A computer is any
device that can perform a sequence of operations. Examples include the
mechanical adding machine, the slide rule, and the ancient abacus. Around 500
BC, the abacus, the first mechanical calculator, was developed. It remained
popular until 1642, when the French scientist Blaise Pascal invented a
calculator made of wheels and cogs. Currently, however, the term refers to an electronic device that executes a list of instructions, called a program, to perform calculations or to store, manipulate, or retrieve information. Note that without a source of electricity the computer is just an expensive paperweight. Today's computers are marvels of miniaturization: machines that once weighed tons now may weigh as little as few ounces and can be carried in a wristwatch. At the heart of today's computers are integrated circuits (ICs), sometimes called microprocessors, microchips, or simply chips, that contain millions of microscopic electronic components and are designed for many specific operations. Some control an entire computer (CPU, or central processing unit); some perform millions of mathematical operations per second (math coprocessors); others can store millions of characters of information at one time (memory chips).
Computers are an integral part of electronic calculators; they can also be found in 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).
