of sensors communicating with an onboard computer.

TRY ITI

Autonomous vehicles, such

> Exactly what is an autonomous vehicle? Cars, trucks, trains,

as self-driving cars, have

drones, planes, and machines that are usually piloted by humans become autonomous as the vehicles, rather than the humans, take over control of

limitations. Can you discover what type of pre-mapping is

speed, braking, and steering. Fully autonomous vehicles operate without a person at the controls. Semi-autonomous vehicles provide assistance to a

takes to the road?

required before a Google car

human operator.

Features available in semi-autonomous automobiles include adaptive cruise control, in-iane steering control, automatic parking, and collision avoidance

systems, which take over some, but not all, driving tasks. I How do autonomous vehicles make control decisions? In

general, autonomous vehicles use sense-plan-act algorithms that emerged with the development of robotic systems. These algorithms may be classi fied as artificial intelligence {A!) because they make decisions and carry out activities without human intervention.

Sense-plan-act algorithms gather data, analyze it, and then carry out the required actions. Multiple sense-plan-act loops operate simultaneously. For example, in a seif-driving car one loop may be sensing lane markings,

while another loop is monitoring the distance to the vehicle ahead, and yet another loop is watching for suddenly appearing objects. Figure 2-71 pro vides additional details pertaining to sense-plan-act. FIGURE 2-71; SINSE-PIAN-ACT ALGORITHMS FOR SELF-DRIVING CARS

BRAKE? REDUCE SPEED?

HONK? Sense. Sensors on the vehicle

gather raw data about the nearby environment and the status of the vehicle itself. Environmental data

Plan. Based on its interpreta tion of sensor data, the onboard

comes from sensing nearby vehi

computer applies a series of rules

cles, people, animals, and other objects, as well as the roadway

to determine the best course of

itself. Vehicle status data includes

indicates that the vehicle ahead is

speed, direction, angle, and alti

slowing down, the computer must decide whether to adjust its speed or change lanes. The decision

tude.

Sensor data is delivered to an

action. For example, if radar data

onboard computer, where software quickly processes the input to identify road hazards and naviga

is based on rules such as "If the

tional points.

move to the left lane."

vehicle ahead slows down gradu

ally, and the left lane is clear, then

Act. After the computer deter mines a course of action, it sends

signals to the vehicle's control sys tems. A signal to the car's steering system can initiate a lane change. Signals could also be sent to the car's throttle or braking system to achieve a change in speed.

145

DIGITAL DEVICES

I What kinds of sensors keep an autonomous vehicle on the road? Lidar (light detection and radar) is a key input for the computer algorithms that steer an autonomous vehicle, but radar, sonar, infrared, GPS, cameras, and internal navigation systems also supply essential data (Figure 2-72). GPS uses orbiting satellites to determine a FIGURE 2-72: AUTONOMOUS VEHICLE SENSORS

vehicle's position. The coordinates received from the GPS are cross-referenced with

Lidar systems determine distance to obsta

digital road maps. Civilian GPS is accurate to

cles using laser range finders. This device

about ten feet, but augmentation technology

calculates the distance to objects based on

improves location accuracy. Soon, augmented

the time it takes for the laser beam to reach

GPS systems should be able to calculate posi

an object and return. The range for this

tion with accuracy of one inch.

device is about 650 feet(200 meters), and Infrared sensors can be used

360-degree Lidar arrays can gather millions of data points per second to map objects in a

to sense the heat signatures of pedestrians and animals, par

65-foot radius of the vehicle.

ticularly when it is dark.

Internal navigation systems(INS) Include gyro scopes and accelerometers that continuously calculate position, orientation, and speed of the vehicle. These systems can monitor position if GPS signals are temporarily blocked by the

Radar adds more data about the nearby environment. Radar, which uses sound

waves, does a good job of sensing metallic objects, but does not sense pedestrians and other non-metallic objects. It is primarily used to track nearby vehicles. It is currently used In adaptive cruise control systems to

signals, which are analyzed by image recogni

maintain a safe distance to the car in front.

tion software.

structures in a dense urban area.

Cameras collect images of road signs and traffic

SECTION E

QUICKQUIZ 1.

The

bus carries data from

4.

The two most common technologies used for touchscreen displays are resistive and

an external device to RAM.

Is a slow wireless technol

2.

ogy used to connect devices within a radius of

handles image data.

freeing the CPU for other processing tasks.(Hint; Use the acronym.)

The most commonly used general-purpose tech nology for connecting gadgets to laptop and

about 30 feet.

3. A(n)

5.

desktop computers is a(n) I port.(Hint: Use the acronym.)

IN THE WEST AFRICAN nation of Ghana, of donations arrive every day in port cities, such as smoldering piles of discarded computers and moni tors ring a mucky river, polluted beyond recovery. Teenage boys play soccer in a toxic haze. When their break is over, they get back to work smashing moni tors, ripping out the innards, and tossing the plastic cases onto a smoking pyre of oozing plastic. In Guiyu, China, thousands of women huddle over primitive stoves "cooking" circuit boards to retrieve trace amounts of gold. Toxic fumes from the cooking process cloud the air; a toddler showing symptoms of lead poisoning plays listlessly with the carcasses of discarded mice and cell phones.

It is called ewaste, e-garbage, or teohnotrash—all unwanted and outdated computers, monitors, print ers, cell phones, disk drives, disks, CDs, and DVDs.

According to the United Nations, an estimated 65 mil

Hong Kong, where they follow a shadowy route to unregulated workshops and dump sites. Some illegal ewaste originates in legitimate recycling centers, where consumers assume electronic com

ponents will be handled in environmentally friendly ways. Many recycling centers do not process malerials on site. Instead, they ship the ewaste to third parties. Without careful monitoring, that ewaste can be diverted to offshore locations where it piles up, waiting to be disassembled by backstreet laborers ungoverned by environmental protection regulations. Developed countries have strict environmental regu lations designed to prevent toxic substances from polluting air, land, and water. Proper disposal is expensive, however.

Some illegal ewaste originates countries with high , .. _ _ labor costs and strinIft legitimate recycling centers^ gent environmental regulations, the value

lion metric tons of ewaste are

discarded worldwide every year. About 10 million tons of that total are discarded by U.S. consumers. More than 7 million tons are discarded in China.

Computers and other electronic gear contain toxic substances such as lead, cadmium, and mercury.

When discarded equipment is buried in landfills, these substances can leach into groundwater and streams. When burned, electronic components can emit toxic dioxin.

Ewaste is a global problem. As countries struggle to deal with discarded electronic components, an

alarming amount of ewaste is shipped to developing countries where villagers, working for pennies a day, are exposed to toxic chemicals as they attempt to reclaim resalable metals from discarded equipment.

of compounds retrieved from ewaste does not cover the cost of extraction.

The high cost of properly processing ewaste makes gray market options attractive. Ewaste can be han dled more cost-effectively in emerging countries where environmental regulations are ignored, wages are pitiful, and workers are not covered by health and safety laws. So, who is responsible for ewaste sweatshops and pollution? Is it consumers in developed countries who deposit unwanted gear at recycling stations that don't carry out the recycling process in-house, or is it the recycling firms that ship ewaste to third parties? Is it the firms that ship ewaste to emerging countries or the governments that can't close the loopholes on

Throughout the emerging world, ugly ewaste dumps defile the landscape and have yet unknown health

ewaste transhipping?

effects.

tries that are unable to control ewaste sweatshops

Where does all this ewaste originate? Every coun try generates ewaste, but the bulk of it comes from prosperous, technology-forward countries such as

and ignore the resulting environmental and human

the United States, Great Britain, Germany, Japan.

of the problem can become more responsible in the way they dispose of unwanted gear to keep it out of

France, and China. Despite laws that ban ewaste transhipping, loopholes allow discarded but work ing electronics to be shipped as "donations." Tons

Perhaps the responsibility lies with emerging coun

casualties.

Wherever the blame lies, consumers who are aware

landfills at home and offshore.

147

DIGITAL DEVICES

TRY IT! Explore the ewaste issue. Watch a video of the Ghana crisis and explore the steps you can take to minimize the number of electronic components that end up in landfills and toxic waste dumps.

Q A group of graduate journalism students from the University of British Columbia investigated the illicit ewaste industry. Their story is presented in a Frontline World report located at www.pbs.org/ fror]tlineworld/stories/gharja804/video/videojndex.html. Watch the video. Where do the researchers drop off the ewaste, and where does it end up?

^ An environmental advocacy group, Basil Action Network, secretly planted 200 tracking devices in elec tronic items donated to recycling centers in the U.S. Read about the project at hltp://tinyurl.com/j34655t and follow the link to the interactive online map. What does this map tell you about the recycling chain? Many computers, mobile phones, and other electronic components pile up in landfills because their own ers are unaware of potential environmental hazards and simply toss them in the garbage. Use Web sites such as Earth911.com, or search for recycling computers and add your city name, as in recycling compub ers Chicago. Where is the nearest drop-off location for old laptop computers? Would you be charged a fee, and if so, how much?

o Before donating or discarding a computer, you should erase all the data it contains. Simply deleting files is not sufficient to prevent data from being recovered. Search online for information about deleting or "wip ing" the data from a hard drive. What are three ways you can securely prevent access to the data on a hard disk?

0 Consumers can select "green" products and purchase equipment from environment-friendly manufac turers. Check out Greenpeace's Green Ranking. What is the ranking for the company that manufactured your computer?

0 You might wonder if the computer you are currently using is environmentally friendly. The Green Electronics Council rates specific computer models as bronze, silver, or gold. Connect to the EPEAT site (www.epeaf.nef), use the Search for Products links, choose the Full Search option, and then fill in the fields to find the rating for your computer brand and model.

Total

Desktops

1

83

132

216

Displays

0

352

308

660

Integrated Desktop

0

51

27

78

Computers li)

Notebooks

50

635

1010

Thin Clients

0

21

4

Workstation Desktops

0

0

20

20

Workstation Notebooks

0

2

7

9

Totals

51

1144

1516

1703 25

2711

What Do You Think? 1. Have you ever thrown away an old computer or other electronic device?

2. Do you research products before purchasing them to find out if they are environmentally friendly throughout their life cycle?

3. Would it be fair for consumers to pay a recycling tax on eiectronic equip ment that they purchase?

ISSUE

f^jtk O'SYK^irRerstncir com

You're looking for information. Where you start depends on how you plan to use the information. The sources

you need for a class research paper often differ from information sources for personal use. information sources can be roughly divided into two categories: those that serve academic audiences and those that serve consumers.

SCHOLARLY AND ACADEMIC SOURCES OWritten by experts D Intended for academic or professional readers Find ttiese

sources using Google Scholar and academic databases/ directories such as DOAJ.

O Peer-reviewed by other experts before publication OContaIn original research, theoretical analysis, or best practices

O Carefully documented by footnotes or endnotes

Use these sources for class

papers, theses, essays,and dissertations.

O Published by academic publishers, professional asso

ciations, or university presses D Include academic books,academic Journals, papers,

conference proceedings, dissertations, textbooks, and monographs In printed or digital format

CONSUMER-LEVEL SOURCES

^Written by reporters, bloggers, or practitioners 3Intended for the general public Use these Find these

sources using Google Web, Google News, and product

0 Usually reviewed by an editor before publication

O Sometimes open to public WngfUM comment after publication

3Printed or displayed In color with included photos

sources

for product information,

troubleshooting. news, and topic overviews.

Web sites.

3 Often published in for-profit publications that Include advertising

3Include trade books, magazines,encyclopedias, press releases, trade Journals, blogs, news sites, and online forums

HELP! Can't access what you need for a research project? Here are some common problems encountered by stu dents, and solutions that help you find the resources you need for a paper that earns you an A.

PROBLEM: Web search engines, such as Google, sometimes miss many of the articles most relevant for a

college-level research project because articles are often locked behind paywalls or firewalls that don't allow search engine access. SOLUTION: Go directly to a journal's Web site and search there. PROBLEM: Many scholarly journals display only abstracts to the general public; viewing the full text of articles

requires a subscription or download fee. SOLUTION: Use your library's online database to locate articles that are included in the physical collection. You might have to go to the library to read the articles or ask for the full article from inter-library loan.

PROBLEM: Access to academic search engines and databases, such as LexisNexis, requires subscriptions.

SOLUTION: Your school might provide registered students with free access to journal databases if you log in from a computer on the school network or from within the library.

149

DIGITAL DEVICES

TRY IT! Research aboul computers and technology relies on information from a broad base of sources. Let's explore these sources by comparing what they offer. Some searches will produce information suit able for academic projects, such as term papers, while other searches tend to produce Information suitable for personal use, such as figuring out if

COMPUTER AND TECHNOLOGY

ACADEMIC DATABASES

someone Is hacking into your home network.

To record the results of this comparison, write down (or screen capture) one example that you get from each source, and then describe an aca demic project or personal use for which that information would be suitable. As an example, suppose that you search for cloud computing using Google Scholar and one of the results Is; Introduction to parallel algorithms and architectures

T LeigMon-see,uhcl.edu ... Catalog Description: This course covers parallel compulations using popular Interconnection networks such as arrays, trees, hypercubes. and pennutation networks such as the star and the pancake networks, as well as grid and cloud computing.... Ciieri hv 2n9fi • Reiarcd articles ■ View as HTML ■ Lihrarv Search ■ All 5 versions

This information is academic and could be a suitable source for a term

DOAJ (Directory of Open Access Journals)

Science.gov TDG Scholar

Microsoft Academic Search

IEEE Xplore CiteSeerX

ACM (Association for

Computing Machinery) Digitai Library

paper about cloud computing in a computer science course. Okay, now see what you can do with the rest. TECHNOLOGY NEWS

Q Check Wikipedia for general information about cloud computing and

SITES

then look at the list of references.

Huffington Post Tech

Search for academic and trade books aboul cloud computing at

Engadget

Amazon Books.

TechCrunch

0 Search for conference proceedings aboul cloud computing at the ACM Digital Library.

Q Search an open access database such as DOAJ (see sidebar) for a recent paper about cloud computing.

0 Search an academic database (see sidebar) for an abstract about cloud computing. Search Science.gov for a full text article about cloud computing.

0 Search an online computer magazine, such as Wired, for a recent arti cle about cloud computing.

0 Use a search engine, such as Google or Bing, to locate a recent press release about cloud computing.

© Search Amazon Electronics for cloud computing products and cus tomer reviews.

© Search a technology news site (see sidebar) for the latest industry news about cloud computing.

ArsTechnica

Google News Sci/Tech WSJTechnology CNET News Tom's Hardware

'Y-j I-J «•

f ••

-

TECHWOtOGYdNtCQII IN ENGINES OF THE MIND, Joei

data was distributed to terminals at other locations

Shurkin writes, "If necessity is the mother of invention, then war can be said to be its grandmother." The mili tary, an early pioneer in computer and communication technologies, continues to be the driving force behind technologies that have revolutionized everyday life.

through rudimentary networks. Because all data communication flowed through the

by hand, each table required weeks of grueling calcu

mainframe, a single point of failure for the entire sys tem was a possible risk. A malfunction or an enemy "hit" could disrupt command and control, sending the military into chaos. Therefore, the armed forces cre ated the Advanced Research Projects Agency(ARPA) to design a distributed communications system that could continue operating without a centralized com

lations.

puter.

Project PX produced ENIAC (Electronic Numerical Integrator And Computer), one of the first generalpurpose electronic computers. When ENIAC was completed in 1946, the war was over, but ENIAC's

The result was ARPANET, which paved the way for

During World War II. the U.S. military Initiated a clas sified research program, called Project PX, to develop an electronic device to calculate artillery firing tables;

versatile architecture could be used for other calcula

tions, such as designing hydrogen bombs, predicting weather, and engineering wind tunnels. ENIAC's tech nology evolved into the computers used today.

the data communications system we know today as the Internet. ARPANET was activated in 1967, but the

.mil domain that designates U.S. military Web sites was not implemented until 1984, The U.S. Department of Defense (DoD) currently maintains several data communications networks,

including SlPRNet, a classified (secret-level) network, and NIPRNet, which provides unclassified services. The DoD's public Web site provides official informa tion about defense policies, organizations, budgets, and operations. Computers and communications technology have also become an integral part of high-tech flight oper ations. U.S. Apache helicopters, for example, are equipped with computer-based Target Acquisition Designation Sights, laser range flnder/deslgnators, and Pilot Night Vision Sensors. Networks are also crucial for combat operations, and

a new generation of communication tools is evolv ing for soldiers deployed to battlefields. Networked communication devices offer immediate situational

After Project PX, the military continued to support computer research. Like most large corporations, the military used mainframe computers to maintain per sonnel. inventory, supply, and facilities records. This

awareness by providing critical information such as orders, imagery, graphics, and maps. The U.S. Army's $150 million Nett Warrior program is essen tially a smartphone carried by the dismounted soldier that displays the locations of friendly troops and facili tates text messaging when verbal communication is not possible.

151

DIGITAL DEVICES

Combat equipment for today's soldiers includes

Autonomous vehicles are another area of research.

"software-defined" radios that are less vulnerable to

Collaboration with the private sector produced technology for unmanned convoys In which a lead vehicle, piloted by a human driver, conducts a string of unmanned trucks through potentially dangerous

cyberthreats than conventional radios. Soldiers can use these radios to communicate voice and data. A small handheld device with a touchscreen allows soldiers to control unmanned robots and drones. A

solar backpacl^ supplements the battery-powered

device. Combat equipment also includes wearable devices, such as helmet-mounted displays and com munications devices.

The military has conducted research in computer simulations that are similar to civilian computer games. "Live" military training is dangerous— weapons are deadly and equipment

territory. Today, a growing cadre of computer and communi cations specialists is needed to create and maintain

Increasingly complex military systems such as the Defense Department's Distributed Common Ground System (DCGS) for sharing surveillance imagery and intelli gence.

In the past, armies

depended primarily on their infantry divi

costs millions of dollars. With com

puter simulations, however, troops

sions, but today's high-tech armies also

can train in a true-to-life environment

without physical harm or equipment damage.

depend on database designers, computer programmers, and

Flying an F-16 fighter, for example, costs thousands of dollars an hour,

but flying an F-16 simulator costs only a few hundred dollars per hour. The military uses simulators to teach Air Force pilots to fly fighter jets, Navy submarine officers to navi gate in harbors, and Marine infantry squads to handle urban combat. Military trainers agree that widespread use of computer games helps prepare troops to adapt quickly to simulations.

A 24-year-old prefllght student at Pensacola Naval Air Station modified the Microsoft Flight Simulator game to re-create a T-34C Turbo Mentor plane's

controls. After logging 50 hours on the simulator, the student performed so well on a real plane that the Navy used his simulation to train other pilots.

The military is quick to borrow civilian technologies that make combat teams safer and more effec

tive. Soon after Google Glass was released to the general public, the U.S. Navy contracted with a

multinational eyewear company to integrate highdefinition display technology into standard military goggles. Hands-free data access and video record

ing capabilities permit sailors to perform tasks without pausing to deal with communications equip ment.

The U.S. Navy also seeks help from civilian devel opers—even college students. In the annual International RoboBoat competition, a $20,000

prize is awarded for the best-designed ships that can operate without crews In harsh environments or dangerous situations.

network specialists.

Even previously lowtech military jobs, such as mechanics

and dietitians, require some computer

expertise. Happily, new recruits are finding military computer systems easy to learn based on their knowledge of civilian technologies, such as the Internet and computer games.

Although most citizens recognize that an adequate national defense is necessary, the cost of defenserelated equipment, personnel, and cutting-edge research remains controversial. In a 1961 speech, President Dwight Eisenhower warned, "We must guard against the acquisition of unwarranted influence, whether sought or unsought, by the military-industrial complex."

Some socially motivated citizens and pacifists tried to withhold tax dollars from the military-industrial complex that Eisenhower cautioned against. In ret rospect. however, military funding contributed to many technologies we depend on today. For example, detractors tried to convince the gov ernment that Project PX was doomed to failure; but without ENIAC research, computers might not exist today. Skeptics saw no future for the fruits of ARPANET research; but it led to the Internet, which

has changed our lives significantly.

i

MODULE 2

FLIPPED CLASS PROJECTS

Critical Thinking

Multimedia Project

For many years, personal computers were desktop models designed around four main components: system unit, monitor, keyboard, and mouse. Today,

Imagine that you are a high school teacher and you have to design materials to teach a unit on how microprocessors work. To kick off the unit, create a 30- to 60-second video showing the control unit, registers, and ALU and how an instruction like ADD

more than half the devices we use are slate form

factors without physical keyboards. Some Indus try analysts speculate that the move away from physical keyboards signals a fundamental change

9 + 2 would be processed. Be creative and make it interestingi

in the use of digital devices. Whereas computers

were once seen as tools for producing, they are now becoming tools for consuming. How significant is a physical keyboard to the creative and produc tive use of digital devices? What kinds of evidence would help to support your opinion?

Group Project For this project, work in groups of three or four. The group should select a trending digital device,

Resume Builder Use the Web and other resources to learn about

the digital devices and other technologies used in your career field. Format the Information you find in a style similar to the Technology In Context sec tion of each module in this textbook. Be sure to

select two photos to accompany your narrative and include a list of relevant citations for your sources.

such as a fitness wristband, a smartwatch, smart-

glasses, a home security system, or a just-released smartphone. If a member of your group owns the device, that's a plus. Create promotional materi als for a tradeshow booth featuring your device.

You might include a product photo, a list of speci fications, and a short instruction manual. If time

permits, your instructor might ask your group to present your sales pitch or a demonstration to the rest of the class.

Cyberclassroom Work in pairs to set up a cloud-based storage loca tion where you can share files. Experiment with the following scenarios to find out what happens; 1) Two people access the same file at approxi mately the same time; neither person changes the file contents.

2) While one person is modifying a file, another person tries to access the file but does not try to modify it.

3) While one person is modifying a file, a second person attempts to access it and change it.

Globalization Digital device ownership is growing worldwide and providing access to productivity tools and a global communications Infrastructure. For this project,

look for statistics and graphs showing the increase in device ownership around the world over time. How does it compare to telephone, television, and radio ownership? Are any aspects of this data unexpected or surprising? Gather your graphs and analysis into a two- to three-page executive summary.

DIGITAL DEVICES

KEY TERMS

2-ln-1 97

head crash 120

read-write head 119

accelerometer 143

recordable 121

recovery drive 126

additive manufacturing 141

hot-plugging 133 Inkjet printer 140 input 85

ALU 108

instruction cycle 108

remote storage 123

application software 86 apps 86

instruction pointer 109

resistive technology 138

instruction set 107

response rate 136

integrated circuit 87 integrated graphics 139

rewritable 121

ROM 114

boot loader 114

laptop computer 96 laser printer 140

screen resolution 137

capacitive technology 138

LCD 136

semiconductors 87

sense-plan-act algorithms 144

access time 120

ARM 105

backup 125 Bluetooth 134

registers 108

RISC 112

capacitors 113

LED 136

card reader122

lidar 145

serial processing 111

central processing unit 85

lithium ion 92

server 95

Chromebook 96

Iocs! storage 117 machine language 107 magnetic storage 119 magnetometer 143

CISC 112

cloud storage 123 compatible 101 computer 85 computer program 86 control unit 108

mainframe 95

memory 85 memory card 122

CPU cache 112

microcontrollers 98

data bus 131

microprocessor 85 microprocessor clock 110 multi-core processor 110

slate tablet 97 smart sensors 142

smartphones 97 software 86 solid state drive 123

solid state storage 122 storage 85 stored program 86

non-volatile 122

supercomputer 95 system board 88 system software 86 system unit 89

oleophobic 92 operating system 86

touchscreen 138

discharge rate 93

optical storage 121

USB flash drive 123

disk image 127

output 85

USB hub 133

dot pitch 137 dynamic RAM 113 expansion ports 131 file synchronization 126

parallel processing 111

virtual keyboard 138 virtual memory 114

data transfer rate 120

dedicated graphics 139 desktop computer 96 development tools 86 device driver 135

PDA 97

form factor 89

peripheral device 130 personal computer 96 pipeline processing 111

gigahertz 110 graphics processing unit 139 gyro sensor 143

portable computer 96 process data 85 programming language 107

hard disk drive 119

RAM 113

hard disk platter 119

read-only 121

tablet computer 97

volatile 113

wearable computers 98 word size 112

X86105

SECTION A: A computer is a multipurpose device

the master controller for all the activities that a digital device

that accepts Input, processes data, stores data, and

performs. Digital devices are constructed using tiny electronic

produces output, all according to a series of stored

components that represent data bits as electrical signals. The

system unit houses the system board, which contains several

The

I circuits made from semiconduct

processing unit of most modern computers is a(n) The instructions that tell a

ing materials. Computers come In three popular form factors;

computer how to carry out a task are referred to as com

component,|

puter

today's digital devices operate on battery power supplied by

I , which are distributed

| . and slate. Many of

as software. Computers run three main types of software:

ion batteries. Battery life and life-

software, system software, and

span can be extended by following good battery management

development tools. An example of system software Is a com

puter!

practices.

