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A microcomputer is a small, relatively inexpensive computer with a microprocessor as its central processing unit (CPU).〔(【引用サイトリンク】 publisher=dictionary.com )〕 It includes a microprocessor, memory, and input/output (I/O) facilities. Microcomputers became popular in the 1970s and 80s with the advent of increasingly powerful microprocessors. The predecessors to these computers, mainframes and minicomputers, were comparatively much larger and more expensive (though indeed present-day mainframes such as the IBM System z machines use one or more custom microprocessors as their CPUs). Many microcomputers (when equipped with a keyboard and screen for input and output) are also personal computers (in the generic sense).〔An early use of the term ''personal computer'' in 1962 predates microprocessor-based designs. ''(See "Personal Computer: Computers at Companies" reference below)''. A ''microcomputer'' used as an embedded control system may have no human-readable input and output devices. "Personal computer" may be used generically or may denote an IBM PC compatible machine.〕 The abbreviation ''micro'' was common during the 1970s and 1980s,〔Proof of "micro" as a once-common term: (i) Direct reference: Graham Kibble-White, ("Stand by for a Data-Blast" ), Off the Telly. Article written December 2005, retrieved 2006-12-15. (ii) Usage in the titles of Christopher Evans' books ("The Mighty Micro" ) (ISBN 0-340-25975-2) and ("The Making of the Micro" ) (ISBN 0-575-02913-7). Other books include Usborne's ("Understanding the Micro" ) (ISBN 0-86020-637-8), a children's guide to microcomputers.〕 but has now fallen out of common usage. == Origins == The term ''microcomputer'' came into popular use after the introduction of the minicomputer, although Isaac Asimov used the term microcomputer in his short story "The Dying Night" as early as 1956 (published in ''The Magazine of Fantasy and Science Fiction'' in July that year). Most notably, the microcomputer replaced the many separate components that made up the minicomputer's CPU with one integrated microprocessor chip. The French developers of the Micral N (1973) filed their patents with the term "Micro-ordinateur", a literal equivalent of "Microcomputer", to designate the first solid state machine designed with a microprocessor. In the USA, the earliest models such as the Altair 8800 were often sold as kits to be assembled by the user, and came with as little as 256 bytes of RAM, and no input/output devices other than indicator lights and switches, useful as a proof of concept to demonstrate what such a simple device could do. However, as microprocessors and semiconductor memory became less expensive, microcomputers in turn grew cheaper and easier to use: * Increasingly inexpensive logic chips such as the 7400 series allowed cheap dedicated circuitry for improved user interfaces such as keyboard input, instead of simply a row of switches to toggle bits one at a time. * Use of audio cassettes for inexpensive data storage replaced manual re-entry of a program every time the device was powered on. * Large cheap arrays of silicon logic gates in the form of read-only memory and EPROMs allowed utility programs and self-booting kernels to be stored within microcomputers. These stored programs could automatically load further more complex software from external storage devices without user intervention, to form an inexpensive turnkey system that does not require a computer expert to understand or to use the device. * Random access memory became cheap enough to afford dedicating approximately 1-2 kilobytes of memory to a video display controller frame buffer, for a 40x25 or 80x25 text display or blocky color graphics on a common household television. This replaced the slow, complex, and expensive teletypewriter that was previously common as an interface to minicomputers and mainframes. All these improvements in cost and usability resulted in an explosion in their popularity during the late 1970s and early 1980s. A large number of computer makers packaged microcomputers for use in small business applications. By 1979, many companies such as Cromemco, Processor Technology, IMSAI, North Star Computers, Southwest Technical Products Corporation, Ohio Scientific, Altos Computer Systems, Morrow Designs and others produced systems designed either for a resourceful end user or consulting firm to deliver business systems such as accounting, database management, and word processing to small businesses. This allowed businesses unable to afford leasing of a minicomputer or time-sharing service the opportunity to automate business functions, without (usually) hiring a full-time staff to operate the computers. A representative system of this era would have used an S100 bus, an 8-bit processor such as an Intel 8080 or Zilog Z80, and either CP/M or MP/M operating system. The increasing availability and power of desktop computers for personal use attracted the attention of more software developers. In time, and as the industry matured, the market for personal computers standardized around IBM PC compatibles running DOS, and later Windows. Modern desktop computers, video game consoles, laptops, tablet PCs, and many types of handheld devices, including mobile phones, pocket calculators, and industrial embedded systems, may all be considered examples of microcomputers according to the definition given above. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Microcomputer」の詳細全文を読む スポンサード リンク
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