Difference between revisions of "SDS Sigma series"

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The '''SDS Sigma series''' from [[Scientific Data Systems|SDS]] was a family of 16-bit and (later) 32-bit computers. They were intended for use partially or wholly in [[real-time]] settings, but also provided [[time-sharing]] and [[batch processing]] facilities. The Sigma 6, 8 and 9 were all produced after the merger of SDS and [[Xerox]] (forming 'Xerox Data Systems') in March 1969.
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The '''SDS Sigma series''' from [[Scientific Data Systems|SDS]] was a family of 16-bit and 32-bit computers (see below). They were intended for use partially or wholly in [[real-time]] settings, but also provided [[batch processing]] facilities (also [[time-sharing]], on the 32-bit systems). This dual capability was described as "multi-use" in SDS' marketing material.
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The Sigma 6, 8 and 9 were all produced after the merger of SDS and [[Xerox]] (forming 'Xerox Data Systems', 'XDS') in March 1969. Xerox sold XDS to [[Honeywell]] in 1975; Honeywell briefly continued support of the Sigmas, but then terminated it. At that point, other companies, including [[Telefile]], Ilene Industries Data Systems, and Realtime Computer Equipment started to build and sell [[program compatible]] machines.
  
 
A Sigma 7 at [[UCLA]] was the first computer connected to the nascent [[ARPANET]].
 
A Sigma 7 at [[UCLA]] was the first computer connected to the nascent [[ARPANET]].
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==Family members==
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There were two lines of program compatible machines; a 16-bit group and a 32-bit group. All used a [[load-store architecture]].
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Below are thumbnail descriptions of the models in the Sigma family, in the order of their dates of introduction.
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===16-bit group===
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Their [[instruction set]] includes 'memory reference' [[instruction]]s:
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{{16bit-header}}
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| colspan=4 | [[Opcode]] || R || I || X || S || colspan=8 | Displacement
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{{16bit-bitout}}
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* R - Self-relative
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* I - Indirect
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* X - Indexed
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* S - Base-relative
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There are also 'copy' instructions ([[register]]-to-register operations) and [[conditional branch]] instructions.
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====Sigma 2====
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First member of the of the Sigma 16-bit group; introduced in 1966.
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====Sigma 3====
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Introduced in 1969.
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===32-bit group===
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Their instruction set is also principally 'memory reference' instructions:
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{{32bit-header}}
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| I || colspan=7 | Opcode || colspan=4 | R || colspan=3 | X || colspan=19 | [[Address]]
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{{32bitbig-bitout}}
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* I - Indirect
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* R - Register (in current [[register block]])
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* X - [[Index register]] (ditto)
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Again, there are also conditional branch instructions. Like the [[PDP-10]], references to the low 16. [[main memory]] locations automagically turn into references to the corresponding register; memory reference instructions thus provide a complete set of register-to-register operations (definitely on the 7 and 5; not confirmed on the others).
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====Sigma 7====
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First member of the of the Sigma 32-bit group; announced in April, 1966.
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====Sigma 5====
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Introduced in 1967; a reduced-cost version, without separate input/output processors.
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====Sigma 6====
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Announced in May, 1970; SDS' initial entry into commercial business data processing.
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====Sigma 9====
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Announced in October 1970.
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====Sigma 8====
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Introduced in 1972.
  
 
{{semi-stub}}
 
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* [http://www.bitsavers.org/pdf/sds/sigma/ sigma] - documentation on [[Bitsavers]]
 
* [http://www.bitsavers.org/pdf/sds/sigma/ sigma] - documentation on [[Bitsavers]]
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** [http://www.bitsavers.org/pdf/sds/sigma/sigmaCPUs.txt Sigma CPUs]
 
* [https://s3data.computerhistory.org/brochures/sds.sigma.1967.102646100.pdf The Sigma Family] - sales brochure; pre-dates the Xerox merger
 
