contributed articles

ALAN TURING IS often praised as the foremost figure in the historical process that led to the rise of the modern electronic computer. Particular attention has been devoted to the purported connection between a “Universal Turing Machine” (UTM), as introduced in Turing’s article of 1936, 27 and the design and implementation in the mid-1940s of the first stored-program computers, with particular emphasis on the respective proposals of John von Neumann for the EDVAC30 and of Turing himself for the ACE. 26

In some recent accounts, von Neumann’s and Turing’s proposals (and the machines built on them) are unambiguously described as direct implementations of a UTM, as defined in 1936. Most noticeable in this regard are the writings of Jack Copeland and his collaborators, as stated in the following example: “[The] essential point of the stored-program computer is that it is built to implement a logical idea, Turing’s idea:

the universal Turing machine of 1936.” 18 This statement is of particular interest because, in his authoritative biography21 of Turing (first published 1983), Hodges typically follows a much more nuanced and careful approach to this entire issue. For instance, when referring to a mocking 1936 comment by David Champernowne, a friend of Turing, to the effect that the universal machine would require the Albert Hall to house its construction, Hodges commented that this “was fair comment on Alan’s design in ‘Computable Numbers’ for if he had any thoughts of making it a prac- Turing’s

Pre-War Analog
Computers:
The Fatherhood
of the Modern
Computer
Revisited
DOI: 10.1145/3104032
Turing’s machines of 1936 were a purely
mathematical notion, not an exploration of
possible blueprints for physical calculators.
BY LEO CORRY
key insights

˽ There is no straightforward, let alone deterministic, historical path leading from Turing’s 1936 ideas on the Universal Machine to the first stored-program electronic computers of the mid-1940s.

˽ Turing’s own pre-war ideas on the Universal Machine were not intended as a possible blueprint for the actual construction of physical automatic calculating machines.

˽ Turing’s personal interaction with von Neumann while at Princeton had little impact, if at all, on the later involvement of both men on the design and construction of the early stored-program computers, beginning in the mid-1940s.