Turing's detailed computer scheme was drawn up in a
continuation of wartime spirit: as a plan that could be effected
immediately with the memory storage (cumbersome acoustic delay
lines, as used in radar) that was to hand. Turing knew that superior
technology would soon transform design: his emphasis was on speed in
every sense, and in the exploitation of the universal machine
concept. This meant, in particular, implementing arithmetical
functions by programming rather than by building in electronic
components, a concept different from that of the American-derived
designs.
The hardware design was short-term; but his prospectus for the
use of the machine was visionary. Turing projected a computer able
to switch at will from numerical work to algebra, codebreaking, file
handling, or chess-playing. Methods for handling subroutines
included a suggestion that the machine could expand its own programs
from an abbreviated form, ideas well ahead of contemporary American
plans. A later talk (February 1947) depicted a national computer
centre with remote terminals, and the prospect of the machine taking
over more and more of its own programming work. In 1947 his
Abbreviated Code Instructions marked the beginning of programming
languages. But not a single component of the ACE was assembled, and
Turing found himself without any influence in the engineering of the
project. The lack of cooperation, very different from the wartime
spirit, he found deeply frustrating.
From October 1947, the NPL allowed, or perhaps preferred, that he
should spend the academic year at Cambridge. Rather than publish
these fundamental principles of computing, he spent his time on new
study amidst the post-war renaissance of science, not in mathematics
or technology but in neurology and physiology. Out of this came a
pioneering paper on what would now be called neural nets, written to
amplify his earlier suggestions that a sufficiently complex
mechanical system could exhibit learning ability. This was submitted
to the NPL as an internal report, and never published in his
lifetime. Meanwhile the NPL made no advance with the construction of
the ACE, and as Turing's position fell back, other computer projects
at Cambridge and Manchester took the lead.
Indeed it was Newman, who had been the first reader of On
computable numbers, and in charge of the electronic breaking of
the 'Fish' ciphers, who was partly responsible for this. On his 1945
appointment to the chair of pure mathematics at Manchester
University, he had negotiated a large Royal Society grant for the
construction of a computer. Newman strongly promoted Turing's
principle of the stored-program computer, but unlike Turing,
intended no personal involvement with engineering. He conveyed the
basic principles to the leading radar engineer F. C. Williams, who
had been attracted to Manchester, and the latter's brilliant
innovation made possible a rapid success: Manchester in June 1948
had the world's first practical demonstration of Turing's computer
principle.
Although losing in the race to implement a universal machine, and
slow to communicate or compete in the game of scientific priority,
Turing ran very competitively in a literal sense. After the war he
developed his strength in cross-country running with frequent
long-distance training and top-rank competition in amateur
athletics. He would amaze his colleagues by running to scientific
meetings, beating the travellers by public transport, and only an
injury prevented his serious consideration for the British team in
the 1948 Olympic Games.
The return to Cambridge helped Alan Turing form an agreeable
circle of lasting friendships, particularly with Robin Gandy, who
began at this period to develop under Turing's influence and would
later inherit his mantle as a mathematical logician. Although never
secretive about his sexuality, he now became more deliberately
outspoken and exuberant, and all thoughts of comfort or conformity
were now left behind. A mathematics student at King's College,
Neville Johnson, became a lover.