[system, which Is essentially

SECTION B: Today, there are many computer cat

egories. A(n) I

I Is the category for

digital device requires consumers to select a platform based on form factor and operating system. MacOS Is the operating sys

tem that runs on Apple laptops and

the world's fastest computers,

computers are large, expensive devices capable of simulta

computers. The operating system for IPhones and iPads Is The

neously processing data for thousands of users. Computers used by Google and Web service providers are classified as

I. Personal computers come in sev I computer fits on

eral varieties. A(n)|

a desk, runs on power from an electrical wall outlet, and can be housed in a horizontal case or vertical case. Three categories

of portable computers include tablets, smartphones, and clam

shell style I

operating system from Microsoft runs on laptop and desktop PCs, whereas a derivative version Is designed for phones.

The open source community produces Linux for desktops and servers. This family of operating systems also includes

Chrome OS, and I

j. which Is popular

for tablets and smartphones.

I computers. Selecting a

SECTION C: The microprocessor Is a(n) Include word size, cache size, and Instruction set complex circuit, which is designed to pro cess data based on a set of instructions. Most desk

ity. Most digital devices contain only one microprocessor chip, but today's multl-

processors contain

top and laptop devices contain a microprocessor based

circuitry that supports parallel processing. Computers con

on the

tain various kinds of memory. Random

standard. Ivlost tab-

jets and smartphones contain processors based on technology. A microproces

memory Is a special holding area for data, program Instruc

tions, and the|

1 system. It stores data

sor's circuitry Is designed to perform a limited number of

on a temporary basis until the processor makes a data

tasks contained in its

i set. During

request. RAM Is different from disk storage because it is

processing, an instruction is loaded Into the processor's

I , which means that It can hold data

j] unit. Data Is loaded Into registers

only when the computer power Is turned on. Computers also

in the processor's|

where arith

contain read-1

|memory, which is a type

metic and logic operations are performed. Microprocessor

of non-volatile memory that provides a set of "hard-wired"

performance can be measured by Its

instructions, called the|

speed. Other factors affecting overall processing performance

a computer uses to boot up.

loader, that

155

DIGITAL DEVICES

state storage technolo

SECTION D: Today's digital devices use a variety of

DVD, or BD.

storage technologies.|

gies, such as USB flash drives, store data by activating elec

|storage tech

nologies, such as hard disks, store data as particles ori

trons in a microscopic grid of circuitry. A backup Is a copy

ented north or south. A hard disk drive provides multiple

of one or more files that have been made In case the original

for data storage that are sealed inside

files become damaged. A good backup plan allows you to

the drive case to prevent airborne contaminants from inter

restore a device's operating system, software, data files, set

fering with the read-write heads. Hard disks are less durable

tings. accounts, and profiles in case of a massive hardware

than many other types of storage, so It is important to make

failure or virus infection. Personal computer backups are typi-

stor-

a copy of the data they contain.

hard drives, USB

caiiy recorded on

age technologies store data as a series of dark spots and

flash drives, network servers, and online storage services. An

light spots on the surface of CDs, DVDs, or BDs. Storage

easy way to get a backup of important data files is to use the

technologies, such as CD-

|, are often

command to make duplicates and store

used for distributing software, but you cannot alter the disc's

them on a USB drive. Backup utilities such as File History and

technology allows you to

contents.

write data on a CD. DVD, or BD, but you cannot delete or

Time Machine use a technique called file to make sure that files on two devices are the same. A disk

change that data. Rerecordable or

is a bit-for-bit copy of the data from ail

technology allows you to write and erase data on a CD,

sectors of a hard disk.

SECTION E: Inside a digital device, a data

tion. Touchscreens use either

connects the processor to RAM, and

itive technology to process gestures. Display devices receive

images from graphics circuitry. A(n)

connects RAM to a series of expansion

or capac-

and

There are four technologies commonly used for general-

special video memory can enhance graphics processing and

purpose ports: Thunderbolt, FireWire, Lightning, and

free the main processor for other tasks. For printed output,

I . For video devices, the most com

most personal computer owners select| 1 , and Mini jet printers, though| |printers are a popu

mon ports are VGA, DVi,|

DIsplayPort. Peripherals can be inserted or removed while

lar option when low operating costs and high duty cycle are

the host device is on, but storage devices should not be

important. The internet of

removed without notification. To connect additional peripher

nology that links smart sensors. Some of these sensors can

als when all USB ports are full, it Is possible to use a USB

also be found In smartphones and autonomous vehicles.

1 . Some peripherals can be connected

wirelessly using

|technology. The soft

A(n) I

is a tech

I can sense if a laptop computer is

droppedorif a car brakes suddenly. A(n)

ware that helps a peripheral device establish communication

sensor measures angular velocity. A(n)

with its host device is called a device| Most devices Include a(n) |

can be used as a compass for navigation and map displays.

. |crystal dis

Autonomous vehicles use sensor data as Input to sense-plan-

play. Image quality for a display device Is a factor of screen size, response rate, dot

, and resolu-

algorithms processed on an onboard computer.

MODULE 2

INTERACTIVE SITUATION QUESTIONS

1. Suppose you're reading a computer magazine and you

SUP-R GAME DESKTOP

come across the ad pictured to the right. By looking

MODEL EEXL

at the specs, you can tell that the microprocessor was

manufactured by which company?

I Intel® Core™ i7

2. The capacity of the hard disk drive In the ad is

i6GBTri-Channel DDR3

GB and the memory capacity is

1500 GB SATA-II (7200 rpm) GB.

121.5" HD widcscreen monitor

iNVIDIA® GeForce™

3. Your friends are chatting about a low-cost laptop that

I Creative Sound Blaster X-Fi Titanium

"runs Google." You figure that they are actually talking about a device called a(n}

I Altec Lansing speakers • Gigabit Ethernet port '3-year limited warranty

that runs

Google's Chrome OS as Its operating system. 4. Looking over the specs for a new clamshell-style device,

'Windows 10

you notice that It contains an A10 ARM-based processor. Is this device more likely to run macOS or ICS?

$549 5.

At the beginning of an update for your smartphone, you notice a warning that says "Make sure your device Is connected to a wall outlet and do not turn the device off

until the update Is complete." You suspect that the update

Is going to|

I the ROM boot loader to

fix a security vulnerability.

8.

After purchasing a new Windows computer, your first step is to get ail your backup tools in order, beginning with

a(n) I

i drive that you can use to boot

your computer In case of a hard drive failure. 9, One of the ports on your laptop is rectangular and the

6. You've decided to archive your vast photo collection on

Inside of It Is blue. It Is a(n)

port.

DVDs. You want the longest possible llfespan. When

10, You need an external keyboard for your Android device,

you go to purchase blank DVDs, you see that some are

and thankfully you can add a wireless one because II has

marked DVD-R, whereas others are DVD-RW, Which should you choose?

capability. 11. Suppose that you volunteer to produce a large quantity

7. You're working on a group project. Each person has to

of black-and-white leaflets for a charity organization, II is

access a dataset and use it to create several graphs.

fortunate that you have access to a(n)

You'll be compiling the graphs Into a final report. Rather

printer with a high duty cycle and low operating costs.

than emailing graphs back and forth, you suggest using Dropbox, a(n)

storage service where

members of the group can access a shared folder.

DIGITAL DEVICES

LAB:WHAT'S GOING ON IN THERE?

l:'"

^.

THE MiCROPROCESSOR CLOCK IS TICKING. Data bits are flying in and out of RAM and zooming over the data bus to a storage device. All that seems invisible, but wait! You can get an idea of what's going on inside the system unit. Who needs to know? You might. If you suspect your computer has a virus, if you think your computer might have been compromised by a botnet. If your computer seems sluggish. Windows and macOS include monitoring utilities that pro vide ail kinds of information about your computer's status.

REQUIREMENTS: For this lab, you'll need a desktop or laptop computer running either Windows or macOS.The instructions are general ized: they provide helpful guidelines, but not specific steps. You may have to explore a bit to find all the tools needed to complete the assignment, but that is all part of the learning experience.

ASSIGNMENT:

o Open your computer's monitoring utility.

Q Check for malware.

On a Mac, select the Applications folder from the dock. Select the Utilities folder, then select Activity Monitor. Use

Some processes are launched by the operating system rather than application software. If you don't recognize a process, you can find out if it is legitimate by checking

the View menu to select All Processes.

A.On a PC with Windows, make sure you are at the Home

online.

screen. Use the Search box to find and launch Task

Select a process with an unusual name and search for it

Manager. It might be necessary to select More Details.

online. What is its name and what does it do?

Examine your computer's CPU usage.

0Check memory.

On a Mac. select the CPU button; on Windows,select the

On a Mac, select the Memory tab: on Windows, remain

Performance tab-

on the Processes tab.

CPU utilization is expressed as a percentage of total pro

As you know, RAM holds the operating system, pro

cessing capability. If CPU utilization exceeds 10% when

grams, and data, but the amount of stuff that's actually in

you are not using software, it might signal a security

RAM is pretty surprising.

breach. Temporary spikes are normal: and when you are playing 3D games or using compute-intensive software, the usage could remain above 70%. What is the current CPU utilization on your device?

Find the listing for Kernel_task (Mac) or System (Windows). That process is part of the operating system. How much memory is it using? What is the name of the software application that uses

@ Check processes.

the most memory?

On a Mac, processes are listed on the CPU tab; on

0 Check storage.

Windows, select the Processes tab.

A process corresponds to a program. Any programs that are currently running put a load on the CPU.

What is the process with the highest CPU usage? Do you recognize the program associated with this process? If not, look it up online.

On a Mac, choose the Disk tab; on Windows, remain on the Processes tab.

Programs send data to storage even when you are not in the process of manually saving files. Some programs cre ate autorecovery files as temporary backups, and Web pages write cookies.

Find a process that is writing data to disk even when you are not actively using it. What is the name of that process and what is its purpose?

Networks

Module Contents SECTION A; NETWORK BASICS

Communication Systems Communication Clianneis

Network Topology Network Nodes Commurtication Protocols SECTION B: THE INTERNET

Background

Networks let us reach out to the world.

But they also let the world into our

personal space. In this module you'll explore how to create and use net works that don't expose your darkest secrets.

internet infrastructure Packets Internet Addresses

Domain Names

TRY IT!

Apply what you learn.

SECTION C; INTERNET ACCESS Connection Basics Cable internet Service

Telephone Network Internet Service

Choose when to use wired connections and when to use wireless connections-

Check the signal strength of a wireless connection.

Satellite Internet Service

Find your router's IP address.

Mobile Broadband Service

Find the private IP address for your device.

Wi-Fi Hotspots Differentiate between IPv4 and IPvG addresses. SECTION D: LOCALAREA NETWORKS

Obtain a domain name.

LAN Basics

Find the owners of domain names and IP addresses.

Ethernet

Find the address of your DNS server and change it if

Wi-Fi

Set UpYour Own Network Network Monitoring loT Networks SECTION E:

FILE SHARING

File Sharing Basics Accessing LAN Files SharingYour Files Internet-based Sharing Torrents ISSUE: WHO WILL CONTROLTHE INTERNET?

necessary.

Check the speed of your Internet connection and com pare it to the speed advertised by your ISP.

Determine the latency, jitter, and packet loss on your Internet connection and gauge whether it affects the quality of streaming services. Use Traceroute to troubleshoot a slow Internet connection.

Select an Internet service provider. Reduce your security risks when connecting to Wi-Fi hotspots.

INFORMATiONTOOLS;

Construct a local area network that allows devices to

FACT CHECKING

share files and an Internet connection.

TECHNOLOGY IN CONTEXT:

Configure and secure a router for a local area network.

EDUCATION

Piece together a small loT network for home monitoring.

MODULE ACTIVITIES LAB: HACK YOUR NET

Access files from other devices on a LAN.

Activate file sharing and use permissions to limit how your files can be used. Obtain files from internet-based services, such as FTP, Dropbox, and Bitlorrent.

158

Networks

PRE-CHECK

Gauge your level of expertise. The answers are in the text.

11=^ What type of network topol ogy does the diagram above

m

Before speeding over the

The major problem with satel

Internet, files are divided Into:

lite Internet access is excessive:

illustrate?

List five types of fixed Internet

LTE

access:

Which is more secure:

Broadband or narrowband?

WEP or WPA

wmv.course.com

What's the top-level domain?

TCP

WPA2

IP

WEP

Which one is the Internet

protocol stack?

To protect the files on your computer when connecting to a Wi-Fi hotspot, what should you turn off?

1 59

160

SECTION A, MODULE 3

Channels

Equipment Communication

Systems

Topologies

SECTION

A NETWORK BASICS

NETWORKS ARE EVERYWHERE.

Terminology

They are an indispensable part of our lives. When there are outages, things go haywire. When there

communication network PAN LAN WAN

are slowdowns, we get frustrated. What do you

communication channel wired channels

need to know about networks7The building blocks

in Section A will get you started.

wireless channels RF signals transceiver TTllcrOWaveS bandwidth

broadband narrowband topology point-to-point topology star topology mesh topology bus topology node DTE dce router modem

communication protocol handshaking protocol stack error correction

Objectives I Replicate Shannon's diagram of a general communication system,including all nine labels.

I Give two examples of PANs,LANs,and WANs. > List four examples of wired channels used for

I Draw a diagram showing how data from a smart thermostat could travel over several networks with different topologies.

I Compare and contrast mesh and star topologies based on dependability, security, capacity, expandability, control, and monitoring.

networks.

I State the two wireless channels most

commonly used for communication networks. I List two advantages and four disadvantages of

I List two examples of PTEs and two examples of DOES.

I Explain the difference between a modem and a router.

wireless channels.

t State what differentiates broadband from narrowband.

I List five tasks that are handled by

communication protocols.

161

NETWORKS

COMMUNICATION SYSTEMS

You use many networks for communication, research, and entertainment. Some networks are large and some are small. The largest networks offer little control to consumers. Smaller networks that you set up can be com

pletely under your control, but they are also your responsibility. Networks can be classified in many ways; as a network user, you'll want to keep in

QUICKCHECK In Shannon's model, signals

(

mind the idea of control and how it affects your privacy and security.

traveling along a communication

I What is a network? A network links things together. A communica

channel can be disrupted by

tion network (or communication system) links together devices so that data and information can be shared among them.

a. a source

In 1948. Claude Shannon, an engineer at Bell Labs, published an article

b. a transmitter

describing a communication system model applicable to networks of all types. His diagram illustrates the essence of a network, so it is a good place to begin this module. Shannon's model (Figure 3-1) is easy to understand.

c. a receiver d. noise

FIGURE 3-1: COMPONENTS OF A GENERAL COMMUNICATION SYSTEM

Noise J y

s„„„ /f ° ■ Communication | channel

Source

Transmitter

Receiver

Destination

\ How are computer networks classified? Networks can be classi fied according to their size and geographic scope, as shown in Figure 3-2. FIGURE 3-2: NETWORK CLASSIFICATIONS

aa a a PAN (personal area network)

LAN (local area network)

WAN (wide area network) WANs cover a large geographi

PANS connect smart devices or con

LANs are data communication

sumer electronics within a range of about 30 feet (10 meters) and with

networks that connect personal cal area and usually consist of computers within a very limited several smaller networks, which geographical area—usually a single might use different computer building. School computer labs and platforms and network technolo home networks are examples of gies. The Internet is the world's

out the use of wires or cables. The

reference to persona/ indicates that the network serves a single indi vidual, rather than multiple users. A

PAN could be used to sync data from a handheld device to a desktop com puter, ship data wirelessly to a printer, or transmit data from a smartphone to a wireless headset.

LANs. Wi-Fi networks that you can

largest WAN. Other public WANs include telephone systems, cable other public places are LANs. The in- television systems, and satellitehouse networks operated by most based communication systems.

access in airports, coffee shops, and

businesses are also LANs,

162

SECTION A, MODULE 3

> Why is geographic scope important? Localized nelworks nor mally include a small number of computers, which can be connected using basic equipment. As the area of network coverage expands, the number of

QUICKCHECK

devices grows, specialized devices are sometimes required to boost sig nals, and the diversity of devices requires sophisticated management tools

Internet access to students in

and strategies.

classrooms is operating what

t What about the Internet of Things? The Intemet of Things (loT)

type of network?

is an evolving concept that may be difficult to classify as a PAN, LAN, or WAN. The loT has the potential to become a global collection of smart devices transmitting to other devices over the Internet. Today,smart devices

a. PAN

are more often grouped into small local pods that report to a centralized device, which in turn exchanges data with local networks and the Intemet.

c. loT

A univeriity that offers wireless

b. LAN

d. WAN

COMMUNICATION CHANNELS

Do you suppose it is easier for a snooper to surreptitiously access your computer when your device is connected to a Wi-Fi hotspot or cabled to a

LAN? Some connections are more secure and more dependable than oth ers, so it pays to understand the ins and outs of communication channels. I What is a communication channel? A communication chan nel is the medium used to transport information from one network device

to another. Data transmitted over a communication channel usually fakes the form of an electromagnetic signal—waves of light, electricity, or sound. These waves can travel through the air or through cables, so channels are divided into two general classifications: wired and wireless. Wired chan

nels transport data through wires and cables. Wireless channels transport data from one device to another without the use of cables or wires.

TRY IT! Are you using a network right now? Is It wired or wireless?

> What are the options for wired channels? Wired channels

If It is wired, can you identify

include twisted pair wires used for telephone land lines, coaxial cables used for cable television networks. Category 6 cables used for LANs, and fiber optic cables used for high-capacity trunk lines that provide main routes for telephone, cable, and Internet communications(Figure 3-3).

the type of cable that connects your computer to the rest of the

FIGURE 3-3: NETWORK CABLES

Telephone cable

Network

cable

Coaxial cable

FIfaer-optIc cabfe

network?

163

NETWORKS

► What are the advantages of wired channels? Before wireless technologies became available, local area networks were exclusively wired. Today, wired connections are used less frequently for home, school, and business networks. They remain the network technology of choice, how ever, for segments of the Internet and local area networks that require fast and secure connectivity. When you set up a wired connection, you don't have to worry about hackers Intercepting your data from the sidewalk outside your house, or your neigh bor stumbling across personal files when your wireless signal reaches past your property line. Yes, there are ways to tap into a wired network, but they require physical access to the cable or fairly sophisticated snooping equip ment. The advantages of wired channels are summarized in Figure 3-4. FIGURE 3-4: ADVANTAGES OF WIRED CHANNELS

QUICKCKECK connections

Data traveling on a wired

Cables can be shielded

Wired

against interference and

are dependable. Their

more secure than their

channel tends to be more secure

encased In protective

carrying capacity and

wireless counterparts

than data traveling on a wireless

casings for installations

speed are not affected by airborne interference

because a device can

channel. True or false?

that are outdoors and

join a wired network

underground-

from rain, snow, or elec

only if it is physically

a. True

trical devices.

connected by a cable.

b. False

Wired connections are

• What are the disadvantages of wired connections? The cables that offer speed and security for a wired connection are also the main weakness of this type of connection. The disadvantages of wired channels include cost, lack of mobility, and installation hassles. Figure 3-5 provides more details. FIGURE 3-5: DISADVANTAGES OF WIRED CHANNELS

QUICKCHECK In WANs, wired instal

LAN devices connected

Cables are unsightly,

Which of the following situations

lation can be costly

by cables have limited mobility. Desktop com puters tend to be better

tend to get tangled, and collect dust. Running cables through ceilings,

that connects most devices with

poles or buried under ground. They can be

candidates for wired connections, whereas

walls, and floors can be challenging. Cables

a. A university campus

damaged by weather events and digging in the wrong place. Repairs

laptops, tablets, and

can also carry electri

b. A bank branch office

handheld devices can

cal surges that have the

retain their mobility

to underground cables

when they are not teth

potential to damage network equipment.

require heavy equip

ered to a cable.

because cables have

to be suspended from

ment to locate, access, and fix the break.

Is most suitable for a network cables?

c. A private home d. A coffee shop

164

SECTION A, MODULE 3

I What are the options for wireless channels? The most wide

spread wireless channels for communication networks are radio signals and microwaves.

i How do radio signals transport data? Most wireless channels transport data as RF signals, commonly called radio waves. RF chan nels are typically used for Bluetooth connections, Wi-Fi networks, and

wide area wireless installations such as WIMAX. It is also the technology used to carry voice and data between a smartphone and a cell tower. RF signals are sent and received by a transceiver (a combination of a trans mitter and a receiver) that is equipped with an antenna (Figure 3-6).

Terminology RF stands for radio frequency.

FIGURE 3-6: TRANSCEIVER-EQUIPPED DEVICES

Terminology Although we use the term wireless connection, there is no

physical connection between wireless devices in a network.

Their connection is conceptual Devices used with wireless connections are equipped with transceivers that

in the sense that data can

include a transmitter for sending data and a receiver for collecting data. A

travel between "connected"

transceiver has an antenna, which may be visible or may be housed out of sight

devices.

within a device's system unit.

I How do microwaves transport data? Microwaves (the waves themselves, not your oven!) provide another option for transporting data wirelessly. Like radio waves, microwaves are electromagnetic signals, but (hey behave differently. Microwaves can be aimed in a single direction and have more carrying capacity than radio waves. However, microwaves can not penetrate metal objects and work best for line-of-sight transmission when a clear path exists between the transmitter and receiver. Microwave installations usually provide data transport for targe corporate networks. They are also used to transmit signals between towers In cellular and wide area wireless installations.

► What are the advantages and disadvantages of wireless? The main advantage of wireless connections is mobility. Wireless devices

QUICKCHECK

are not tethered to network cables, so battery-operated laptops, tablets,

What type of wireless channels

and smartphones can be easily moved from room to room, or even out doors. With wireless networks, there are no unsightly cables, and power spikes are much less likely to run through cables to damage equipment. The main disadvantages of wireless channels are speed, range, security,

are most typically used for networks in homes and coffee

shops? a.

RF

and licensing, b. Coax

► Why is wireless slower than wired? Wireless signals are sus ceptible to interference from devices such as microwave ovens, cordless telephones, and baby monitors. When interference affects a wireless sig nal, data must be retransmitted, and that takes extra time.

► What limits the range of a wireless connection? The range of a wireless signal can be limited by the type of signal, the transmitter strength,

and the physical environment. Just as radio stations fade as you move away from their broadcasting lowers, data signals fade as the distance between network devices increases. Signal range can also be limited by thick walls, floors, or ceilings.

c.

Microwave

d. WIMAX

155 NETWORKS

As signal strength decreases, so can speed. A weak signal usually mearis slow data transfers. You can get a rough idea of signal strength for your

desktop, laptop, tablet, or smartphone by checking the network signal strength meter {Figure 3-7).

TRY HI

Your digital devices may connect to various networks with

differing signal strengths. Check the wireless signal strengths for

FIGURE 3-7; WIRELESS NETWORK SIGNAL STRENGTH METER

any devices you have handy.

10:23 AM ^rah Smith ^ ® Network signal strength meter Network signal strength

on the Windows desktop

meter on the Mac desktop

I What's the problem with wireless security? Wireless signals float through the air and penetrate walls. The signals that carry your wire less data can be accessed from outside your premises. Someone outside

of your house, for example, could surreptitiously join your network, access files, and piggyback on your Internet connection. To make wireless data useless to Intruders, it should be encrypted. Later in this module, you'll

learn how to use encryption to secure data sent over wireless connections.

I How does licensing affect wireless connections? Government agencies, such as the Federal Communications Commission (FCC), regu late signals that are sent through the air. To broadcast at most frequencies, including those used by radio and television stations, a license is required. Wireless connections use unlicensed frequencies that are available for pub-

Terminology

tic use. These frequencies include 2.4 GHz and 5 GHz. Of the two, 5 GHz is subject to less Interference from other devices, but it has a more limited

Hz Is an abbreviation for hertz,

range.

of times a wave oscillates, or

I What's bandwidth? Network channels must move data and move

peaks, per second. Telephone signals are transmitted in the 1,200 Hz range. Many wireless

it quickly. Bandwidth is the transmission capacity of a communication channel. Just as a four-lane freeway can carry more traffic than a two-lane street, a high-bandwidth communication channel can carry more data than a low-bandwidth channel. For example, the coaxial cable that brings you more than TOO channels of cable TV has a higher bandwidth than your

which refers to the number

networks transmit a 2.4 GHz

signal that peaks 2.4 billion times per second.

home telephone line.

The bandwidth of a channel that carries digital data is usually measured in

bits per second (bps). For example, your wireless LAN might be rated for an average speed of 27 fvlbps. The bandwidth of a channel carrying analog

QUICKCHECK You have a choice of network

data is typically measured in hertz (Hz). For instance, the copper wires that carry voice-grade telephone signals are often described as having a

connections. Which one of the

bandwidth of 3,000 Hz.

following Is broadband?

