students with teachers, and family with friends computer how to perform a task. Some people and other family members call the series of input, process, output, and Through computers, people have instant storage activities the information processing cycle. o access to information from around the world Most computers today can communicate with Local and national news, weather reports, sports other computers, As a result, communications scores, airline schedules, job listings, and also has become a very important part of the countless forms of educational material are information processing cycle always available In the workplace, employees use computers to create letters and calculate payroll, and weather <\THE COMPONENTS OFA forecasters use computers to predict weather COMPUTER Patterns. Teachers use computers to prepare for and help with classroom teaching, and A computer contains many electric, electronic, students finish homework and do research on and mechanical components known as computers in lab rooms and at home hardware. These components include input People also spend hours of free time on the devices, output devices, a system unit, storage computer. They play games, listen to music, devices, and communications devices. Figure create music, watch movies, read books or 1-1 shows some common computer hardware magazines, make videos, edit photos, or plan components vacations As technology continues to advance, Input Devices computers are becoming more a part of dail An input device is any hardware component that life. Therefore, many people believe that allows you to enter data or instructions into a computer literacy is key to success. Computer computer. Six widely used input devices are the literacy means having the know ledge and keyboard, mouse, microphone, scanner, digital understanding of computers and their uses. camera, and PC video camera( Figure 1-1) This book presents the knowledge you need to A computer keyboard contains keys you press be computer literate. As you read this first to enter data into the computer. A mouse is a chapter, remember it is an overview. Many of small handheld device. With the mouse, you the terms and concepts introduced in this control movement of a small symbol on the chapter will be discussed in more detail later in screen, called the pointer, and you can select the book things on the screen. A microphone allows people to speak into the computer to enter data and instructions. A WHAT IS A COMPUTER? scanner changes printed material (such as words and pictures)into something that the computer A computer is an electronic device, operating under the control of instructions stored in its can use. For example, you can scan a picture and own memory, that can accept data, manipulate then put the picture in invitations you create on the computer the data according to certain rules, produce results, and store the results for future use. a With a digital camera, you take pictures and then transfer the pictures to the computer or printer instead of storing the pictures on Data and Information traditional film. a PC video camera is a digital Data is a collection of items that have not ye video camera that allows you to create a movie been processed. Data can include text, numbers, or take photos electronically With the PC video pictures, audio, and video Information camera attached to the computer, you can make communicates meaning, i.e. is useful to people a video telephone call -a call that lets you and For example, when data such as class names the one you call see each other when you talk student names, and class grades are arranged into a grade report, a student has information Output Devices An output device is any hardware component Information Processing cycle that conveys information to one or more people Computers process input(data)into output Three commonly used output devices are a (information), A computer often holds data. printer, a monitor, and speakers(Figure 1-1). information, and instructions in storage for future A printer produces text and graphics on paper use Instructions are the steps that tell the or other material. A monitor displays text
graphics, and videos on a screen. Many a floppy disk and remove it from a floppy disk monitors look similar to a television. Speakers drive( Figure 1-2). A Zip disk looks similar to a allow you to hear music, voice, and other audio floppy disk but can store much more-aImost sounds 170 times as much as a floppy disk. Zip disks are inserted into and removed from Zip drives. System Unit A hard disk can store even more than a floppy The system unit is a box-like case that contains disk or Zip disk. Although some hard disks can electronic components of the computer. The be easily removed, most hard disks are usually circuitry of the system unit usually is part of or in a closed, airtight case inside the system unit is connected to a circuit board called the A compact disc is a flat, round, metal disc. One motherboard. kind of compact disc is a CD-ROM, which can ce two main components on the motherboard are be used in most CD and DVD drives. Another the processor and the memory. The processor is is kind of compact disc is a DVD-ROM, which can the electronic component that interprets and store a large amount of data-as much as a carries out the basic instructions that operate the movie. To use a DVD-ROM, you need a DVD computer. Memory consists of electronic drive( Figure 1-3) components that store instructions waiting to be executed and data needed by those instructions Most