All plans to the Colossus were destroyed for secrecy, but this is as close as anyone can get. It still uses tubes and a paper tape reader, and so it is still, uh, colossal. A standard COTS personal computer will be programmed to emulate the Colossus, and decryption times will be compared.
Last Updated: Thursday, 15 November 2007, 14:59 GMT
Colossus cracks codes once more
By Mark Ward
Technology Correspondent, BBC News website
For the first time in more than 60 years a Colossus computer is cracking codes at Bletchley Park.
The re-built Colossus will be put to work on intercepted radio messages transmitted by radio amateurs in Paderborn, Germany that have been scrambled using a Lorenz SZ42 machine - as used by the German high command in wartime.
Speaking to the BBC, Andy Clark, one of the founders of the Trust for the National Museum of Computing, said radio problems had stopped the challenge getting under way on time.
"The radio path has not been particularly good between Germany and here," he said. "We are at a bad point in the sunspot cycle."
Signals had improved throughout the day, he added, and he hoped to get 100% of the ciphertext - the code - through soon.