user and data. A computer is a programmable device that
can automatically perform a sequence of calculations or other operations on data without human aid. It can store, retrieve, and process data according to internal instructions.
A computer may be analog, digital, or hybrid, although most today are digital. Digital computers express variables as numbers, usually in the binary system. They are used for general purposes, whereas analog computers are built for specific tasks, typically scientific or technical. The term "computer" is usually synonymous with digital computer, and computers for business are exclusively digital.
The core of any computer is its central processing unit (CPU), commonlycalled a processor or a chip. The typical CPU consists of an arithmetic-logic unit to carry out calculations; main memory to store data temporarily for processing; and a control unit to control the transfer between memory, input and output sources, and the arithmetic-logic unit.
REVIEW OF COMPUTER SYSTEMS. EVOLUTION OF COMPUTER SYSTEMS.