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Issue No.04 - October-December (2004 vol.26)
pp: 38-45
B. Jack Copeland , University Of Canterbury
ABSTRACT
The British Colossus computer was one of the most important tools in the wartime effort to break German codes. Based on interviews and on recently declassified documents, this article clarifies the roles played by Thomas Flowers, Alan Turing, William Tutte, and Max Newman in the events leading to the installation of the first Colossus at Bletchley Park, Britain?s wartime code-breaking establishment, in December 1943.
INDEX TERMS
Turing, Flowers, Newman, Tutte, Bletchley Park, Lorenz Sz40/42, Tunny, Heath Robinson, Colossus, First Electronic Computer, Differencing, Turingery, Statistical Method
CITATION
B. Jack Copeland, "Colossus: Its Origins and Originators", IEEE Annals of the History of Computing, vol.26, no. 4, pp. 38-45, October-December 2004, doi:10.1109/MAHC.2004.26
REFERENCES
1. Colossus is described in T.H. Flowers, "The Design of Colossus," IEEE Annals of the History of Computing, vol. 5, no. 3, July— Sept. 1983, pp. 239-252.
2. J. Good, D. Michie, and G. Timms, General Report on Tunny, With Emphasis on Statistical Methods; in the National Archives (Kew, Richmond, Surrey), document reference HW 25/4 (vol. 1), HW 25/5 (vol. 2), 1945, p. 35. A digital facsimile ofGeneral Report on Tunnyis in The Turing Archive for the History of Computing; seehttp://www.AlanTuring.nettunny_report.
3. B.J.Copeland, ed., "Letters on Logic to Max Newman," The Essential Turing, Oxford Univ. Press, 2004, pp. 204-216.
4. A.M. Turing, "On Computable Numbers, with an Application to the Entscheidungsproblem," Proc. London Mathematical Soc., Series 2, vol. 42, 1936–1937, pp. 230-265.
5. or an account of Turing's life and work, see B.J. Copeland, ed., The Essential Turing, Oxford Univ. Press, 2004.
6. For more information about the ACE and the DEUCE, see B.J. Copeland, ed., Alan Turing's Automatic Computing Engine, Oxford Univ. Press, 2004.
7. The story of Tunny and the Bletchley attack is revealed in the recently declassified (2000) General Report on Tunny in Ref. 2. A digital facsimile of the complete report is available on the author's Web site at http://www.AlanTuring.nettunny_report.
8. The Tunny machine was manufactured by the Lorenz company, the first model bearing the designation SZ40 ("SZ" stood for "Schlüsselzusatzgerät," meaning "cipher attachment"). A later version, the SZ42A, was introduced in February 1943, followed by the SZ42B in June 1944 ("40" and "42"perhaps refer to years). The physical machine is described in section 11 of the General Report on Tunny and in D. Davies, "The Lorenz Cipher Machine SZ42," Cryptologia, vol. 19, 1995, pp. 517-539; the machine's function and use is described in sections 11, 94, et passim,General Report on Tunny.
9. M. Davis, The Universal Computer: The Road from Leibniz to Turing, Norton, 2000, pp. 174-175.
10. J.A.N. Lee, Computer Pioneers, IEEE CS Press, 1995, pp. 306, 671.
11. Ibid, p. 492.
12. E. Enever, Britain's Best Kept Secret: Ultra's Base at Bletchley Park, 2nd ed., Alan Sutton, 1994, pp. 36-37.
13. J. Good, D. Michie, and G. Timms, General Report on Tunny, 1945, p. 458.
14. W.T. Tutte, "My Work at Bletchley Park," 2000. To appear in Colossus: The First Electronic Computer, B.J. Copeland, ed., Oxford Univ. Press, 2005.
15. J. Good, D. Michie, and G. Timms, General Report on Tunny, 1945, pp. 313-315.
16. A Cryptographic Dictionary, Government Code and Cypher School, Bletchley Park; in the US National Archives and Records Administration (College Park, Maryland), document reference RG 457, Historic Cryptographic Collection, box 1413, NR 4559, p. 89. A digital facsimile of A Cryptographic Dictionary is in The Turing Archive for the History of Computing; see http://www.AlanTuring.netcrypt_dic_1944.
17. J. Good, D. Michie, and G. Timms, General Report on Tunny, 1945, p. 313.
18. The reasoning is as follows. Let p1 and p2 be the first and second impulses of the plaintext and let Δ(p1 + p2) mean "the result of differencing (p1 + p2)." Then the above account of the workings of the Tunny machine implies that Δ(c1 + c2) = Δ(p1 + p2) + Δ(χ1 + χ2) + Δ(Ψ1 + Ψ2). Tunny addition has the property that x + • = x for either value of x,dot or cross. So, since Δ(p1 + p2) and Δ(Ψ1 + Ψ2) are predominantly dot, Δ(c1 + c2) and D(χ1 + χ2) must agree with one another more often than not.
19. See further B.J. Copeland, "Colossus and the Dawning of the Computer Age," Action This Day, R. Erskine and M. Smith, eds., Bantam, 2001, pp. 342-369.
20. J.A.N. Lee and G. Holtzman, "50 Years After Breaking the Codes," IEEE Annals of the History of Computing, vol. 17, no. 2, Spring 1995, pp. 32-43. The quotation is from p. 33.
21. Flowers in interview with Copeland, July 1996. Except where indicated otherwise, all material in this article relating directly to Flowers derives from Flowers in interviews with Copeland, 1996— 1998; and Flowers in interview with Christopher Evans in 1977 ( "The Pioneers of Computing: An Oral History of Computing," Science Museum, London).
22. S. Turing, Alan M. Turing, Heffer, 1959, p. 71.
23. C.E. Wynn-Williams was among the first to suggest that electronic valves be used in place of relays, in connection with the counting of a-particle emissions; see C.E. Wynn-Williams, "The Use of Thyratrons for High Speed Automatic Counting of Physical Phenomena," Proc. Royal Soc., Series A, vol. 132, 1931, pp. 295-310. (See also A.W. Hull, "Hot-cathode Thyratrons," General Electric Rev., vol. 32, 1929, pp. 390-399; and N.A. de Bruyne and H.C. Webster, "Note on the Use of a Thyratron with a Geiger Counter," Proc. Cambridge Philosophical Soc., vol. 27, 1931, pp. 113-115. ) In 1931, Wynn-Williams reported (p. 302) that rings of three and four valves had been tried out experimentally. In contrast, Colossus I contained approximately 1,600 valves and the later Colossi approximately 2,400.,
24. Flowers in interview with Copeland, July 1996.
25. J. Good, D. Michie, and G. Timms, General Report on Tunny, 1945, pp. 33, 458.
26. D. Horwood in interview with Copeland, October 2001.
27. J. Good, D. Michie, and G. Timms, General Report on Tunny, 1945, pp. 28, 33.
28. H. Fensom, "How the Codebreaking Colossus Was Conceived, Built and Operated: One of its Engineers Reveals its Secrets," 2001. To appear in Colossus: The First Electronic Computer, B.J. Copeland, ed., Oxford Univ. Press, 2005.
29. Flowers in interview with Copeland, July 1996; see also J. Good, D. Michie, and G. Timms, General Report on Tunny, 1945, p. 33.
30. Flowers in interview with Copeland, July 1998.
31. Flowers in interview with Copeland, July 1996.
32. Flowers in interview with Christopher Evans, 1977.
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