View source for SWAC (computer)

{{Short description|Early electronic digital computer built in 1950}}
{{Infobox information appliance
| name         = SWAC
| image        = SWAC 001.jpg
| image_size   = 
| alt          = 
| caption      = SWAC. Williams tube memory is in center rear.
| aka          = Standards Western Automatic Computer
| developer    = 
| manufacturer = [[United States|U.S.]] [[National Institute of Standards and Technology|National Bureau of Standards]] (NBS)
| type         = 
| releasedate  = {{Start date and age|1950}}
| price        = 
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| lifespan     = 
| unitssold    = 1
| media        = 
| os           = <!-- operating system -->
| input        = 
| camera       = 
| power        = 
| cpu          = 
| CPUspeed     = 
| storage      = 
| memory       = 256 words, with each word being 37 [[bit]]s
| RAMtype      = [[Williams tube]]s
| display      = 
| audio        = 
| service      = <!-- online service/s offered -->
| dimensions   = 
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| touchpad     = 
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}}
[[File:Museum of Science, Boston, MA - IMG 3160.JPG|thumb|right|250px|SWAC [[Williams tube]] memory unit]]
[[File:SWAC 003.jpg|thumb|250px|Memory pattern on SWAC Williams tube CRT]]
The '''SWAC''' ('''Standards Western Automatic Computer''') was an early electronic digital [[computer]] built in 1950 by the [[United States|U.S.]] [[National Institute of Standards and Technology|National Bureau of Standards]] (NBS) in Los Angeles, California.  It was designed by [[Harry Huskey]].<ref>{{cite book|last1=McMurran|first1=Marshall William|title=ACHIEVING ACCURACY: A Legacy of Computers and Missiles|date=2008|publisher=Xlibris Corporation|isbn=9781462810659|page=49|url=https://books.google.com/books?id=UU3v0tbq8acC&q=SWAC+1950&pg=PA49|language=en}}</ref>{{Self-published inline|certain=yes|date=December 2017}}

==Overview==
Like the [[SEAC (computer)|SEAC]] which was built about the same time, the SWAC was a small-scale interim computer designed to be built quickly and put into operation while the NBS waited for more powerful computers to be completed (in particular, the [[RAYDAC]] by [[Raytheon]]).

The machine used 2,300 [[vacuum tube]]s.  It had 256 words of [[computer storage|memory]], using [[Williams tube]]s, with each word being 37 [[bit]]s.  It had only seven basic operations: add, subtract, and [[Fixed-point arithmetic|fixed-point]] multiply;<ref>{{cite encyclopedia |last=Davis |first=Philip |editor-last=Alt |editor-first=Franz |title=Advances in Computers: Volume 2 |url=https://books.google.com/books?id=rDFWva4HhHcC&pg=PA85 |access-date=2023-06-27 |date=1961 |publisher=Elsevier Science| isbn=9780080566344 |page=85 |quote=SWAC, a fixed-point computer }}</ref> comparison, data extraction, input and output. Several years later, [[drum memory]] was added.<ref>[http://umedia.lib.umn.edu/node/89595 Oral history interview with Alexandra Forsythe] {{Webarchive|url=https://web.archive.org/web/20181122171941/http://umedia.lib.umn.edu/node/89595 |date=2018-11-22 }}, [[Charles Babbage Institute]], University of Minnesota.</ref>

When the SWAC was completed in August 1950,<ref>{{Cite journal|date=December 1950|title=6. National Bureau of Standards Western Automatic Computer (SWAC)|url=http://www.dtic.mil/docs/citations/AD0694599|journal=Digital Computer Newsletter|language=en|volume=2|issue=4|pages=3}}{{dead link|date=June 2022|bot=medic}}{{cbignore|bot=medic}}</ref> it was the fastest computer in the world. It continued to hold that status until the [[IAS machine|IAS computer]] was completed a year later. It could add two numbers and store the result in 64 [[microseconds]].  A similar multiplication took 384 microseconds. It was used by the NBS until 1954 when the Los Angeles office was closed, and then by [[University of California, Los Angeles|UCLA]] until 1967 (with modifications). It was charged out there for $40 per hour.