memory keeps data and instructions temporarily, although some kinds of memor are permanent I Storage Devices Storage holds data, instructions, and information for future use. For example, computers can store hundreds or millions of customer names and addresses, Storage holds these items permanently A computer keeps data, instructions, and FIGURE 1-3 To use a DVD-ROM, you need a DVD dr Some hand-held devices, such as digital cameras, use memory cards or other types of very small storage media. You then can use a card reader( Figure 1-1)to move stored things, such as the digital photographs, from the FIGURE 1-2 A floppy disk is inserted in and memory card to a computer or printer. removed from a floppy disk drive Communications Devices information on storage media. Examples of A communications device is a hardware storage m edia are floppy disks, Zip"disks, hard component that enables a computer to send disks, CDs, DVDs, and memory cards. A storage ( transmit)and receive data, instructions, and device writes and /or reads items to and from information to and from one or more computers storage media. Drives and readers are types of A widely used communications device is the torage devices, They accept only a certain kind modem( Figure 1-1) of storage media. For example, a CD drive Communications occur over cables, telephone (storage device)accepts a CD (storage media) lines, mobile phone networks, satellites, or other A floppy disk consists of a thin, round, flexible kinds of media. Some, such as satellites and disk in a square-shaped plastic shell. You insert mobile phone networks, are wireless, which
means they have no real lines or wires, Pe Many computers store huge amounts of data to around the world communicate with each other use for processing whenever it is needed using these kinds of media Most computers today can communicate with WHY IS A COMPUTER other computers. Computers with this ability SO POWERFUL? can share any of the four information processing Computers are powerful for many reasons cycle operations-input, process, output, and They perform the information processing cycle storage- with another computer. For example, two computers connected by a communications operations(input, process, output, and storage) with amazing speed, reliability, consistency, device such as a modem, can share stored data instructions, and information These two ts of data and information. also computers can be in the same room or computers allow users to communicate with thousands of kilometers away from each other other users or computers. A user is anyone who in two different countries communicates with a computer or makes use of ts information 5, 7NETWORKS AND THE INTERNET ■peed A network is a group of computers and devices In the system unit, operations go through connected together by communications devices electronic circuits, When data, instructions, and and transmission media Networks allow information flow along these circuits, they travel computers to share resources, such as hardware, at amazingly fast speeds. Most computers carry software, data, and information Sharing out billions of operations in a single second. The resources saves time and money. For example, worlds fastest computer can perform trillions of instead of buying one printer for every operations in one second computer in a school, you can connect all computers to one printer by using a network I Reliability and Consistedmnodere'S This enables all connected computers to use the The electronic components in same printer. computers are dependable because their In many networks, one or more computers act of failure is very low. The high reliability as a server. The server controls access to a components make it possible for the computer networks resources. The other computers on the to produce the same results over and over network are called clients. They request ayaIn resources from the server(Figure 1-4). The main clie Computers process lar amounts of data and produce error-free results if the data is input correctly and th instructions work properly. If data is not correct, the results will not be correct. A phrase often used in the computer world, known as garbage in, garbage out, points out that the correct output depends on whether the input is correct. Storage With todays storage devices server the computer can transfer data quickly from storage to FIGURE 1-4 A server manages the resources on a network and chents access memory, process it, and then the resources on the server. This network enables three separate computers store it again for future use. to share the same printer
5 differences between the server and client related discussion) computers are that the server usually has more power, more storage space, and is more reliable. B: ISSUE 1-1 lany homes and most businesses and schools network their computers together. Home Is Everything You Read True? networks usually are small Business and school It is against the law for citizens to contact space aliens networks can be small or quite large. A network can connect computers in a school laboratory, an An ingredient in many popular shampoos has been proven to cause cancer. Chicken feet were discovered in office building, a group of buildings, or across a the meal of a national fast food chain. None of these city, country, or the world. The worlds largest statements is true, but each has appeared on a world network is the Internet Wide Web page. In today s society. many people think that anything in print is true. Yet, authors with a wide