The rebuilding of Colossus at Bletchley Park

Rebuilding the Colossus Mk2 computer used in code breaking during World War II has been particularly difficult and challenging - almost nothing remained of the original machines. The original drawings and nearly all the circuit diagrams had been destroyed. Then, too, what Colossus actually did was kept secret until recently. These difficulties have been gradually resolved, however. The result? A working example of early electronic computer designs at its innovative best.