In January 1952, [[Raphael M. Robinson]] used the SWAC to discover five [[Mersenne prime]]s—the [[Largest known prime number|largest prime numbers known]] at the time, with 157, 183,<ref>{{Cite journal|date=April 1952|title=4. The SWAC|url=http://www.dtic.mil/docs/citations/AD0694604|journal=Digital Computer Newsletter|language=en|volume=4|issue=2|page=3}}{{dead link|date=June 2022|bot=medic}}{{cbignore|bot=medic}}</ref> 386, 664 and 687 digits.

Additionally, the SWAC was vital in doing the intense calculation required for the X-ray analysis of the structure of [[vitamin B12]] done by [[Dorothy Hodgkin]].<ref>Hodgkin, D.C.; Pickworth, J.; Robertson, J.H; Trueblood, K.N.; Prosen, R.J; White, J.G. Nature. 1955. 176. 325.</ref> This was fundamental in Hodgkin receiving the [[Nobel Prize in Chemistry]] in 1964.

==See also==
* [[List of vacuum tube computers]]

==References==
{{reflist}}
* Williams, Michael R. (1997). ''A History of Computing Technology''. [[IEEE Computer Society]].
* {{Cite journal|date=1951|title=Automatic Computing Machinery: News - Institute for Numerical Analysis|journal=Mathematics of Computation|language=en-US|volume=5|issue=33|pages=46–47|doi=10.1090/S0025-5718-51-99443-4|issn=0025-5718|doi-access=free}}
**{{Cite journal|last=Huskey|first=H. D.|date=1950|title=Characteristics of the Institute for Numerical Analysis computer|journal=Mathematics of Computation|language=en-US|volume=4|issue=30|pages=103–108|doi=10.1090/S0025-5718-1950-0037592-7|issn=0025-5718|doi-access=free}}

==Further reading==
*{{cite web |title=Documents about SWAC |url=http://www.bitsavers.org/pdf/nbs/swac/ |website=www.bitsavers.org}}
*{{cite journal |last1=Rutland |first1=David |title=THE SWAC: First Computer on the West Coast |journal=The Analytical Engine |date=1997 |volume=4 |issue=1 |pages=31–34 |url=http://www.bitsavers.org/pdf/chac/CHAC_Analytical_Engine/4.1_Winter_1997.pdf}}

==External links ==
* [https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=586073 IEEE Transcript: SWAC—Standards Western Automatic Computer: The Pioneer Day Session at NCC July 1978]{{Subscription required}}
* [http://purl.umn.edu/107291 Oral history interview with Alexandra Forsythe], [[Charles Babbage Institute]], University of Minnesota.  [[Alexandra Illmer Forsythe]] discusses the career of her husband, [[George Forsythe]]. At [[UCLA]] he became involved with the National Bureau of Standards Western Automatic Computer (SWAC) until 1957, when the [[National Bureau of Standards]] closed its operation at UCLA.  Also discusses his founding of the Stanford Computer Science Department.
* [http://purl.umn.edu/41420 Margaret R. Fox Papers, 1935-1976], [[Charles Babbage Institute]], University of Minnesota.  collection contains reports, including the original report on the ENIAC, UNIVAC, and many early in-house National Bureau of Standards (NBS) activity reports; memoranda on and histories of SEAC, '''SWAC''', and DYSEAC; programming instructions for the UNIVAC, LARC, and MIDAC; patent evaluations and disclosures relevant to computers; system descriptions; speeches and articles written by Margaret Fox's colleagues; and correspondence of Samuel Alexander, Margaret Fox, and Samuel Williams.
* [https://primes.utm.edu/mersenne/LukeMirror/lit/lit_024s.htm MERSENNE AND FERMAT NUMBERS] by RAPHAEL M. ROBINSON. February 7, 1954. From "The Prime Pages".

{{commonscat|position=left|SWAC (computer)}}

[[Category:One-of-a-kind computers]]
[[Category:Vacuum tube computers]]
[[Category:National Institute of Standards and Technology]]
[[Category:1950s computers]]
[[Category:Computer-related introductions in 1950]]
[[Category:1950 in California]]
[[Category:Science and technology in Greater Los Angeles]]