The computers that won the war: Bletchley Park's codebreaking equipment is rebuilt


The Tunny Gallery at the National Museum of Computing

Source:  Robert Dowell, TNMOC

The Tunny Gallery at the National Museum of Computing

In the Bletchley Park Testery, Bill Tutte used a few encrypted and decrypted messages to deduce the workings of the German’s Lorenz cipher machine, a device that he had never seen. His deductions were so accurate that the first Tunny machine was able to start decoding messages in 1942 using wheel settings laboriously found by hand, sometimes with the help of the sluggish and somewhat unreliable Robinson machines. In early 1944, the development of the Colossus computer provided Tunny with the wheel settings in a matter of hours and reduced the total job deciphering a message from several weeks to up to four days.


The Tunny Gallery, opened at The National Museum of Computing at Bletchley Park on 26 May 2011, tells the incredible story of the interception and decryption of German High Command radio teleprinter messages during World War Two. The gallery shows the entire wartime code-breaking process from intercept to decrypt and recognises the remarkable achievements of the men and women who contributed to the process in the 1940s. The centrepiece of the gallery is a fully functioning rebuild of a Tunny machine that produced the final decrypts of enciphered communications of the German High Command. The original Tunny, a British re-engineering of the then-unseen German Lorenz S42 cipher machine, was completed in 1942.

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