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The NCR 315 Data Processing System, released in January 1962 by NCR, was a second-generation computer. All printed circuit boards used resistor-transistor logic to create the various logic elements. It used 12-bit slab memory structure using core memory. The instructions could use a memory slab as either two 6-bit alphanumeric characters or as three 4-bit BCD characters. Basic memory was 5000 "slabs" of handmade core memory, which was expandable to a maximum of 40,000 slabs in four refrigerator-size cabinets. The main processor included three cabinets and a console section that housed the power supply, keyboard, output writer (an IBM electric typewriter), and a panel of lights that indicated the current status of the program counter, registers, arithmetic accumulator, and system errors. Input/Output was by direct parallel connections to each type of peripheral through a two-cable bundle with 1-inch-thick cables. Some devices like magnetic tape and the CRAM were daisy-chained to allow multiple drives to be connected. Later models in this series include the 315-100 and the 315-RMC (Rod Memory Computer). ==Memory organization== The addressable unit of memory on the NCR 315 series is a "slab", short for "syllable", consisting of 12 data bits and a parity bit. Its size falls between a byte and a typical word (hence the name, 'syllable'). A slab may contain three digits (with at sign, comma, space, ampersand, point, and minus treated as digits) or two alphabetic characters of six bits each. A slab may contain a decimal value from -99 to +999. A numeric value contains up to eight slabs. If the value is negative then the minus sign is the leftmost digit of this row. There are instructions to transform digits to or from alphanumeric characters. These commands use the accumulator, which has a maximum length of eight slabs. To accelerate the processing the accumulator works with an effective length.〔Bardin, H (1963). "NCR 315 Seminar", ''Computer Usage Communique'', Vol.2, No. 3., 1963. ()〕 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「NCR 315」の詳細全文を読む スポンサード リンク
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