As of 2015, the FCC defines networks that are capable of moving at least 25 megabits of data per second (25 Ivlbps) as broadband. Channels slower than 25 Mbps are classified as narrowband. Broadband capacity is essential for networks that support many users and those that carry lots of

a. A 56 Kbps phone link

audio and video data, such as music and movie downloads.

b. A 2.4 GHz cordless phone c. A

cable connection

d. A 1.2 Mbps satellite link

166 SECTION A, MODULE 3

NETWORK TOPOLOGY

A spider weaves a web by making silky connexions between leaves, branches, and other surfaces. Most spiderwebs have a structure, and the same can be said for communication networks. The topologies of the net

works you use have an effect on their dependability, security, and scope. i What is network topology? in the context of communication net works, topology refers to the structure and layout of network components, such as computers, connecting cables, and wireless signal paths. When

QUICKCHECK

you envision how devices are connected by communication channels, you

In the full mesh network

are creating a picture of the network's topology.

illustrated in Figure 3-8, how

Module 2 explained how peripheral devices can connect to a host device

many possible paths are there

using expansion ports, USB cables, or Bluetooth. These connections are

between any two points?

an example of point-to-point topology. When connecting several devices,

a. 1

two network topologies are popular. Star topology connects multiple b. 5

devices to a central device. Mesh topology connects multiple devices to each other, either as a full mesh or as a partial mesh. The less popular

c. 9

bus topology connects devices in a linear sequence. Figure 3-8 illustrates

d. 10

these network topologies. FIGURE 3-8; NETWORK TOPOLOGIES

VS\ AV Point-to-point

Star

Full mesh

Partial mesh

Bus

> Can a network use more than one topology? Data can flow over multiple networks that have different topologies. As shown in Figure 3-9, data from a fitness wristband connects to a laptop via a point-to-point con nection (A). The laptop is part of a home network configured as a star (B). The home network uses Comcast, so it is part of a larger star network (C). Finally, the data is passed to the Internet, which has a mesh topology (D). FIGURE 3-9: MULTIPLE TOPOLOGIES

Comcast

LAN

167

NETWORKS

> Which topology is best? Every topology has strengths and weak nesses, so there is no best network topology. Figure 3-10 compares strengths and weaknesses of the two most popular network topologies based on dependability, security, capacity, expandability, control, and monitoring. FIGURE 3-10: STAR OR MESH?

vs\ as ■a

c u

a 9i

Q

If the central point fails, data cannot flow anvwhere on the

There is no central point of failure;

network. If one of the other

can be used to bypass failed devices.

redundant paths between devices

devices fails, however, the rest of the network remains operational.

vs\ u

between the sender and desti

a u V

nation. The threat area for any transmission encompasses only

Within a mesh, data travels through several devices and over multiple channels. Each leg presents a poten tial security risk. The chance of a security breach rises as the number

CA

three devices and two channels.

of devices and channels increases.

Data that travels on a star

pathway makes only one stop

U

es a

ts

•XStar topologies are limited by

Mesh topologies offer higher capaci

the amount of data that can be

ties because data can be transmitted

handled by the central device.

from different devices simultane

ously.

(S ■o s

ce a

•X-

vs\

•X-

VS\

The network can be expanded infi number of devices that can be nitely. As new devices are added, attached to the central device the network continues to repeat within its immediate area of the signal as necessary until it wireless coverage or maximum reaches the farthest devices. cable length. Expandability is limited by the

Setup and updates are primar ily done on the central device, o

u

which also can be used to shut down the entire network.

Setup Is more complex, as each device must be configured to send, receive, and forward network data. There is no central point at which the network can be shut down.

•«J3

O

•XAll data passes through a central point, which is easy to monitor for legitimate or illicit purposes.

Data does not pass through a central point, making data more challenging to monitor.

i

168

SECTION A, MODULE 3

NETWORK NODES Communication networks connect all kinds of devices: from smartphones to satellite dishes, from computers to cell towers, and even between tiny sensors and RFID tags. Any device in a network is called a node. You are familiar with network nodes such as laptops, smartphones, tablets, desk­ tops, and peripheral devices. There are many other nodes that you don't interact with directly, yet they ultimately control how smoothly your Netflix movie streams and whether your email arrives at its destination. t What should I know about network nodes? Devices on a network are classified as DTEs or DCEs. DTE stands for data terminal equipment. A DTE can be any device that stores or generates data. When connected to a network, your laptop is a DTE, as are your smartphone, tablet, and fitness tracker. The servers that house Web sites, handle email, offer cloud storage, and stream videos are also DTEs. Your own DTEs are under your control, and many servers are open to public access. DCE stands for data communication equipment. These devices control the speed of data over networks, convert signals as they jump from cables to wireless, check for corrupted data, and route data from its origin to its desti­ nation. The most well-known DCEs are routers and modems.

QUICKCHECK When you connect a cell phone to a network, it is considered a(n)______ a. DTE b. DCE c. SPT d. TCP

t How does a router work? You probably have a DCE in your home network. A router is a device that controls the flow of data within a net­ work and also acts as a gateway to pass data from one network to another. Routers are used to direct traffic over major Internet trunk lines. And they are commonly used to route data from home networks to the Internet (Figure 3-11 ). FIGURE 3-11: ROUTERS

To other networks

t How does a modem work? A modem contains circuitry that con­ verts the data-carrying signals from a digital device to signals that can travel over various communication channels. The kind of modem you use depends on whether you are connecting to a dial-up, wireless, cable, satel­ lite, or DSL Internet service. A modem is usually supplied by your Internet service provider (Figure 3-12).

QUICKCHECK A typical home network with Internet access would have a. a single DTE b. multiple DCEs, but no DTEs

FIGURE 3-12: MODEMS

c. a modem and a router Modem

d. multiple routers

169

NETWORKS

i What about other DCEs? DCEs perform all sorts of tasks. Suppose you want to extend the range of your home network out onto your bal cony. What if your Internet provider wants to streamline network traffic in a neighborhood where lots of subscribers stream HD movies? DCEs such as repeaters, switches, and hubs can get the job done (Figure 3-13). FICURE 3-13; NETWORK DEVICES

More

Hub

Router

Computers

computers

Hub

'

Extends a wired network by adding more ports

Switch

Computers

Switch

Sends signals to individual nodes rather than broadcasting to all of them

Bridge

Computers ^^Router

Bridge

Router

Connects two similar networks

*>■ '

Repeater

Computers W

Repeater

Extends the range of a network by restoring signals to maximum strength and retransmitting them

Wireless access

point (WAP)

Router Router

More

Computers

computers Allows wireless devices to connect to a wired network

QUiCKCHECK To extend the read) or your wireless network out onio your balcony, which of the following devices would be best? a. A hub

b. A router

c. A repeater d. A gateway

170

SECTION A, MODUtE 3

COMMUNfCATION PROTOCOLS A protocol is a set of rules for interacting and negotiating. In some respects, it is like the hand signals used by pitchers and catchers during base

ball games. Before the ball Is thrown, the pitcher and catcher use hand signals to negotiate the speed and style of the pitch. Similar to the way pitchers and catchers use signals, networks use communication proto cols to coordinate data transfer.

TRY IT! People use many verbal and

► What is a communication protocol? In the context of networks, a

nonverbal communication

communication protocol refers to a set of rules for efficiently transmit ting data from one network node to another. Two devices on a network negotiate their communication protocols through a process called hand shaking. The transmitting device sends a signal that means "I want to communicate." It then waits for an acknowledgment signal from the receiving device. The whooshing sounds you hear as two fax machines connect are examples of handshaking.

protocols. Think of a nonverbal signal that you might use in a restaurant to indicate that

you'd like the bill. How does

the server acknowledge your request?

> What can communication protocols do? Protocols set standards for encoding and decoding data, guiding data to its destination, and reduc ing the effects of interference. Networks use more than one protocol, and the collection of protocols for a network Is referred to as a protocol stack. Some protocols set standards for the physical cables and signals used to connect network nodes. Other protocols deal with the way data flows over network channels. And even more protocols specify standard formats for data so that it can be accessed by communication software. Figure 3-14 explains. FIGURE 3-14: COMMUNICATION PROTOCOLS

¥

PHYSICAL PROTOCOLS

specify cable and signal standards for the channels that carry data

TRANSPORT PROTOCOLS

Make sure data gets to its destination by establishing stan dards for dividing data into chunks, assigning addresses, and correcting errors

QUICKCHECK Which protocol category Is responsible for the standards that attempt to block junk mail?

ARRIVAL PROTOCOLS

[jl]

Convert data into standard formats that can be used by

applications, such as email. Web browsers, and Skype

a. Physical b. Transport c. Arrival

171

NETWORKS

► How can a network detect if a signal has been corrupted? Error correction is one of the responsibilities of communication protocols.

Remember from Module 1 that text, numbers, sound, images, and video all are represented by bits. Suppose that some of those bits are garbled in transmission. Did that email say to meet at 29:00? Did your music track stop halfway through? Without error checking, the data you receive may not be reliable or complete.

Digital networks—those that transmit digital signals—can be easily mon itored to determine if interference has corrupted any signals. At its most

primitive level, digital equipment is sensitive to only two frequencies—one that represents 1s and one that represents Os. Suppose that a 0 is sent as -5 volts and a 1 is sent as +5 volts. What if. dur ing transmission, some interference changes the voltage of a 1 bit from +5 volts to +3 volts?

To correct the corrupted bit, the receiving device realizes that +3 volts is not one of the two valid voltages. It guesses that a 1 bit {- Who siipervises Internet standards? Although each country can develop laws, policies, and regulations for the networks within their jurisdic tion, there is one crucial administrative task necessary to keep the internet

from sinking into chaos. Every Internet node—each server, each computer, and each piece of data communication equipment—must have a unique address in order to send and receive data.

The organization that supervises Internet addressing is ICANN, the Internet

Corporation for Assigned Names and Numbers. iCANN is a not-for-profit private sector organization operated by an international board of directors. Its advisory committee has representatives from more than 100 nations, and public comments pertaining to ICANN policies are accepted at its Web site.

QUICKCHECK

The primary role of ICANN is to • a. run the Internet

b. provide funding for the Internet

Control of Internet address assignments is a powerful tool. It provides the means to block users from accessing specific network nodes. Local govern ments exercise this power within their jurisdictions to shut down servers that violate copyright and distribute inappropriate content. The power to globally shut down access to a server, however, only rests with ICANN. You will discover more about the key role of internet addresses later in this section.

c. supervise Internet address assignments d. make sure that every country in the world gets equal access to the Internet

NETWORKS

175

INTERNET INFRASTRUCTURE The Internet Is not one huge communication network, but rather a net

work of networks. The way these networks fit together is referred to as the Internet infrastructure, internet networks are organized into tiers. As a consumer, you are subject to the fees, policies, and technologies of the tiers that provide your Internet service.

• What are the components of the Internet? The Internet is structured as a hierarchy of networks. Tier 1 networks are at the top of the hierarchy, followed by Tier 2 and Tier 3 networks. Tier 1 networks, such as AT&T, CenturyLink, Verizon, and NTT Communications, form the Internet backbone, a system of high-capacity routers and fiber-optic communica

tion links providing the main routes for data speeding across the Internet. Routers on the Internet backbone store routing tables that calculate and track the most efficient routes for data to travel from point A to point B. The Internet backbone is configured as a mesh network that offers redun dant routes for data transport. The backbone's mesh infrastructure is

probably the basis for the myth that the internet originated as a Department of Defense project to create a network that could survive nuclear attacks. Networks that form the Internet are maintained by Internet service provid ers (ISPs)that supply routers and other data communication equipment, as well as physical and wireless channels to carry data. ISPs exchange data at Internet exchange points (IXPs). Consumers generally connect to Tier 2 or Tier 3 networks. Use the infographic in Figure 3-18 to become familiar with the Internet infrastructure and its terminology: pay attention to the arrangement of network tiers and

QUiCKCHECK The Internet backbone

a. became the ARPANET In 1985

b. is maintained by ISPs

c. has IXPs where data can get sidetracked

d. is operated by the NSA

points where data moves between them. FIGURE 3-18; INTERNET INFRASTRUCTURE

■ Routers •IXPs

TIER 1

Jffjj ir^il iqor

. fSi.i

TIER 2

TIER 3

School network

Homo network

Business network

SECTION B, MODULE 3

176

> Who pays for the Internet? The Internet is not free. ISPs make a substantial investment in equipment and the cable or wireless infrastruc tures to connect consumers. The largest providers each have close to 200,000 miles of cables Installed across continents and laid over the ocean floor.

Tier 1 ISPs also own and maintain millions of dollars of data communication

equipment. In addition to Infrastructure expenses, ISPs are subject to data transport fees, especially when shipping data up through higher tiers. To offset expenses, ISPs charge consumers for access. Figure 3-19 explains how it works.

FIGURE 3-19: HOW ISPs CHARGE FOR ACCESS

FREE

Tier 1 service providers exchange data with other Tier 1 providers on a

FREE

no-cost basis.

S

$

s

_

$

free

I

QUICKCHECK Which ISP tier is not subject to transport fees from other tiers?

Tier 2 service providers exchange data on a no-cost basis with other

a. Tier 1

Tier 2 providers, but they pay fees to connect to the backbone through

b. Tier 2

Tier 1 providers.

c. Tiers

Tier 3 service providers connect to

Tier 2 or Tier 1 providers and pay transit fees for the data exchanged.

Consumers either pay fees directly

A

U

or their access is subsidized by an organization or government.

PACKETS

(Viost people envision their files, email, and other data flying through the Internet as a continuous stream of bits. This is not the case. Files are

QUICKCHECK Files are divided into before being shipped over the

chopped up into small pieces called packets. The technology that breaks a file into packets and routes them to any location on Earth in the blink of an

Internet.

eye Is absolutely amazing.

a. packets

t What's a packet? A packet is a parcel of data that is sent across a computer network. Each packet contains the address of its sender, the des

b. email messages

tination address, a sequence number, and some data. When packets reach

c. bits

their destination, they are reassembled into the original message according

d. tiers

to the sequence numbers (Figure 3-20). FIGURE 3-20: DATA PACKETS

li Messages divided into equal-size packets are easier to handle than an assort ment of small, medium, large, and extra large files.

177

NETWORKS

► Why not just send an entire message? Some communication networks, such as telephone systems, use a technology called circuit switching, which essentially establishes a dedicated, private link between one telephone and another for the duration of a call. Unfortunately, circuit switching is rather inefficient. For example, when someone is on hold, no communication is taking place—yet the circuit is reserved and cannot be used for other communications.

A more efficient alternative to circuit switching is packet switching tech nology, which divides a message into several packets that can be routed independently to their destination. Packets from many different messages can share a single communication channel, or circuit. Packets are shipped over the circuit on a first-come, first-served basis. If some packets from a message are not available, the system does not need to wait for them, instead, the system moves on to send packets from other messages. The end result is a steady stream of data (Figure 3-21).

Terminology The telephone network is sometimes referred to as the

public switched telephone network (PSTN).

FIGURE 3-21: SHIPPING PACKETS

Each circuit dedicates

CIRCUIT-SWITCHING NETWORK

A single channel can carry packets from many devices.

QUICKCHECK Which of the following dedicates a communication channel to each data transmission? a. The Internet b. Packet-switched network PACKET-SWITCHING NETWORK

Packet-switching networks (bottom) provide a more efficient communication system than circuit-switching networks (top).

c. Circuit-switched network

d. FedEx

SECTION B, MODULE 3

178

► How are packets created? One of the core Internet protocols, TCP (Transmission Control Protocol) is responsible for dividing files into chunks, adding headers containing information for reassembling packets in their original order, and verifying that the data was not corrupted while in transit (a process called error checking). When data is sent over the Internet using TCP, it will reliably reach its destination. TCP is built into applications that transmit data from one digital device to another.

► How are packets transported? TCP is also responsible for estab lishing a connection, transferring packets, and dosing the connection when the transmission is complete. Most of the data that fiows over the Internet is

QUICKCHECK Which data transport protocol includes robust error-checking? a. TCP b. UDP c. ARPANET

d. Circuit switching

under the control of TCP.

An alternative transport protocol, UDP (User Datagram Protocol) is faster than TCP but does not perform error checking and cannot reorder packets

if they are received out of order. UDP, therefore, is suitable for applications in which a bit of lost data is not critical, such as streaming video and music,

and Internet-based multiplayer games and voice calls. UDP and TCP both use communications ports to shuttle data into and out of a network device.

► What is a communications port? Here's the problem: On a packetswitching network, packets for Web pages, email, streaming videos, and other downloads may arrive at your digital device in the same stream and over the same channel. The packets may not arrive in neat little bundles; some video packets could arrive interspersed with Web page packets. Which packets should go to the browser and which to the Netflix player? Acommunication poit (usually referred to simply as a port) is a virtual end point for data entering and leaving a digital device. These ports are virtual in the sense that they are not physical ports, as are USB ports, for example. A communication port is not a physical circuit, but rather an abstract concept of a doorway, an opening, or a portal through which data flows.

QUICKCHECK Communication ports. a. include USB and audio ports b. simulate the dedicated circuits that exist on circuit-

Ports work in conjunction with Internet addresses, as you'll learn in later modules. Computers can have up to 65,535 ports. Typically about 10-20 ports are in use and open for various types of data. Data originating from the Web, for instance, uses port 80, whereas streaming video uses port 554. When ports are open, data is allowed to flow freely. Closing ports can block data, and that strategy is used by firewalls to prevent unauthorized

switching networks c. are designed to increase the download speed of video data

d. do not recognize packets

intrusions.

Ports create simulated end-lo-end connections on packet-switching net

works. So although the devices on two ends of a communication channel are not connected by a single dedicated circuit, ports create a conceptual circuit for each type of data, as shown in Figure 3-22. FIGURE 3-22: COMMUNICATION PORTS WORK WITH DATA FOR SPECIFIC APPLICATIONS

Port 80

a

■aaaa-

0,(S)fl

Port 554

Port 554

\j Data pours into a digital device from multiple sources.

Port 80

Data with simliar port numbers is channeled to associated apps.

browser Netflix

179

NETWORKS

INTERNET ADDRESSES

You might have heard that Internet addresses are running out. Does that mean some people will be unable to get online? Will people have to share addresses? Networks use several kinds ot addresses to determine where

packets originate and where they are headed. To find out how internet addresses might affect your online access, read on.

Terminology Internet Protocol is often

referred to as TCP/IP (pronounced "T-C-P-l-P").

i Exactly what is an Internet address? Although most people are accustomed to entering something such as www.wikipedia.org to access Internet locations, those "www" addresses are not the underlying address used to transport data to its destination. Internet addresses are controlled by IP (Internet Protocol), which—along with TCP—is part of the Internet protocol suite. IP defines two sets of addresses: IPv4 and IPv6.

► What is the difference between IPv4 and IPv6? IPv4, which stands for Internet Protocol version 4, is the Internet address standard

that has been used since the early 1980s. IPv4 uses 32-bit addresses to uniquely identify devices connected to the Internet. In binary, IPv4 addresses are written as:

11001111 01001011 01110101 00011010

For convenience, 32-bit binary addresses are usually written in decimal as four sets of three digits separated by periods: 207.75.117.26

Using 32 bits. IPv4 offers about 4 billion unique addresses. In 2011, that supply of addresses was completely allocated. Yes. IP addresses can be recycled when the original assignees no longer want them, but the demand far outstrips the number of addresses coming up for recycling. Another set of addresses was needed.

IPv6 (Internet Protocol version 6) uses 128 bits for each address, producing billions and billions of unique Internet addresses. An IPv6 address is usually written as eight groups of four hexadecimal digits, like this: 2001:48a8:800:1192:198:110:192:54

Don't worry, there are enough IPv6 addresses for the foreseeable future,

even with the anticipated influx of 2 billion new Internet users and the Internet of Things poised to add an estimated 50-100 billion devices to the Internet by 2020.

► Does every Internet user need an IP address? It is more accurate to say that every device on the Internet needs an IP address. Many, but not all, devices on the Internet have permanently assigned IP addresses, called static IP addresses. As a general rule, routers and computers on

QUICKCHECK An IP address that contains

84a3 would be a(n)

the Internet that act as servers use static IP addresses.

ISPs. Web sites. Web hosting services, and email servers that always need to be found at the same address also require static IP addresses. There is an emerging trend for individuals to request static IP addresses for their home networks, and a static address might be useful for remotely commu nicating with sensors and other devices in the Internet of Things.

a. IPv4 address

b. IPv6 address

c. corrupted address d. static address

SECTION B, MODULE 3

180

I What happens when a device doesn't have a static IP address? IP addresses can be temporarily allocated so that a device uses an address only while it is actively online. When the device is turned off or its Internet connection is disabled, the address can be recycled to another device. The next time the device is tumed on, it will be assigned a different IP address. Internet addresses that are temporarily assigned are called dynamic IP addresses.

QUICKCHECK When connected to a network, your computer can receive an address from

In practice, dynamic IP addresses do not change very often. Today, most consumers have always-on Internet connections that remain active as long as the router that connects to the Internet remains powered on. Turning a computer off or on does not affect the IP address stored in the router. Customers who access the Internet using Comcast XFINITY and AT&T U-verse, for example, could have the same IP address for weeks or

a.

DHCP

b.

packets

c.

IPv4

d. the CPU

months.

I How do devices get IP addresses? IP addresses can be assigned by a network administrator, but more commonly they are automatically assigned by DHCP (Dynamic Host Configuration Protocol). Most devices are preconfigured to receive an IP address by sending a query to the net work device acting as the DHCP server. That device could be a router for a local area network or a DHCP server from your ISP. IP addresses get a bit tricky because a device can have a public IP address and a private IP address.

TRY IT!

I What is a private IP address? Let's suppose that your laptop is con nected to your school network. The DHCP server for the school assigns a dynamic IP address to your laptop when you log in. That address, which probably begins with 10, 172, 192, FD. or FcOO, is classified as a private IP address because it works only within the school network.

Find your IP uddress. Is it m the

range of private addresses listed in Figure 3-23?

A private IP address can be allocated by any network without supen/ision from ICANN. However, the address cannot be used to send data over the

Internet; it is not routable. Figure 3-23 demonstrates how to find your pri vate IP address. FIGURE 3-23: FIND YOUR PRIVATE IP ADDRESS IN WINDOWS 9 •r 5- - N«yr_

Networt; Connection Details

filkietooth NCMOrk Co Not connected

1. Access Network

X

V Giu«lcoih OeY'ice (Peti

Connections, then

C«mectMtyt

UdAsSatt;

select your LAN or

L.tl l'.V.Fc Wi'crWi'«lr>1>S

DHCf>ETt«Md

Ym

15KWMlluMHiBll|

Si^uiQgiirr; UkMOOttrted

2. Select Details.

litoMay liecetTtberS

Lene

Qstrivay Server DtvS Semper

3. Your computer's

private IP address

^WNS S««v«

Ne£lOS ovei Tcpap E Unk-lecel

AAdrtse

PvCMuKGewwey

Private IPv4 addresses are within

these ranges: 10.0-0.0-10,255.255.255

172.16.0.0-172.31.255.255 192.168.0.0-192.168.255.255

is shown here. —offTOBffTBaser

181

NETWORKS

i If my private IP address can't be routed over the Internet, how does my data get anywhere? Here is where your local router plays a crucial role. Any network you use to access the Internet—a campus network, your home network, or a Wi-Fi hotspot—has a router that con nects to the Internet. The router has a public IP address that is routable over the Internet. Figure 3-24 explains how public and private IP addresses

TRY IT!

What is your public IP address?

You can find it by googiing What's my IP. Compare your public IP address to your private address.

work. FIGURE 3-24; ROUTING DATA USING PRIVATE AND PUBLIC IP ADDRESSES

Your request is forwarded to the music store using the

router's public IP address.

0The router records

192.168.1.J

for 35.24.35.7,

your IP address as the

0The request,

with your private IP address, goes to your local router,

Thriller for 192.168.1.1

music store

^ You request a stream ing music track from an online music store.

'"'"•'l/er to 35.24.35'

^ The music store

J-Thrittet to

sends the stream to

© The router looks in its records and

your router.

finds that your private IP address sent the request to the music store, so the music stream Is forwarded to your computer.

I Does using a private IP address make me anonymous? No. the router's network address translation table keeps track of your activities,

QUICKCHECK

so your footprint across the Internet can be traced back to you. However,

A local network's router uses

a private IP address can protect you from some threats. For example, a

an address table to keep track of private IP

hacker who randomly enters IP addresses looking for unauthorized access

will never find your private IP address because the only address that is vis ible to the public is the address of your local router. This security technique is usually referred to as NAT (network address translation).

That being said, private IP addresses cannot protect your devices from many other attacks. Clicking corrupted links or downloading infected files sends packets and also makes a path in the network address translation table that can allow malware into your device.

addresses. a.

IP

b. routing c.

translation

d. dynamics

182

SECTION 8, MODULE 3

DOMAIN NAMES

If the Internet has an Achilles' heel, it is the domain name system. When a wide swath of the Internet goes dark, when you hear about massive outages, or when you struggle to get to a Web site that seems to have

disappeared, the domain name system is probably at fault. The ability of governments to censor information by blocking sites is also made possible by the domain name system. And if there is an Internet kill switch, you can bet that the domain name system will be involved.

