Editing Colossus computer (section)

{{Short description|Early British cryptanalysis computer}}
{{Distinguish|text=the fictional computer of the same name in the movie [[Colossus: The Forbin Project]]}}
{{Distinguish|text=the [[Colossus supercomputer]]}}
{{Use dmy dates|date=June 2020}}
{{Infobox information appliance
| name         = Colossus computer
| image        =  [[File:Colossus.jpg|300px]]
| caption      = A Colossus Mark 2 computer being operated by [[Women's Royal Naval Service|Wrens]].{{efn|The two operators have been variously identified as Dorothy Du Boisson (left), Elsie Booker, Vivian Vorster (left), Catherine Kennedy, (unknown) and Patricia Davis (right).{{citation needed|date=July 2018}}}} The slanted control panel on the left was used to set the "pin" (or "cam") patterns of the Lorenz. The "bedstead" paper tape transport is on the right.
| developer    = [[Tommy Flowers]], assisted by Sidney Broadhurst, William Chandler and for the Mark 2 machines, [[Allen Coombs]]
| manufacturer = [[Post Office Research Station]]
| type         = Special-purpose electronic digital programmable computer
| generation   = First-generation computer
| releasedate  = {{plainlist|
* Mk 1: {{Start date|1943|12|df=y}}
* Mk 2: {{Start date|1944|06|01|df=y}}}}
| discontinued = 1960
| unitsshipped = 12
| input        = [[Punched tape|Paper tape]] of up to 20,000 × 5-bit characters in a continuous loop
| media        = {{plainlist|
* [[Typewriter#Electric designs|Electric typewriter]] output
* [[Computer programming|Programmed]] using switches and plug panels}}
| power        = 8.5 kW{{efn|Based on what the National Museum of Computing state is the power consumption of the Colossus rebuild. In the absence of information to the contrary, the original is presumed to be similar.}}
| cpu          = Custom circuits using thermionic [[vacuum tube|valves]] and [[thyratron]]s. A total of 1,600 in Mk 1 and 2,400 in Mk 2. Also [[relay]]s and [[stepping switch]]es
| memory       = None (no [[Random-access memory|RAM]])
| display      = Indicator lamp panel
| dimensions   =
| weight       =
}}

'''Colossus''' was a set of [[computer]]s developed by British [[cryptanalysis|codebreakers]] in the years 1943–1945<ref name="tnmoc">{{cite web |title=Colossus |url=https://www.tnmoc.org/colossus |website=The National Museum of Computing |access-date=25 January 2021}}</ref> to help in the [[cryptanalysis of the Lorenz cipher]]. Colossus used [[vacuum tube|thermionic valves (vacuum tubes)]] to perform [[Boolean algebra (logic)|Boolean]] and counting operations. Colossus is thus regarded{{sfn|Copeland "Introduction"|2006|p=2}} as the world's first [[computer programming|programmable]], [[electronics|electronic]], [[digital electronics|digital]] computer, although it was programmed by switches and plugs and not by a [[stored-program computer|stored program]].{{sfn|Sale|2000}}

Colossus was designed by [[General Post Office]] (GPO) research telephone engineer [[Tommy Flowers]]<ref name="tnmoc"/> based on plans developed by mathematician [[Max Newman]] at the [[Government Code and Cypher School]] at [[Bletchley Park]].

[[Alan Turing]]'s use of probability in cryptanalysis (see [[Banburismus]]) contributed to its design. It has sometimes been erroneously stated that Turing designed Colossus to aid the [[cryptanalysis of the Enigma]].<ref>{{Citation | last = Golden | first = Frederic | title = Who Built The First Computer? |magazine=[[Time (magazine)|Time]] | volume = 153 | issue = 12 | date = 29 March 1999 |url=http://www.time.com/time/magazine/article/0,9171,990596,00.html|archive-url=https://web.archive.org/web/20060106193802/http://www.time.com/time/magazine/article/0,9171,990596,00.html|url-status=dead|archive-date=6 January 2006}}</ref> (Turing's machine that helped decode [[Enigma machine|Enigma]] was the electromechanical [[Bombe]], not Colossus.)<ref>{{Citation | last = Copeland | first = Jack | author-link = Jack Copeland | title = Colossus: The first large scale electronic computer | url = http://www.colossus-computer.com/colossus1.html#sdfootnote96sym|website=Colossus-computer.com|access-date = 21 October 2012}}</ref>

The prototype, '''Colossus Mark 1''', was shown to be working in December 1943 and was in use at Bletchley Park by early 1944.<ref name="tnmoc"/> An improved '''Colossus Mark 2''' that used [[shift register]]s to run five times faster first worked on 1 June 1944, just in time for the [[Normandy landings]] on D-Day.{{sfn|Flowers|1983|p=246}} Ten Colossi were in use by the end of the war and an eleventh was being commissioned.{{sfn|Flowers|1983|p=246}} Bletchley Park's use of these machines allowed the [[Allies of World War II|Allies]] to obtain a vast amount of high-level [[military intelligence]] from intercepted [[wireless telegraphy|radiotelegraphy]] messages between the [[Oberkommando der Wehrmacht|German High Command]] (''OKW'') and their [[Wehrmacht|army]] commands throughout occupied Europe.

The existence of the Colossus machines was kept secret until the mid-1970s.<ref>{{cite book|title=Who Broke the Wartime Codes? |url=https://books.google.com/books?id=mRprCwAAQBAJ&q=Bletchley+destroyed+Colossus+machines+and+plans&pg=PT59 |first=Nicola|last=Barber |date=21 December 2015 |publisher=Capstone |access-date=26 October 2017 |via=Google Books |isbn=9781484635599}}</ref><ref name=lorenz/>  All but two machines were dismantled into such small parts that their use could not be inferred. The two retained machines were eventually dismantled in the 1960s. In January 2024, new photos were released by [[GCHQ]] that showed re-engineered Colossus in a very different environment from the Bletchley Park buildings, presumably at GCHQ Cheltenham.{{sfn|GCHQ|2024}} A functioning reconstruction of a Mark 2 Colossus was completed in 2008 by [[Tony Sale]] and a team of volunteers; it is on display in [[The National Museum of Computing]] at Bletchley Park.<ref>{{cite web |title=coltalk_2 |website=Codesandciphers.org.uk |url=https://www.codesandciphers.org.uk/lorenz/pods/coltalk_2.html |access-date=26 October 2017}}</ref><ref name="auto">{{cite web |first=Martin |last=Campbell-Kelly |date=31 August 2011 |title=Tony Sale obituary |url=https://www.theguardian.com/theguardian/2011/aug/31/tony-sale-obituary |access-date=26 October 2017 |website=The Guardian}}</ref><ref name="The Colossus Computer">{{Citation |title=Colossus – The Rebuild Story |publisher=The National Museum of Computing |url=http://www.tnmoc.org/colossus-rebuild-story |archive-url=https://web.archive.org/web/20150418230306/http://www.tnmoc.org/colossus-rebuild-story |archive-date=18 April 2015 |url-status=dead |access-date=13 May 2017}}</ref>