Editing Automatic Computing Engine (section)

== Pilot ACE ==
{{main|Pilot ACE}}
Turing's colleagues at the NPL, not knowing about Colossus, thought that the engineering work to build a complete ACE was too ambitious, so the first version of the ACE that was built was the [[Pilot ACE|Pilot Model ACE]], a smaller version of Turing's original design. Turing's assistant, [[James H. Wilkinson|Jim Wilkinson]], worked on the logical design of the ACE and after Turing left for Cambridge in 1947, Wilkinson was appointed to lead the ACE group.<ref>{{cite web |url=https://www.npl.co.uk/famous-faces/jim-wilkinson |title= Jim Wilkinson led the team that built the Pilot ACE.|publisher=National Physics Laboratory |access-date= 1 October 2019}}</ref> The Pilot ACE had fewer than 1000 [[vacuum tube|thermionic valves]] (vacuum tubes) compared to about 18,000 in the [[ENIAC]].<ref>''The ACE test assembly'', H.&nbsp;D. Huskey, in Copeland (2005).</ref> It used [[delay-line memory|mercury delay lines]] for its main memory. Each of the 12 delay lines was 5&nbsp;feet (1.5&nbsp;m) long and propagated 32 instructions or data words of 32&nbsp;bits each. This ran its first program on 10 May 1950, at which time it was the fastest computer in the world; each of its delay lines had a throughput of 1&nbsp;Mbit/s.<ref>''Programming the Pilot ACE'', J.&nbsp;G. Hayes. In Copeland (2005).</ref>

The first production versions of the Pilot ACE, the [[English Electric DEUCE]], of which 31 were sold, were delivered in 1955.{{sfn|Copeland|2012|pp=4,164,327}}