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 use a list of instructions, called a program, to perform calculations or to store, manipulate, and retrieve information. Today's computers are marvels of miniaturization. Machines that once weighed 30 tons and occupied warehouse-size rooms now may weigh as little as three pounds (1.4 kilograms) and can be carried in a suit pocket. The heart of today's computers are integrated circuits (ICs), sometimes called microchips, or simply chips. These tiny silicon wafers can contain millions of microscopic electronic components and are designed for many specific operations: some control an entire computer (CPU, or central processing unit, chips); some perform millions of mathematical operations per second (math oprocessors); others can store more than 16 million characters of information at one time (memory chips). 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 more than 110 million programmable computers are being used in homes, 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)....