► What is the domain name system? People find it difficult to remember the string of numbers in an IP address. Therefore, most internet destinations also have an easy-to-remember domain name, such as nike.com. A domain name is a key component of Web page addresses and email addresses. You can easily recognize the domain name in a Web site address such as www.nike.com or an email address such as

[email protected]. The mechanism for tracking domain names and their cor responding IP addresses is called the domain name system (DNS).

QUICKCHECK What's the purpose of the

domain name system? a. Hand out IP private addresses. b. Translate domain names Into IP addresses.

c. Route packets to their destinations.

d. Encrypt data that is sent over the Internet.

► Do I need a domain name? For client-style Internet activities, such as Web browsing, email, and downloading, you do not need your own

domain name. Today, social networking sites give ample opportunity for making your presence known on the Internet. However, domain names are quite useful for businesses and individual art ists, musicians, or crafters who want to engage in online commerce. The

fees associated with obtaining a domain name might initially seem small. The first year may cost only S1, but prices for subsequent years are typi cally around S15. Then there is the question of how many domain names you need: one might not be enough. You might need domain names with more than one extension, such as .com or .club.

server space for Web sites (Figure 3-25). FIGURE 3-25: CHOOSE YOUR OWN DOMAIN NAME

^

4*

^

^ fl*5Btfnoi>, ifK juij re^nif«((yn

reglster.com

IM

domom noM you oKvoyt wonted

Enter the name you'd like to use for your domain.

FOA^Ut BAND DCLtVCRY

if you want to know who owns a domain name or an IP address,

google WHOIS and then a

iCANN is the top-level authority for supervising domain name requests. Rather than going directly to ICANN, domain names can be obtained from several domain registrars and hosting services that provide internet-based

O WA Ocxuin

TRY IT

space followed by the name or

address. Give it a try. Who owns 199.181.132.250?

183

NETWORKS

> What is a top-level domain? A domain name ends with an exten sion that indicates its top-level domain. For example. In the domain name msu.edu, .edu indicates that the computer is maintained by an educa tional institution. Country codes also serve as top-level domains. Canada's top-level domain is .ca, the United Kingdom's is .uk, Australia's is .au, and the European Union uses .eu as a top-level domain. Historically, businesses used the .com domain, while nonprofit organiza tions used .org. Educational institutions used .edu. The .net domain was usually used by communication companies. Businesses generally obtained domain names with all applicable top-level domains (e.g.. nike.com, nike.org, and nike.net) to prevent their use by competitors or fake businesses. Businesses also tried to acquire domain names with similar sounding names or those that are common misspellings

QUICKCHECK What Is the top-level domain m www.nike.com7 a. www

b. nike c..com

d. "dot"

of their corporate names.

Today, there are hundreds of additional top-level domains, such as .biz, .CO, and .fit. Obtaining all the TLDs for a business name is not practical.

Even within a sector such as education,.edu has been joined by .academy, .education, .guru, .institute, .training, and .university.

> How does the domain name system work? Scattered around the world are several domain name servers that maintain lists of all domain

names and their corresponding IP addresses. In addition, frequently used domain names are stored by ISPs, educational institutions, organizations, and Internet companies such as Google. When new domain names are added, these lists are updated. New domain

names may take several days to propagate to all of the lists, which is why new Web sites can be accessed only by their IP addresses for the first few days they are in operation. A Web site can be accessed by its domain name once the name is added to the domain name server lists.

Suppose you want to look at the newest selection of Nike athletic shoes. You enter nike.com in your browser's address bar. Your browser must find the IP address that corresponds to nike.com before it can connect you to the site. Your browser queries a domain name server to get the IP address,

a process that generally happens without noticeable delay (Figure 3-26). FIGURE 3-26: HOW DOES THE DOMAIN NAME SYSTEM WORK?

NIKE 66.54.56.30 Show us the Nike

home page at Hmmm. I need to

66.54.56.30.

Nike's IP address

check the DNS for Nike's IP address.

I want some Info from

Is 66.54.56.30. 66.54.56.30

What is Nike's IP address?

www.nlke.com. DNS server

1 84

SECTION B, MODULE 3

I So what makes the DNS one of the Internet's weaknesses?

Altering the DNS records can change the destination of email, browser con nections, and download requests. Unauthorized changes to the DNS are called DNS spoofing.

Hackers use DNS spoofing so that queries for legitimate sites are directed to fake sites. Some governments use DNS spoofing to redirect searches from culturally or politically Inappropriate sites to government-approved sites. Figure 3-27 illustrates what happens when unauthorized changes are

QUICKCHECK Each record in the domain name

system

.

a. represents a correspondence between a domain name and an IP address

b. protects domain names from

DNS spoofing

made in the DNS.

c. routes packets over the FIGURE 3-27; ONS SPOOFING

Internet

d. has a spoofed IP address that Is easy for hackers and governments to change

lo^eadofgoingtp

'^www^iivelocity.com, yoti^ll end up at the

o A hacker changes the DNS records.

Domain

Q You enter the address

name server

www.travelocity.com.

_

_

www.travelocitv.coti^^Bs®^*di38 www.travelocity.com = 181.177.105.123

> Can domain name servers be turned off? Yes, though more com monly a DNS server operated by your ISP will go offline as a result of an equipment failure. When the DNS you're using goes down, the process of accessing the Internet can get very slow while DNS requests are routed

TRY IT

For security, you should periodically check your DNS to make sure it hasn't been

through alternate servers. It is even possible that a DNS outage can leave you without Internet access unless you enter raw IP addresses.

changed by a hacker. What is

It Is a good idea to know how to find your DNS server and how to change it in case of an outage. Figure 3-28 demonstrates how to find your DNS

it a private address residing on your router or a public address?

the IP address of your DNS? Is

settings. FIGURE 3-28: FIND YOUR DNS SETTINGS WINDOWS

1. Use the Control Panel to access the Network and

Sharing Center,

2. Right-click your network, then select Properties. 3. Select Internet Protocol Version 4 (TCP/IPv4),

O Obtain DNS serve add*ess automatialy ($)Use the fotowing DNS server addresses: Referred DNS server:

a . S . B . 8|

AltEmate DNS server:

4. Select Properties. If the DNS server address Is

obtained automatically, your device is likely using your ISP's DNS. You can override the automatic settings as shown at right. macOS

1. Click the Apple menu and select System

joir

Preferences. 2. Select Network. The DNS server is listed in the Network window.

3. To add an alternative DNS server, select the Advanced button and the DNS tab before entering the iP address for the DNS server.

I Ciaai I [

OS

I

185

NETWORKS

I What can I use as an alternative DNS server? Surprisingly, you

might be able to bypass DNS outages, blocks, and hacks by changing your DNS server. Errors in the domain name tables may be limited to the domain name server that you are using. Connecting to a different domain name server might restore full access. In addition, when you are traveling—espe cially overseas—a local DNS server might be closer and quicker. Keep the numbers in Figure 3-29 handy In case you need to change your domain name server. Write them down,or store them locally on your device.

Remember, if your domain name server has an outage, you won't be able to use domain names to search the Internet for a solution.

QUICKCHECK When might you want to change your DNS server? a. When the DNS server that I'm

using goes down b. When I'm traveling and other DNS servers are closer

c. If I suspect that my DNS server has been hacked d. All of the above

FIGURE 3-29; PUBLIC DOMAIN NAME SERVERS

Google's public DNS 8.8.8.8 2001:4860:4860::8888 8.8.4.4 2001:4860:4860:;8844

OpenDNS 208.67.222.222

208.67.220.220

r SECTION B

QUICKQUIZ 1.

2.

The Internet

is a system of

3.

and UDP are two of the

high-capacity routers and fiber-optic communica

main protocols used to transport data over the

tion links.

Intemet.

The Internet uses

switch-

4.

ing technology to route data from many different messages over a single communication channel.

The Internet's supply of addresses ran out in 2011.

5.

IP addresses are not

routable over the Internet.

186

SECTION C, MODULE 3

Quality

Internet Access

Portab e

SECTION C

Mobile

INTERNET ACCESS

A HUMAN RIGHTS VIOLATION.

Terminology

That's what the United Nations had to say about

laws in France and England that penalize copy right violators by banning them from the internet.

connection speed bandwidth cap

Whether or not you agree that Intemet access is a human right, there is little doubt that global net work access is increasingly required to participate in activities ranging from politics to education to

symmetric connection Ping latency jitter

dating. As you read Section C, consider which of

mobile Internet access cable Internet

the access technologies are likely to be available in

service dial-up voiceband modem ISDN

various regions of the globe.

DSL FTTH satellite Internet service

bandwidth throttling asymmetric connection

packet loss Traceroute fixed Internet access portable Internet access

mobile broadband service tethering

mobile hotspot Wi-Fi hotspot

Objectives List three acceptable speeds for the following: basic Skype video calls, streaming standarddefinition movies,and viewingVouTube videos. Explain the significance of asymmetric Intemet connections.

Define latency and state the type of Internet

service that it affects most negatively. List online activities that are most affected by

jitter and packet loss. Name three tools that you can use to troubleshoot an Internet connection.

> Explain the pros and cons of fixed, portable, and mobile Intemet access.

I Rank each type of Intemet service according to speed,then rank them according to dependability. I Draw diagrams of the infrastructures for cable, dial-up, DSL, mobile broadband,and Wi-Fi hotspot Intemet services.

I Discuss why mobile Intemet access is globally the most popular way to connect to the Intemet.

187

NETWORKS

CONNECTION BASICS With online access becoming an essential component in our daily

lives, sociologists have been tracking Internet "haves" and "have-nots." According to the Pew Research Center, an estimated 80% of American adults have Internet access. Worldwide, about 40% of the population has

Internet access. Not all of these connections are fast and dependable. Let's take a look at what makes a good Internet connection. I How fast is the Internet? Data travels over the Internet at an incred

ible speed, but that speed varies. Some Internet services are faster than others. Speed is affected by the amount of traffic flowing over the connec tion. It slows down when usage is heavy. Slowdowns also occur as a result

of faulty routers and when hackers launch denlal-of-service attacks that overwhelm sen/er capacity.

It is easy to check the speed of your Internet connection by running a few online tests. Figure 3-30 shows results from testing speed in a rural area. Is this connection suitable for streaming movies, playing online games, and conducting video chats? FIGURE 3-30:15 YOUR CONNECTION FAST ENOUGH? "cr

TRY IT! 6 O

What is the speed of your Internet connection right now? Connect to www.ooklo.net or

www.bandwidthplace.com and run a speed test to find out. Download

User's ISP

Destination ISP

Corne Hem Telacoifi

This speed test measured the rate of data flowing between the user's ISP In Macon, GA, and a Comcast server in Moncks Corner, SC.

QUICKCHECK

I What does connection speed measure? Speed is the distance something (ravels in a specified amount of time. The speed of a car, for

Would the connection used for

example, is measured in miles(distance)per hour(time). What we casually

the speed test in Figure 3-30 be

refer to as "connection speed" has little to do with distance. The most com

classified as broadband?

mon measurement of connection speed is the amount of data that can be

3. Yes, it is synchronous,

transmitted in a specified time. Technically, it is a measure of capacity. But let's use nontechnical terms and call it speed.

b. Yes, the download speed Qualifies as broadband.

The speed test in Figure 3-30 produced a download speed of 46.42 Mbps because it was able to move 46 megabits of data down from a server to the user's computer in one second. The upload speed at which data is transferred from the computer to a server was only 24.27 Ivlbps. With this connection, downloading a two-hour movie from ITunes would take about 4 minutes. Uploading a 4 MB photo would take less than a second.

c. No, Its minimum speed of 17.22 Mbps Is not fast

enough.

d. No, its average speed is only 24.27 Mbps.

188

SECTION C, MODULE 3

► How much speed do I need? For email, browsing the Web, and streaming videos. 0.5 Mbps (500 Kbps) speeds are adequate. However, other activities require higher speeds, as shown in Figure 3-31. FIGURE 3-31;CONNEaiON SPEEDS FOR POPULAR INTERNET-BASED SERVICES SERVICE

RECOMMENDED

RECOMMENDED ■

UPLOAD

DOWNLOAD

Skype video calling and screen sharing

300 Kbps

300Kbps

Skype video calls (HD)

1.5 Mbps

1.5 Mbps

Skype three-person group calling

2 Mbps

512 Kbps

Netfllx movie on a laptop computer

1 Mbps

Netfllx SD movie on a TV

2 Mbps

1

In the table at left, why are there recommended upload speeds only for Skype? a, Skype doesn't use uploads.

b. Skype requires two-way communication, whereas

Netfllx 72Qp HD movie

4 Mbps

Netfllx "best video and audio experience"

5 Mbps

the other services use most

—

of the bandwidth only for —

downloads.

c. Skype is the slowest service

—

of those listed, —

d. Amazon. YouTube, and Netfllx YouTube basic videos

YouTube movies, TV shows, and live events

offer different levels of

500 Kbps

service, so the upload speed 1 Mbps

Amazon Prime Instant Video (SO)

900 Kbps

Amazon Prime Instant Video (HD)

3.5 Mbps

Netfllx and Amazon 4K Streaming Video

15-25 Mbps

» L

•

•

m

cannot be specified.

—

—

► Why are upload and download speeds different? ISPs control connection speeds based on the service plan you've selected. Your band width cap is the top speed aiiowed by your plan. During peak times. ISPs

can place further limits on speed, a process called bandwidth throttling. When Internet upload speed differs from download speed, you have an asymmetric connection. When upload and download speeds are the same, you have a symmetric connection.

Most Internet connections are asymmetricai, with upload speeds considerabiy iess than download speeds. Asymmetric connections discourage subscribers from setting up Web and emaii servers that wouid transmit

lots of outgoing data. For most users, however, an asymmetric connection is sufficient, but downioad speeds of less than 1.5 Mbps may not provide the full internet experience.

► What Is Ping? Ping is utiiity software designed to measure respon siveness. Ping rate indicates how quickly data can reach a server and bounce back to you. Ping was named after the sound that a submarine's sonar makes when it bounces off an undersea object. Technicaliy. Ping measures iatency. Latency is the elapsed time for data

to make a round trip from point A to point B and back to point A. Latency is measured in milliseconds (ms). A millisecond is a thousandth of a second, so data transmitted on an internet connection with 100 ms iatency makes a round trip in one-tenth of a second.

Terminology Download and upload speeds are sometimes referred to

as downstream speeds and

upstream speeds, respectively.

189

NETWORKS

¥ What is an acceptable ping rate? Latency generally averages less than 40 ms (milliseconds) within North America, but increases to about 75 ms for transatlantic transmissions. If you want to play online multiplayer

games, it is best to have less than 100 ms latency. Good-quality video streaming and videoconferencing require latency rates of 200 ms or less. Speed and latency are not the only factors that affect your Internet experi ence. Even if your connection gets good marks on speed tests, jitter and packet loss can degrade the quality of online services.

I What are jitter and packet loss? Jitter measures the variability of packet latency. Network traffic and interference can delay some packets and create erratic data fiow. If the variation between packets exceeds 5 ms, Internet voice and video call quality is likely to be poor. Packet loss refers to data that never reaches its destination or gets dis carded because it arrives too late to be of any use. Packet loss of less than 2% is required for acceptable streaming, gaming, Skype, and voice calls. Too many lost packets during an online gaming session can cause the

game to stutter or stall. And if packets don't arrive in the correct order, your game character might seem to act randomly for a few seconds. You can test the jitter and packet loss on your Internet connection by using a ping test similar to the one in Figure 3-32. FIGURE 3-32; CHECK THE JITTER AND PACKET LOSS ON YOUR CONNECTION

QUICKCHECK The connection in Figure 3-32 gets a grade of D For bad performance. What are the

©Pir«.

problems?

17

a. The speed is too low and

JiHtr

packet loss is too high. b. The ping rate is too low and

YQURGRAOE D Ccnc«m>r^ Mo»1onUn« •ppUution* wili not perform wvll bu1 thould

packet loss is too high.

funolion in some

capKity TMlloolher

^ 4'2WA

PINGTESTiET

c. The ping rate and the jitter rate are too high.

errwrm to confirm LLUN MWtEABOt/I CfUDCS

d. The ping rate is too high, but

W 178,. O PKOCIUSS.0% SEKiTS

ISP

Stanlsn. Ml nSIANCC -

Merit Netwcrk mi

FORUM LINK

*•*1

34/5

DIRECT UNK

This test was performed using the PINGTEST tab at www.speedtest.nef, powered by Ookla.

the jitter rate is too low.

190

SECTION C, MODULE 3

I Can I troubleshoot an Internet connection? Suppose your Internet connection seems unusually slow one day. Or, perhaps you cannot access a favorite Web site. You wonder, Is the problem on my computer, my ISP, or somewhere else on the Internet?" To find out, you can use Traceroute, a network diagnostic tool that lists each router and server that your data encounters as it travels over the Internet.

Traceroute sends three packets of data to a specified destination. It records the address of each router along the way and the elapsed time for each "hop." When a connection is inoperable, the packets will not reach their destination and they will become lost. Figure 3-33 illustrates how to use Traceroute and how to interpret its results. FIGURE 3-33: WHERE DOES YOUR DATA TRAVEL?

On a Mac,open the Utilities folder, then select Terminal. Enter the

A

TRY IT!

command traceroute followed by any domain name, like this:

Find out how many hops your «

•walismlth — i>ath — 65x24

If

Last login: Sun See !4 lB:47:ee on console

sarohlHac:- sarahsmthS traceroute msu.edu |

data makes before it arrives at www.hotwiredcom. What was

the slowest leg of the trip? / rui'

I'll-

On a PC, from the Home screen, type com and choose the option for Command Prompt. Enter the command tracert followed by any

U

domain name, like this: m Command Promnl

□

X

licrusuiL Uiiidows [Versiuii iU.U.143'J3j (tracert msu.edUa

Traceroute results appear as a list, showing each router, the router's IP ndhrnci: .nnrl tlip ol.nrc'r) timn for nach Hot). X, Comnund Prempl

QUiCKCHECK

C:\Wirc>Ows>tracert mww.hotwired.cdn

How many AT&T routers did

Tracing route to wviw.hotwired.com [216.32.2; over a maaiaun of 30 hops: 1 2 3 4 5 6 7 8 9 10 11 12 13 14

1479 928 640 78S 761 1S93 757 763 3378 903 2261 1614 1S97 946

»» ns ms ms ms ms ms ms ms ms ms ms ms ms

1526 1203 1559 830 1552 1300

ms ms ms ms ms ms

774 782 813 1512

ms ms ms ms

each packet pass through when this Traceroute report was

8SS 1576 818 764

ms ms as ms

172.9.1.253 148.74.246.254

835 2258 621 1557 1519

ms ms ms ms ms

9br6-p53.wswdc.ip.att.net [12.123.8.190

I

generated?

148.74.3.2 12.125.10.37

gbr4-p90.wswdc.ip.att.net [12.122.5.2C6, ggrl-p370.wswdc.ip.att.net [12.123.9.53] ibr01-p5-0.stng01.e«odus.net

216.32.173.1:

822 ms 647 ms 2325 ms

bbr02-p4-0.$tn902.e>odos.net bbr02-p5-0.sntc04.e>odus.nec

209.185.9.2] 2u9.185.9.11

973 ms

1074 ms

1027 ms

2414 ms

dcr03-g4-0.sntc03.e>odus.n' r$ml4-v] an921.sntc03.e«odu,

865 ms 1340 ms

bbr02-g3-0.stng01.e'Odos.net bbr01-pl-l.sncc03.eiodus.n^ Heouest timed out.

Request timed out. . Request timed out.

Request timed out.

a.

1

b. 3

216.33.96.14: I'l ■>

trace timed out before the

, packets arrived at their destination,

in all. this is a I connection.

rx « Ml

do)

c.

14

d. 18

191

NETWORKS

I What else affects the speed of my connection? Your Internet connection can be affected by outages and traffic. In Section B, you found out what can happen wtien a DNS server goes down. Service disrup tions can also occur at ISPs, cloud storage sites, email servers, and other Internet-based services. You can use online tools such as Akamai's Real

time Web Monitor and downrightnow.com to check the status of various

TRY ITI Are any service disruptions

occurring right now? Connect to downrightnow.com to find out.

Internet services.

I What are my Internet connection options? Although public Internet access is available in many locations, such as coffee shops and libraries, most consumers like the convenience of having their own Internet

connection. Depending on your geographical location, you may have several options for connecting to the Internet. Before we look at the most

popular internet access options such as cable Internet service and cellu lar broadband, consider the pros and cons of the three classifications of Internet connections in Figure 3-34. FIGURE 3-34: INTERNET CONNECTION OPTIONS

Fixed Internet Access Fixed Internet access links your computer to an ISP from

a stationary point,such as a wall socket or roof-mounted antenna. This service Is dependable and relatively cost effective. You can't take It with you, so when you're away from home, you must depend on public access points.

|^0®(«H|.))X ^^

Cable, DSL, ISDN, Fixed WiMAX,Satellite, Fiber-to-the-home

Portable internet Access

III

Portable Internet access allows you to easily move your access device, as In the case of vehicle-mounted satellite dishes that can be deployed when the vehicle Is parked. This

service is primarily used in situations where mobile and fixed access are not available.

Mobile satellite

QUICKCHECK A local ISP advertises a modem

Mobile internet Access Mobile Internet access allows you to use the Internet while you are on the go, such as using a cell phone to col lect your email while you are traveling by train or querying SIrl while riding In a car. These services usually require a data plan.

that you can carry to any location and plug In to access the Internet. This device would

be used for access.

a. fixed

(((«')){«mo)

(((m»)((cm ((dHOXdmo)

kui

ini

Mobile broadband

Mobile WIMAX

b. portable c. mobile

d. none of the above

Internet

192

SECTION C, MODULE 3

CABLE INTERNET SERVICE

The gold standard of fixed Internet access is cable internet service, which is offered by the same companies that supply cable television.

Cable service is a luxury enjoyed by developed countries; emerging nations cannot afford its expensive infrastructure, nor can device owners

afford the high cost of monthly subscriptions.

I How does cable Internet service work? The cable television sys tem was originally designed for remote areas where TV broadcast signals could not be received with a roof-mounted antenna. These systems were called community antenna television, or CATV. The CATV concept was to install one or more large, expensive satellite dishes in a community, catch TV signals with these dishes, and then send the signals over a system of cables to individual homes.

With cables branching out from a central location, the topology of a CATV system happened to also work as the infrastructure for a digital data net work. Now, in addition to carrying signals for cable television, the CATV

infrastructure also carries Internet data. When your cable TV company becomes your Internet provider, your computer becomes part of a neighbor

hood network linked together by the cable company's wiring (Figure 3-35). FIGURE 3-3S: CABLE TELEVISION INFRASTRUCTURE

{ t How does the system transport data? The cable modem supplied with your subscription converts signals from your computer to signals that can travel over the cable infrastructure. CATV coaxial and fiber-optic cables have plenty of bandwidth to carry television signals for hundreds of chan nels in addition to digital data. CATV cables provide bandwidth for television signals. Incoming data signals, and outgoing data signals (Figure 3-36). FIGURE 3-36;TV AND DATA STREAMS ON ONE CABLE

V CHANNELS Downstream Data

QUICKCHECK Which one of the following is most likely to affect the actual

> How fast is cable Internet service? Most cable Internet service

is asymmetric, with upload speeds considerably slower than download speeds to discourage subscribers from setting up public Web servers. Service plans range from economy packages offering speeds of 3 Mbps to an expensive 150 Mbps package. Your actual speed may be less than the advertised speed due to traffic from other subscribers in your neighborhood.

speed of your cable Internet connection from day to day? a. Your ISP service plan b. Weather

c. High traffic from other users d. Watching TV shows

193

NETWORKS

TELEPHONE NETWORK INTERNET SERVICE Some people limp along with narrowband access to the Internet, which is frustratingly slow. Telephone companies offer four types of service: dialup, ISDN, DSL, and FTTH. Only one of these technologies is considered broadband. Are the other three of any use at all?

k What is a dial-up connection? A dial-up connection is a fixed Intemet connection that uses a voiceband modem and the telephone com

pany's circuit-switched network to transport data between your computer and your ISP. A voiceband modem converts digital signals from a com puter into audible analog signals that can travel over telephone lines. A modem transmits a 1070 Hz tone for a 0 data bit and a 1270 Hz tone for a

1 data bit (Figure 3-37). FIGURE 3-37: A VOICEBAND MODEM CHANGES VOLTAGES TO AUDIO TONES

+5 volts

1270 Hz tone

A voiceband modem mnHom changes rhanop< A

A computer

generates digital signals.

outgoing digital signals into analog audio tones. Incoming signals are converted from tones to voltages.

Signals are sent over the same channel used for voice calls.

I How does a dial-up connection work? When you use a dial-up connection, a voiceband modem places a regular telephone call to your ISP. When the ISP's computer answers your call, a dedicated circuit is established between you and your ISP—just as though you had made a voice call and someone at the ISP had picked up the phone.

