The Colossus series of electronic computers, considered by some to be the first fully electronic (as opposed to electromechanical) computer in the world, was originally a British state secret. This means that many documents pertaining to the computers, including original blueprints, were destroyed.

However, enough information remained for the Computer Conservation Society to later build a working almost-replica of a Colossus Mark II. A search of their website and cursory examination of the National Museum of Computing (where the Colossus rebuild is housed) showed no signs of any schematics for the Colossus Mark II, its reconstruction or in fact any Colossus at all. Where can these schematics be found?

  • 1
    The Colossus Mark II rebuild was a project of the Computer Conservation Society. None of the the schematics are published there, but someone associated with the CCS might remember where the plans went.
    – scruss
    Aug 7 '17 at 22:02
  • I'd contact The National Museum of Computing and see if they can tell you. If you Google "colossus schematics" you do get some results.
    – JeremyP
    Aug 8 '17 at 8:37
  • @scruss I don't think it is correct that it was a project of the Computer Conservation Society. Colossus is not listed as one of their projects but as an "Other Project".
    – JeremyP
    Aug 8 '17 at 8:38
  • @JeremyP It wasn't one of "their projects" but it was a project that they did. Certainly Tony Sale was involved. It also seems that the National Museum of Computing is very closely related to the Computer Conservation Society.
    – wizzwizz4
    Aug 8 '17 at 9:00
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    @wizzwizz4 When you say Tony Sale was involved, it was effectively his project. I have the privilege of having met him twice, once at BP where he gave us a demo of Colossus and once when he was giving a lecture at the Ipswich branch of the IEE about Enigma and Colossus.
    – JeremyP
    Aug 8 '17 at 9:04

I have found a high-level diagram of the structure of Colossus I. This cites an entry in the National Archives which has not yet been digitised but looks promising.

  • There's a direct path from 'The Forbin project' to SkyNet to -- oh, that's a loop. ;)
    – amI
    Feb 21 '19 at 10:35

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