National Physical Laboratory

Turing's time at NPL

Alan Turing began work on the design of an electronic digital stored-program computing machine in 1945, which would later become the ACE (the name Automatic Computing Engine, or ACE, was actually devised by John Womersley. He joined NPL in October 1945, and continued his work on the logical and practical design of this machine).


No doubt a complete genius, but the antithesis of an engineer. He had brilliant ideas, but as to getting the machine working, he was a positive disadvantage.

Donald Davies

In early 1946, the proposal for the ACE computer was finished and, after it was presented and discussed at an Executive Committee meeting on the 19th March, the Committee then ‘resolved unanimously to support the proposal with enthusiasm’. Unfortunately, at the time NPL did not have the talent or the resources to turn Turing’s proposed machine into reality. Although it was considered as a high-priority project within the Mathematics Division, there was nothing like the appropriate amount of resources available.

Importantly for the eventual development of the ACE, Jim Wilkinson and Michael Woodger were hired in 1946 as Turing’s assistants. They helped to modify and improve the logical design of the ACE and the programming work was expanded, with library routines written for mathematical functions such as multiplication and square root. However, the lack of work on the hardware itself did not improve until 1947, when Harry Huskey joined Turing’s group.

It was Huskey who was instrumental in getting the project to the next stage: he suggested to Womersley that a prototype should be built. Work soon started on a prototype that became known as the ‘Test Assembly’, created both to prove the feasibility of the various machine parts and to carry out actual calculations.

The initial ACE team was completed in September 1947 when Edward Newman arrived at NPL, as a specialist in the pulse techniques needed for the digital circuits, as well as Gerald Alway and Donald Davies.

However, soon after this, Charles Galton Darwin – the Head of NPL at the time – decided that work on the Test Assembly should stop, and given the lack of real progress up until that point, Turing decided to take a year’s sabbatical at Cambridge for half pay from NPL. However, part way through this year, Turing accepted a position at Manchester University, despite this breaking the terms of his sabbatical from NPL.

The world’s first working computer, built at Manchester, ran its first program on 21 June 1948. Over two years later, the Pilot ACE was ready to be demonstrated to the public, a more compact and universal computer that paved the way for the larger ACE computer and NPL’s other achievements in the field of computing.  

Last Updated: 9 Mar 2012
Created: 8 Feb 2012


Please note that the information will not be divulged to third parties, or used without your permission