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The SDS Sigma series was a series of computers that was introduced by Scientific Data Systems in 1966.〔 〕 The first machines in the series were the 16-bit Sigma 2 and the 32-bit Sigma 7; the Sigma 7 was the first 32-bit computer released by SDS. At the time the only competition for the Sigma 7 was the IBM 360. Memory size increments for all SDS/XDS/Xerox computers was stated in kWords, not kBytes. For example, the Sigma 5 base memory was 16K 32-Bit words (64K Bytes). Maximum memory was limited by the length of the instruction address field of 17 bits, or 128K Words (512K Bytes). Although this is a trivial amount of memory in today's technology, Sigma systems performed their tasks exceptionally well, and few were deployed with, or needed, the maximum 128K Word memory size. The Xerox 500 series computers, introduced starting in 1973, were compatible upgrades to the Sigma systems using newer technology. In 1975 Xerox sold its computer business to Honeywell, Inc. which continued support for the Sigma line for a time. The Sigma 9 may hold the record for the longest lifetime of a machine selling near the original retail price. Sigmas 9s were still in service in 1993. In 2011 the Living Computer Museum in Seattle, Washington acquired a Sigma 9 from a service bureau (Applied Esoterics/George Plue Estate) and has made it operational.〔(【引用サイトリンク】url=http://www.livingcomputermuseum.org/TemplateMain.aspx?contentId=32 )〕 That Sigma 9 CPU was at the University of Southern Mississippi until Nov. 1985 when Andrews University purchased it and took it to Michigan. In Feb. 1990 Andrews University via Keith Calkins sold and delivered it to Applied Esoterics in Flagstaff. Keith Calkins made the Sigma 9 functional for the museum in 2012/13 and brought up the CP-V operating system in Dec. 2014. The various other system components came from various other user sites, such as Marquette, Samford, Xerox/Dallas. ==Models〔(【引用サイトリンク】title = sigmaCPUs.txt at bitsavers.org ) 〕== ===32-bit systems=== 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「SDS Sigma series」の詳細全文を読む スポンサード リンク
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