That must have been a very
in which to work?
Very. Yes, it was a very responsible one.
I mean no one else in the laboratory
was sure that it was going to work but I
was the one who could see it first. And
so you see, we then had an enormous
advantage. This is what really gave us
the edge. Because quite a number of
these computers, especially the one in
Manchester, were beginning to work at
the same time. But they all had to hire
an engineer to build a computer for
them but that wasn’t the case with me.
I was fully qualified on both sides.
I got a group of students working on
programming before the computer
was running and so we could make a
very quick and rapid transition to the
user side and that was where we got the
er and we both got the highest honors
you could. So that was all right.
He was a real mathematician except
that he only learned one little bit of
mathematics and then didn’t learn any
more. He was no practical organizer
and, well, if you had Turing around in
the place you wouldn’t get it going.
could you say a little about
the different contributions
mathematicians and engineers
made to early attempts to
build computers? Was there
any tension between them?
PHo ToGRAPH CoPyRIGH T CoMPUTER LABoRAToRy, UnIVERsI Ty oF CAMBRIDGE. REPRoDUCED By PERMIssIon
Well, of course. Mathematicians
weren’t particularly well qualified.
They’d all done a bit of numerical
analysis but it wasn’t the same as digital computing. I think perhaps tension
arose from entirely different backgrounds. Take the question of Boolean
algebra. Mathematicians often write
and speak as though Boolean algebra
and mathematical logic was at the basis of computing but it wasn’t that
way at all. The mathematicians did not
understand switching really, electronic
switching; the engineers did.
Mathematicians, when it was pointed out to them, that Boolean algebra
modeled electronic switching at once
understood and because they could understand digital switching to a certain
degree by understanding mathematical
logic, they assumed that everyone would
look at it that way.
Whereas engineers, when they
were first told about Boolean algebra,
thought “What a daft idea this all is!”
and it was only later when Shannon told
them about the connection that they
saw any use for Boolean algebra.
But there wasn’t any use. Boolean
algebra has no time element to it and
while it is good for shaking up a bit of
complex logic we didn’t have complex
logic. We all had very simple logic in
the early days. Eckert is on record somewhere saying that he looked at Boolean
algebra but it didn’t seem to him to be
useful. None of the practical people
made much use of Boolean algebra but
it was regarded as absolutely essential
to the mathematicians. But there was a
tension between them that is perfectly
m.V. Wilkes during eDSac i construction;
eDSac i became operational in 1949.
Did that give rise to any problems
at cambridge or elsewhere?
Of course so many of the physicists
of the period had been through the
mathematical tripos that was one of
its strengths. But not all of them, many
Cavendish people and supervisors like
[John Ashworth] Ratcliffeh had no understanding of mathematics.
I was ensconced in the four walls
of a computer laboratory and I never
counted myself as a mathematician.
Von Neumann, of course, rather despised engineers. He got on with them
all right but I don’t think he regarded
them as important for such matters as
having credit for what they were doing.
[Alan] Turingi was an exact contemporary of mine and that means that I
don’t have to regard him as a great man
because you don’t regard your contemporaries as great men. I don’t remember him very clearly from the undergraduate days but he was certainly in
the class and we took the tripos togeth-
That certainly wasn’t a
problem with the eDSac.
No, I mean we just barged ahead on
the EDSAC and the rule was that if
you had got something that would
work you didn’t spend another hour
on making it simpler or cheaper, you
went ahead with it.
It demanded very strict discipline
and keeping your eye on the ball. There
were all sorts of interesting things to
follow up but we resisted them.
We concentrated on the one objective with no demonstrations on
the way. We didn’t need to show that
the ultrasonic memory would work.
I mean when the electronics end,
it was working that was sufficient.
Whereas, you see, at Manchester
they had an electrostatic storage
depending on quantum theory and
they had to be very sure that it would
work. It was [Tom] Kilburn’sj idea
to build a ‘Baby’. He was able to do
it. Validating the memory was what
the Baby was all about. It was absolutely essential because they had to
validate it not for themselves but for
I wasn’t troubled with sponsors.
Somehow the money came.
To what extent would you say
that the work of [charles]
Babbagek was significant in
shaping the early development
of stored-program computers?
I didn’t know anything about Babbage.
People started writing letters to the
Times and Hartree got interested and I
remember him coming into our building with a copy of Babbage’s memoirs
in his hand. It was Hartree who got
me interested in Babbage. Of course,
Babbage never had the concept of the
stored program, instructions being
coded as numbers; Babbage certainly
wasn’t influencing me.
h John Ashworth Ratcliffe (1902–1987)
i Alan Mathison Turing (1912–1954)
j Tom Kilburn (1921–2001)
k Charles Babbage, FRS (1791–1871)