QUICKCHECK Dial-up connections use a voiceband modem to convert

signals from

The circuit remains connected for the duration of the call to carry data

a. analog to digital

between your computer and the ISP. As your data arrives at the ISP, a

b. tones to pulses for outgoing signals, and voltages to binary digits for incoming signals

router sends it out over the Intemet (Figure 3-38). FIGURE 3-38: DIAL-UP INFRASTRUCTURE

c. digital to analog

d. digital to analog for outgoing ISP s modem

Your computer and modem

Telephone jack

ISP's router

• How fast is dial-up service? ISPs, such as NetZero, AOL, and EarthLInk, still offer dial-up Internet access. The service ordinarily costs

less than $10 per month, but the access speed is slow. The maximum speed of a dial-up connection is 56 Kbps, so it is not classi

fied as broadband. Actual data transfer speeds are affected by factors such as the quality of your phone line and connection. In practice, the top speed for downloads is about 44 Kbps. For uploads, the data rate drops to 33 Kbps or less. Dial-up service is the Internet connection of last resort for people who live in remote areas where land lines are the only communication services.

signals, and analog to digital for incoming signals

194

SECTION C, MODULE 3

• How about ISDN? ISDN stands for Integrated Services Digital Network. It essentially divides a telephone line into two channels: one for data and one for voice. The data channel uses packet switching and sends data in digital format, unlike dial-up. which uses analog tones to carry data. With data rales of 128 Kbps, ISDN was only briefly popular in the United States, though in Europe it still has an active base of users.

I What is DSL? DSL (digital subscriber line) is a high-speed, digital, aiways-on, internet access technology that runs over standard phone lines. It is best known as the technology offered by AT&T's U-verse ser vice.

Several variations of DSL technology exist. ADSL(asymmetric DSL)offers faster speeds for downloads than for uploads, and it is the most common. SDSL (symmetric DSL) offers the same speed for uploads as for down loads. Other flavors of DSL include HDSL (high bit rate DSL) and VDSL (very high bit rale DSL).

QUICKCHECK When using a DSL connection, can you expect similar upload and download speeds?

a. Yes, if it is an asymmetrical connection

b. Yes, if it Is a broadband

I How does DSL work? A DSL modem converts computer signals into high-frequency data signals. Voice and data signals travel over tele phone lines to your telephone company's local switching station. There, voice signals are routed to the regular telephone system and data signals

connection

c. Yes, if it is ADSL

d. Only If It is SDSL

are routed to the internet (Figure 3-39). FIGURE 3-39; DSL DATA PATH

Phone Company Modem

Switch Voice and Data

Voice

Voice

I How fast is DSL? The speed of a DSL connection varies according to the characteristics of your telephone line and your distance from the tele phone company's switching station. The least expensive plans offer speeds of 768 Kbps. Premium plans offer 6 Mbps sen/ice. DSL installations require filters on every phone to screen out frequencies that interfere with data sig nals (Figure 3-40). FIGURE 3-40: DSL MODEM AND FILTERS

QUICKCHECK What is the fastest type of ► What is FTTH? FTTH stands for fiber-lo-the-home. It is the use of

Internet access plan available from telephone networks?

high-capacity fiber-optic cables, rather than coaxial cables or twisted pair

a. Dial-up

wires, to connect homes to broader municipal networks. As telephone com

b. FTTH

panies upgrade their infrastructure with fiber-optic cables, they are able to offer faster access speeds. AT&T, for example, offers an Internet access plan with 1,000 Mbps speeds. That plan is available only in areas where fiber runs to homes.

c.

DSL

d.

ISDN

195

NETWORKS

SATELLITE INTERNET SERVICE Communications satellites seem so retro. They settled into orbit during an

era when your grandparents watched The Jetsons and the United States rushed to catch up to the Soviet Union's manned spaceflight program. And yet at one point in time, satellites used for continent-to-continent telephone communications appeared to be a natural fit with the emerging Internet. Unfortunately, satellites have a fatal flaw that reduces their suit ability for today's Internet. What's the problem? Read on to find out. > What is satellite Internet service? Most people are familiar with services that provide access to television programming over a personal satellite dish. Many companies that provide satellite TV also offer Internet access. Satellite Internet service is a means of distributing broadband asymmetric Internet access by broadcasting signals to a satellite. In many rural areas, satellite Internet service Is the only alternative to a slow dial-up connection.

t How does satellite Internet service work? Figure 3-41 illustrates how data from a customer's computer (1) is converted into signals by the customer's modem (2) that are carried by cable to a personal satellite dish (3) and broadcast to a communication satellite (4). Signals are rebroadcast from the satellite to a ground-based ISP (5) that forwards them to the Intemet (6). FIGURE 3-41: YOUR DATA TRAVELS INTO SPACE AND BACK

% 22,000 miles % o above Earth

250 ms up

250 ms down

> How fast is satellite Internet service? Satellite service averages 1.0-1.5 Mbps for downloads but only 100-256 Kbps for uploads. Satellite

QUICKCHECK

signals can be slowed or blocked by adverse weather conditions, such as

What is the main problem with

rain and snow, which makes this type of data transport less reliable than

satellite Internet service?

wired Internet access services, such as cable and DSL.

a. Speed

Satellite data transport is subject to latency delays of one second or more,

b. Latency

which occur as your data is routed between your computer and a satel

lite. Medium Earth Orbit satellites positioned about 5,000 miles (8,000 km)

c. Traceroute

above Earth have a latency of 132 ms. The latency for geosynchronous satellites 22,000 miles (35,786 km)above Earth is about 500 ms.

d. Cost

Geosynchronous latency might not pose much of a problem for general Web surfing and downloading files, but it can become a showstopper for

interactive gaming that requires a quick response, and for video calling with Skype, FaceTime, and similar services.

196

SECTION C, MODULE 3

MOBILE BROADBAND SERVICE

Worldwide, more people access the Internet using cellular data plans than with fixed connections. Many of these subscribers can afford only one device. They make do with the nuisance of a small screen in exchange

for the convenience offered by a pocket-sized device with voice and data capability. Mobile broadband service has become so compelling that In 2015 most of the Web underwent a visual makeover to fit the require

ments of smartphone-sized screens. • How does mobile broadband work? Cell networks transmit voice

and data using radio signals. The signals flow between a device, such as a mobile phone, and a cellular radio tower (1), as shown in Figure 3-42. The transmitters and receivers on each tower cover a specific area and use a

unique frequency. Data signals are passed to ground stations (2). where they are forwarded over a packet-switched network to the Internet (3); voice signals may be routed to a circuit-switched network (4). FIGURE 3-42; FROM A CELL PHONE TO THE INTERNET

(('Ifi'))

n I («J0)

(CHtD)

(('Hi'))

Q.6

o Voice and Text

Messages

I What happens when I move between towers? When you are accessing the Internet and move out of range of one tower, the cellular net work automatically searches for a new channel so that it can hand off your call to the next tower. To coordinate the handoff, the cellular network tells the handset to switch to the new channel. At the same time, the Internet data link is also switched to the new channel and tower.

QUICKCHECK On the cellular network, how are

text messages handled? a. They are combined with

> Why do I need a data plan? Mobile broadband providers typically

Internet data, but extra

offer two plans: voice and data. They can be separated because voice and data travel over essentially two different networks.

charges apply.

Voice calls travel from a tower to a circuit-switched network and then to

public switched telephone network land lines. Data travels from a tower to a packet-switched network and then to the Internet. Text messages travel over the circuit-switched network along with voice

calls, but they are handled by SMS service centers for yet another billing charge. Text messages can be sent successfully even when signal strength Is tow because they are a store-and-forward technology that does not require a round-trip circuit to be established between sender and receiver.

b. They use the same channels as voice data but are routed

by SMS service centers. c. They are sent from lower to tower rather than being transmitted by land lines. d. They take priority over voice and Internet data in order to

arrive faster.

197

NETWORKS

• How fast is mobile broadband service? Mobile broadband has

evolved through several generations. The most recent of these generations are 3G and 4G.

3G {third generation) service was available In the United States beginning

QUICKCHECK

in 2001. Common protocols included CDMA, which reached maximum download speeds of 4.9 Mbps, and GSM EDGE, with 1.6 Mbps speeds.

Which of the following is true

4G (fourth generation) technologies, such as WiMAX and LTE, rolled out in 2011. Of the two, LTE is most widespread. LTE has maximum down load rates of 300 Mbps and upload rates of 75 Mbps. The actual speeds enjoyed by consumers are significantly slower. In the United States, down load speeds of 5-12 Mbps are common, and upload speeds of 2-5 Mbps

a. It is 3G technology.

are typical.

c. Users can expect faster

Mobile broadband speed decreases at the edges of coverage. It can be reduced by obstacles, such as trees, hills, walls, and even metal roofs. Electromagnetic interference from speakers, microwave ovens, and other electrical devices can reduce speeds, too. Rain, snow, and high humidity

about LTE?

b. It is not affected by weather like earlier mobile

technologies were.

speeds than with basic cable Internet plans. d. It uses circuit-switched networks for data.

can also reduce speeds.

i Can I get mobile broadband for my laptop? Mobile broadband isn't just for your smartphone. You can also use it to access the Internet from a laptop or desktop computer. Most of today's smartphones include a tethering feature that connects wirelessly with other digital devices. Figure 3-43 demonstrates how to set up tethering to create a mobile hotspot. Just remember that data sent over the tethered connection accumulates toward

your monthly data usage total.

r

CREATE A NETWORK WITH YOUR CELL PHONE E

(CIH'))

I

□

1. Activate tethering by turn ing on your phone's mobile

hotspot.

a

2. On your computer, connect

to the network created by your mobile phone.

Mobile hotspot on/off switch

.

I

List of devices connected

to the mobile hotspot

UoMe HoisoM eoflSum«a mote banevy. Connect the device to an oultel to ejitend

baUcry hie

■iT"

Bnnr'i

Allowed dovKi'v

,

...

Ccnrt.^utv

Cell phone

Computer

HOI1KAIV 2.4

198

SECTION C, MODULE 3

WI-FI HOTSPOTS

Wi-Fi hotspols are everywhere. Pull out your smartphone in any coffee shop, airport, hotel lobby, or university building and you'll likely find more than one network that serves as an Internet on-ramp. But public Wi-Fi hotspots are fraught with security risks, so it pays to know how they work.

I How do Wi-Fi hotspots work? A Wi-Fi hotspot is a wireless local area network, usually operated by a business, that offers Intemet access to the public. The network has an Internet connection and a device called an

access point that broadcasts Wi-Fi signals within a range of about 150 feet. Any and all devices with Wi-Fi capability can detect the signal (Figure 3-44). FIGURE 3-44: BEHIND THE SCENES OF A COFFEE SHOP Wl-Ff HOTSPOT

•

Coffee shop

Coffee shop

Internet connection

wireless router

Wi-Fi signals *

Coffee shop customers

I How fast is hotspot access? The speed of a hotspot is related to the speed of the Wi-Fi network and the service that connects it to the Internet. A hotspot that goes through a 1 Mbps DSL line will be slower than a hotspot that goes through a 50 Mbps cable Internet connection. You can expect speeds of 2-8 Mbps, but the speed can vary depending on your distance from the access point, the number of people logged in, and interference from other networks.

QUICKCNECK Which of the following is most

likely to affect the maximum speed of a WI-FI hotspot? a. The hotspot's Internet service

provider b. Your Internet service provider

► Is hotspot access secure? The data that travels over unsecured hotspots is not encrypted, so eavesdroppers can easily tap into data that flows over the network. Figure 3-45 summarizes hotspot risk levels.

c. The number of people who are using the hotspot

FIGURE 3-4S: GAUGE YOUR RISK AT WI-FI HOTSPOTS

d. Whether the hotspot is

Browsing. When using a WI-FI hotspot for simple browsing activities such as checking sports scores, reading Google news, and looking for direc tions, your security risk Is fairly low if your computer's antivirus software is up to date. Using secure sites. Your security risk Is low when you are accessing secured Web sites that have addresses beginning with HTTPS. These secured sites, which are used for activities such as online banking, access

ing medical records, and making credit card purchases, encrypt the data that you enter to keep it safe from eavesdroppers. ; ill. Eavesdroppers might be able to access the flies on your com puter If you have file sharing turned on. When using public networks, you should turn file sharing off. You can do so manually if your operating sys tem does not offer that option when you connect. Using unsecured sites. When you log in to unsecured sites while using public Wi-Fi hotspots, a wireless eavesdropper could potentially snag

your user ID and password information, then use It later to access your accounts. Logging in to your Webmall account, for example, could be risky If your user ID and password are transmitted over an unsecured connection.

secured or not

199

NETWORKS

► How do I access a Wi-Fi hotspot? Your computer's networking utili

QUICKCHECK

ties automatically sense a Wi-Fi network and add it to the list of available connections. You can then connect using your network utilities. Some Wi-Fi

In Figure 3-46, what tells you

hotspots can be accessed simply by starting your browser and accepting

that the Hclidaylnn-FREE!

the license. Other networks require you to enter a password, which you can

network is not secured?

obtain from the hotspot manager.

a. The misspelled SStD

Select public networks with care. Hackers create networks that have names similar to those of legitimate hotspots. Those networks are not usually

b. The word FRff?

secured. Network utilities indicate unsecured hotspots in various ways.

Microsoft Windows displays a shield icon for hotspots that are not secured.

c. The shield icon d. The number of bars

If you mistakenly connect to a non-secured network, any passwords you enter or data you transmit could fall into the hands of a hacker. You can view a list of available networks and connect to one as shown in Figure 3-46.

FIGUItE 3-46: ACCESS WI-FI HOTSPOTS SECURELY

10.59.2.1

HoliOey Im Mvquem

Unsecured Wi-Fi hotspot Log In

^ Holidaylnn-FREE!

Cancel

to h::l.c!jy Ion' I li;i'i

access

Open 11

.

'.man

iM-« nnfin*. ►w.

re,6

e iwr*.

«ui*. Swe ■>

Tm*. Owe Mm*

i,^.rii«

II

SMa«*, c».nin,n Vicabii« Veee*, ••••• •

"MAOrMXIVMr -wu

h
Diagram the components and connection In a typical home LAN, k Explain the roles of MAC addresses and IP addresses in local area networks.

k List five advantages of Ethernet wired network standards.

k Explain the pros and cons of wireless mesh networks as compared to centralized wireless

I List five steps for securely configuring a wireless router.

k State the purpose of an SSID.

k List four types of wireless encryption. k Provide two example scenarios for using RFID tags and NFC tags. k List three low-power wireless standards used for loT networks.

networks.

k Compare the speeds and ranges of Ethernet and Wi-Fi.

k Evaluate potential security exposure for data that is collected by loT networks.

201

NETWORKS

LAN BASICS In the early years of personal computers, networks were scarce. Most personal computers functioned as standalone units, and computing was essentially a solitary activity in which one person interacted with one com puter. Some computer engineers, however, had the foresight to anticipate that personal computers could be networked to provide advantages not available with standalone computers. ► What are the characteristics of LANs? Local area networks are

often referred to as LANs. They are designed to provide connectivity for devices within a limited area, typically within the premises of a home, office building, business, or school.

LANs use many of the same network technologies as the Internet, just on a smaller scale. They have a topology. They use communication protocols to ship packets. They require communication channels such as cables or wireless signals. They also include data communication equipment such

as routers and modems. Figure 3-47 illustrates a LAN that you can easily build. FIGURE 3-47: BUILD THIS LAN

To an ISP

Wireless connections

and Internet I Wired connections

Cable, DSL. or satellite modem Router

File server

Printer

for Internet access

A a bo Computer

Computer

Smartphone

The plan for your network hinges on a centralized router that supports wired and wireless connections.

.Connect a computer to a wired connection for maximum speed. Use it for online games or as a file server where you store and back up your data.

Connect your smartphone and

o you'll be able to use the LAN's Internet connection instead of

your expensive data plan.

Connect a printer to a wired

The router is the centerpiece of your network. Most wire

all devices on the network can

less routers support five wired devices and a maximum of 255

access it.

wireless devices.

o or wifeless connection so that

.Connect computers wirelessly so you can use them in various rooms.

.All the devices in your LAN can access the Internet If you con nect the router to a modem

supplied by an ISP.

QUICKCHECK

In the LAN depicted in Figure 3-47, all the network data goes

through the a. modem

b. printer c.

router

d. Internet

.

202

SECTION D, MODULE 3

I Are there different kinds of LANs? LANs can be classified by their protocols; Ethernet and Wi-Fi are the two most popular. The Windows oper ating system includes a tool for setting up a LAN called a homegroup that makes it easy to share files among local computers, but does not provide Internet access. MacOS also provides a tool called AirDrop for making a

QUICKCHECK

point-to-point connection between two computers. Most LANs, however, are set up using a router so that they have proper security and Internet

Whlcli frequencies does tlie TCC not regulate?

access.

a. Wireless frequencies

> Are LANs regulated by the government? Most wireless LANs use the 2.4 GHz and 5.0 GHz unlicensed frequencies so that they can be

set up without applying to the FCC for permission. The few unlicensed fre quencies are crowded, however, and neighboring networks that are forced to use the same frequencies pose security risks.

b. Radio frequencies c. Internet frequencies d. 2.4 GHz and S GHz

► Are my devices equipped to access LANs? The circuitry that enables a device to access a LAN is called a network interface controller

(NIC). NICs are built into the circuit boards of most digital devices. NICs are also available as add-on circuit boards and USB devices.

NICs contain a MAC address (media access control address) used to

uniquely identify devices on LANs. MAC addresses are usually assigned by

Terminology The term MAC address has

the manufacturer of digital devices and embedded in the hardware.

nothing to do with Apple's Mac computers. Both PCs and

A MAC address functions in conjunction with an IP address on a LAN. Each device on a LAN has a MAC address (sometimes listed as the Wi-Fi

do smartphones, routers, and

address or physical address). DHCP assigns an IP address to a device and

other data communication

links it to the device's MAC address. Figure 3-48 illustrates how to Hnd the

equipment.

Macs have MAC addresses, as

MAC address on various devices.

FIGURE 3-48: FIND THE MAC ADDRESS

iPhone or iPad: Tap 5 ettlngslGeneral

TRY IT! Find the MAC address for the

□ Android Phone: Tap the 1=1 button, then tap

device you're currently using. Does it look similar to an IP address?

U a

IMac macOS computer: Select

ystem Preference

NetworklAflvancedlHardwar

Windows 10 computer: Select the 8' button, type CMD, select

, then type IPconfIg /all

Chromebook: Select IWatWiffPIBtHniiliB from the tray, select

the

section, then dick the © button

203

NETWORKS

ETHERNET

The first computer networks were configured with wired connections. These networks used a variety of topologies and protocols, but a technology called Ethernet emerged as the dominant standard and became a key element in

large and small computer networks.

> What is Ethernet? Ethernet is a wired network technology that is defined by IEEE 802.3 standards. It was first deployed in 1976 and is now used for wired connections in just about every local area network.

• Why is Ethernet so popular? Ethernet's success is attributable to several factors:

Terminology IEEE is the Institute of Electrical

Secure. The wired connections in an Ethernet LAN are more secure than

and Electronics Engineers, a professional organization that develops technical standards In

wireless LAN technologies.

areas such as electronics and

Inexpensive. As a nonproprietary technology, Ethernet equipment is avail able from a variety of vendors, and market competition keeps prices low.

are grouped and numbered.

Easy. Ethernet is easy to understand, implement, manage, and maintain.

Flexible. Current Ethernet standards allow extensive flexibility In network configurations to meet the needs of small and large installations. Compatible. Ethernet is compatible with popular Wi-Fi wireless technol ogy,so it is easy to mix wired and wireless devices on a single network.

> How does Ethernet work? Ethernet was originally a bus topol ogy in which computers were all strung along a cable like birds on a power line. Today's Ethernet LANs are usually arranged in a star topology with computers wired to central switching circuitry that is incorporated in modern routers. Data sent from a computer on the network is transmitted to the router, which then sends the data to the network nodes (Figure 3-49). FIGURE 3-49: ETHERNETTOPOLOGY

The central router handles all the traffic within the Ethernet. The router receives data and then broadcasts it to all of the nodes. The data

is accepted only by the device to which it was addressed.

networking. These standards Many IEEE LAN standards begin with the number 802.

QUICKCHECK Ethernet and Wi-Fi are

compatible network standards. a. True

b. False

204

SECTION D, MOOUEE 3

I How fast is Ethernet? The original Ethernet standard carried data over a coaxial cable at 10 Mbps. Ethernet encompasses a family of LAN technologies that offer various data transmission rates as shown in Figure 3-50. Today, most personal computers and LAN equipment work with Gigabit Ethernet. FIGURE 3-50 ETHERNET STANDARDS

ETHERNET STANDARD

IEEE DESIGNATION

SPEED

lOBaseT Ethernet

IEEE 802.3i

10 Mbps

Pest Ethernet

IEEE8D2.3U

100 Mbps

Gigabit Ethernet

IEEE802.3Z

1,000 Mbps

10 Gigabit Ethernet

IEEE802.3ae

10 Cbps

40/100 Gigabit Ethernet

IEEE 802.3ba

40 or lOOGbps

> How can I tell if a device is Ethernet ready? Many computers have a built-in Ethernet port located on the system case. The port looks

very similar to an oversized telephone jack (Figure 3-51). FIGURE 3-51; DOES YOUR COMPUTER HAVE AN ETHERNET PORT? TRY III

Check your computer. Does it

have an Ethernet port for wired network connections?

An Ethernet port is slightly larger than a telephone jack.

• What if a computer doesn't have an Ethernet port? If you want a wired network connection but your computer has no Ethernet

port, you can purchase and install an Ethernet adapter (also called an Ethernet card). A USB Ethernet adapter plugs Into a USB port and can

QUICKCHECK Suppose you have a Fast Ethernet connection to your

be used with laptop and desktop computers. You also have the option of

LAN. Will it keep up with the data you exchange with the

installing an Ethernet card In an expansion slot inside the system unit of

Internet?

a desktop computer. Figure 3-52 Illustrates two types of adapters for add a. Yes, Fast Ethernet is faster than my Internet connection speed.

ing Ethernet ports. FIGURE 3-52; ETHERNET ADAPTERS

b. Yes, my iSP uses Fast Ethernet for my modem.

c. No, my Internet connection is faster than my Ethernet connection.

d. No, Fast Ethernet makes Ethernet adapter for USB port

Ethernet adapter for expansion slot

streaming video pause occasionally.

205

NETWORKS

Wi-Fi

Wi-Fi refers to a set of wireless networking technologies defined by IEEE 802.11 standards. A Wi-Fi device transmits data as radio waves and is

compatible with Ethernet, so you can use the two technologies in a single network.

• How does Wi-Fi work? You can set up Wi-Fi in two ways. One option is to use wireless mesh topology in which devices broadcast directly to each other (Figure 3-53).

Terminology

FIGURE 3-53: WIRELESS MESH CONFIGURATION

Wireless mesh networks

©

are sometimes called peer networks or ad-hoc networks.

Wireless networks that depend on a router are sometimes

called wireless infrostructure

--1^

networks or managed networks.

Wireless ad-hoc networks are conceptually simple but provide few security safeguards. This type of connection is best limited to occasional use when you want to temporarily connect two computers to share a few files.

A second option for Wi-Fi networks is a star topology in which a centralized broadcasting device—a wireless access point—coordinates communication among network devices. Technically, the centralized device is a wireless

access point, but that function is built into most routers (Figure 3-54). FIGURE 3-54: WIRELESS STAR CONFIGURATION

a

e 0 0 0 0 a

The most common wireless network technology uses a centralized device to handle data that travels from one device to another.

QUiCKCHECK Which Wi-Fi infrdStructure is most similar to Ethernet?

a. Wireless ad-hoc

b. Wireless infrastructure

206

SECTION D. MODULE 3

> How can I tell if a device Is Wi-Fi ready? Today, Wi-Fi capabiiity is Inciuded wilh just about every desktop, iaptop, tabiet, and smartphone. Don't worry if your device has no visibie antenna for transmitting and receiv ing data; the antenna is likeiy integrated into the case. Older equipment without Wi-Fi can be outfitted with a Wi-Fi adapter that plugs into a USB port or an internai expansion siot.

> How fast is Wi-Fi? Wi-Fi is availabie in severai versions that operate

QUiCKCHECK Are Wi-Fi actuai speeds faster than Ethernet actual speeds? a. Yes. b. No.

c. Some Wi-Fi speeds are faster

at different speeds and have different ranges. Current standards inciude

than IGBasel Ethernet.

802.11n, 802.11ac, and 802.11ad. d- Only 802.llac Wi-Fi Is slower

With wired connections, such as Ethernet, the rated speed and range are usuaily very ciose to actuai performance. Wireless connection speed and range, however, are often theoreticai maximums because signais can easiiy deteriorate. Although Wi-Fi 802.11 n is capabie of 600 Mbps speeds, its actuai performance is normaliy 50-100 Mbps. 802.11ac has a theoreticai speed of 7 Gbps, but actual speeds are 400-800 Mbps.

than Ethernet.

