|Born||16 November 1916|
|Died||18 May 1975 (aged 58)|
|Alma mater||King's College, Cambridge|
|Known for||CPL, denotational semantics, Fundamental Concepts in Programming Languages|
|Institutions||University of Cambridge,|
University of Oxford
|Doctoral students||Peter Mosses|
Christopher S. Strachey (//; 16 November 1916 – 18 May 1975) was a British computer scientist. He was one of the founders of denotational semantics, and a pioneer in programming language design and computer time-sharing. He was a member of the Strachey family, prominent in government, arts, administration, and academia.
Christopher Strachey was born on 16 November 1916 to Oliver Strachey and Rachel (Ray) Costelloe in Hampstead, England. Oliver Strachey was the son of Richard Strachey and the great grandson of Sir Henry Strachey, 1st Baronet. His elder sister was the writer Barbara Strachey. In 1919, the family moved to 51 Gordon Square. The Stracheys belonged to the Bloomsbury Group whose members included Virginia Woolf, John Maynard Keynes and Christopher's uncle Lytton Strachey. At 13, Christopher went to Gresham's School, Holt where he showed signs of brilliance but in general performed poorly. He was admitted to King's College, Cambridge (the same college as Alan Turing) in 1935 where he continued to neglect his studies. Strachey studied mathematics and then transferred to physics. At the end of his third year at Cambridge, Strachey suffered a nervous breakdown, possibly related to coming to terms with his homosexuality. He returned to Cambridge but managed only a "lower second" in the Natural Sciences Tripos.
Unable to continue his education, Christopher joined Standard Telephones and Cables (STC) as a research physicist. His first job was providing mathematical analysis for the design of electron tubes used in radar. The complexity of the calculations required the use of a differential analyser. This initial experience with a computing machine sparked Strachey's interest and he began to research the topic. An application for a research degree at the University of Cambridge was rejected and Strachey continued to work at STC throughout the Second World War. After the war he fulfilled a long-standing ambition by becoming a schoolmaster at St Edmund's School, Canterbury, teaching mathematics and physics. Three years later he was able to move to the more prestigious Harrow School in 1949, where he stayed for three years.
In January 1951, a friend introduced him to Mike Woodger of the National Physical Laboratory (NPL). The lab had successfully built a reduced version of Alan Turing's Automatic Computing Engine (ACE) the concept of which dated from 1945: the Pilot ACE. In his spare time Strachey developed a program for the game of draughts (also known as "checkers"), which he finished a preliminary version in May 1951. The game completely exhausted the Pilot ACE's memory. The draughts program tried to run for the first time on 30 July 1951 at NPL, but was unsuccessful due to program errors. When Strachey heard about the Manchester Mark 1, which had a much bigger memory, he asked his former fellow-student Alan Turing for the manual and transcribed his program into the operation codes of that machine by around October 1951. By the summer of 1952, the program could "play a complete game of Draughts at a reasonable speed".
Strachey programmed the first ever music performed by a computer; a rendition of the British National Anthem "God Save the Queen" on the Mark II Manchester Electronic Computer at Manchester, in 1951. Later that year, short extracts of three pieces were recorded there by a BBC outside broadcasting unit: "God Save the Queen", "Baa, Baa, Black Sheep", and "In the Mood". Researchers at the University of Canterbury, Christchurch restored the acetate master disc in 2016 and the results may be heard on SoundCloud.
Strachey worked for the National Research Development Corporation (NRDC) from 1952 to 1959. While working on the St. Lawrence Seaway project, he was able to visit several computer centres in the United States and catalogue their instruction sets. Later, he worked on programming both the Elliott 401 computer and the Ferranti Pegasus computer. Together with Donald B. Gillies, he filed three patents in computing design including the design of base registers for program relocation. He also worked on the analysis of vibration in aircraft, working briefly with Roger Penrose.
In 1959, Strachey left NRDC to become a computer consultant working for NRDC, EMI, Ferranti and other organisations on a number of wide-ranging projects. This work included logical design for computers, providing autocode and later the design of high-level programming languages. For a contract to produce the autocode for the Ferranti Orion computer, Strachey hired Peter Landin who became his one assistant for the duration of Strachey's consulting period.
In 1962, while remaining a consultant, he accepted a position at Cambridge University.
In 1965, Strachey accepted a position at Oxford University as the first director of the Programming Research Group and later the university's first professor of computer science and fellow of Wolfson College, Oxford. He collaborated with Dana Scott.
Strachey was elected as a distinguished fellow of the British Computer Society in 1971 for his pioneering work in computer science.
In 1973, Strachey (along with Robert Milne) began to write an essay submitted to the Adams Prize competition, after which they continued work to revising it into book form. Strachey can be seen and heard in the recorded Lighthill debate on AI (see Lighthill report).
Strachey developed the concept of time-sharing in 1959. He filed a patent application in February that year and gave a paper "Time Sharing in Large Fast Computers" at the inaugural UNESCO Information Processing Conference in Paris where he passed the concept on to J. C. R. Licklider. This paper is credited by the MIT Computation Center in 1963 as "the first paper on time-shared computers".
