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Rebuild of 1944 Colossus MK 2 Computer


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This was used to find the 12 wheel settings on a German Lorenz cipher machine which was used to encipher an intercepted German teleprinter message.
The intercepted message was punched onto paper tape in the teleprinter code and loaded as an endless loop onto the 'bedstead' on the right hand side of Colossus. It is then read optically at 5,000 characters per second as data going into Colossus. Colossus the uses its 2,500 valves and switched programs to try possible wheel starts, looking for the maximum score that appears on the lamp panel on the left had side of colossus. When the highest score has been found it is printed on the typewriter together with wheel setting it has found. When all 12 wheel positions have been found another machine called Tunny is then used to decipher the message. It took around 8 hours to find all 12 wheel setings.

20th May 2009 by Diane Earl


Key Stages:
Key Stage 2, Key Stage 3, Key Stage 4, Key Stage 4+

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National Education Network
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