> What is the range of a Wi-Fi network? Wi-Fi signais may reach up to 300 feet(90 meters)from the router. Thick cement waiis, steei beams, and other environmental obstacles can drastically reduce this range.

QUICKCHECK In Figure 3-55, how many of the routers are dual-band?

The standard that is used to transmit data—whether it is 802.iln or the

faster 802.11 ad—depends on the router and your network device. A smartphone with 802.11 n Wi-Fi cannot send data at 802.11 ad speeds even if the network has an 802.11ad router. When setting up a Wi-Fi network, check

your devices. The router you select should support the fastest device you'll want to use on the network. Routers have severai ways to boost speed (Figure 3-55).

a.

0

b. 1 c.

2

d. 3

FIGURE 3-55; WIRELESS ROUTER OPTIONS MAX SPEED

Basic Router

300 Mbps

BANDS

2.4 GHz

RANGE

ANTENNAS

.a

Browsing, email, voice chat

Basic Dual-

450 Mbps

band Router

Full-featured Router

eoo Mbps

2 MIMO

ISO Mbps at 2.4 GHz 300 Mbps at 5 GHz

300 Mbps at 2.4 GHz 300 Mbps at 5 GHz

Online gaming, simultane ous music downloads

.mi

4 MIMO

Video streaming, multiplestory buildings

Speed: Router speed can be designated by a single

Bands: Wi-FI can be transmitted over 2.4 GHz or 5

number or a combination of numbers. A single

GHz frequencies. When a router uses both frequen

number, such as 300 Mbps, means that the router transmits one set of sigr^als at a given bit rate. A

cies, it Is referred to as dual-band. Dual-band offers flexibility to support various network devices and

combination of numbers, such as 300+300, means that the router can transmit more than one set of

also can overcome interference on either of the

signals. Such a router might be sold as a 600N router, but savvy consumers understand that no single device connected to such a modem can use all 600

Mbps; each connection is limited to 300 Mbps.

bands. Antennas: Devices with one or more antennas use

MIMO (multiple-input multiple-output) technol

ogy to boost signals and spread them more evenly over the signal range. Routers usually have one to four antennas; more antennas generally mean more

coverage area and good speed even as devices get farther from the router.

207

NETWORKS

SET UP YOUR OWN NETWORK Having your own network is great. You can access the Internet from muitiple devices, share files, and download apps to your smartphone without maxing out your data plan. But LANs can be a security risk. Here's how to set up your own safe and secure LAN.

t What's the general procedure for setting up a network? The basic steps for setting up a LAN are:

Q Plug in the router and connect it to your Internet modem. Configure the router. Connect wired and wireless devices.

• How do I connect the router to my Internet modem? Use a cable to connect the router's WAN port to the Internet modem's Ethernet port {Figure 3-56). FIGURE 3-56: CONNECT THE ROUTER TO THE INTERNET MODEM

Connect the router's WAN Of Internet

port to the modem

provided by your ISP.

I How do I set up a router? A router has no screen or keyboard of its own; so to access the router's configuration software, you'll use a computer and connect to the router using a browser. Instructions are included with the router.

Change the password. The first step is to change the router password. All routers are shipped with a standard password. Your router can be

accessed and controlled by anyone who enters that password until you've created a secure password as shown in Figure 3-57. FIGURE 3-57: CHANGE TOUR ROUTER'S PASSWORD D KfTCtiR RsvIK MJOCO * s«curity

Security Options 'J None

Select an encryption

■r WPA2-PSK[AES1 ^ protocol. O WPA-PSK[T)aP)-WPA2-PSK(AES O WPAWPAZ Enterprise Security Options (WPA2-PSK)

> Administration

Password iNetwork Key) I pwsa/ah222

Enter a key

or password. *■ Advanctd Setup

b. WEP c. WPA

209

NETWORKS

Configure the Guest network. A Guest network is essentially a sec ond network that you can configure on your LAN's router. Guest networks allow visitors to access the Internet through your LAN, but don't allow them to access other resources on your network, such as your data files. Some routers come preconflgured with a Guest network. You should be sure to check your router's settings to verify that they meet your security requirements.

TRY IT

Does the network you usually use have a Guest network?

How can you tell?

You can view Guest network settings using your router's configuration soft ware. Your Guest network will have Its own SSID and security settings. You may be allowed to change these settings, or the router manufacturer may have designated permanent settings. If the Guest network Is secured, It should have its own unique encryption key or password, which you'll have to supply to your visitors. Leaving the Guest network unsecured makes access open to anyone—not a good idea. Even when secured, a Guest network offers a potential security risk, so It should be disabled when you are not expecting visitors. Activate DHCP. Each workstation requires a unique address for send ing and receiving data. When you configure your router to act as a DHCP server, It will automatically assign an address to each device that joins your network. Figure 3-60 Illustrates how to set up DHCP. FIGURE 3-60; ACTIVATE OHCP Q WTSEAII e

tr

PiUCCO *

O

X

QUiCKCHECK

C ■© t«.168.i68.VJt. i

If you have four wireless devices

NETGEAR genie ~

connected to your network and

you do not want any interlopers

ADVANCED UIWNCEDHm

to join, you can configure

Ml Snup

to assign only four IP

StttvWtaHd

addresses.

WPSViaitf IAN TCPTP

• Sttup

CW ].US .lit

Enable DHCP. 1

|2S) ■•'in !.ij» .\o

1 T

Wutkii

VUnwi

'DhMM • '

a. SSID b. WEP

ymmac ¥ um AmIm m DHCP

c.

StArhng tP

JM )•; ; JM '-3«n.'u8 '.JSJ '

CMPf tP

» USB Stoiege » Seeutlly » AdrmniaUation

can adjust the

» Advancetl S«fiip

j2l22E«!!3 Htfp ft Suppert »

iQ)

tEAACHNEl

range of addresses assigned for addi tional security. V

O'i

e

I How do I connect devices to a LAN? Simply connect wired devices to the router using a Category 5 network cable. Routers automatically sense wired devices and allow them to Initiate a connection. A password is not needed for wired devices because the signals do not travel through the air where they are easy to Intercept.

A wireless router Is constantly broadcasting its SSID. Wireless devices,

such as smarlphones. laptops, and tablets, sense the router's signal and add the SSID to a list of nearby networks. The first time you connect to a secured network, you must enter the encryption key. Your device remem bers the key for future logins.

DHCP

d. the Guest network

210

SECTION D, MODUIE 3

Laptops and tablets running Windows display a list of nearby networks and their security status. Figure 3-61 illustrates the process of connecting to a secured network from a device using Windows 10. FIGURE 3-61: CONNECTING TO A LAN WITH WINDOWS 10

/S UtUtWII bi-ajtcit

0

/

Enter the encryption key you created when you

U ConrwclaJtomMcily

^ irOKU

nfigurod the router.

0 LollcWih :.l I Micsl tntet (l>cn«tw

^ NEtGEM.Ut Hi....

Clicking the Connect

^ ifmitywin

VcNj can Also connect OypuilwiQ Itw buRon 0*1

button initiates a

irp f^^tcr

connection to the selected network.

»u

How many devices are set to .

> Mum

»

*

T it.

PgbftC

c. 3 d. 5

> Muac

K-OilCO

On a PC, File Explorer lists network devices under

the Network heading. ^ tptMvrvK

TRY IT!

Check your computer. Are any network devices visible?

Window'. I'll-' l" N«f>K!rtM]SF«nngCMfr > AmkM AanAQsranQt

v O

9

X P

CKange Ehsrifig options lor dlllererM network profiles 'iV'(iG0wi(r«4t«sai«p4ritenm*crtfi'eUeterMOiA«biv«i«utM '■Dbc«nOKo»«BwetK.«

I (Ml

•B

^ I Oe'e» VdM ••waaa CMJ

K-j*? * sy * o c gi'» macOS Finder

ichMlMli

Cwunwts

1. Choose the remote

computer from the list

(hctrnma

V ^

Stfvhiw- fi

of devices connected to the network.

"tosTT

HifA B.

HNC

^ AcccH PDF1.bn« ^ Access POFLbmp

BUll

LJ AddtMAdHMfcfPmeMecieA

PfaC

«; vwfo ^

Hm'i Pu^ F Can I control how files are modified? You can control who modi

fies a file, but not what they do to it. Once a shared file is bestowed with read and write permission, it can be modified to the extent that it is unrecogniz able. If you are not checking shared files frequently, you may be surprised by what some of those files contain. You can see the potential problem. Read and write permission is not to be given without considerable thought.

QUICKCHECK Suppose you would like to allow friends to access some

photos, but you don't want

One Important consideration about file sharing is whether to provide access to the original file or to a copy of It. Your decision depends on the reason for

them to make changes. What permissions would you assign?

sharing the file.

a. Read

As a general guideline, do not offer read and write access to the original version of a file. Instead, make a copy of the file and designate the copy as shared with write permissions. If the file gets modified in some bizarre way. you will have a version of the original file that was not shared or modified.

b. Read and write c. Write

d. Drop box

220

SECTION E, MOOUIE 3

I How do I share files from a Mac? The first step is to turn on file sharing, then select the folders you'd like to share. The macOS operating system allows folder sharing but does not give you the option of marking an individual file for sharing. The recommended procedure is to place all the files you want to share in a Public folder as shown in Figure 3-72. FIGURE 3-72: SHARING FILES FROM A MAC

^ Access System Preferences from the Apple menu.There, you can select Sharing to turn on file sharing.

Coo^utef

Dan's Mac CoopgtM OA yov Iocs! nsNfVk e«i•CUM your coApiftv St

BAH..

• Ri* Sharine: On

On

OVD or CO Shanna

Oin#r uMTt c*n acoow

folOcrt on iruf oemputtr. tnd ■dmMMntaii

igvalumai.aI-atpy/10J11.6S.I9-or*unk«10J1t.SS.ig'.

OpScna...

0 Add folders to the Shared Folders list, then specify who can have access and the permissions they are allowed.

QUiCKCHECK

0.

What kind of llles should Dan Computer Kamo:

OsnS Mm

store In his Public folder?

Compuaar* on your locir nntwnrti un MMM yov oanomv M

Edct...

a. files for a drop box

Oira.UKJDca

S«rvc*

DVD or CO SnsrlftQ

ScMA snarirtQ

b. Files he would prefer not to

• flWSMngtOn

share

Omer umts cm sccms stared Wdsn en tMe contpiAti. and sAhMeireiere m vetanes. al -«fp/r 10.211.55.15* or *vnby/tO.21145.10*.

msrmiriQ

c. Copies of files that he doesn't mind being altered

Opbota...

Printer &nar«>g Remote Logm

Remote MansQement

Shared Potdere:

Remote ApoJe Events

Imrnei Sharing

'

Uoan:

RoodiWrilo ;|

fe Dw'iPiieiicFoMar

i This Public folder Is shared.

ASIaO 1 E-.cr,ai-e

Readonly ;| 1 ^ HudAWrite

1

L.

d. Files that he doesn't want

deleted

RaadOnlyA

Write Onl^Prop Cox] No Aooeeol

Everyone can Add more folders to share.

access the folder and all the files it contains.

Cfck Vw loek 10 prmn lUnMr cnangM.

TRY IT! If you're using a Mac, check to see If file sharing is turned on. Which folders are shared?

22

NETWORKS

I How do I share files from a PC? On a PC using Windows, the first step is to use the Control Panel's Network and Sharing utility to make sure that network discovery is on and then tum on file sharing. Windows File Explorer includes a Share tab that's used to select folders or files you want to share. The Share tab also lets you specify permissions

QUICKCHECK Which operating sysiein olfers a way to designate individual files as shared? a. macOS

(Figure 3-73).

b. IDS FIGURE 3-73: SHARING FILES FROM WINDOWS

c. Android

Q Use the Control Ponel to access the Network and Sharing settings. Turn

d. Windows

on network discovery and then turn on file and printer sharing.

File And printer sh4nr>9

.

.

.

When file end printer shering Is orv files end prmtert thatyou hasre(hered from thts computer cert be Accessed by people on the network. File and printer sharing options

')9' Tum on file and printer sharing > Tum off file and printer sharing

In File Explorer, you can select a folder or file that you want to share. Use the Share tab to access settings where you can specify users and permissions. TRY IT!

Share tab

If you're using a PC, check to see

O a Ll VZ" Shirt

^ Soft'KatvMc-

St'S*n$

^

'1^

*4 Mflaryoup h»fw> indidrfj

CmA

if file sharing is turned on. Does

Access to permissions

SMtt nrth

« •r 1 » TNtPC

Deewmcfib > CwibnAfcAoets *

Q'

A DmaIm*

Se*r(hCa— fi

your computer allow shared access to any of your files?

Ki^r

~ Amher Ph«(e.prt^

S OnHnp

V ^

and SeuffrLdecx

PNcn* MKr««cn Wwd Oocumcrt

Q' Aaek: CKtb PreMMKrdA ppti

PewvtPeutt Presifiuo

B Decumoes

File selected for sharing 9iiriiig

i CirBftrtAytog*l •iccdb

0

Musk

s SmI Fil«uip T XC«VsSo
oose

to shaie svith

Select who can share the

file and specific permissions. d W OTd Mn

orIMS

QimnPh«]

222

SECTION E, MODULE 3

INTERNET-BASED SHARING

As more and more activity moves to the cloud, companies that provide cloud services have increased their interest in encouraging consumers to use those services. Cloud storage and sharing services are commonly hyped as being more convenient and more secure than local options, but many consumers are wary of cloud security, not to mention the rampant advertising that accompanies many of the free cloud storage services. The concept of pulling files from remote servers traces back to a protocol called FTP. Newer technologies now power Dropbox and similar services. So what are they all about? > What Is FTP? FTP (File Transfer Protocol) provides a way to transfer flies from one computer to another over any TCP/IP network, such as a LAN or the Internet. The purpose of FTP is to make it easy to upload and QUICKCHECK

download computer files without having to deal directly with the operating system or file management system of a remote computer, FTP also allows

FTP is

authorized remote users to change file names and delete files.

a. a cloud hosting service

i How can i access FTP servers? You can access FTP servers with

b. a file sharing protocol

FTP client software, such as FlleZllla, or with a browser. Addresses of FTP

servers usually begin with ftp, rather than www. To use a Web browser to download a file, simply enter the address of the FTP server as shown In Figure 3-74.

c. LAN-based secure file sharing d. a permission-free file sharing service

FIGURE 3-74: FTP FROM YOUR BROWSER 1. Enter the address of the FTP server in the browser's address bar. At an

anonymous FTP server, a user lb and password would not be necessary. Q FfPdMvctary/p4jWiA0i(^

^

-

-

. ✩

O

- 25

o

x

A -

FTP (Jirecloiy /pub/intlices/ at np.sec.nonii.gov

TRY IT!

Use your browser and try to

connect to ftp://ftp.epa.gov. What happens?

L'fito hiibgt

defection'

:;/ca?*ci£ :2/0?/2C16 IS/Of/ZOlfl OFtlSFM l2/2''/2C12 litC-JAM

Z.K9 :r«,4:c

r; I li/C;/201f

rt cry be

2. Select the file you want to download. Di:«ct=cy ©l Is BitTorrent safe? Because BitTorrent files are assembled from little

segments that come from a jumble of computers, they would seem to be bad candidates for distributing malware. Intelligent hackers would realize that their malicious code could easily be chopped up, too, and that pieces of it might not be delivered. And yet BitTorrent files have become a source of adware and spyware. If you use BitTorrent, make sure your computer is protected with a security software suite that offers good spyware protection.

QUICKCHECK BitTorrent can be called a(n)

a. distributed network

b. peer-to-peer network c. file sharing network d. all of the above

SECTION E

QUICKQUIZ 1.

2.

When network

is on, your 4. |

|client software, such as

computer can see other devices that are con

FileZilia, provides a way to upload and download

nected to a LAN.

files from an Internet-based server to a computer

Read and

permission

allows a shared file to be opened, viewed, modi

5. Torrents exchange segments of flies over a distributed network using a logical

fied, and deleted.

3. File I

on a LAN.

I has to be turned

on before any flies on your computer can be accessed by other devices on a network.

topology.

IT ALL STARTED in October 2007, when the "preserve the Internet as an open platform enabling FCC accused Comcast of slowing and in some cases blocking internet traffic from BitTorrent. Comcast claimed that it was attempting to even the playing field for the average internet user whose online speeds were languishing due to file sharing traffic from a

minority of its customers.

consumer choice, freedom of expression, end-user control, competition, and the freedom to innovate

without permission." Shortly after the Open Internet Order, Comcast was

back In court again to contest the FCC's right to regu late the Intemet. The court ruled in favor of Comcast,

Comcast's ability to adjust some users' bandwidth for the benefit of other users might seem beneficial

based on the fact that the FCC's jurisdiction did not extend to the Internet.

until you consider that ISPs could manipulate Internet speeds to give preferential

Yet the FCC persisted. In 2014, FCC

chairman Tom Wheeler proposed a compromise form of net neutrality that

access to certain sites and

services while slowing access

to others. That practice could essentially give ISPs the power to deny access to sites based

on business, political, or other values.

What if your ISP institutes a

Today's actio n at the FCC could begin the dismantling ofthe open Internet as we know it,..

Senator Edward J. Markey

system whereby you have to pay extra for high-bandwidth services, such as movie downloads? You might be

thinking, "There ought to be a law against that!" That is exactly the opinion of net neutrality supporters. The term net neutrality was created by Columbia

would allow ISPs to offer "faster lane"

options at a premium rate to content providers such as Netflix, Facebook, and Amazon. That proposal absolutely confused the issue; the FCC's pro

posed version of net neutrality was not neutral at all.

Opponents to this new non-neutral neu trality pointed out that considering the finite amount of bandwidth available on the internet,

users outside the proposed "faster lanes" would have their bandwidth squeezed while the added cost of fast lane services would be passed directly on to the con

media law professor Tim Wu in a 2003 paper Network Neutrality. Broadband Discrimination. Although the term net neutrality is relatively new, its roots can be traced to pre-1860 telegram technology. Back then,

sumers of such services.

standard telegrams were routed equally, without

that operate on small budgets—thus, stifling innova

discrimination, and without regard to their contents, source, or recipient. Telegraphs were end-to-end neutral networks. Because telegraph and—later— telephone networks were considered to be public utilities, or common carriers, they were not allowed

Additionally, opponents of this idea feared that the operational costs for fast-lane services would sky rocket and those costs would pose barriers to startups tion and competition. The FCC's "faster lanes" brand

of net neutrality satisfied no one. The net neutrality controversy boils down to simple

ideology; Should the government regulate the Internet

to give preferential treatment to one customer over

or not? On the one hand, regulation could prevent

another. The Federal Communications Commission

abusive business practices on the part of ISPs. On

(FCC) was formed to regulate common carriers and

the other hand, if the Internet were to fall under the

ensure equal access and fair prices.

regulatory control of the FCC, where would the regu lation end? The FCC currently regulates telephone and cellular service. It imposes a variety of taxes and fees that add to your monthly bill. Would similar taxes

As the Internet evolved into a massive communication

network, the FCC began to regard it as a common carrier that should fall under the FCC's umbrella of

influence. The first step would be to ban ISPs from stowing or blocking traffic indiscriminately. In 2010, under the banner of net neutrality, the FCC issued the

Open Internet Order, a set of regulations designed to

and fees be added to your monthly Internet service? And would FCC Internet monitoring add yet more

points where the government can collect data on the activities of its citizens?

227

NETWORKS

TRY IT! Net neutrality has become a political Issue, and organizations with vested interests add to the confusion with misleading ads. Here's a chance for you to explore the current status of net neutrality and to read arguments both for and against regulating ISPs.

o

What Is the current status of net neutrality regulation? Connect to the InfoWorld Net Neutrality page www.infowoi1d.eom/t/net-neutraHtylo find recent articles on this topic.

&

Take a look at your monthly cell phone or land line bill. Locate the amount you pay for taxes and fees. How much do you pay in taxes and fees annually?

e

Go to the FCC Web site and read the Communications Act oi'iQZA transition.fcc.gov/Reports/1934new.pdf. Does the wording in this act appear to apply to the Internet? Why or why not?

o

Many ISPs and media companies have published written statements about their stance on net neutrality. What do you guess are the positions of Amazon, Mozilla, Netflix, Comcast, and the Electronic Frontier

Foundation? Find the net neutrality statements of these companies online. Do they take the positions you expected? Why or why not?

0 In 2016, a U.S. federal court of appeals handed down a controversial net neutrality decision. The case involved a dispute between the United States Telecom Association and the FCC's Open Internet Order. What three practices does the Open Internet Order prohibit? Did the court rule in favor of this order or against it?

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Search online for the article Open vs. Closed: What kind of internet do we want? What Is the difference between an open Internet and a closed Internet? How does that difference relate to net neutrality?

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ISSUE

What Do You Think? 1. Do you support the Idea that internet traffic should flow freely? 2. Do you believe that the U.S. government should regulate the Internet as a common carrier?

3. Were you aware of the net neutrality controversy?

r

These days, you have to be a skeptic. Bioggers have opinions that are not always based on facts. Scam artists

say anything to get your money. Fake news sites are proliferating. Just because an article shows up in Google results, doesn't mean its contents are factual. Even reputable journalists sometimes make mistakes.

Before you form an opinion, make a decision, or take action based on what you read, see, or hear, you can easily use your computer or smartphone to verify facts and look up background information. Search Google. You can use Google or a similar search engine to find information from ail corners of the Web. You can search for information in specific formats, such as videos, images, and news reports. Check out Google Scholar for links to authoritative information in peer-reviewed journals, theses, and other professional publications. Remember that you can formulate searches such as Define DNS spoofing \o learn the meaning of technical terms and find the meaning of acronyms. Search within sites. Rather than conducting a wide-ranging Google search, you can go to a specific Web site and search within it. Search Wikipedia for definitions and topic overviews. Search news sites for articles and video footage about current events. Start at www.snopes.com or www.facfcheck.org to identify email scams. When you check facts or use them in your own research papers, primary sources tend to be more reliable than secondary or tertiary sources. How can you tell the difference?

PRIMARY SOURCES

SECONDARY SOURCES

TERTIARY SOURCES

Original material such as speeches, interviews, letters, photos, email messages, tweets,

Reviews, critiques, panel discus sions, biographies, and other

A list or compilation of material that

sources that analyze, summarize, or otherwise repackage informa tion from primary sources

that include bibliographies, dic

artwork, diaries, laws, database reports, and accounting records

pertains to a topic; from sources tionaries, almanacs, indexes,

timelines, and inventory lists

Example: A video of Apple's CEO announcing a new music product

Example: An article on Google

Example: Apple's ecommerce site

News that describes Apple's new

that lists and sells all versions of

for the iPhone and iPad

music product

its new music product

FACT-CHECKING TIPS I Two sources are better than one. Cross-check facts between two or more sites. I Use common sense. Claims that seem outlandish

require extra verification.

> Understand your priorities. For example, you can go to YouTube and view the trailer for Live Free or Die Hard. That might be fun. but it might not be relevant for a term paper on cyberterrorism. I Use primary sources when possible. Go to the original text of a speech, check the product manufacturer's Web site, or watch the video clip. I Use reputable sources. The Web contains billions of documents; few of them follow strict journalistic standards for accuracy. Check the author's credentials, look at the general quality of the Web site, and make sure the Information Is up to dale.

t Maintain a list of the sites you frequently use for fact checking. You can create a Fact Check folder In your browser's Bookmarks or Favorites list.

I Nail down your search terms. When using voice search on your mobile phone, think about an exact set of keywords before you launch Speak Now.

Speak now

i.'iooglr »4icM

229

NETWORKS

TRY IT! Fact checking can be fun and it can lead you to all sorts of intriguing factoids as well as to sub stantive information. Practice your fact-checking skills by completing the following activities;

o The truth is not always clear cut. Sometimes it is nuanced. Statements can sometimes be literally true, but still manage to misrepresent reality. After the 2016 presidential election, the Russian government was

implicated in obtaining and releasing kompromat[compromising information] gathered from illegal hacking and intended to influence American voters. A statement fay the Russian government said, "The Kremlin does not collect kompromat." Is that statement true? Explore online to discover why this statement may be true, but is misleading. What kind of research would be required to prove this statement true or false? Fact checking Web sites, such as snopes.com, polidfact.com, and factcheck.org, have been accused of being biased in the stories they choose to fact check and in the way they present conclusions about the veracity of information. In July of 2015 presidential candidate Bernie Sanders stated that the unemploy ment rate for African Americans between the ages of 17 and 25 was 51%. A year later, Donald Trump stated that the unemployment rate for young African Americans was 59%. Which statement was true?

Connect to www.politifact.com. a reputable fact-checking Web site. Use the search box to find out how Politifact evaluated the truthfulness of these two statements. Be sure to read the fact checks on both

statements, then answer the following questions: a. According to Politifact, which statement was closer to the truth?

b. According to the Bureau of Labor and Statistics, the actual unemployment rate for African Americans is about 27%, but a different figure can be obtained from the employment-population ratio. How

does that relate to the 51% and 59% unemployment rates that were quoted by Sanders and Trump, respectively?

c. Do you think that Politfacfs conclusions about the statements made by Sanders and Trump were accurate and unbiased?

d. What is the potential danger of simply accepting the bottom-line, true-or-false conclusion presented by fact checking Web sites?

