A computer that (a) contains a microprocessor, (b) is smaller than a large-scale mainframe computer, i.e., a central processing unit, but not necessarily of small capacity, (c) usually executes computer programs in read-only memory (ROM) that also serves as main storage or internal memory, and (d) usually runs specific applications in communications, computer, automatic data processing, information, and control systems. Note: Generally computers have been classified into (a) microcomputers that are constructed of microcircuits. (b) minicomputers that are smaller in size but not necessarily smaller in capacity, and (c) mainframes that are larger in size and have a higher capacity. All of these are loosely based on size and capacity. However, these distinctions are becoming less valid as computer capabilities increase with advances in technology. Microcomputers of today can be more powerful and more versatile than the minicomputers of yesterday, and even more powerful than the mainframes of a few years ago. See also  automatic data processing system,  central processing unit,  communications system,  computer,  computer program,  computer system,  control system,  execute,  information system,  mainframe,  microcircuit,  microcomputer,  microprocessor,  read-only memory.