Computer Fundamentals
- 1. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 1 Overview: Computers in Our World Computers are everywhere. In fact, you can find them in some preny unlikely places, including your family car, your home appliances, and even your alarm clock! In the past two decades, computers have reshaped our lives at home, work, and school. The vast majority of businesses now use computerized equipment in some way, and most companies’ arc networked both internally and externally. More than half of all homes in the United States have at least one computer, and most of them are connected to the Internet. Workers who once had little use for technology now interact with computers almost every minute of the workday. This lesson examines the many types of computers that arc in common use today. Although this class will focus on personal computers, you will first learn about the wide variety of computers that people use, and the reasons they use them. As your knowledge of computers grows, you will understand that all computers—regardless of their size or purpose—arc basically similar. That is, they all operate on the same fundamental principles, are made from the same basic components, and need instructions to make them run. The Computer Defined In basic terms, a computer is an electronic device that processes data, converting it into information that is useful to people. Any computer—regardless of its type—is controlled by programmed instructions, which give the machine a purpose and tell it what to do. Which are everywhere around you— arc digital computers (see Figure 1A.1). “Processing Data," digital computers are so called because they work “by the numbers." That is, they break all types of information into tiny units, and use numbers to represent those pieces of information. Digital computers also work in very strict sequences of steps, processing each unit of information individually, according to the highly organized instructions they must follow. A lesser-known type of computer is the analog computer which works in a very different way from digital computers. The earliest computers were analog systems, and today's digital systems owe a great deal to their analog ancestors. Analog and digital computers differ in many respects, but the most important distinction is the way they represent data. Digital systems represent data as having one distinct value or another; with no other possibilities. Analog systems, however represent data as variable points along a continuous spectrum of values. This makes analog computers somewhat more flexible than digital ones, but not necessarily more precise or reliable. Early analog computers were mechanical devices, weighing several tons and using motors and gears to perform calculations (see Figure 1 A.2). A more manageable type of analog computer is the old-fashioned slide rule (see Figure 1A3). Computers can be categorized in several ways. For example, some computers are designed for use by one person, some arc meant to be used by groups of people, and some are not used by people at all. They also can be categorized by their power, which means the speed at which they operate and the types of tasks they can handle. Within a single category, computers may be
- 2. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 2 subcategorized by price, the types of hardware they contain, the kinds of software they can run, and so on. Computers for Individual Users Most computers are meant to be used by only one person at a time. Such computers are often shared by several people (such as those in your school’s computer lab), but only one user can work with the machine at any given moment (sec Figure 1 A.4). The six primary types of computers in this category arc ≫ Desktop computers ≫ Workstations ≫ Notebook computers ≫ Tablet computers ≫ Handheld computers ≫ Smart phones These systems are all examples of personal computers (PCs) a term that refers to any computer system that is designed for use by a single person. Personal computers arc also called Microcomputer because they are among the smallest computers created for people to use. Note, however, that the term personal computer or PC is most often used to describe desktop computers, which you will learn about in the following section. Although personal computers are used by individuals, they also can be connected together to create networks. In fact, networking has become one of the most important jobs of personal computers, and even tiny handheld computers can now be connected to networks. You will learn about computer networks in Chapter 7, “Networks." Desktop Computers The most common type of personal computer is the desktop computer—a PC that is designed to sit on (or under) a desk or table. These are the systems you sec all around you, in schools, homes, and offices, and they are the main focus of this book. Today's desktop computers are far more powerful than those of just a few years ago, and are used for an amazing array of tasks. Not only do these machines enable people to do their jobs with greater ease and efficiency, but they can be used to communicate, produce music, edit photographs and videos, play sophisticated games, and much more. Used by everyone from preschoolers to nuclear physicists, desktop computers arc indispensable for learning, work, and play. As its name implies, a desktop computer is a full-size computer that is too big to be carried around. The main component of a desktop PC is the system unit, which is the case that houses the computer’s critical parts, such as its processing and storage devices. There are two common designs for desktop computers. The more traditional desktop model features a horizontally oriented system unit, which usually lies flat on the top of the user’s desk. Many users place their monitor on top of the system unit. Vertically oriented tower models have become the more popular style of desktop system. This design allows the user to place the system unit next to or under the desk, if desired. Workstations
