Tony Sale led the team that reconstructed a Colossus Mark 2 computer, which was completed in 2007 at Bletchley Park, near Milton Keynes, UK. Here he is seen describing how Colossus was used and a little about the rebuild.

The original Colossus was the world's first programmable digital computer. Colossus machines were used by the codebreakers at Bletchley Park during WW II to read encrypted messages and used valves (vacuum tubes) to perform the calculations. The machines were designed by engineer Tommy Flowers with Allen Coombs, Sid Broadhurst and Bill Chandler.

The Colossus machines were used to help decrypt German messages sent using the Lorenz S40/42 machines which, unlike Enigma, had 12 setting wheels. Colossus determined the starting positions for the wheels so that the Tunny machine (see separate video) could decrypt the message itself.

This video was recorded at Bletchley Park, near Milton Keynes in England. Please help keep this historic location alive by making a donation at bletchleypark.org; and support the Museum by visiting tnmoc.org