This the awesome British Bombe electro-mechanical codebreaking machine which only had one purpose: to determine the rotor settings on the German cipher machine “ENIGMA” during WW2.
The Bombe was a development of an original Polish “cryptologic bomb”: designed in 1938 by Polish Cipher Bureau cryptologist Marian Rejewski. Legendary “father of cybernetics” Alan Turing also was one of the original designers of this machine (together with Gordon Welchman), which succesfully emulated wheel-settings of ENIGMA during WW2.
Each of the rotating drums is a simulation of an individual Enigma rotor. ENIGMA had only four rotors, but without knowing the proper settings, it took twenty minutes for a Bombe to complete a run, going through all 456,976 possible setting combinations. “Different Bombes tried different wheel orders, and one of them would have the final correct settings. When the various U-boat settings were found, the Bombe could be switched over to work on German Army and Air Force three-rotor messages.”
To get a feel on how intense this machine crunched the numbers, here are some facts: the bottom commutator moved at 850 rpm (British machine has been only slightly slower), the machine itself was electromechanical, featuring the Amplifier Chassis, Thyratron Chassis (the machine’s memory), Motor Control Chassis and multitude switch banks, indexing through all potential wheel settings.