radar I didn’t know anything about what was going on with mathematical machines but I soon began to learn.

 

Did you have any help with your education in computing machinery? I learned a great deal from [Douglas] Hartreec who was in touch with American people and one day I had a telegram out of the blue from the Moore School at Philadelphia asking me to go to a course. I got there with great difficulty as crossing the Atlantic in those days was no simple matter. I missed the early part of the course.

 

Did that cause you any serious difficulties?

No, I had got a singular set of qualifications because I had done some computing as a student. I was one of the people that worked a hand-operated calculating machine. I was a thoroughly qualified electronics person having done ham radio and all that sort of thing. I had the mathematical background insofar as it was necessary for computing.

[John Presper] Eckertd and [John] Mauchlye were the instructors and they put me absolutely and fully in the picture. I heard them talking about stored-program computers—people say the Von Neumannf computer, it’s really the Eckert-Von Neumann computer and I thought I might have a shot at building one.

 

Was that the first time that you had encountered the notion of

c Douglas Rayner Hartree (1897–1958) d John Presper Eckert Jr. (1919–1995) e John William Mauchly (1907–1980) f John von Neumann (1903–1957)

although there were
no digital computers
in the immediate
pre-war period,
there was a lot of
digital computing.

the stored-program computer? No, John Von Neumann wrote a report on behalf of the group and [Leslie] Comrieg was given a copy in America and he showed it to me. He lent it to me and I sat up all night reading it, so it wasn’t the first time.

 

how did comrie come to have a copy of the report? They gave copies away to people who visited. Comrie’s copy is now in the library of the Computer Laboratory.

 

What did you do next? The first thing to do was to make sure an ultrasonic memory would work and we did that by January 1947 and then we went ahead.

 

This was quite a departure from the pre-war work of the laboratory. Did you need any special permission to start this work? Cambridge is a very strange place, there are little departments like mine, and big ones like the Cavendish. But from the administrative point of view they are on a level. That meant I didn’t have to ask anybody or make any proposals. I was able to just go ahead and do it. There were some funds that went with the lab in effect and I guessed that more funds would become available in due course.

 

Did you have a large staff at your disposal? No, no; very small. Most projects—in industry and university—depend on a small handful of three or four people and we had less than that to provide the drive. There were a lot of people who were paid on the funds, mathematicians and other hangers-on and there were also a number of assistants. We had instrument makers and electronic people on the assistant level. But I was the one who brought all the information about computers into it so there was no argument with me you see; it all came from me. I had a very loyal team and so we went ahead.

 

how long was it before you achieved some success? The EDSAC began to work in the summer of 1949 on May 6th. That was the

 

g Leslie John Comrie (1893–1950)

day we did the first program and we’d all got little programs ready to run.

 

how was computer development viewed at cambridge?

Oh I don’t know, I always like to make a joke and say that they thought we were mad and if, at a cocktail party, you enlarged on your enthusiasm you would find people moving away from you!

You see, I never tried to do any proselytizing, I simply built a computer.

 

Did you have a clear sense from the start of who your users were likely to be? They were all around me, they were students who didn’t like spending weeks, or a week, or more computing. They rushed at a computer, even an unsatisfactory experimental one, as EDSAC was to begin with. And it was through those students that the idea spread. They went to their supervisors and said “Look what I’ve done.” The supervisors were duly impressed and before very long important people in Cambridge were saying that computers were important. It was very low-key, bottom-up, students-upward. That’s not a bad way for ideas to spread.

 

Did you have any concerns about how the computer-building work of the laboratory would be funded going forward? Well, I assumed it would all happen. We were a very low-cost outfit because we didn’t have a lot of the mathematicians and people on the payroll for the sake of the money and I was in 100% charge, which made it very easy.

 

am i correct in thinking that
the initial capital budget or the
laboratory in 1936 was around
£ 10,000?
Yes.

 

That was a very large sum at the time. It was. Lennard-Jones was a man of enormous vision and although analog computers were in the air the laboratory was not biased toward analog computers. We could drop them as soon as it appeared that they didn’t work out and I could go ahead and build a stored-program computer.