He developed the Combined Programming Language (CPL). His influential set of lecture notes Fundamental Concepts in Programming Languages formalised the distinction between L- and R- values (as seen in the C programming language). Strachey also coined the term currying, although he did not invent the underlying concept.
He was instrumental in the design of the Ferranti Pegasus computer.
In November 2016, a Strachey 100 event was held at Oxford University to celebrate the centenary of Strachey's birth, including a viewing at the Weston Library in Oxford of the Christopher Strachey archive held in the Bodleian Library collection.
- Christopher Strachey: British computer scientist, Encyclopædia Britannica.
- Catalogue of the papers and correspondence of Christopher Strachey (1916–1975), The National Archives, United Kingdom.
- Gordon, M.J.C., Christopher Strachey: Recollections of His Influence, Higher-Order and Symbolic Computation, 13(1–2):65–67, April 2000. ISSN 1388-3690. (PostScript version Archived 13 March 2017 at the Wayback Machine.)
- F. J. Corbató, et al., The Compatible Time-Sharing System A Programmer's Guide (MIT Press, 1963) ISBN 978-0-262-03008-3. "the first paper on time-shared computers by C. Strachey at the June 1959 UNESCO Information Processing conference"
- Campbell-Kelly, M. (January 1985). "Christopher Strachey, 1916–1975: A Biographical Note". IEEE Annals of the History of Computing. 7 (1): 21. doi:10.1109/mahc.1985.10001. S2CID 17188378.
- "The Priesthood at Play: Computer Games in the 1950s". They Create Worlds. 22 January 2014. Retrieved 28 August 2017.
- "What is Artificial Intelligence". AlanTuring.net. May 2000. Retrieved 28 August 2017.
- Strachey, C. S. (September 1952). Logical or non-mathematical programmes. ACM '52: Proceedings of the 1952 ACM National Meeting (Toronto). p. 47. doi:10.1145/800259.808992.
- "First recording of computer-generated music – created by Alan Turing – restored". The Guardian. 26 September 2016. Retrieved 28 August 2017.
- "Restoring the first recording of computer music – Sound and vision blog". British Library. 13 September 2016. Retrieved 28 August 2017.
- "Science Survey – BBC Home Service Basic – 1 May 1952 – BBC Genome". BBC. Retrieved 28 August 2017.
- "Science Survey – BBC Home Service Basic – 8 May 1952 – BBC Genome". BBC. Retrieved 28 August 2017.
- bilkable (12 September 2010), The Lighthill Debate (1973) – part 6 of 6, retrieved 27 October 2017
- "Computer Pioneers - Christopher Strachey". history.computer.org. Retrieved 23 January 2020.
What Strachey proposed in his concept of time-sharing was an arrangement that would preserve the direct contact between programmer and machine, while still achieving the economy of multiprogramming.
- "Computer - Time-sharing and minicomputers". Encyclopedia Britannica. Retrieved 23 January 2020.
In 1959 Christopher Strachey in the United Kingdom and John McCarthy in the United States independently described something they called time-sharing.
- Gillies, James M.; Gillies, James; Gillies, James and Cailliau Robert; Cailliau, R. (2000). How the Web was Born: The Story of the World Wide Web. Oxford University Press. pp. 13. ISBN 978-0-19-286207-5.
- "Reminiscences on the Theory of Time-Sharing". jmc.stanford.edu. Retrieved 23 January 2020.
in 1960 'time-sharing' as a phrase was much in the air. It was, however, generally used in my sense rather than in John McCarthy's sense of a CTSS-like object.
- C. Strachey: "A General Purpose Macrogenerator", The Computer Journal, 8(3):225–241, 1965.
- "Samson Abramsky". UK: Department of Computer Science, University of Oxford. Retrieved 18 January 2017.
- "Strachey 100: Celebrating the life and research of Christopher Strachey". UK: Department of Computer Science, University of Oxford. 2016. Retrieved 18 January 2017.
- Bowen, Jonathan P. (2016). "Strachey 100 Centenary Conference: Photographs of Strachey 100" (PDF). FACS FACTS. UK: BCS-FACS. 2: 44–52. Retrieved 18 January 2017.
- Copeland, B.J. A Brief History of Computing, AlanTuring.net, June 2000.
- Lavington, S. The Pegasus Story, Science Museum, 2000. ISBN 1-900747-40-5.
- Strachey, C. An impossible program, The Computer Journal, 7(4):313, January 1965.
- Christopher Strachey at DBLP Bibliography Server
- Christopher Strachey (1916–1975) at the Wayback Machine (archived 26 September 2007) at the Virtual Museum of Computing
- A simulator of the Manchester Mark 1, executing Christopher Strachey's Love letter algorithm from 1952
- A web based version of Christopher Strachey's Love letter algorithm showing word lists
- Higher-Order and Symbolic Computation Volume 13, Issue 1/2 (April 2000) Special Issue in memory of Christopher Strachey
- "Pioneer Profiles – Christopher Strachey" in Resurrection. The Bulletin of the Computer Conservation Society. Number 43. Summer 2008. ISSN 0958-7403.
- Supplementary Strachey Papers held at the British Library