range of expertise, authority, and biases create web The Internet pages Web pages can be as accurate as the most The Internet is a worldwide collection of scholarty journal, or no truer than the most disreputable networks that connects millions of businesses supermarket tabloid, The Web makes it easy to obtain governments, schools, and individuals information, but Web page readers must make an extra People use the Internet every day for many effort to determine the quality of that information. In reasons, such as: ing a Web page, experts suggest that yo Communicate with and meet other people consider such factors as the purpose, scope, sponsor. around the world page. Ultimately, who is responsible for the accuracy of Access a wealth of information news, and information on the Web? Why? What factors are most research important in evaluating the accuracy of a Web page? Shop for products and services why? Bank and invest · Take a class Access sources for fun and relaxation, such as online games, music, videos, books, and COMPUTER SOFTWARE The Web. short for World Wide Web, is one of Software, also called a program, is a series of the more popular services of the Internet. Think instructions that tells the computer what to do of the Web as a world-wide library of and how to do it. a program exists on storage information that is available to anyone media such as a floppy disk or compact disc connected to the Internet. The Web has billions Installing is the process of setting up the of documents called Web pages. A Web page can software to work with the computer, printer, and contain text, graphics, audio, and video other hardware components. To begin installing 4 Web pages often have built-in connections, or the software from a cD or DVD, a user inserts nks, to other documents, graphics, other Web the program disc into a CD or dvd drive. The pages, or Web sites. A Web site is a group of computer then copies all or part of the program related Web pages. from the disc to the computers hard disk. After People also connect to the Internet to exchange the software is installed, you can use it information with others around the world. e- Software is the key to productive use of mail allows you to send messages to other users. computers. A computer can be a valuable tool With instant messaging, you can have a live with right software. The two kinds of software conversation with another user who is online. In are system software and application software a chat room, you can communicate with The following sections describe these kinds of different users at the same time- similar to a software group discussion. Some Web sites offer online 2 FAQ 1-1 calendars and address books so you can share information with each other Which spelling is correct, disk or dise? In addition to accessing and using information Both are correct, depending on usage. when on the Web, many people use the Web to share referring to CD, DVD, and other optical (laser) personal information, Photographs, videos, or storage, computer professionals typically use artwork with the world. Anyone can create a the term disc. Floppy disks, Zipdisks, hard Web page and then make it available on the disks, and other nonoptical storage media Internet for others to see(read Issue 1-1 for a normally use the term disk
System Software Many of todays computers use one of System software consists of all the programs Microsoft's operating systems, such as that control or maintain the operations of the Windows XP(Figure 1-5) computer and its devices System softwar When a user starts a computer, parts of the serves as the interface between the user, the operating system load into memory from the application software, and the computer's computer's hard disk. It stays in memory while hardware the computer is on The operating system Two kinds of system software are the provides a way for users to communicate with operating system and utility programs. the computer and other software. OPERATING SYSTEM An operating system is UTILITY PROGRAMS A utility program a set of programs that coordinates all the allows a user to perform operations usually activities among computer hardware devices. related to managing a computer, its devices,or The operating system also contains instructions its programs. For example, one kind of utility that allow users to run application software program can examine a floppy disk or hard disk icons Sc Series e图闸●v ( wi weet s FIGURE 1-5 The graphical user intertace of windows XP. to find if it has any physical problems such as a and look at Web pages. Other popular scratch. Most operating systems have severa application software includes word processing utility programs for managing disk drives, software, spreadsheet software, database printers, and other devices. You can also buy software, and presentation graphics software. utility programs, which allow you to to manage Word processing software allows users to the computer in other ways create documents like letters, memos, and brochures. Spreadsheet software calculates Application Software numbers arranged in rows and columns and Application software consists of programs display data in different ways. Wil,and abase allows users to perform financial tasks. Dat that perform specific tasks for users. A widely software provides a way to store, us used type of application software related to communications is a Web browser, which allows presentation graphics software, users create users who are connected to the Internet to access visual aids for a presentation