- 3. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 3 A workstation is a specialized, single-user computer that typically has more power and features than a standard desktop PC. These machines are popular among scientists, engineers, and animators who need a system with greater-than-average speed and the power to perform sophisticated tasks. Workstations often have large, high-resolution monitors and accelerated graphics handling capabilities, making them suitable for advanced architectural or engineering design, modeling, animation, and video editing. Notebook Computers Notebook computers, as their name implies, approximate the shape of an 8.5-by-ll-inch notebook and easily fit inside a briefcase. Because people frequently set these devices on their lap, they are also called laptop computers. Notebook computers can operate on alternating current or special batteries. These amazing devices generally weigh less than eight pounds, and some even weigh less than three pounds! During use, the computer’s lid is raised to reveal a thin monitor and a keyboard. When not in use, the device folds up for easy storage. Notebooks arc fully functional microcomputers; the people who use them need the power of a full-size desktop computer wherever they go (see Figure I A.10). Because of their portability, notebook PCs fall into a category of devices called mobile computers—systems small enough to be carried by their user. Some notebook systems are designed to be plugged into a docking station, which may include a large monitor, a full-size keyboard and mouse, or other devices. Docking stations also provide additional ports that enable the notebook computer to be connected to different devices or a network in the same manner as a desktop system. Tablet PCs The tablet PC is the newest development in portable, full-featured computers. Tablet PCs offer all the functionality of a notebook PC, but they are lighter and can accept input from a special pen—called a stylus or a digital pen—that is used to tap or write directly on the screen. Many tablet PCs also have a built-in microphone and special software that accepts input from the user's voice. A few models even have a fold-out keyboard, so they can be transformed into a standard notebook PC. Tablet PCs run specialized versions of standard programs and can be connected to a network. Some models also can be connected to a keyboard and a full-size monitor. Handheld PCs Handheld personal computers are computing devices small enough to fit in your hand. A popular type of handheld computer is the personal digital assistant (PDA). A PDA is no larger than a small appointment book and is normally used for special applications, such as taking notes, displaying telephone numbers and addresses, and keeping track of dates or agendas. Many PDAs can be connected to larger computers to exchange data. Most PDAs come with a pen that lets the user write on the screen. Some handheld computers feature tiny built-in keyboards or microphones that allow voice input. Many PDAs let the user access the Internet through a wireless connection, and several models offer features such as cellular telephones, cameras, music players, and global positioning systems. Smart Phones Some cellular phones double as miniature PCs. Because these phones offer advanced features not typically found in cellular phones, they are sometimes called smart phones. These features can include Web and c-mail access, special software such as personal organizers, or special hardware such as digital cameras or music players. Some models even break in half to reveal a miniature keyboard. Computers for Organizations
- 4. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 4 Some computers handle the needs of many users at the same time. These powerful systems are most often used by organizations, such as businesses or schools, and are commonly found at the heart of the organization’s network. Generally, each user interacts with the computer through his or her own device, freeing people from having to wait their turn at a single keyboard and monitor. The largest organizational computers support thousands of individual users at the same time, from thousands of miles away. While some of these large-scale systems are devoted to a special purpose, enabling users to perform only a few specific tasks, many organizational computers are general purpose systems that support a wide variety of tasks. Network Servers Today, most organizations’ networks are based on personal computers. Individual users have their own desktop computers, which are connected to one or more centralized computers, called network servers. A network server is usually a powerful personal computer with special software and equipment that enable it to function as the primary computer in the network. PC- based networks and servers offer companies a great deal of flexibility. For example, large organizations may have dozens or hundreds of individual servers working together at the heart of their network. When set up in such groups— sometimes called clusters or server farms—network servers may not even resemble standard PCs. For example, they may be mounted in large racks or reduced to small units called “blades," which can he slid in and out of a case. In these large networks, different groups of servers may have different purposes, such as supporting a