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The RCA Spectra 70 was a line of electronic data processing (EDP) equipment manufactured by the Radio Corporation of America’s computer division beginning in April 1965. The Spectra 70 line included several CPU models, various configurations of core memory, mass-storage devices, terminal equipment, and a variety of specialized interface equipment.〔(【引用サイトリンク】title=RCA Spectra 70 )〕 The system architecture and instruction-set were largely compatible with the non-privileged instruction-set of the IBM System/360. While this degree of compatibility made some interchange of programs and data possible, differences in the operating system software precluded transparent movement of programs between the two systems. == System overview == Four models of the Spectra 70 CPU were offered in 1965, ranging from a small system (70/15) to the large scale (70/55). Some of the main features were: * The systems were upward-compatible, allowing programs written for a smaller model to run on any larger machine in the series. * Larger machines in the series were also faster, with memory access times ranging from two microseconds in the 70/15 to 0.84 microseconds in the 70/55. * Memory capacities ranged from a minimum of 4,096 bytes in the 70/15 to a maximum of 524,288 bytes in the 70/55. * All used the Extended Binary Coded Decimal Interchange Code (EBCDIC) of eight bits plus parity for internal data representation. * The use of a standard electrical interface allowed the same peripherals to be used with any CPU model in the series. * Simultaneous input and output was accomplished by the use of intelligent communication channels. Like the IBM 360, two types of channel were available (on all but the 70/15): selector channels which could address up to 256 devices (one at a time), and multiplexer channels (not on the 70/15) which could simultaneously address up to 256 channels by time-sharing the channel. 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「RCA Spectra 70」の詳細全文を読む スポンサード リンク
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