* [https://s3data.computerhistory.org/brochures/sds.sigma.1967.102646100.pdf The Sigma Family] - sales brochure; pre-dates the Xerox merger
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* [https://dl.acm.org/doi/pdf/10.1145/1464291.1464296 The SDS Sigma 7: A Real-Time Time-Sharing Computer]
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* [https://archive.computerhistory.org/resources/access/text/finding-aids/102733948-Calkins/102733948-Calkins.pdf Guide to the Keith G. Calkins collection on Sigma systems]
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* [https://dl.acm.org/doi/pdf/10.1145/1464291.1464296 The SDS Sigma 7: A Real-Time Time-Sharing Computer] <!-- http://www.bitsavers.org/pdf/sds/sigma/sigma7/670314A_Sigma7_Overview_Nov66.pdf -->
 
* [https://www.andrews.edu/~calkins/profess/SDSigma7.htm The Computer That Will Not Die: The SDS Sigma 7] ''Narrator: it died.''
 
* [https://www.andrews.edu/~calkins/profess/SDSigma7.htm The Computer That Will Not Die: The SDS Sigma 7] ''Narrator: it died.''
 
* [https://uclaconnectionlab.org/internet-museum/ 3420 Boelter Hall: Where It All Began] - UCLA Internet Museum, displaying a Sigma 7 front panel
 
* [https://uclaconnectionlab.org/internet-museum/ 3420 Boelter Hall: Where It All Began] - UCLA Internet Museum, displaying a Sigma 7 front panel
  
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[[Category: 16-bit Computers]]
 
[[Category: 32-bit Computers]]
 
[[Category: 32-bit Computers]]
 
[[Category: Xerox]]
 
[[Category: Xerox]]

Latest revision as of 16:24, 1 August 2025

The SDS Sigma series from SDS was a family of 16-bit and 32-bit computers (see below). They were intended for use partially or wholly in real-time settings, but also provided batch processing facilities (also time-sharing, on the 32-bit systems). This dual capability was described as "multi-use" in SDS' marketing material.

The Sigma 6, 8 and 9 were all produced after the merger of SDS and Xerox (forming 'Xerox Data Systems', 'XDS') in March 1969. Xerox sold XDS to Honeywell in 1975; Honeywell briefly continued support of the Sigmas, but then terminated it. At that point, other companies, including Telefile, Ilene Industries Data Systems, and Realtime Computer Equipment started to build and sell program compatible machines.

A Sigma 7 at UCLA was the first computer connected to the nascent ARPANET.

Family members

There were two lines of program compatible machines; a 16-bit group and a 32-bit group. All used a load-store architecture.

Below are thumbnail descriptions of the models in the Sigma family, in the order of their dates of introduction.

16-bit group

Their instruction set includes 'memory reference' instructions:

Opcode R I X S Displacement
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
  • R - Self-relative
  • I - Indirect
  • X - Indexed
  • S - Base-relative

There are also 'copy' instructions (register-to-register operations) and conditional branch instructions.

Sigma 2

First member of the of the Sigma 16-bit group; introduced in 1966.

Sigma 3

Introduced in 1969.

32-bit group

Their instruction set is also principally 'memory reference' instructions:

I Opcode R X Address
00 01 02 03 04 05 07 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Again, there are also conditional branch instructions. Like the PDP-10, references to the low 16. main memory locations automagically turn into references to the corresponding register; memory reference instructions thus provide a complete set of register-to-register operations (definitely on the 7 and 5; not confirmed on the others).

Sigma 7

First member of the of the Sigma 32-bit group; announced in April, 1966.

Sigma 5

Introduced in 1967; a reduced-cost version, without separate input/output processors.

Sigma 6

Announced in May, 1970; SDS' initial entry into commercial business data processing.

Sigma 9

Announced in October 1970.

Sigma 8

Introduced in 1972.

External links

Retrieved from "https://gunkies.org/w/index.php?title=SDS_Sigma_series&oldid=36643"