certain set of users, handling printing tasks, enabling Internet communications, and so on. A PC-based server gives users flexibility to do different kinds of tasks. This is because PCs are general-purpose machines, designed to be used in many ways. For example, some users may rely on the server for e-mail access, some may use it to perform accounting tasks, and others may use it to perform word-processing or database management jobs. The server can support these processes, and many others, while storing information and programs for many people to use. Depending on how the network is set up, users may be able to access the server in multiple ways. of course, most users have a standard desktop PC on their desk that is permanently connected to the network. Mobile users, however, may be able to connect a notebook PC or a handheld device to the network by wireless means. When they are away from the office, users may be able to use the Internet as a means of connecting to the company’s network servers. Mainframe Computers Mainframe computers are used in large organizations such as insurance companies and banks, where many people frequently need to use the same data. In a traditional mainframe environment, each user accesses the mainframe’s resources through a device called a terminal. There are two kinds of terminals. A dumb terminal does not process or store data; it is simply an input/output (I/O) device that functions as a window into a computer located somewhere else. An intelligent terminal can perform some processing operations, but it usually does not have any storage. In some mainframe environments, however, workers can use a standard personal computer to access the mainframe. Mainframes are large, powerful systems. The largest mainframes can handle the processing needs of thousands of users at any given moment. But what these systems offer in power, they lack in flexibility. Most mainframe systems are designed to handle only a specific set of tasks. In your state's Department of Motor Vehicles, for example, a mainframe system is probably devoted to storing information about drivers, vehicles, and driver's licenses, but little or
- 5. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 5 nothing else. By limiting the number of tasks the system must perform, administrators preserve as much power as possible for required operations. Minicomputers First released in the 1960s, minicomputers got their name because of their small size compared to other computers of the day. The capabilities of a minicomputer are somewhere between those of mainframes and personal computers. For this reason, minicomputers are often called midrange computers. Like mainframes, minicomputers can handle much more input and output than personal computers can. Although some ‘‘minis’’ arc designed for a single user, the most powerful minicomputers can serve the input and output needs of hundreds of users at a time. Users can access a central minicomputer through a terminal or a standard PC. Supercomputers Supercomputers arc the most powerful computers made, and physically they are some of the largest. These systems can process huge amounts of data, and the fastest supercomputers can perform more than one trillion calculations per second. Some supercomputers can house thousands of processors. Supercomputers are ideal for handling large and highly complex problems that require extreme calculating power. For example, supercomputers have long been used in the mapping of the human genome, forecasting weather, and modeling complex processes like nuclear fission. Importance of Computer People can list countless reasons for the importance of computers. For someone with a disability, for example, a computer may offer freedom to communicate, learn, or work without leaving home. For a sales professional, a PC may mean the ability to communicate whenever necessary, to track leads, and to manage an ever-changing schedule. For a researcher, a computer may be the workhorse that docs painstaking and time-consuming calculations. But if you took all the benefits that people derive from computers, mixed them together, and distilled them down into a single element, what would you have? The answer is simple: information. Computers are important because information is so essential to our lives. And information is more than the stuff you see and hear on television. Facts in a textbook or an encyclopedia are information, bur only one kind. Mathematical formulas and their results arc information, too, as arc the plans for a building or the recipe for a cake. Pictures, songs, addresses, games, menus, shopping lists, resumes— the list goes on and on. All these things and many others can be thought of as information, and they can all be stored and processed by computers. (Actually, if you work in one place and need to perform various tasks, a desktop computer is the best choice. Choose a desktop computer if you want to » Work with Graphics-Intensive or Desktop Publishing Applications. Complex graphics and page-layout programs require a great deal of system resources, and a desktop system’s large monitor reduces eye fatigue. » Design or Use Multimedia Products. Even though many portable computers have multimedia features, you can get the most for your money with a desktop system. Large screens make multimedia programs easier to see, and stereo-style speakers optimize sound quality. » Set Up Complex Hardware Configurations. A desktop computer can support multiple peripherals—including printers, sound and video sources, and various external devices—at the same time. If you want to swap components, or perform other configuration tasks, a desktop system will provide many options.
