Information Technology
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COMPUTERS Part 1
Generally, a computer is any device that can perform numerical calculations–even an adding machine, an abacus, or a slide rule. Currently, however, the term usually refers to an electronic device that can perform a series of tasks according to a precise set of instructions. The set of instructions is called a program, and the tasks may include making arithmetic calculations, storing, retrieving, and processing data, controlling another device, or interacting with a person to perform a business function or to play a video game. Todays computers are marvels of miniaturization. Machines that once weighed 30 tons and occupied warehouse-size rooms now may weigh as little as 3 pounds (1.4 kilograms) can carried in a suit pocket or a purse. The “brains” of todays computers are integrated circuits (ICs), sometimes called microchips, or simply chips. These tiny silicon wafers can each contain millions of microscopic electronic components and are designed for many specific operations. Some chips make up a computers central processing unit (CPU), which controls the computers overall operation; some are math coprocessors that can perform millions of mathematical operations per second; and others are memory chips that can each store more than 16 million characters of information at one time.
In 1953 there were only about 100 computers in use in the entire world. Today hundreds of millions of computers form the core of electronic products, and programmable computers are being used in homes, schools, businesses, government offices, and universities for almost every conceivable purpose Computers come in many sizes and shapes. Special-purpose, or dedicated, computers are designed to perform specific tasks. Their operations are limited to the programs built into their microchips. These computers are the basis for electronic calculators and can be found in thousands of other electronic products, including digital watches (controlling timing, alarms, and displays), cameras (monitoring shutter speeds and aperture settings), and automobiles (controlling fuel injection, heating, and air conditioning and monitoring hundreds of electronic sensors). General-purpose computers, such as personal computers and business computers, are much more versatile because they can accept new programs. Each new program enables the same computer to perform a different set of tasks. For example, one program instructs the computer to be a word processor, another instructs it to manage inventories, and yet another transforms it into a video game.
Although some general-purpose computers are as small as pocket radios, the smallest class of fully functional, self-contained computers is the class called notebook computers. These usually consist of a CPU, data-storage devices called disk drives, a liquid-crystal display (LCD), and a full-size keyboard–all housed in a single unit small enough to fit into a briefcase.
Todays desktop personal computers, or PCs, are many times more powerful than the huge, million-dollar business computers of the 1960s and 1970s. Most PCs can perform from 150 to 400 million operations per second, and some can even perform more than 500 million. These computers are used not only for household management and personal entertainment, but also for most of the automated tasks required by small businesses, including word processing, generating mailing lists, tracking inventory, and calculating accounting information. The fastest desktop computers are called workstations, and they are generally used for scientific, engineering, or advanced business applications.
Servers are fast computers that have greater data processing capabilities than most PCs and workstations and can be used simultaneously by many people. Often several PCs and workstations are connected to a server via a local area network (LAN). The server controls resources that are shared by the people working at the PCs and workstations. An example of a shared resource is a large collection of information called a database. Mainframes are large, extremely fast, multi-user computers that often contain complex arrays of processors, each designed to perform a specific function. Because they can handle huge databases, simultaneously accommodate scores of users, and perform complex mathematical operations, they are the mainstay of industry, research, and university computing centers. The speed and power of supercomputers, the fastest class of computer, are almost beyond human comprehension, and their capabilities are continually being improved. One of the most sophisticated of these machines can theoretically perform 32 billion operations per second, can store 256 billion characters in its memory, and can do the work of thousands of PCs. Supercomputers attain these speeds through the use of several advanced engineering techniques. For example, critical circuitry is supercooled to nearly absolute zero so that electrons can move at the speed of light, and many processing units are linked in such a way that they can all work on a single problem simultaneously. Because these computers can cost millions of dollars, they are used primarily by government agencies and large research centers.
Computer development is rapidly progressing at both the high and the low ends of the computing spectrum. On the high end, by linking together networks of computers and programming them to use a language called Linda, scientists employ a technology called parallel processing, in which a problem is broken down into smaller subproblems that are then distributed among the networked computers. A goal of this technology is the creation of a machine that could perform a trillion calculations per second, a measure known as a teraflop. At the other end of the spectrum, computer companies are developing small, handheld personal digital assistants (PDAs). For example, a PDA called the Palm Pilot lets people use a pen to input handwritten information through a touch-sensitive screen and to send mail and faxes to other computers. Researchers are currently developing microchips called digital signal processors (DSPs) to enable computers to recognize and interpret human speech. This development, which will permit people in all professions to use a computer quickly and easily, promises to lead to a revolution in the way humans communicate and transfer information.
Computers at Work–Applications
Communication. Computers make all modern communication possible. They operate telephone switching systems, coordinate satellite launches and operations, help generate special effects for movies, and control the equipment in all phases of television and radio broadcasts. Local-area networks (LANs) link the computers in separate departments