Colossus

At last - the secrets of Bletchley Park's powerful codebreaking computers. This is a history of Colossus, the world's first fully-functioning electronic digital computer. Colossus was used during the Second World War at the Government Code and Cypher School at Bletchley Park, where it played an invaluable role cracking enemy codes. Until very recently, much about the Colossus machine was shrouded in secrecy, largely because the codes that were employed remained in use by the British security ser