Note
Purpose and Origins:
Cryptanalysis: Colossus was designed to aid in the cryptanalysis of the Lorenz cipher, used by the German High Command.
Electronic Digital Computer: It used over 1,700 vacuum tubes (valves) to perform Boolean and counting operations.
World’s First Programmable Computer:
Colossus is often regarded as the world’s first programmable, electronic, digital computer. Although it was programmed using switches and plugs (not a stored program), it marked a significant leap in computing technology.
Design and Development:
Tommy Flowers, a General Post Office (GPO) research engineer, led the design based on plans by mathematician Max Newman at Bletchley Park. Alan Turing’s use of probability in cryptanalysis influenced Colossus’s design.
Operational Timeline:
Colossus Mark 1: The prototype was operational by December 1943 and used at Bletchley Park by early 1944.
Colossus Mark 2: An improved version that used shift registers for faster processing, operational by June 1944 (just before D-Day).
Impact and Intelligence Gathering: Colossus allowed the Allies to obtain vast amounts of high-level military intelligence from intercepted German radiotelegraphy messages. These messages were exchanged between the German High Command (OKW) and their army commands throughout occupied Europe.
Secrecy and Legacy:
The existence of Colossus was kept secret until the mid-1970s.
Most machines were dismantled into small parts to prevent inference. New photos of re-engineered Colossus were released by GCHQ in January 2024.
In summary, Colossus’s role in breaking the Lorenz cipher significantly contributed to Allied victory during World War II, and its pioneering work shaped the future of computing.