The CDC logic module was set of components used in CDC computers in the 1960s.
When Seymour Cray joined Control Data Corporation in 1958, he had just finished work on the Univac M-460 computer, also known as the AN/USQ-17. This computer used very small circuit boards, each holding one logical building block, and Cray brought this board format with him to CDC.J. E. Thornton, M. MacAulay, and R. H. Toth, The Univac M-460 Computer, Proceedings of the 1958 Western Joint Computer Conference, pages 70–74.
As refined at CDC for use in the CDC 1604 and CDC 160, these building blocks were packaged on circuit boards with a 15-pin male connector on one of the long edges. The power supply voltages were +15 V and −15 V, and the logic levels were −3 V and −0.5 V. Each inverter used two transistors with feedback used to prevent either from saturating. Diodes on both inputs and outputs allowed both Boolean AND and OR functions in the wiring between inverters.Control Data 160 Computer, Control Data Corporation, Minneapolis, 1961, pages 4-5.1604 Computer: Vol II, Principles of Operation, Control Data Corporation, Minneapolis, 1960 pages 1–13 to 1–22.
Modules used on the CDC 6600 were compatible with the backplane connectors used with earlier machines, but modules could be and some were double-thickness, occupying two adjacent backplane slots and built from two circuit boards with components hanging between them like cordwood.Gordon Bell, A Seymour Cray Perspective, slides from a 10 Nov. 1997 talk at the University of Minnesota, slide 34.
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