- 6. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 6 Computers store these things as data, not as information, but you’ll learn the difference between the two later in the book.) So, when you consider the importance of computers in our society, think instead about the importance of information. As tools for working with information, and for creating new information, computers may be one of humanity's most important creations. Home In many American homes, the family computer is nearly as important as the refrigerator or the washing machine. People cannot imagine living without it. In fact, a growing number of families have multiple PCs in their homes; in most cases, at least one of those computers has an Internet connection. Why do home users need their computers? » Communications. Electronic mail (e-mail) continues to be the most popular use for home computers, because it allows family members to communicate with one another and to stay in contact with friends and coworkers. » Business Work Done at Home. Thanks to computers and Internet connections, more people are working from home than ever before. It is possible for many users to connect to their employer’s network from home and do work that could not be done during regular business hours. Computers also are making it easier for people to start their own home-based businesses. » Schoolwork. Today’s students are increasingly reliant on computers, and not just as a replacement for typewriters. The Internet is replacing printed books as a reference tool, and easy- to-use software makes it possible for even young users to create polished documents. » Entertainment. If you had ever played a computer game, you know how enjoyable they can be. For this reason, the computer has replaced the television as the entertainment medium of choice for many people. As computer; audio, video, and broadcast technologies converge, the computer will someday be an essential component of any home entertainment center. » Finances 'Computer’s and personal finance software can make balancing your checkbook an enjoyable experience. Well, almost. At any rate, they certainly make it easier, and home users rely on their PCs for bill paying, shopping, investing, and other financial chores. Education More and more schools are adding computer technology to their curricula, not only teaching pure computer skills, but incorporating those skills into other classes. Students may be required to use a drawing program, for example, to draw a plan of the Alamo for a history class, or use spreadsheet software to analyze voter turnouts during the last century’s presidential elections. Educators see computer technology as an essential learning requirement for all students, starting as early as preschool. Even now, basic computing skills such as keyboarding are being taught in elementary school classes. In the near future, high school graduates will enter college not only with a general diploma, but with a certification that proves their skills in some area of computing, such as networking or programming. Small Business Many of today’s successful small companies simply could not exist without computer technology. Each year, hundreds of thousands of individuals launch businesses based from their homes or in small-office locations. They rely on inexpensive computers and software not only to perform basic work functions, but to manage and grow their companies. These tools enable business owners to handle tasks—such as daily accounting chores, inventory management,
- 7. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 7 marketing, payroll, and many others—that once required the hiring of outside specialists. As a result, small businesses become more self-sufficient and reduce their operating expenses. Industry Today, enterprises use different kinds of computers in many combinations. A corporate headquarters may have a standard PC-based network, for example, but its production facilities may use computer controlled robotics to manufacture products. Here are just a few ways computers are applied to industry: » Design. Nearly any company that designs and makes products can use a computer-aided design or computer-aided manufacturing system in their creation. » Shipping. Freight companies need computers to manage the thousands of ships, planes, trains, and trucks that are moving goods at any given moment. In addition to tracking vehicle locations and contents, computers can manage maintenance, driver schedules, invoices and billing, and many other activities. » Process Control. Modem assembly lines can be massive, complex systems, and a breakdown at one point can cause chaos throughout a company. Sophisticated process-control systems can oversee output, check the speed at which a machine runs, manage conveyance systems, and look at parts inventories, with very little human interaction. Government Not only are government’s big consumers of technology, but they help to develop it as well. “Presenting the Internet," the U.S. government played a key role in developing the Internet. Similarly, NASA has been involved in the development of computer technologies of all sorts. Today, computers play a crucial part in nearly every government agency: » Population. The U.S. Census Bureau was one of the first organizations to use computer technology, recruiting mechanical computers known as “difference engines" to assist in tallying the American population in the early 20th century. »Taxes. Can you imagine trying to calculate Americans’ tax bills without the help of computers? Neither could the Internal Revenue Service. In fact, the IRS now encourages taxpayers to file their tax returns online, via the Internet. Military. Some of the world's most sophisticated computer technology has been developed primarily for use by the military. In fact, some of