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himself. He might well be called the midwife, perhaps, but he firmly emphasized to me, and to others I am
sure, that the fundamental conception is owing to Turing - insofar as not anticipated by Babbage, Lovelace, and
others. In my view von Neumann's essential role was in making the world aware of these fundamental con-
cepts introduced by Turing and of the development work carried out in the Moore school and elsewhere.
11
And in 1946, von Neumann wrote to his friend Norbert Wiener of “the great positive contribution of
Turing . . . one, definite mechanism can be 'universal.'”
12
Some of the early pioneers of computers did not recognize that they were, in essence, building a vari-
ant of a universal Turing Machine. In 1956 Howard Aiken said:
[If ] it should turn out that the basic logics of a machine designed for the numerical solution of differential
equations coincide with the logics of a machine intended to make bills for a department store, I would regard
this as the most amazing coincidence I have ever encountered.
13
Alan Turing himself, in contrast with Howard Aiken's remarks, said in 1950:
This special property of digital computers, that they can mimic any discrete state machine, is described by
saying that they are universal machines. The existence of machines with this property has the important con-
sequence that, considerations of speed apart, it is unnecessary to design various new machines to do various
computing processes. They can all be done with one digital computer, suitably programmed for each case. It
will be seen that as a consequence of this all digital computers are in a sense equivalent.
14
In 1945 Turing produced a report for the construction of his ACE Automatic Computing Engine. Compared to
von Neumann's EDVAC Report, which “is a draft and is unfinished,” the ACE Report “is a complete descrip-
tion of a computer, right down to the logical circuit diagrams.” In contrast to the computer designs based on
the EDVAC ideas - which were focused on delivering fast numerical calculations - Turing's design recognized
the full power of digital computers as all-purpose machines, capable of manipulating symbols and playing
chess as well as performing numerical operations. To characterize these designs as merely embodying the
“stored-program concept” is to underappreciate the breadth of Turing's vision - of which von Neumann was
well aware.
Turing and Church
In April 1936, Turing had just delivered his paper to Max Newman, much to Newman's surprise.
Newman read the paper and realized the significance of Turing's work. He encouraged Turing to publish the
paper in the
Proceedings of the London Mathematical Society
. As Turing was tidying up his paper for publication,
in mid-May Newman received a copy of Church's paper. Since the subject matter of the two papers had much
overlap and Church had priority in terms of publication, there was some doubt as to whether Turing's paper
could be published. Newman wrote to the editor of the journal:
I think you know the history of Turing's paper on Computable numbers. Just as it was reaching its final state
an offprint arrived, from Alonzo Church of Princeton, of a paper anticipating Turing's results to a large extent.
I hope it will nevertheless be possible to publish the paper. The methods are to a large extent different, and
the result is so important that different treatments of it should be of interest.
15
Fortunately, the editor agreed, and Turing's paper with his machines was published in the
Proceedings
.
Newman also wrote to Church in Princeton:
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