National Physical Laboratory

The Pilot ACE computer

Pilot ACE computer

The Pilot ACE computer was based on the plans for the 'Test Assembly', the original prototype that the team had been working on before the NPL Director at the time called a halt to the project in 1947. It had a few improvements that the team had been working on, but the main difference was that between the plans for the Test Assembly and those for the Pilot Ace, Newman had arrived at NPL. With other experts, he would aid the electronic design and finally get the project off the ground.

By late 1950, the Pilot ACE was, despite technical quirks and unreliability, ready to show to the press and public. From the 29 November to 1 December, the machine was demonstrated, marking NPL as the fourth group in the world to achieve a working general-purpose stored-program computer.

What set Pilot ACE apart from its contemporaries was Turing's system of optimum coding - when the chosen program for the Pilot ACE had been created, the programmers also had to decide how to store each instruction in the memory so that the program could be carried out in the fastest time possible. Other computers at the time simply had the instructions stored at random in the memory.


Very handy for abstruse scientific calculations and industrial measurements - even for football pool permutations.

John Womersley

The Pilot ACE generated so much publicity and interest that the intended 'pilot', test machine was in demand for commercial computing services, and was soon upgraded further in order to improve its reliability and memory. Once it had been improved, it was housed in the Mathematics Division and used to solve a variety of problems, from differential equations and optical ray-tracing to optimum traffic signal settings and mathematical descriptions of the freezing of a slab of fish.

The Pilot ACE was so popular and widely used that a production version, with the improvements that had been slowly added to the Pilot ACE, was built. This was DEUCE, the computer used at both NPL and the Royal Aircraft Establishment from 1955. Once DEUCE was built and operating, the load on the Pilot ACE reduced and eventually, in June 1956, it was closed down for good.

Last Updated: 28 Oct 2014
Created: 8 Feb 2012


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