Turing's 'Giant Brain': The Pilot Model ACE Story
As WWII ceased, according to the BBC, renowned mathematician Alan Turing ‘hid himself away’ in the Government Communications Centre of the Foreign Office (Hanslope Park). Here in the Buckinghamshire countryside he put together his design of an electronic stored program computer.
Animated Journey from Bletchley Park to Hanslope Park (2021) by The National Museum of ComputingThe National Museum of Computing
Setting the Scene
Hanslope Park (red pin) was situated just a few miles from the nerve centre of the British codebreaking operation, Bletchley Park (blue pin), where Turing had conducted his groundbreaking work as a cryptologist during the war.
Electronic Discrete Variable Automatic Computer (EDVAC)
At the University of Pennsylvania in 1945, a team of engineers/mathematicians published a remarkable report on EDVAC for the US Army. A universal, stored-program electronic computer, EDVAC applied high-speed automatic digital calculations to a diverse selection of problems.
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'On Computable Numbers'
Aged 33 years, Turing took up a post at the National Physical Laboratory (NPL), where he hoped to pursue his idea for a British version of EDVAC. As early as 1936 he had been contemplating his own theory of universal computation, published in ‘On Computable Numbers.’
A Foundation for Theoretical Computer Science
'On Computable Numbers' proposed a theoretical universal machine. However, it was not until well after Turing's death in 1954 that this publication was more widely recognised as one of the foundations of theoretical computer science.
The Pilot Model ACE (1) (1950) by The National Physical Laboratory (NPL)The National Museum of Computing
What is an Automatic Computing Engine (ACE)?
In 1946, Turing presented a detailed proposal for the construction of an Automatic Computing Engine (ACE). Turing’s vision was to build a computer to aid researchers, completing calculations in full and replacing the compartmentalised capabilities of other contemporary machines.
The Pilot Model ACE is Born
Initial progress was slow due to the complexity of Turing’s design. Harry Huskey, who arrived from the US in 1947, proposed a ‘pilot’ version of the machine. Working alongside Jim Wilkinson and Donald Davies, he was heavily involved in the construction of the Pilot Model ACE.
Turing Leaves the Project
By this point, Turing had left the NPL for a sabbatical, having become fed up with the slow progress and in disagreement with Huskey’s construction scheme. Tom Vickers became the operations manager for the Pilot ACE, picking up the ideas that Turing had left behind.
The Pilot Model ACE (2) (1950) by The National Physical Laboratory (NPL)The National Museum of Computing
The Pilot Model ACE is Completed
In Spring 1948, construction of the Pilot ACE got underway. It ran its first test program in May 1950 and came into regular operation in 1952. At the time it was the fastest computer in the world, using a third of the electronics compared to other contemporary British computers.
The Post Office, English Electric and the Bendix Corporation
Turing’s extraordinary technology, exhibited in the Pilot ACE, inspired the MOSAIC Computer, built by the Post Office and English Electric’s commercial computer, the DEUCE. On returning to the USA, Harry Huskey produced the Bendix G15 computer directly inspired by the Pilot ACE.
The Pilot ACE as a General Purpose Computer
Originally created in an experimental context, there was significant demand for the practical services of the Pilot ACE. Its capabilities were showcased at the NPL in December 1950. Its success in solving practical problems carried the Pilot ACE into public usage.
De Havilland’s Comet and Ordnance Survey
Some of the Pilot ACE's first assignments were performing a series of intricate calculations for de Havilland to resolve a deadly metal fatigue issue with their Comet airliner, the world’s first commercial jet, and analysing aerial photographs for Ordnance Survey maps.
The Full-Scale ACE Computer (1958) by The National Physical Laboratory (NPL)The National Museum of Computing
Powerful Potential
The Pilot ACE demonstrated the potential of what very powerful computers could achieve. In 1955, the NPL acquired a DEUCE and it gradually took over the workload of the Pilot ACE, which was shut down in 1956. In 1957, the full-scale ACE Computer came into operation.
Input and Output
The Pilot ACE was operated using a separate console adjacent to it. Input/output used a modified version of Herman Hollerith’s punched cards. Data is stored on a punched card using carefully placed holes, the location of which represents the information being recorded.
Processing
All computation/data manipulation executed by the Pilot ACE can be understood as a series of transfers of words from one of 32 possible sources to the equivalent number of destinations. Transfers can take place at a maximum rate of 16,000 per second.
Memory
For memory, the Pilot ACE used an ultrasonic acoustic signal sent back and forth through liquid mercury held in a long tube, known as a delay line. The Pilot ACE used 16 delay lines, amounting to a storage capacity of 256 32-bit numbers or words (equivalent to 9 decimal digits).
The Sieve of Eratosthene (Prime Number Sieve) (2021) by The National Museum of ComputingThe National Museum of Computing
Functions
The machine could carry out
arithmetic/some logical operations.
Trial instruction sequences used
to test the Pilot ACE included
finding the smallest prime factor
of any whole number less than
4 million, which involved up to
1,000 divisions, completed in less
than 7 seconds.
Brain (2021) by Daniel Roberts (Pixabay)The National Museum of Computing
Legacy
In his desire to build a small but very fast machine Turing developed ‘optimum programming’. The Pilot Model ACE was one of the earliest general purpose digital automatic electronic stored-program computers, referred to as ‘giant brains’ which captured the public imagination.
The Father of Computer Science and Artificial Intelligence
Turing’s theories anticipated the development of the modern computer, but not until after his death did his ideas start gaining more traction. Turing also delved into Artificial Intelligence; today, he is referred to as the father of Computer Science and Artificial Intelligence.
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