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Turing's Influence on Computer Construction is Overestimated

Herbert Bruderer

What marks did Turing leave behind?

  • Post Office Research Station, Dollis Hill (London Northwest)
    The Colossus vacuum tube computer (1943) was built to decode the secret messages of the German Lorenz cryptographic machine. The person responsible was Thomas Flowers. Although the Colossus remained secret until 1975, this machine influenced the efforts at the University of Manchester. Alan Turing did not participate in the development of the Colossus.
  • National Physical Laboratory, Teddington (London)
    In 1945, Alan Turing designed a stored program vacuum tube computer with the name Ace for John Womersley. However, delays ensued with its construction (Pilot Ace, 1950) (see Fig. 1). The disillusioned Turing left before its completion for the University of Manchester.
  • Cambridge University
    Maurice Wilkes was given a brief insight into the pioneering work on the von Neumann computer (1945) by Douglas Hartree. This report came about in connection with the Eniac electronic computer. A visit to the lecture series at the University of Pennsylvania in Philadelphia (1946) was the inspiration for his resolve to build a computer. This resulted in the Edsac stored program vacuum tube machine of 1949.
  • University of Manchester
    In Bletchley Park, Max Newman recognized the capabilities of digital computers. In 1945, he proposed that the University of Manchester should develop an electronic computer and pointed out the existence of the Colossus. The stored program Manchester Baby, built by Frederic Williams and Thomas Kilburn, first saw the light of day in 1948. Kilburn had attended lecture series of Wilkinson and Turing on computer design in 1946/47. The Manchester experimental computer operated initially in June 1948. Alan Turing only came to the University of Manchester in September 1948, by which time the project was well underway.

Fig. 1: The Pilot Ace. Alan Turing designed the Automatic computing engine (Ace)
at the National Physical Laboratory in London.
The trial machine was finished in 1950.
The Pilot Ace is one of the few surviving electronic digital computers from the early days.
Credit: Science Museum, London/Science & society picture library



The groundbreaking work on the (universal) Turing machine was published in 1936/37. From this theoretical model to Turing's design of the Ace vacuum tube computer (1945), several years had passed. The plugboard-controlled Colossus (1943) was not a stored program machine. It appears that Wilkes only became aware of the importance of future-oriented digital computers by way of a detour through the U.S.

The Ace reveals the direct influence of Turing. In Manchester, where he drafted the specifications for the input-output unit and wrote the programming manual, his hand is less apparent. The stored program machines constructed in Cambridge and Manchester reflect the von Neumann architecture. Turing probably had little influence on computer construction. Even with the British stored program machines, with the exception of the Ace, he contributed little or nothing at all. At least in the beginning, the builders of the first relay and vacuum tube computers (Aiken, Atanasoff, Eckert, Lebedev, Mauchly, Stibitz, and Zuse) were not aware of Turing's pioneering concepts. With the exception of Lebedev, their early machines were not stored program computers.



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Herbert Bruderer (; is a retired lecturer in the Department of Computer Science at ETH Zurich and a historian of technology.


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