the earliest digital computers were created for such purposes as calculating the trajectory of missiles. Today, from payroll management to weapons control, the armed forces use the widest array of computer hardware and software imaginable. Police. When it comes to stocking their crime-fighting arsenals, many police forces consider computers to be just as important as guns and ammunition. Today’s police cruisers are equipped with laptop computers and wireless Internet connections that enable officers to search for information on criminals, crime scenes, procedures, and other kinds of information. Overview: Dissecting the Ultimate Machine Most people believe that computers must be extremely complicated devices, because they perform such amazing tasks. To an extent, this is true. As you will learn later in this book, the closer you look at a computer’s operation, the more complex the system becomes. But like any machine, a computer is a collection of parts, which are categorized according to the kinds of work they do. Although there are many, many variations on the parts themselves, there are only a few major categories. 1/ you learn about those families of computer components and their basic functions, you will have mastered some of the most important concepts in computing. As you will see, the concepts are simple and easy to understand. This lesson gives you a glimpse inside a
- 8. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 8 standard desktop computer and introduces you to its most important parts. You will learn how these components work together and allow you to interact with the system. You also will discover the importance of software, without which a computer could do nothing. Finally, you will see that the user is (in most cases, at least) an essential part of a complete computer system. Parts of a Computer System Computers come in many varieties, from the tiny computers built into household appliances, to the astounding supercomputers that have helped scientists map the human genome. But no matter how big it is or how it is used, every computer is part of a system. A complete computer system consists of four parts » Hardware » Software » Data » User Hardware The mechanical devices that make up the computer are called hardware. Hardware is any part of the computer you can touch. A computer’s hardware consists of interconnected electronic devices that you can use to control the computer’s operation, input, and output. (The generic term device refers to any piece of hardware.) Software Software is a set of instructions that makes the computer perform tasks. In other words, software tells the computer what to do. (The term program refers to any piece of software.) Some programs exist primarily for the computer's use to help it perform tasks and manage its own resources. Other types of programs exist for the user, enabling him or her to perform tasks such as creating documents. Thousands of different software programs are available for use on personal computers. Data Data consist of individual facts or pieces of information that by themselves may not make much sense to a person. A computer’s primary job is to process these tiny pieces of data in various ways, converting them into useful information. For example, if you saw the average highway mileages of six different cars, all the different pieces of data might not mean much to you. However; if someone created a chart from the data that visually compared and ranked the vehicles’ mileages, you could probably make sense of it at a glance. This is one example of data being processed into useful information. Users People are the computer operators, also known as users. It can be argued that some computer systems are complete without a person’s involvement; however, no computer is totally autonomous. Even if a computer can do its job without a person sitting in front of it, people still design, build, program, and repair computer systems. This lack of autonomy is especially true of personal computer systems, which arc the focus of this book and are designed specifically for use by people. The Information Processing Cycle Using all its parts together, a computer converts data into information by performing various actions on the data. For example, a computer might perform a mathematical operation on two numbers, then display the result. Or the computer might perform a logical operation such as
- 9. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 9 comparing two numbers, then display that result. These operations are part of a process called the information processing cycle, which is a set of steps the computer follows to receive data, process the data according to instructions from a program, display the resulting information to the user, and store the results. The information processing cycle has four parts, and each part involves one or more specific components of the computer: » Input. During this part of the cycle, the computer accepts data from some source, such as the user or a program, for processing. » Processing. During this part of the cycle, the computer’s processing components perform actions on the data, based on instructions from the user or a program. » Output. Here, the computer may be required to display the results of its processing. For example, the results may appear as text, numbers, or a graphic on the computer’s screen or as sounds from its speaker. The computer also can send output to a printer or transfer the output to another computer through a network or the Internet. Output is an optional step in the information processing cycle but may be ordered by the user or program. » Storage. In this step, the computer permanently stores the results of its processing on a disk, tape, or some other kind of storage medium. As with output, storage is optional and may not