WWII Codebreaking and the First Computers, Malcolm A.H. MacCallum
COPERNICUS FESTIVAL, May 6-11, 2014, Kraków
http://www.copernicusfestival.com
This is the story of why and how the first computers came into being. They were built to assist British codebreaking during World War II, specifically to make possible automated codebreaking of the German teleprinter codes which the British called "Tunny". The story of Tunny is much less well-known than that of the Enigma machines. The General report on "Tunny" was published only in 2000 and some parts of the Tunny story are still classified. It has less Polish connection than Enigma, where three Polish mathematicians played a crucial role by breaking a pre-war version of the Enigma machine: Marian Rejewski, Henryk Zygalski and Jerzy Jerzy Różycki.
Like Enigma (where the UK built on the Polish work), the Tunny codes were broken by mathematicians at Bletchley Park, the wartime home of the UK's "Government Code and Cipher School". During the war Bletchley Park was called "Government Communications Headquarters" (GCHQ), so as to give only a vague idea of its purpose. After the war, that became the official name of the UK Government's signals intelligence agency.
Because the messages were of high strategic value, the breaking of Tunny was very successful although it decrypted many fewer messages than from Enigma. (27631 Tunny messages were intercepted and 13508 were broken.) As examples, Bletchley decrypted messages direct from Hitler himself in 1944, allowed the British to forewarn the Russians of the German attack around Kursk in July 1943, gave the Allies the German dispositions before D-Day, and showed them the value of the rather slow Italian campaign in tying down German forces.
Colossus - machine used for breaking Tunny code - deserves to be called the first computer, although it was not a general purpose computer, but a special purpose cryptographic device. So one has to choose qualifying adjectives a bit carefully. (Many histories say the American ENIAC was the first computer. This just reflects the British ability to keep a secret). Not all features of later machines were present in Colossus: for example it did not have electronically stored programs. But many were: for example, Tommy Flowers introduced the term Arithmetic-Logic Unit (ALU) for the core processing parts and Jack Good's experience with it led him to develop the idea of microprogramming. There is also an interesting comparison of Colossus with the first generation IBM PC.
Its first break of a message was on 5 February 1944. By the end of the war there were 10 Colossi. At the end of the war Churchill ordered the destruction of the Colossi. All but two Colossi were broken up and designs destroyed. The remaining two are alleged to have been kept in case the Russians started to use captured German Tunny machines: those Colossi were destroyed around 1960. Information about the machines' existence only emerged in the 1970s due to Brian Randell in particular. Photos were released in 1975, and Flowers was allowed to publish the hardware design of the first Colossus in 1983 (without the explanation of what it was used for). In 1996 the US published the information it had about the machines and, due to Donald Michie, the "General report on Tunny" was published in June 2000. The general report on the Testery's work is still classified. There is a working reconstructed Colossus at Bletchley Park, built by Tony Sale and a team of volunteers.
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Professor Malcolm AH MacCallum is a British cosmologist , astrophysicist and applied mathematician - an Emeritus Professor of Applied Mathematics at the Queen Mary University of London, Deputy President of the International Society on General Relativity and Gravitation, member of the London Mathematical Society, and a chairman of the advisory Board of Mathematics Department at University of York. His field of interests covers most aspects of classical non-Newtonian gravity theory as well as computer algebra applied to differential equations.