Bletchley Park

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Bletchley Park is an English country house and estate in Bletchley, Milton Keynes, that became the principal centre of Allied code-breaking during the Second World War. During World War II, the estate

The mansion in 2017

Bletchley's Polish Memorial, commemorating "the [prewar] work of Marian Rejewski, Jerzy Różycki and Henryk Zygalski, mathematicians of the Polish intelligence service, in first breaking the Enigma code. Their work greatly assisted the Bletchley Park code breakers and contributed to the Allied victory in World War II."

Stephen Kettle's 2007 Alan Turing statue

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Colossus computer

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Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves to perform Boolean and count

Bletchley Park

…and Stuart Milner-Barry. The team at Bletchley Park, 75% women, devised automatic machinery to help with decryption, culminating in the development of Colossus, the world's first programmable digital electronic computer. Codebreaking operations at Bletchley Park ended in 1946 and all information about the…

A Colossus Mark 2 computer being operated by Wrens. The slanted control panel on the left was used to set the "pin" (or "cam") patterns of the Lorenz. The "bedstead" paper tape transport is on the right.

A Lorenz SZ42 cipher machine with its covers removed at The National Museum of Computing on Bletchley Park

The Lorenz SZ machines had 12 wheels, each with a different number of cams (or "pins"). Wheel number 123456789101112 BP wheel name ψ1 ψ2 ψ3 ψ4 ψ5 μ37 μ61 χ1 χ2 χ3 χ4 χ5 Number of cams (pins) 434751535937614131292623

Cams on wheels 9 and 10 showing their raised (active) and lowered (inactive) positions. An active cam reversed the value of a bit (0→1 and 1→0).