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Tully Machine Restoration - The National Museum of Computing Videos for Engineers
In the news recently was restoration to operational condition a Tunny code-breaking machine from the World War II era. It is part of the collection of calculating machines on display at the UK's National Museum of Computing, located in the renowned Blechley Park complex. Tunnys were used to decipher messages generated on the Lorenz SZ42 enciphering machines and sent from Hitler to his generals. Work was at a fever pitch in the days running up to the D-Day invasion. Keep in mind that the computers did not crack the code, they were for rapid deciphering of the volumes of messages sent daily. Restoration work on Tunny was performed by a team led by computer conservationists John Pether and John Whetter. "As far as I know there were no original circuit diagrams left. All we had was a few circuit elements drawn up from memory by engineers who worked on the original," per Mr. Pether. One of the original electrical designers, Sid Broadhurst, reportedly left an envelope filled with his engineering sketches sitting in the building's bathroom during the time when many of the machines were being dismantled. British Telecom (BT) engineers helps by providing expertise and a source of spare parts. I could not find a reference as to how many valves (tubes, to us Yanks), relays, switches, and feet of wire were used, but according to one source, a requirement for the project was that parts count be kept to a minimum in order to assure that it would be operational before the war was over - in favor of the Germans! Here is a really good write-up on the Colossus project that talks about Tully machines that includes detail on how the codes were cracked.