viewpoints VDOI:10.1145/1562164.1562180 David P. Anderson Interview An Interview with Maurice Wilkes Maurice Wilkes, the designer and builder of the EDSAC—the first computer with an internally stored program—reflects on his career. RESENTED HERE ARE excerpts What was your role? from an interview with Sir The university took me on as the boy Maurice Vincent Wilkes, the who did the work! Analog computers developer of the Electronic were much in the air then and a differ- Display Storage Automatic ential analyzer was ordered. We were PCalculator (EDSAC), microprogram- starting up this mathematical labora- ming, symbolic labels, macros, and tory when I received an invitation to subroutine libraries. Wilkes, the 1967 join in the war effort working on radar. ACM A.M Turing Award recipient and Of course, I didn’t know the exact na- winner of the ACM lifetime member- ture of the work at the time of the invi- ship award, is a former member of tation but I was one of a small group of Olivetti’s Research Strategy Board people from the Cavendish who were and an emeritus professor at the Uni- let into the secret. versity of Cambridge Computer Labo- ratory in the U.K. David P. Anderson, Who was it that told you? Principal Lecturer in the History of It was [Robert] Watson-Wattb himself at Computing at the School of Creative the Air Ministry. So, I went off to do that, Technologies, University of Ports- deserting Lennard-Jones very ungrate- mouth, U.K., conducted the interview fully because he’d got it all fixed up. with Wilkes, 96, earlier this year. How did Lennard-Jones When did you first get react to losing you? involved with computers? Who was leading that activity? He didn’t mind—I went off anyway. Well, you’ve got to realize that although We had here [John] Lennard-Jonesa When I came back after the war, in Sep- there were no digital computers in the who was a great pioneer of structural tember 1945, I found myself tempo- immediate pre-war period, there was chemistry. And he and his small group rarily, but later permanently, head of a lot of digital computing. The impor- of very able people showed that in the Mathematical Laboratory. tance and power of it was beginning to spite of the computational bottleneck be recognized. you could, in fact, achieve quite signifi- How much latitude did you The actual computing was then on cant results. Lennard-Jones was a man have in deciding the priorities desk machines with people to work of much vision and he was successful of the laboratory? them, mostly research students, but pro- persuading the university to establish As head of the laboratory I didn’t have fessional computers were beginning to a computing laboratory, which was to ask people if I could do things. The SON MP O be employed for organizations such as initially called a mathematical labo- overall terms of reference were to de- H T the army, for calculating range tables ratory. It was Lennard-Jones who gave velop mathematical methods and ILL B Y or firing tables as they were called in me my first opportunity to get practi- equipment for doing computation. So America. That was all beginning to cal experience of computing. that was all fine. As I had been doing GRAPH B O grow up. Cambridge was a very lively T O PH example of this digital computing. a Sir John Edward Lennard-Jones (1894–1954) b Sir Robert Alexander Watson-Watt (1892–1973) SEPTEMBER 2009 | VOL. 52 | NO. 9 | COMMUNICATIONS OF THE ACM 39 viewpoints radar I didn’t know anything about the stored-program computer? day we did the first program and we’d what was going on with mathematical No, John Von Neumann wrote a report all got little programs ready to run. machines but I soon began to learn. on behalf of the group and [Leslie] Comrieg was given a copy in America How was computer development Did you have any help with your and he showed it to me. He lent it to viewed at Cambridge? education in computing machinery? me and I sat up all night reading it, so Oh I don’t know, I always like to make a I learned a great deal from [Douglas] it wasn’t the first time. joke and say that they thought we were Hartreec who was in touch with Ameri- mad and if, at a cocktail party, you en- can people and one day I had a tele- How did Comrie come to larged on your enthusiasm you would gram out of the blue from the Moore have a copy of the report? find people moving away from you! School at Philadelphia asking me to go They gave copies away to people who You see, I never tried to do any pros- to a course. I got there with great diffi- visited. Comrie’s copy is now in the li- elytizing, I simply built a computer. culty as crossing the Atlantic in those brary of the Computer Laboratory. days was no simple matter. I missed Did you have a clear sense the early part of the course. What did you do next? from the start of who your The first thing to do was to make sure users were likely to be? Did that cause you any an ultrasonic memory would work and They were all around me, they were serious difficulties? we did that by January 1947 and then we students who didn’t like spending No, I had got a singular set of qualifica- went ahead. weeks, or a week, or more computing. tions because I had done some comput- They rushed at a computer, even an ing as a student. I was one of the people This was quite a departure from unsatisfactory experimental one, as that worked a hand-operated calculating the pre-war work of the laboratory. EDSAC was to begin with. And it was machine. I was a thoroughly qualified Did you need any special through those students that the idea electronics person having done ham ra- permission to start this work? spread. They went to their supervisors dio and all that sort of thing. I had the Cambridge is a very strange place, and said “Look what I’ve done.” The mathematical background insofar as it there are little departments like mine, supervisors were duly impressed and was necessary for computing. and big ones like the Cavendish. But before very long important people in [John Presper] Eckertd and [John] from the administrative point of view Cambridge were saying that comput- Mauchlye were the instructors and they are on a level. That meant I didn’t ers were important. It was very low- they put me absolutely and fully in the have to ask anybody or make any pro- key, bottom-up, students-upward. picture. I heard them talking about posals. I was able to just go ahead and That’s not a bad way for ideas to stored-program computers—people do it. There were some funds that went spread. say the Von Neumannf computer, it’s with the lab in effect and I guessed that really the Eckert-Von Neumann com- more funds would become available in Did you have any concerns puter and I thought I might have a shot due course. about how the computer-building at building one. work of the laboratory would Did you have a large staff be funded going forward? Was that the first time that you at your disposal? Well, I assumed it would all happen. We had encountered the notion of No, no; very small. Most projects—in were a very low-cost outfit because we industry and university—depend on a didn’t have a lot of the mathematicians c Douglas Rayner Hartree (1897–1958) small handful of three or four people and people on the payroll for the sake d John Presper Eckert Jr. (1919–1995) and we had less than that to provide of the money and I was in 100% charge, e John William Mauchly (1907–1980) the drive. There were a lot of people which made it very easy. f John von Neumann (1903–1957) who were paid on the funds, math- ematicians and other hangers-on and Am I correct in thinking that there were also a number of assistants. the initial capital budget or the Although there were We had instrument makers and elec- laboratory in 1936 was around tronic people on the assistant level. £10,000? no digital computers But I was the one who brought all the Yes. in the immediate information about computers into it so there was no argument with me you That was a very large pre-war period, see; it all came from me. I had a very sum at the time. there was a lot of loyal team and so we went ahead. It was. Lennard-Jones was a man of enormous vision and although analog digital computing. How long was it before you computers were in the air the labora- achieved some success? tory was not biased toward analog com- The EDSAC began to work in the sum- puters. We could drop them as soon as mer of 1949 on May 6th. That was the it appeared that they didn’t work out and I could go ahead and build a stored- g Leslie John Comrie (1893–1950) program computer. 40 COMMUNICATIONS OF THE ACM | SEPTEMBER 2009 | VOL. 52 | NO. 9 viewpoints That must have been a very er and we both got the highest honors liberating environment you could.