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Reference / Glossary

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Cross References
           
2 [1] Introduced in April 1987 by IBM's Entry Systems Division, the Personal System/2 family of PCs originally featured four systems -- Models 30, 50, 60 and 80 -- in a range of eight configurations providing customers with a variety of performance, memory and storage options.
 
2 [2] The Model 30 was an Intel 8-megahertz system, with either two 720K diskette drives or one 720K diskette drive and a 20-megabyte fixed disk drive. At the high end of the family, the Model 80 was a floor-standing machine running at 16 megahertz, containing one megabyte of memory and featuring a 44 megabyte fixed disk drive. A second 44 MB fixed disk drive could be added. Prices ranged from $1,695 for the Model 30 with two diskette drives to $10,995 for the Model 80 with two fixed disk drives.
 
2361 [1] The IBM 2361 Core Storage Unit was introduced in April 1964 and built by IBM's Poughkeepsie, N.Y., manufacturing facilities with 16 times the capacity of any previous IBM memory. In each 2361, almost 20 million ferrite cores -- tiny doughnut-shaped objects, each about the size of a pinhead -- were strung in two-wire networks and packaged, with associated circuitry, into a cabinet only five by 2 feet and less than six feet tall.
 
2361 [2] The 2361's design provided for storage of 524,000 36-bit words and a total cycle time of eight microseconds in each memory. The 2361 was the first IBM memory to use two-wire core storage to increase storage capacity, improve performance and reduce unit size.
 
2361 [3] Cores were woven into each juncture of a screen-like mesh of wire to form a plane resembling a small window screen. Memory circuits were associated with core planes in the 2361 and included some 3,500 Solid Logic Technology modules and 35,000 high-current silicon diodes. Major feats in fabricating the 2361 included soldering and testing 180,000 connections, and welding and testing another 180,000 connections. The 2361 was withdrawn from marketing in April 1965.
 
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