Suppose you're gathering information for a term paper about the emergence of the Internet, and you come across the following short article posted on Facebook. Internaut Day could be an interesting addition to your report; but before you include material from this article, you should do a fact check. Go online and find answers to the questions in the diagram below.

Happy Internaut Day! Few people would disagree, especially those who call themselves internauis.

.^n "internaut" is a person who pos--

c. Is there such

sesses a thorough knowledge of how

a thing as an

10 use the Inierncl and its history.

Internaut?

T he word, a combination of Internet

a. Was tKe

This year's calendar will feature a new

and astronaut first appeared in a 1990 article about response rates to inforinalion posted ott the Web. A group

Internet

U.S. national holiday recognizing the

of hardy iniemauts has been petition

with including

ing presidems, from Nixon to Obama.-.

Nixon here?

Invented on

August 23rd?

b. Is this an accurate quote from a U.S.

president?

"tlay the Internet was invented. Circle

August 23rd. That is the date when

for naiittnai recognition of this special

then Vice President Al Core, threw the

day.

switch that opened the Internet to pub

The hashlag #internautday has-"

lic use.

become a rallying point for Internet

The liilemet has become an indispens able part of everyday life. In declaring

enthusiasts and was instrumental

this new national holiday, the President

-stated,"The Internet is not a Itixtiry, it is a necessity."

in garnering more than five million

digital signatures on the petition to itistiiuic a national Internaut Day.

d. What's wrong

c, Is Internaut

Day a U.S.

national holiday?

t

ECHNOLOGY IN ClfRllxTrtDUCATION

m

THE FIRST EDUCATIONAL applica

simulations, whereas Battlefield 1942 is a first-person

tion of computers emerged in the 1960s, when huge

shooter game based on historic World War II battles.

mainframes with clunky interfaces introduced stu dents to computer-aided instruction (CAI). Based on

The line between the two types of simulations is blurred. Is Guts and Bolts an anatomy simulation or a game for designing bizarre organisms?

operant conditioning research by B. F, Skinner and Ivan Pavlov—remember dogs salivating when a bell

rings?—CAI uses basic drill and practice; The com puter presents a problem, the student responds, and

Most educators believe that computers can help

monochrome display and found the regimented drill

create an Individualized and interactive learning envi ronment, which can make learning more effective and efficient. According to the National Center for Education Statistics, 99% of American public schools have computers and 93% of students use them in some way. However, these statistics can be deceiving. The reality falls far short of the ideal situation in which every student has access to a computer throughout

format boring-

the school day.

the computer evaluates the response.

Studies in the 1970s indicated that programmed instruction systems, such as Programmed Logic for Automated Teaching Operations (PLATO), Improved test scores, but students soon became bored with the

The challenge for K-12 schools is to figure out how to achieve the computers' potential In an educational setting when supplying computers for every student is often cost prohibitive. Compromise solutions have been tried with varying degrees of success. Some schools have installed learning labs where students go for scheduled lab time. In elementary schools, often a few computers are placed in special work areas of classrooms and used for small group projects or indi vidual drill and practice. Some schools have relegated most computers to the media center, where they are connected to the Internet and used for research. In

some classrooms, a single computer can be used as an effective presentation device. Educators know that students have diverse learn

ing styles and are equipped with varying degrees of background knowledge about a topic. Computers, with all their processing power, should be able to provide individualized instruction. With prom ising breakthroughs In artificial intelligence during the 1980s, deploying computers for indi vidualized instruction seemed within easy grasp.

The problem, however, was more complex than first expected. Thirty-some years later, individualized instruction in the form of adaptive learning is just beginning to mature.

Simulations have become a popular educational tool. There are educational simulations that mimic

An emerging bring your own technology(BYOT)trend in elementary schools encourages students to bring their own devices to class. Laptops, smartphones.

and even videogame consoles—any device that can access the Web—might be used to access a wide variety of online educational content. The challenge for teachers is to find appropriate content and inte grate it into the curriculum and lesson plans. Some schools—primarily colleges—have tackled the problem of computer access by requiring all incom ing first-year students to purchase laptop computers. Most colleges offer campus-wide Wi-Fi service with Internet access so that laptop-toting students can

real-world situations through narrative descriptions,

easily take notes in class, contact instructors via

2D graphics, or virtual reality. There are also game

email, use the Internet as a research resource, and

simulations that educate within an entertaining envi

run educational software.

ronment. Flight simulators are an example of real-word

231

NETWORKS

The proliferation of tablet computers has led to a bevy of experiments under the umbrella of mLearning, a buzzword for mobile learning and defined as learning that happens across locations, or that takes advantage of learning opportunities offered by por table technologies. Another educational use of computers can be seen in distance education (DE)courses (also called dis tance learning). -

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froae 152922: ISU byUt «a mirt (IJIU bits), 1514 byt Are links URLs? No, but a link contains the URL that points to another Web page. Before linking to a page, for security reasons, you might want to preview the URL for the page. Figure 4-10 shows how.

TRY III Can you connect to the CNN

Web site without using http:// in the address? Can you connect without using www?

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nRpMn«M>Joekalmy*tf.coin/sp«aaiarii>t'vouciK Why are URLs so long? When visiting Web sites, glance at the address bar from time to time. Many of the URLs are long and complex.

Here's a long URL that's the Web page for a short story: http:/Avww.edisonjones.com/short-stories-for-kids-edison-jones/stories-forkids-samuel-and-the-pirates.html

t Is there any way to shorten URLs? Long URLs can be a prob lem. The longer they are. the easier it is to make a typing error. Aiso. long URLs consume too many characters in short messaging applications such as Twitter.

Several services, such as Bitly and Goo.gl, create short URLs. Anyone can request a short URL by entering the normal URL at one of these services. The service wili generate a short URL. The originai URL and the short URL are stored in a translation tabie on the service's server. Figure 4-12 iliustrates how short URLs work.

FIGURE 4-12; SHORTEN THAT URL

I Copy and paste the fuli URL into the box pro vided by a short URL service such as Goo.gl.

^The service produces a short URL.

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rii forward you to the full URL.

with the fuil URL. Short URL

©Links to the short URL are directed to the server, which forwards the iink to the full URL. Short URL service server

I Why use a short URL? Suppose you want to share an article or video with your friends on Twitter. Easy. Just find the Twitter icon and click It, right? Twitter automatically shortens the URL to 22 characters. Sure that works on Twitter and a few other social media sites, but what if

you want to share something from a site without Share links to social media sites? You can copy the iink and obtain a short URL before pasting it into an email message or social media post. Posting a short URL takes up less space in a Tweet or post. Aiso, if you expect recipients might manually type the URL, they will make fewer mislakes when typing a short one.

TRY IT! Use Goo.gl or Buiy to create a short URL for an article or video

Some URL shortening services, such as Goo.gl, provide tracking data.

you've found on the Web. Mai!

You can create a short URL and then track how many clicks it receives. To collect click statistics, it is necessary to have an account with the service,

the link to yourself. Test the link. Does it produce the article or

but accounts are free. Goo.gl is operated by Google and it will use your

video you specified?

Googie+ orGmaii login.

253

THE WEB

I Do short URLs expire? Short URL services may lead consumers to believe that all short URLs will last forever, but they last only as long as the service maintains its servers. If a service ceases operations, the short URLs maintained on its servers will no longer work. Short URLs are sometimes used to disguise the real address of a Web site

that is illegitimate. This practice has resulted in short URL services being blocked by Web hosts and ISPs. When URL services are blocked, the short URLs on their servers will not work.

Web surfers should be aware that short URLs may lead to questionable Web sites and scams. Never click a short URL link in an email message

if you are not certain it leads to a legitimate site. As shown in Figure 4-13, several sites, such as checkshorturl.com and getlinkinfo.com, provide ways to check the actual destination of a shortened URL before you click it. FIGURE 4-13: EXPAND THAT URL

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Online services such as checkshorturl expand short URLs and display the original, full URL.

SECTION A

QUICKQUIZ 1.

2.

The World Wide Web is one of the many tech

In the URL http://www.mus/cw/re.com/6/f.Wrn,

nologies that uses the

the

infrastructure to distribute data.

com.

The basis for Ted Nelson's original idea for was to use bidirectional

links to navigate between digital documents. 3.

4.

A(n) cates a query.

symbol In a URL i ndl-

5.

name is

musicwire.

Http;//bit.ly/MY67dd93B is an example of a(n) URL.

254

SECTION B, MODULE 4

Browsers

Popular

Cache/Historv

Microsoft Internet

Explorer

SECTION

B BROWSERS T!

GO INCOGNITO.After you read Section B,

Terminology

you might want to put dark glasses on your browser so you can surf the Web in private without accumulating a trail of Web sites, images, and ads

default browser browser home page

that trace your Web activity.

browser tabs browser extension

predictive services bookmarks plugin browser cache History list private browsing

Objectives I identify the following elements of a browser window: address box, refresh and home buttons, back and forward buttons, tabs, and

settings menu.

I Describe the difference between a browser

extension and a plugin. ^ Describe what is in a browser cache and explain how it can affect your privacy.

t List four popular browsers.

I Describe what is in a browser's history list.

I State the difference between the default browser and the browser home page.

I Explain how private browsing works.

» Summarize the potential problem with allowing I Explain the purpose of predictive services.

your browser to store passwords.

255

THE WEB

BROWSER BASICS

Web browsers are the all-purpose tool for accessing the Web and every thing it has to offer. They are used on all personal computer platforms. What's surprising is that the essential elements of browsers for small screen

devices, such as smartphones, are so similar to those for large screen Terminology devices, such as desktops and laptops. I What's in the standard browser window? The essential ele

ments of a browser include an entry area for URLs and searches, navigation controls to move from one page to another, a refresh button, a home but ton, a settings menu, and a display area for Web page content. Additional elements, such as tabs, facilitate the browsing experience. Figure 4-14 illustrates essential browser elements and several additional features com mon to browsers on full-screen and mobile devices.

The address box originally was used only for entering URLs. Today, the trend Is to also use it for entering search terms. The address box is sometimes called an Omnibox to reflect its dual use.

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Compare the browsers thai

you use on mobile devices to those you use on your laptop.

John RonaiO Rouel Ttjikien CBO FRSL

known by N9 oeit name J. R. R. Tolioen,

How many of the user interface

CD

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elements are similar?

255

SECTION B, MODULE 4

► What are the most popular browsers? Today's popular browsers are Apple Safari, Google Chrome, Microsoft Internet Explorer, Microsoft Edge, and Mozilla FIrefox. In Figure 4-15, compare the placement and design of the address bars and navigation controls of these popular browsers. FIGURE 4-1S: POPULAR BROWSERS

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Edge, account for about 10% of the browsing

Apple Safari is shipped with lOS

activity that takes place

devices. About 15% of desktop

on the Web.

and mobile traffic on the Web is

generated by Individuals using Safari.

#

fvdoa Start

Mozilla Firefox is a descendant ' o.-cQ HOOAafi'itfe

of the first graphical browser, Netscape Navigator. As open source software, Firefox is avail

able for free and is easy to download and install. Firefox

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its streamlined design and billed for its speed and security. Chrome Is free and available from Google's

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Web site.

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browser to Internet Explorer. It offers built-in support for PDF and Flash, and eliminates the use of

several legacy technologies that are security risks.

257

THE WEB

• When should I upgrade my browser? It is a good idea to upgrade when a new version of your browser becomes available. Because most

browser updates are free, you can get up-to-date functionality simply by spending a few minutes downloading and installing an update. The most important reason to upgrade is for increased security. As hack ers discover and take advantage of security holes, browser publishers try to patch the holes. Upgrades normally contain patches for known security exploits, although new features might sometimes open new holes. New versions of browsers also reflect changes in operating systems and specifications for the HTML used to create Web pages. To take advantage of the latest innovations and to experience Web pages with all the bells and whistles intended by their designers, an updated browser is recommended.

QUICKCHECK Which of the following is not a reason to upgrade your browser?

a. To improve security

b. To keep up with new Web technologies c. To get a free one

I Is it possible to use multiple browsers? It is allowable to have more than one browser installed on a device, and you can open any installed browser and use it to surf the Web. Only one browser can be des ignated as the default browser, which is automatically used, for example, when you click a link in an email message or PDF file. You can add browsers and change which browser is used as the default.

Suppose that your device is equipped with Microsoft Edge, but you'd pre fer to use Chrome or Firefox. There is no need to delete Microsoft Edge. Simply download and install Google Chrome or Firefox, then set it as your default browser using one of the methods shown in Figure 4-16.

TRY IT!

How many browsers are installed on the device you use most frequently? What is the default browser?

FIGURE 4-16: WHAT'S YOUR DEFAULT BROWSER? o Settings «•

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Using a service such as Protopage, you can create a customized home page that helps you easily access the sites you use most frequently and the Informa tion you want at your fingertips.

TRY IT!

You can adjust the behavior of predictive services from

I What about predictive services? Predictive services look ahead and anticipate what you might do when searching or filling out forms while using a browser. These services can automatically fiji in form data based on entries you've made to earlier forms. They can also complete search requests based on previous searches. In addition, they can display search and site predictions as you type queries. Predictive services may track your actions and store data about you online. If you are nervous about privacy intrusions, then you might want to disable these services.

Chrome's Settings menu. Safari's Preferences menu,

Internet Explorer's Internet Options menu, Microsoft Edge's Advanced Settings menu, and Firefox's search box. Are

predictive services turned on in your browser?

259

THE WEB

> How do I customize bookmarks and favorites? Bookmarks (or Favorites, as they are called in Microsoft browsers) link to pages that you use frequently. When the browser is configured to show bookmarks, they appear on the browser toolbar and are easy to access.

Consider creating bookmarks to your favorite social networking and infor mational sites. Set a bookmark to your favorite music service, or create a bookmark to quickly check the caloric content of the food you eat. Perhaps a bookmark to an online thesaurus can help improve your writing (Figure 4-18). One caution; Create bookmarks for sites that help, not hinder. That addictive cat video site? Don't bookmark it if the site becomes a distraction. FIGURE 4-18; CUSTOMIZE YOUR FAVORITES TOOLBAR O

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TRY IT!

Take a look ai your browser's Web sites added to the Favorites toolbar

can be accessed with one click or tap.

Favorites or Bookmarks toolbar.

Does it cor^tain sites you access

n

often?

QUICKCHECK

I Can I control tabs? Browser tabs allow your browser to queue up

Which one of the following

multiple Web pages so that you can easily switch between them. Your browser's Settings menu allows you to specify whether to use tabs or a new browser window. Each tab holds a page, and simply clicking the tab displays the corresponding page.

cannot be customized?

An alternative to tabs is opening new pages in separate browser windows—

c. The home page

a process that allows you to see multiple pages at the same time, rather

d. The Close button

a. Tabs b. Predictive services

than switching among them (Figure 4-19). FIGURE 4-19: DISPLAY MULTIPLE SITES AS TABS OR SEPARATE WINDOWS

' SITE1 ISIT^^Sr^^^

SITE 3 SITE 2 SITE 1

260

SECTION 8, MODULE 4

• What is an extension? A browser extension adds features to a

browser. For example, one very popular extension called AdBlock removes advertisements from Web pages. Other extensions add various toolbars to the browser window: the Google Toolbar, the Merrlam-Webster Online Toolbar, and the StumbleUpon toolbar are popular.

TRY ITl

Even more extensions include a grammar checker to proofread your social media posts, a URL shortener for adding links to Twitter, and encryption that

Search online for a list of extensions that are available for

protects the data passing between your device and Web servers. There

your browser. If you don't have AdBlock, you might consider

are even extensions that detect and display cookies and other devices that

track your activity on the Web.

downloading it from a reputable

I How do I manage extensions? Browsers provide a list of Installed

source, such as the Chrome Web

extensions and provide tools for disabling, enabling, or deleting them, as shown in Figure 4-20.

Store.

FIGURE 4-20: FIND YOUR BROWSER'S EXTENSIONS a

How do I manage plugins? Plugins have been exploited by hackers to access computers without authorization and plant malware.Technologies companies are attempting to phase out the use of plugins. Microsoft Edge does not use pluglns, but for other browsers the phase-out period Is ongoing.

If you are using a browser that requires a plugin or a plugin update, it can be easily downloaded. Plugins come in different versions for different brows ers. When looking for plugins, let your browser do the searching and it will find ffre correct version.

You can view, disable, and delete plugins. In Chrome, Safari, and Firefox, plugins are managed from the browser. In Internet Explorer, plugins are managed along with other installed software through the Control Panel. Figure 4-21 provides a guide so that you can find them in the browser that you use. FIGURE 4-21: FIND YOUR BROWSER'S PLUGINS

Google Chrome: Enter Chrome://plugins/ In the address bar.

TRY IT!

If your browser uses plugins, Apple Safari: Select

Safari Preferences , then

select the BUI icon.

Microsoft Internet Explorer: Open the Control Panel and select the icon for

Programs and Features .

Mozllla Firefox: Enter www.mozllla.crg/en-US/pluglncheck/ In the Firefox address bar.

look at its list of Installed

pluglns. Are there plugins for a Flash player and PDF viewer?

262

SECTION B, MODULE 4

BROWSER CACHE

Browsers pull HTML documents, images, and other Web page elements to your local device—and not just the main elements of a page. All those funky ads are pulled down, too. It is somewhat troubling that these ele ments may remain In a Web cache on your device, leaving a trail of digital bread crumbs to the Web sites you've visited.

Which of the following would

I What is a browser cache? When your browser fetches pages and

you not expect to find In a

graphics to form a Web page, it stores that material on your device in temporary files referred to as a browser cache, Web cache, or browser

browser cache?

QUiCKCHECK

a. Passwords

history. b. Image files from Web pages

A browser cache comes in handy if you switch back and forth between pages or sites. Rather than fetch the entire page and all Its graphics again, your browser can simply load them from the local cache (Figure 4-22). FIGURE 4-22; YOUR BROWSER CACHE IN ACTION

Browser cache

When a Web page Is first accessed, all the ele

If you return to the Web site in a later session, your

ments are downloaded

browser first checks the

and stored locally In the

cache. Any elements that

browser cache before

are stored locally do not

they are displayed on the

have to be downloaded

screen.

again.

I How does a browser cache affect my privacy and security? Files can remain in the Web cache for days or weeks, depending on your

browser's settings. Because a browser cache stores Web page elements from all the sites you've visited, anyone with access to your device can view this trail of Web sites. In addition, when you use a public or lab computer, the next person who uses the computer may be able to see the cache of your Web activity.

c. Images from ads d. HTML documents

263

THE WEB

• Can I see what's in a browser cache? Yes. With some browsers, such as Google Chrome, it is easy to see a listing of files in the browser cache and even retrieve them. So, if you want to access a photo that you saw during a previous browsing session but can't get back to the site,

you may be able to access the photo from the browser cache. The steps for viewing files in the browser cache depend on the browser you're using. It is also worth mentioning that if you use more than one browser, each one has a separate cache. Figure 4-23 illustrates how to access files stored in Chrome's cache. FIGURE 4-23: WHAT'S IN YOUR BROWSER CACHE? £>

"O—T"

>v>Tk C

®

a

til O

C.

-UULiaULiJi

TRY IT!

Take a look at your browser's cache. Do you recognize images

l'i'opI- .-otn Mi

ik

and other content from sites

1,'tns ,

Enter this in the

Cached files include the URL of the

ijif

r,im,

address bar.

originating site and a file name.

itilioiUELdElnE

.1

you've visited recently?

Uma_i)I!S!5!S3?T5!^3SIE55ij! File extensions, such as .png, pro pixrlf coi,i.^llc

vide clues to the file contents. „u-,\

C[,,n

lirT^s

,T,n r-,i .'')J'r,l%T -

ti[iiL,i,'.t-r.irf^ A'srr 1.'-I? I

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0 I fc fli ,n 0 I t

tir.ttro&eiBaiEiiui ioiui'lrlc

^i-.-hipnii-

i.o.C-Titi=t.C-rt=fhipfr,'X'fnTs1Arf>

Lllei_iUi2H£2£k.s.cm.ccLiriclcj,:MdCdiniydurai:5fliiujU5-U=£hcsic:ah2mE^amzl&a=ikiflsu&fiU^lAs85 hltiH

»nivco,i«l. f,.m

lv>?S u «l»l

R,.7;i Qgrtum ferfr«« Hts»t M> IZscdoc Aftmn

TRY IT!

Do you go incognito? Malx sure you know how to activate

the private browsing mode for

traces of the sites you

the browser that you use most

visited will be deleted.

frequently.

255

THEWEB

► Is it safe to allow my browser to store passwords? Browsers ask to save passwords when you log in to sites. If you agree, your pass word is stored in an encrypted file on your local device. The next time you log in to a site, your browser will use the corresponding stored password. Storing passwords is a useful feature. You can create unique and hard-toguess passwords without fear that you might forget them and without the hassle of looking them up each time you log in. The potential risk of stored passwords Is that anyone who gains access to your device can easily log in to your password-protected sites because the passwords are supplied by your browser. If you allow your browser to store

QUICKCHECK How would you bummoriZL"

the security risk involved in allowing your browser to store passwords? a. It is not a risk.

b. It is a security risk and should be avoided.

passwords, be sure to use a password to protect access to your device.

You can discover which passwords are saved by the browsers you use. To view passwords stored by Microsoft Edge, use the Start menu to open

c.

It is more secure to store

passwords online.

the Credential Manager. For Safari, select the Preferences menu, then

d. The convenience of stored

select the Passwords tab. In Firefox, open the Security panel and select Saved Passwords. Figure 4-26 illustrates how to find passwords stored by

passwords might be worth the small risk.

Chrome. FIGURE 4-26: FIND YOUR CHROME PASSWORDS

'cr C ' 0

i

Passwords

1. Select this menu, then choose

Settings. Scroll down and select the sign -n lowvbsitcs using vtoteiS avbenridU

loi tonfirmiStic'n rvi'iy time before su)iiuh] in to a wcbuti'

link to show advanced settings. Select the option to manage passwords.

Saved passwords Q KCttmc^ooglexsni I ur So HTML documents look a lot different from Web pages, right? Exactly. An HTML document is tike a screenplay, and your browser is like a director who makes a screenplay come to life by assembling cast

qUICKCHECK

members and making sure they deliver their lines correctly.

The text for a Web page and the HTML togs is stored in

As the HTML "screenplay" unfolds, your browser follows the instructions in an HTML document to display lines of text on the screen in the right color,

a. a source document

size, and position. b. a file with a .web extension

If the screenplay calls for a graphic, your browser collects It from the Web server and displays it. Although the HTML screenplay exists as a perma nent file, the Web page you see on the screen exists only for the duration of the "performance."

c. a browser d. all of the above

An HTML document is sometimes referred to as a source document

because it Is the source of the HTML tags used to construct a Web page.

Figure 4-28 illustrates the difference between an HTML source document (bottom)and the Web page it produces (top).

Open your browser and connect to any Web page. Can you

FIGURE 4-28; HTML SOURCE DOCUMENT

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SvihSfflilh 0. ^ sS 6

d'

THE GLOBAL CHEF Trivd flffiund the viwld. A de^ecUbte fuftt fo

AOLSTALKER.COM

Enter a (iiieiy

- —

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batman }usk tnta' a wors

User 6497 spent several minutes

uwttatsia D.

o qs Cq a sp«ctA
What should i keep in mind about geolocation? Location-aware apps may use more than one type of location service. The location services settings for a digital device can be used to enable or disable location track

ing for each individual app. Geosocial networking depends on geolocation, so your participation requires an accurate assessment of your location. If you want to be found, activate all available location services by making sure GPS, cellular, and Wi-Fi are turned on. It you don't want to be found, make sure that all of those iocation services are turned off.

I What is geotagging? Presenting information about what's nearby requires places and landmarks to be tagged with their location. Restaurants featured on Yelp, for example, must have a street address or longitude and latitude available in a machine-readable format that can be interpreted by the geosocial networking service's search engines. Geotagging and geocoding provide the necessary geographical information.

QUiCKCHECK A service that displays the

location of a post office on a map is using

Geocoding is the process of determining the coordinates of a specific place, such as the street address or the longitude and latitude of Cathy's

a. geotagged

Cafe. Geotagging is the process of adding location data to photos. Web

b. geocoded

sites, HTML documents, audio files, blog posts, and text messages. Standard formats for geotagging and geocoding ensure that location data

c. social media

can be read by the computer programs operated by geosocial networking

d. cfowdsourced

services.

data.

321

SOCIAL MEDIA

SOCIAL NETWORK ANALYTICS The now infamous game Six Degrees of Kevin Bacon is based on a notion that any Hollywood actor can be linked to Kevin Bacon in six steps through the actors' roles in various films. The Six Degrees of Separation concept originated in a 1929 short story by author Frigyes Karinthy, whose charac ters devised a game of figuring how to most quickly relay a letter between any two people on Earth based on links between their personal acquain tances. Today, tools let us map and analyze social networks. What do they tell us?