always be required by the user or program. Essential Computer Hardware A computer’s hardware devices fall into one of four categories: 1. Processor 2. Memory 3. Input and output 4. Storage While any type of computer system contains these four types of hardware, this book focuses on them as they relate to the personal computer or PC. Processing Devices The procedure that transforms raw data into useful information is called processing. To perform this transformation, the computer uses two components: the processor and memory. The processor is like the brain of the computer; it organizes and carries out instructions that come from either the user or the software. In a personal computer the processor usually consists of one or more specialized chips, called microprocessors, which are slivers of silicon or other material etched with many tiny electronic circuits. To process data or complete an instruction from a user or a program the computer passes electricity through the circuits. The microprocessor is plugged into the computer’s motherboard. The mother-board is a rigid rectangular card containing the circuitry that connects the processor to the other hardware. The motherboard is an example o f a circuit the microprocessor board. In most personal computers, many internal devices such as video cards, sound cards, disk controllers, and other devices—are housed on their own smaller circuit boards, which attach to the motherboard. In many newer computers, these devices are built directly into the motherboard. Some newer microprocessors are large and complex enough to require their own dedicated circuit boards, which plug into a special slot in the motherboard. You can think of the motherboard as the master circuit board in a computer. A personal computer’s processor is usually a single chip or a set of chips contained on a circuit board. In some powerful computers, the processor consists of many chips and the circuit boards on which they are mounted. In either case, the term control processing unit (CPU) refers
- 10. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 10 to a computer’s processor. People often refer to computer systems by the type of CPU they contain. A "Pentium 4” system, for example, uses a Pentium 4 microprocessor as its CPU. Memory Devices In a computer, memory is one or more sets of chips that store data and/or program instructions, cither temporarily or permanently. Memory is a critical processing component in any computer Personal computers use several different types of memory, but the two most important arc called random access memory (RAM) and read-only memory (ROM). These two types of memory work in very different ways and perform distinct functions. Random Access Memory The most common type of memory is called random access memory (RAM). As a result, the term memory is typically used to mean RAM. RAM is like an electronic scratch pad inside the computer. RAM holds data and program instructions while the CPU works with them. When a program is laundered, it is loaded into and run from memory. As the program needs data, it is loaded into memory for fast access. As new data is entered into the computer, it is also stored in memory— but only temporarily. Data is both written to and read from this memory. (Because of this, RAM is also sometimes called read/write memory.) Like many computer components, RAM is made up of a set of chips mounted on a small circuit board (see Figure 1B.9). RAM is volatile, meaning that it loses its contents when the computer is shut off or if there is a power failure. Therefore, RAM needs a constant supply of power to hold its data. For this reason, you should save your data files to a storage device frequently, to avoid losing them in a power failure. (You will learn more about storage later in this chapter.) RAM has a tremendous impact on the speed and power of a computer. Generally, the more RAM a computer has, the mote it can do and the faster it can perform certain tasks. The most common measurement unit for describing a computer’s memory is the byte—the amount of memory it takes to store a single character such as a letter of the alphabet or a numeral. When referring to a computer's memory, the numbers are often so large that it is helpful to use terms such as kilobyte (KB), megabyte (MB), gigabyte (GB), and terabyte (TB) to describe the values (see Table 1B.1). Today’s personal computers generally have at least 256 million bytes (256 MB) of random access memory. Many newer systems feature 512 MB or more. Read-Only Memory Unlike RAM, Read-only memory (ROM) permanently stores its data, even when the computer is shut off. ROM is called nonvolatile memory because it never loses its contents. ROM holds instructions that the computer needs to operate. Whenever the computer's power is turned on, it checks ROM for directions that help it start up, and for information about its hardware devices. Input and Output Devices A personal computer would be useless if you could not interact with it because the machine could not receive instructions or deliver the results of its work. Input devices accept data and instructions from the user or from another computer system (such as a computer on the Internet). Output devices return processed data to the user or to another computer system. The most common input device is the keyboard, which accepts letters, numbers, and commands from the user. Another important type of input device is the mouse, which lets you select options from on-screen menus. You use a mouse by moving it across a flat surface and pressing its buttons. Figure IB .10 shows a personal computer with a keyboard, mouse, and microphone. A variety of other input devices work with personal computers, too: The trackball and touchpad are variations of the mouse and enable you to draw or point on the screen.
