SDS Sigma series
series of computers introduced by Scientific Data Systems in 1966
The SDS Sigma series is a series of third generation computers that were introduced by Scientific Data Systems of the United States in 1966.
The first machines in the series are 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 in the scientific space was the IBM System/360.
The Sigma 5, 6, 7, 8 and 9 were word addressed systems, memory sizes are stated in K (kilowords). For example, the Sigma 5 base memory is 16K. Maximum physical memory is not limited by the length of the instruction address field of 17 bits, or 128K because the effective address could be augmented using memory mapping. Due to the width of the map registers, the maximum physical memory was 512K.
The CII 10070 computer was a rebadged Sigma 7 and served as a basis for the upgraded, yet still compatible, Iris 50 and Iris 80 computers. The Xerox 500 series computers, introduced starting in 1973, were also 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. Sigma 9 computers were still in service in 1993.
“SDS Sigma series” enters the record as series of computers introduced by Scientific Data Systems in 1966. Crown Archives preserves that source wording while asking what Sigma, series and computers can confirm, complicate or overturn.
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The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Sep 14, 2026. The linked authority identifier is Q11703763. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1966, 1973, 1975 and 1993.
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This entry incorporates text from “SDS Sigma series” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.