Oral history of British science
Tootill, Geoff (Part 4 of 12). An Oral History of British Science.
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Computer Hardware; Electronics
Interviewee's home, Wokingham
Tootill, Geoff, 1922- (speaker, male)
Lean, Thomas (speaker, male)
Part 4: Describes development of the computer from when he arrived at Manchester: how it was built on Post Office racks: drawing up circuit diagrams of new units, standardising on eight valve units, production of chassis with valve holders. Remarks on TK designing eight valve circuits on the train from Dewsbury and GT designing them at home with parents in Oldham. [05:07] Detailed technical comments on designing a circuit. Remarks on role of the wireman and sketching out circuit diagrams. [09:00] Comments on Norman and Ida Fitzgerald, the wiremen, who wired up chassis from circuit diagrams and their level of technical skill and knowledge. [12:15] Clarification of the process of circuit production. Comments on errors and problems in the building of the computer. Detailed discussion of building up the computer unit by unit, testing as they went along. [16:47] Describes completion of the computer: entering data, seeing the computer had performed a computation, informing FCW of success. Remarks on the first programs for the basic Baby computer. Comments on the facilities and workings of the Baby and its subtracter and store.[19:43] Comments on programming: using data as instructions, jumping out of the middle of loop, restrictions of 32 line memory store. Comparison of his first program, to search for prime numbers, with that of TK, which performed successive divisions by subtraction, and their use in demonstrating the computer. [24:00] Describes process of programming Baby: instructions, accumulator, test facility. [26:35] Compares Manchester computer with the work of Charles Babbage, though not being aware of Babbage work in the 1940s, but suspecting FCW and TK were. Remarks on it being obvious how to build a computer. [29:40] Detailed comments on significance of Baby in proving that direct access memory could work, the benefits of direct access memory over delay lines, and programming with delay lines. Remarks on a programmer developing a rudimentary high level programming language. Comments on delay line machines not being wholly electronic. [33:20] Description of the the Post Office power supplies used, mentions role of MN, previously at Bletchley Park, in providing power supplies. [36:24] Describes computer laboratory in Manchester: dark, dirty, high ceilings, very warm. Mentions pollution entering through windows, but this not being a problem. [38:15] Discussion of Baby computer with aid of photograph from The Illustrated London News, June 25th 1949, with remarks on the use of program entry switches and the later installation of punched paper tape equipment. [43:34] Comments on teleprinter paper tape, relevance of working with five binary digits, use of teleprinter tape as a storage mechanism, re-perforator and tape readers. Further remarks on installation of paper tape equipment. [47:20] Detailed comments on Mersenne primes. Mentions Marin Mersenne and H. S. Uhler. Description of the computer's use in searching for Mersenne primes. Remarks on working overnight due to interference from electric trams and not finding any Mersenne primes with the target range. [52:52] Remarks on choice of Mersenne prime problem as a test of the computer's capability that involved limited input and output. Remarks on reading information from the CRT and choice of a small CRT size. [54:18] Comments on supply of components: Post Office racks courtesy of MN, electrical components from TRE stores as part of FCW arrangements with Ministry. Remarks on: combining trips to TRE for components with visits to his wife and son who were still in Malvern; quality of TRE component supply compared to other sources and on other computer projects. [56:50] Remarks on other computer development projects: National Physical Laboratory [NPL] and JHW, and Maurice Wilkes [MW] at Cambridge. Remarks on competition element to getting computer working first. Mentions Donald Booth at Birkbeck and magnetic drum storage. Remarks on GT's later attempt to build a demonstration computer at Shrivenham and his use of electronic teaching aids. Comments on visits to and from other computer development teams: visit of Ted A Newman from the NPL, where he worked with JHW, who GT had later contact with. [1.02:15] Comments on the dichotomy between mathematicians and engineers and their relationship. Comments on FCW wanting to limit MN's influence on the project, as he already had independent funds and component supplies. Remarks on MN's Royal Society grant being used years later to provide a computer laboratory and his interest in having a computer mathematical problems. Remarks on knowing about mechanical calculators. [1:07:10] Further comments on FCW' relationship with MN, MN's involvement with Mersenne prime program, MN giving a lecture to GT and TK on the subject and their writing a program for him. Comments on Alan Turing [AT] work on the Riemann zeta function and his transfer to Manchester to use the computer. Comments on FCW and TK having no time for AT, possibly due to his his homosexuality, of which GT was unaware, [1:11:46] and so left assisting AT to GT. Comments on TK's improved Mersenne prime program, Mersenne Express. Comments on learning of AT's casual approach to supervising his staff, from a friend in the maths department. Short story about AT asking him to find the errors in a huge binary multiplication table he had written by hand. [1:15:12] Remarks on AT's celebrity in the popular press and within mathematics, mentions a play about AT [Cracking the Code?] [1:16:48] Comments on Newman and AT not discussing their work at Bletchley Park: Short story about AT disguising his prior knowledge of five hole teleprinter code by pretending to learn it again, comments on Newman admitting he had good contacts with the Post Office, but how neither Newman or AT never admitted to knowing anything about binary numbers before Manchester. Mentions FCW may have known AT and Newman had been working on code breaking due to Newman's good post office contacts.
Life story interview with Geoff Tootill, computer engineer who was part of the team that built Baby, the world's first stored program computer.