- 11. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 11 The joystick is a swiveling lever mounted on a stationary base that is well suited for playing video games. A scanner can copy a printed page of text or a graphic into the computer's memory, freeing you from creating the data from scratch. A digital camera can record still images, which you can view and edit on the computer » A microphone enables you to input your voice or music as data. The function of an output device is to present processed data to the user. The most common output devices are the monitor and the printer the computer sends output to the monitor (the display screen) when the user needs only to see the output. It sends output to the printer when the user requests a paper copy—also called a hard copy—of a document. Just as computers can accept sound as input, (hey can use stereo speakers or headphones as output devices to produce sound. Printer; and speakers. Some types of hardware can act as both input and output devices. A touch Screen, for example, is a type of monitor that displays text or icons you can touch. When you touch the screen, special sensors detect the touch and the computer calculates the point on the screen where you placed your finger. Depending on the location of the touch, the computer determines what information to display or what action to take next. Communications devices are the most common types of devices that can perform both input and output. These devices connect one computer 10 another—a process known as networking. The most common kinds of communications devices are modems, which enable computers to communicate through telephone lines or cable television systems, and network interface cards (NICs), which let users connect a group of computers to share data and devices. System Software System software is any program (hat controls the computer’s hardware or that can be used to maintain the computer in some way so that it runs more efficiently. There are three basic types of system software: » An operating system tells the computer how to use its own components. Examples of operating systems include Windows, the Macintosh Operating System, and Linux. An operating system is essential for any computer; because it acts as an interpreter between the hardware, application programs, and the use when a program wants the hardware to do something, it communicates through the operating system. Similarly, when you want the hardware to do something (such as copying or printing a file), your request is handled by the operating system. » A network operating system allows computers to communicate and share data across a network while controlling network operations and overseeing the network’s security. » A utility is a program that makes the computer system easier to use or performs highly specialized functions. Utilities arc used to manage disks, troubleshoot hardware problems, and perform other tasks that the operating system itself may not be able to do. Application Software Application software tells the computer how to accomplish specific tasks, such as word processing or drawing, for the user. Thousands of applications are available for many purposes and for people of all ages. Some of the major categories of these applications include. Word processing software for creating text-based documents such as newsletters or brochures. » Spreadsheets for creating numeric-based documents such as budgets or balance sheets. Database management software for building and manipulating large sets of data, such as the names, addresses, and phone numbers in a telephone directory. » Presentation programs for creating and presenting electronic slide shows.
- 12. Fundamentals of Computer Unit I Vikram Neerugatti P a g e | 12 » Graphics programs for designing illustrations or manipulating photographs, movies, or animation. » Multimedia authoring applications for building digital movies that incorporate sound, video, animation, and interactive features. » Entertainment and education software, many of which are interactive multimedia events. » Web design tools and Web browsers, and other Internet applications such as newsreaders and e mail programs. » Games, some of which arc for a single player and many of which can be played by several people over a network or the Internet.