► How are social networks mapped? Social networks are not exclu sively online. Everyone has faoe-to-face networks of family, friends, and acquaintances, who in turn have their own networks of social connections. You may envision these networks as points connected by lines. Sociologists use social network diagrams called sociograms to depict connections between people.

The circles in these diagrams are referred to as sociogram nodes. The lines connecting nodes are referred to as sociogram edges. Two-way edges exist when two people consider each other to be friends. One-way edges exist when a relationship is not reciprocal, such as a Twitter follower who does not follow back. What do the connections in Figure 5-9 tell you about the relationships between characters in The Lord of the Rings? FIGURE 5-9: ANATOMY OF SOCIAL NETWORKING

QUiCKCHECK In a sociogram, edges indicate

Ell^an j* Saruman

Berait

.A

Qoidberry

a. connections b. the boundaries of

Geebom

(rand

relationships c. Individuals with few friends

Boromir

Si\bo

Qtomnddl

d. 3D connections

Qaladnol

Araao Qollum Gandalf

Cardan

Baregond

\

Elrohir yi

Arwe Sam

Faramif

Imrahit

TRY HI Oenethor

Lego las

The thickness of connecting lines (edges) indicates connection strength. Node colors indicate which characters are most important.

Do the most important characters in Figure 5-9 appear to have the most "friends"?

322

SECTION A, MODULE 5

► Is it possible to sort through the complexity? Sodograms can get extremely complex, which makes connections difficult to trace and analyze. An aitemative method for depicting social connections is with an adjacency matrix.

A binary adjacency matrix is simply a set of cells containing a 0 if there is no connection between two people and a 1 if there is a connection. The adjacency matrix in Figure 5-10 depicts the relationships between some of the elves and hobbits of Middle Earth as a sociogram and as an adjacency matrix.

FIGURE 5-10: HOBBITS AND ELVES

BILBO

ELROND

FRODO

LEGOLAS

BILBO

\1

ELROND

LEGOLAS

In this sociogram, Bilbo

The intersection of dark blue cells in the adjacency matrix contains a

considers EIrond his friend,

1 to show that Bilbo considers EIrond his friend. Can you find the cell

but EIrond does not con

that indicates EIrond does not consider Bilbo to be his friend?

sider Bilbo to be his friend.

I What else does the matrix reveal? Matrices can be manipulated visually and mathematically to reveal more information about social connec tions. These manipulations can reveal pathways, connections, and groupings that lead to all sorts of revelations. Law enforcement agencies hope to use

such techniques to uncover criminal organizations, and national security agencies hope to follow links to identify members of terrorist groups. Suppose we rearrange the matrix so the two hobbits and the two elves are adjacent. The results are interesting. The rearranged matrix in Figure 5-11 seems to indicate that the hobbits chose each other as friends, but the elves

were not friends with other elves. Therefore, the elves would not be likely to conspire with each other to overthrow Middle Earth or to save it.

QUICKCHECK Hov; does the adjacency matrix indicate that the elves are not

friends?

a. It has a zero (0) where the elf rows intersect with elf columns.

b. It has a dash (-) where the elf rows intersect with elf columns.

c. It has a one (1) where the FIGURE 5-11: INFERRED CONNECTIONS

BILBO

FRODO

elf rows Intersect with elf ELROND

columns.

LEGOLAS

B LBO

FRODO ELROND

HOBBITS

ELVES

HOBBITS

100%

75'^

ELVES

50%

0%

In the rearranged matrix, the two hobbits are adjacertt, as

This matrix shows the percentage of connections

are the two elves. Color blacks illustrate the general rela

within each block, with hobbits well connected,

tionships between hobbits (red) and between elves (green).

but elves not connected to each other.

323

SOCIAL MEDIA

I How do analytic tools apply to online social networks? Sociograms and other analytic tools help us understand the quality and quantity of our personal social networks. The concept of one-way edges Is important, for example, In understanding that although you may receive status updates directly from the President of the United States and the First Lady, you are not likely to enjoy a similar link In the other direction. Social network analytic tools also uncovered a very odd phenomenon. Does it seem like most of your friends have more friends than you have? It turns out that is the case with more than 80% of Facebook users. This phenomenon Is referred to as the class size paradox because It Is related to the reason

students feel that they are always in larger than average classes. The expla nation is that people tend to choose popular classes and friends, and such popularity does indeed mean that the classes are larger and your friends will have more friends than you have. Figure 5-12 offers a few additional interest ing friend facts. FIGURE 5-12: FRIEND FACTS

\ / 1 1 1

'

' ' ' ■ ' • M I j I ff 1\ 1 If '1 «i »1

lii'ililtli lOO+frienciy miM M .'

#

' '

t

Can 1 assign a CC license to my own work? When you create a work, it is automatically protected by copyright and you have exclusive rights to its distribution, modification, and sale. If you would like to release some

of those rights to make the work easier for othere to use and share, you can assign a Creative Commons license. Figure 5-20 explains how to assign CC licenses to various types of media. FIGURE 5-20: HOW TO ASSIGN CC RIGHTS

^ Connect to the Creative Commons license chooser at creativecommons.org/choose.

Choose the rights you want to grant to others.

License Features YourchoicKonihis panel will updM

other pinels on this p^e.

Allow adaptation* of your work to b*(harodt u Yes

i< No

[T1 Yei, at lone as olhors share jilkt

Allow cemmtrclaltua* of your work? • Yes

. No

© ®@ 6Place the license where it can be easily accessed. TYPE OF WORK Web page. Web site, orblog

Image

WHERE TO PLACE LICENSE At the Creative Commons site creativecommons.org/ choose/, select a license, copy ttie HTML code provided,

then paste it onto a Web page or blog. Reference the CC license you've selected In the image caption or in the image tag.

Reference the CC license you've selected on the title Presentation

slide or the last slide. Adda link, if possible, to the license.

c.

BY

d. BY NC

333

SOCIAL MEDIA

► What about fair use? Earlier modules touched on the concept of fair use, which allows for the limited use of copyrighted material without obtain ing permission from the copyright holder. United States copyright regulations include four factors that characterize fair use:

Qjhe purpose and character of the use. The use of copyrighted mate rials without permission is more likely to be "fair" when the materials are

transformed and used for a purpose different from that of the original work.

^The nature of the copyrighted work. Guidelines for fair use of photos may differ from guidelines for music, videos, or written works.

@The amount of the copyrighted work that is used. Quoting a para graph from a book is more likely to be fair use than reproducing an entire chapter.

O^he effect on the value of the copyrighted work. Uses that deprive the copyright holder of income are not generally considered fair use.

> Is a transformative work different from a derivative work?

Yes. A derivative work modifies a copyrighted work but does not substan tially change its content or purpose. Translations, adaptations, musical arrangements, dramatizations, reproductions, condensations, and similar modifications would all be considered derivative.

Mashups that combine two or more music tracks into a single recording are usually regarded as derivative works because they are intended for the same uses as the original recordings. Derivative works are not fair use. and they require permission directly from the copyright holder or from an appli

QUICKCHECK Suppose thai you creulc a YouTube video and add a music track from a recent hit film.

Would your work be considered

cable license, such as CC BY.

transformative?

A transformative work repackages a copyrighted work to add new mean ing or produce a work that is used for a purpose different from the original work. Parodies, for example, are considered transformative. Cutting up magazine covers to create a collage to hang on a wall would also be con sidered a transformative use.

Transformative works are considered fair use; they can be produced and distributed without the copyright holder's permission. Although the differences between derivative and transformative works may seem clear, in practice copyright holders are free to sue anyone who pro duces a work that is based on their copyrighted works. The courts are the

a. Yes, I've created a new, original work.

b. Yes, the copyrighted sound track is just part of the new work.

c. No, I'm not going to make any money from It. d. No, the sound track is used

in my work for the same

ultimate decision makers in copyright infringement cases. If you want to

purpose as in the original

safely incorporate the works of others into your own work, use only works

work.

that have a 00 BY or 000 license.

SECTION B

QUICKQUIZ 1.

A media element goes

pany I

is accessed by millions of people around the

from misuse by law. 5.

Content communities form around usercontent.

3.

The Twitter bird logo is an example of a com

when it quickly infiltrates popular culture and globe. 2.

4.

Dublin Core is an example of a formal standard.

j that is protected

A Creative Commons license designated as CC BY derivative works.

does not allow

334

SECTION C, MODUIE 5

Twitter

Text-based Content Communities

Wikipedia

SECTION

BLOGS AND MORE

BLOGS, TWEETS. AND WIKIS.ihe

Terminoiogy

major text-based content communities offer up a mountain of content. Some of it is accurate and

blog RSS reader blog aggregator

dependable: some of it is downright false.Yet more

blogosphere tweetS microblogging service

of it is misleading in subtle ways. In this section,

@username retweet promoted tweet

you'll explore the origins of this text-based content and how to cull the good from the bad.

Twitter stream/timeline follow follower

follow back ri'mention#hashtag DM trending wlkl NPOV NOR V

Objectives > Identify the six major eiements of a blog page.

t identify the major elements of alwitter page.

I Describe the purpose of RSS readers and blog

I Describe the characteristics of a wiki.

aggregators.

I Discuss why blogs are considered a disruptive technology.

I Explain how Wikipedia articles are written and edited.

I Explain the meaning of NPOV, NOR,andV in the context ofWikipedla.

I List five questions that help to evaluate the quality of information presented in a blog.

> Identify the eiements of a Wikipedia article.

i Give examples of six ways in whichTwitter

I Identify the purpose of each Wikipedia tab.

has expanded its focus to go beyond personal status updates.

335

SOCIAL MEDIA

BLOGS The democratization of culture is not limited to art: it spills over into the mainstream news media. Today, blogs provide alternative news sources

that offer a greater diversity of topics and opinions than pre-lnternet gatekeepers such as Reuters, Associated Press, and CNN. The ease of broadcasting information has become a major disruptive force with no clear

i

outcome in sight.

► What is a blog? A blog (short for Web log) is a sequence of infor mational articles posted in reverse chronological order and displayed on a scrollable Web page. Blogs are generally maintained by a person, a com pany, or an organization. Blog entries are text based, but can also include graphics and video.

i What are the basic elements of a blog? Whether you are creating your own blog or browsing blogs created by others, you should be aware

that blogs are based on a standard set of elements illustrated in Figure 5-21.

FIGURE S-21:ANAT0MY OF A BLOG Main content area with

posts listed in reverse chronological order

r W

n;^4'dsAFLL'-\

- i-

'o -

r/i,

SKATEBOARD MARQUETTE Vi1»kAetir?M«rQtjeu«.Ukch^4n hav i rocking »k2t*bfl^ fadliry complete

vmh helf pipe. So ukt a brcek Irpm thoic ncfcecy nfings and parting M cvrtn. H«ul LiPnerth to Michigen't (J.P. (thet't Upper PeniniuU) for a Quick

ikate Ctefore nHnter sets fn. Check in with (he locel commurtitv kt TMrd Street Bagel end connect with the bike erewe who meet ecroes the street.

RECENT POSTS Sketeboerd livQueae Bllie Jckyll IsUnd

More on thet In e later post. Foitecl in Uncaiegorizeij 01 Octot>f-r 1

Comments from readers

RECENT COMMENTS frrti Mrehmeeernlth on Skjceboerd

Mvqweoe

BIKEJEKYLL ISLAND Street bikee et tne Jekyti t$Und Club hevt ihet histork vibe. Perfect for loohng Mst eMndoned ninstont liuih tri the

Kortof. Hou«. once occopiri b, Mejol Archive of older articles operated Georgia's firti brewery. On the eastern side of the island, you can park your bike, peel down to your swimsuit. and scoot over pristine sand to

ARCHIVES SaMOMpw n

QUICKCHECK

lake a swim. As the sun sets, settle into a rocker on the club house veranda

and sfp a cool drink, Southern style. '

I . • 7 7 , ■ Links to related sites

Posted in UnciTegorired 00 07ti)tKir

. iJit

BLOGROLL Discuss

Cat Inspired

a. By making a comment

A way to set up a feed

to automatically send new posts to readers

If you subscribe to WordPress, how would you add the Boards & Bikes blog to your list?

. QitSS- Pesu

b. By subscribing to the archive c. By joining the blogroll

A way to add the blog to the reader's list of

favorite blogs

d. By selecting the Following button

SECTION C, MODUIE 5

336

I Is it easy to become a blogger? Popular blogging platforms Include Blogger, WordPress, and Medium. A blogging platform provides tools for creating blogs. It may also provide a Web site where blogs can be posted for access by the public. Bloggers may post to a subdomain, such as htips://medium.com/@sarah, offered by the blogging platform. Bloggers who want a dedicated domain name, such as www.edisonJones.com, can use a Web hosting service, such as HostGator or GoDaddy. These hosting services offer blogging plugIns for authoring and managing blog posts.

TRY IT!

How would you discover n" liiere are any skateboarding blogs on WordPress?

> How can I find and access blogs? You can find blogs by going to Blogger, WordPress, and Medium or by simply launching a Google search such as Skateboard Blogs. You can use an RSS reader or blog aggrega tor to set up a "feed" that monitors your favorite blogs, collects the latest

posts, and displays them. Another option is to use a blog catalog, such as Alltop (Figure 5-22), to view a list of current blogs arranged by topic. FIGURE S-22; BLOG CATALOGS

Terminology «e • «

HecefHTrViftiv*

Wruw#

r

• ■eMUMiM

. y wemWew. Toch«•■•*? !•■*)■

•«*«* (I

hMMu (M am kav • »i#

M *■*•« TMMNr UtT WW

tanrtiartrM'ri'ill IUHl Tim '

SkmnaUcAM H«M tonCKM««FVCCT*M»i.^ Classify communications technologies as

synchronous,asynchronous, public, or private. > List the pros and cons of Webmail and local mail.

t Explain how the term store-and-forward relates to email.

> Differentiate between IMAP and PGR

ft List four steps that help to reduce the security risk of accessing email on a public computer.

ft Explain the circumstances under which a

person might want to forward email between a Webmail account and a local account.

ft Describe the evolution of online chat.

ft List four services that use VoIP technologies. ft Explain the controversy pertaining to Snapchat and its significance for using social media services.

345

SOCIAl. MEDIA

COMMUNICATION MATRIX The Internet offers many tools for communicating and collaborating; more are appearing every day. These tools can be classifled into a four-cell matrix as shown in Figure 5-29. FIGURE 5-29: COMrdlUNtCATION MATRIX

PUBLIC ASYNCHRONOUS

PUBLIC SYNCHRONOUS

Blogs

Chat rooms

Microfalogs(Twitter)

live streaming video

Forums and discussion groups Public social media posts

PRIVATE ASYNCHRONOUS

PRIVATE SYNCHRONOUS

Email

Voice over tP(Skype)

Text messaging service(SMS)

Videoconferencing(WebEx)

Multimedia messaging service(MMS)

Instant messaging(ICQ, AIM)

Private social media posts Snapchat

I How are synchronous and asynchronous communications different? Think about email and Skype. You use them differently because one is synchronous and the other is asynchronous. Synchronous. When communication is synchronous, interchanges hap pen in real time while all parties are online. Synchronous communications have the advantage of immediacy. They can convey your thoughts as you speak and events as they happen. Telephone calls are synchronous, as are video conferences and live streaming video. Asynchronous. When communication is asynchronous, messages are held until the recipient is ready to view them. Asynchronous communication offers convenience because information can be gathered whenever you want it. That information can, however, be out of date by the time you obtain it. Email is an example of asynchronous communication.

I What is significant about public or private communications? There are times when you want to communicate with certain people, and there are times when you want to reach a wider audience. Networks offer opportunities for both public and private communications. Public. Public communications can be accessed by individuals unknown to the person who created a message. The word posting is associated with this type of communication because it is similar to posting a billboard, sign, or poster. Public communication platforms, such as Twitter and blogs, are useful for disseminating information to a wide audience. Private. Communications for which you specify one or more recipients would be classified as private. Text messaging is a popular type of private communication. A limited audience can be an advantage or a disadvantage, depending on what you hope to accomplish with your message. Be aware, however, that private messages can be forwarded by recipients, so they do not necessarily remain private.

QUICKCHECK Email is an example of communication. a. synchronous

b. asynchronous c. mediated

d. public

345

SECTION D, MODULE 5

EMAIL

An estimated 225 billion email messages speed over the Internet each day. You can access email using Webmall or local mail, or both. Which system you use has implications for your security and prlvacy.

QUICKCHECK The message header In Figure

► Exactly what is email? The term email can refer to a single message or to the entire system of computers and software that transmits, receives, and stores email messages. An email message Is an electronic document transmitted over a computer network.

5-30 indicates that the message originated . a. from a Yahoo! account b. from a Facebook user

The computers and software that provide email services form an email sys

c. from a Gmail account

tem. At the heart of a typical email system Is an email server—a computer

d. from a POP mail server

that essentially acts as a central post office for a group of people. Email serv ers run special email server software, which provides an electronic mailbox for each person, sorts Incoming messages Into these mailboxes, and routes outgoing mail over the Internet to other email servers. Email messages have a standard format that consists of a message header and the message body. The message header contains the sender and recipient addresses, date, and subject line. When you view an email mes sage. this information is a simplified version of a more complex header that contains a huge amount of routing information, which traces the path of the message and reveals how It was treated by various servers. If you want to know exactly where a message originated or why a message was retumed

TRY IT!

Open one of your own email messages and take a look at

the header. Can you locate any Information indicating security checks on the sender?

to sender, check the header (Figure 5-30). FIGURE 5-30; EMAIL MESSAGE HEADERS

When using Gmail. click the More button and

then select Show original.

M Original Messaga

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23 OCC 2017 07:47:57 -0700

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origin of the message and its route.

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Return-Path: Olexdelamaraggmail.com> caggraail.con Received-SPF: pass (google.com: doinain of alexdel designates 10.140.92.146 as permitted sender) cliencip=10.140.92.146 Authentication-Results: mr.google.com;

3p£=pass (google.com: domain of alexdelaniara0gmail.com designates 10.140.92.146 as permitted sender)

smtp.mail=alexdelamara6gmail.coim

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make sure this sender's domain was not on a blocked list.

DKIM-Signature: v=l; a=rsaTsnajbb,' d=gmail.com; 3=20120113; h=mime-version: date: message-id: subject: from: to: con tersetype;

bh=uyOUOA3NoaR3qirnKIfiG+Hjg36inLoJcrarx2qQZP)tXQ=;

I

347

SOCIAL MEDIA

I How does Webmail work? Webmail is typically a free service

TRY III

accessed using a browser. In a classic Webmail configuration, incoming messages are stored in an Inbox on the Web. When you want to read or

send mail, use a browser to go to your email provider's Web site and log in. The controls for reading, composing, and managing messages are all

presented in the browser window. While reading and composing mail, you

An email address is frequently

used to verify your identity when subscribing to social media services. But that email

address may easily fall into

generally must remain online (Figure 5-31).

the hands of marketers. You

can use a "junk" email address FIGURE 5-31:WEBIVIAIL

or work with a service such A Web-based server han

Messages held in your Inbox on the

a temporary email address

the tools you need to

that lasts only long enough to

compose and read maii.

subscribe to a service, receive the confirmation email, and

Webmail server

click the verification link. Check it out!

Webmail server

can be displayed in

the Internet

your browser. Your computer runs a browser

while connected to the Internet.

> What are the pros and cons of Webmail? Webmail accounts are handy. They offer several advantages, but they also have a few disadvan tages that require consumer awareness. Affordable. Most Webmail is free. In addition to your primary account, you can establish additional accounts to use as throwaways for online activities that require registration, but that you don't intend to continue using. Access from any device. Webmail can be accessed from any device that has a browser. With smartphones and tablets, as well as laptops and desktops, simply open a browser and log in to your Webmail account. Access anywhere. Webmail is ideal for people who travel, because mes sages can be accessed from any computer connected to the Internet. Security risks. Your email messages are stored on Web servers that can be targets for hackers and are monitored by government agencies. Accessing email from a public computer is handy when traveling, but it can be a security risk. To reduce the risk, you should: • Reboot the computer before logging in to your email account. • Avoid entering sensitive information, such as your credit card number, in case your keystrokes are being monitored by malicious software lurking on the public computer. • Be sure to log off when your session is finished. • Log out and shut down the computer.

Advertising. Free Webmail is supported by advertising, so expect to see advertisements. Today's sophisticated ad servers can search the contents

of an incoming message looking for keywords and then use them to display targeted ads in your browser window.

as 10 Minute Mail to obtain

dles mail and provides

348

SECTION D, MODULE 5

I How does local email work? When you use local email, an Internet-based email server stores your incoming messages until you launch your email client and get your mail. Messages are then down loaded to a folder on a local storage device that serves as your email Inbox. This telecommunications technique is sometimes referred to as

TRY IT! Do you customarily use

Webmall or do you use a local email client?

store-and-forward.

Using your email client, you can read your mall at your leisure. You can also compose new mail and reply to messages. This outgoing mail can be tem porarily stored In an Outbox or it can be sent immediately. The protocols POPS (Post Office Protocol version 3)and 1IVIAP (Internet Message Access Protocol) can be used to manage your incoming mail. P0P3 deletes messages from the server after they are downloaded, whereas IMAP leaves messages on the server until you specifically delete them. SMTP (Simple Mall Transfer Protocol) handles outgoing mail. Keep these protocols In mind when setting up local email, because the server you specify for outgoing mall might be different from the server for Incoming mail (Figure 5-32). FIGURE 5-32; LOCAL EMAIL

From the To the Internet

P0P3 server

Internet

SMTP server

Incoming mail

Outeoing mail

Outbox

Inbox

Your computer

I What are the advantages of local email? Local email has the fol lowing advantages: Offline access. Because local email stores your Inbox and Outbox on your computer, you can compose and read mail offline. You are required to go online only to transfer outgoing mail from your Outbox to the email server, and to receive incoming messages. This feature is useful if you have

QUICKCHECK Which server handles outgoing mail? a. POP

a dial-up connection or sporadic Internet access. b, IMAP

Control. When you use P0P3 to collect your mail, your messages are transferred to your computer's hard disk, where you can control who has access to them. With this control, however, comes the responsibility for maintaining backups of your important email messages.

c. SMTP

d, LOCAL

349

SOCIAL MEDIA

► How do I set up local email? To set up local email, the first step is selecting a local email client. Macs include an email client called Mail. Microsoft Outlook is one of the most popular email clients for Windows. After installing an email client, you can configure it for the email service you're using. Your email provider can supply the information needed for this task. That information can include the following:

QUICKCHECK

• Your email user ID, which is the first part of your email address (e.g., in AlexHamilton@gsu-edu, the user ID Is AlexHamilton)

What happens on the server

• Your email password, if required to access the email server

when mail is downloaded for the

• An address for the outgoing (SMTP) server, such as mail.viserver.net or smtp.charter.com

account in Figure 5-33? a. The messages In Sarah's

• An address for the incoming (POPS or IMAP) server, such as mail.gsu.edu or pop.media.net

Inbox are deleted.

b. Sarah's outgoing mail is

• Port numbers for incoming and outgoing servers, which are usually Port 110 (incoming) and Port 25 or 587 (outgoing)

blocked.

c. The messages are forwarded

• Whether the connection uses SSL security

to an online account.

Figure 5-33 displays basic information needed to set up a local email

d. The messages remain on the

account.

server.

FIGURE 5-33: HOW TO SET UP LOCAL MAIL

Email Address:, sarahmae®medla.net User Name; SarahMae Password;

Account Type; . Incoming Mail Server mail.media.net

Outgoing Mall Server, smtp.media.net

The incoming server might have pop or mail as part of its name.

The outgoing server might have smtp as part of its name.

Cancel

I What about email apps for mobile devices? Webmail and local email services, such as Gmail, Apple Mail, Windows Mall, and Microsoft Outlook, are available as mobile apps. Downloading an email app to a mobile device places the necessary client software on your smartphone or Cablet.

When an email app opens, it collects the most recent messages from your Inbox on the email server. These messages are temporarily copied to your

device so that you can read them. The original copy of the message is retained on the email server.

When you delete messages and mark them as read while using a mobile app, IMAP protocols generally perform the same actions on the email server. Deleting a message using a mobile app deletes the message from the server. Some email apps provide menu options for customizing this syn chronization. Be sure to understand the synchronization settings for your mobile app, so you don't mistakenly delete messages you might later want to access.

350

SECTION D, MODULE 5

I Can I use both local email and Webmail? Yes. You can mix and

match Webmail and local mail in various ways. Use local email software to access messages sent to your Webmail

account. This approach is useful If you want to compose mail offline or if you prefer the Interface of a local email client such as Outlook compared to the Interface offered by Webmail services, such as Gmall. Using Gmall as an example, once you've created a Gmall account, you can access Settings to enable POP mall and then forward your mail to your local client (Figure 5-34). FIGURE 5-34: HOW TO FORWARD MAIL FROM GMAIL TO A LOCAL CLIENT

Settings

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