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81 Shannon, Claude Elwood
[br]b. 30 April 1916 Gaylord, Michigan, USA[br]American mathematician, creator of information theory.[br]As a child, Shannon tinkered with radio kits and enjoyed solving puzzles, particularly crypto-graphic ones. He graduated from the University of Michigan in 1936 with a Bachelor of Science in mathematics and electrical engineering, and earned his Master's degree from the Massachusetts Institute of Technology (MIT) in 1937. His thesis on applying Boolean algebra to switching circuits has since been acclaimed as possibly the most significant this century. Shannon earned his PhD in mathematics from MIT in 1940 with a dissertation on the mathematics of genetic transmission.Shannon spent a year at the Institute for Advanced Study in Princeton, then in 1941 joined Bell Telephone Laboratories, where he began studying the relative efficiency of alternative transmission systems. Work on digital encryption systems during the Second World War led him to think that just as ciphers hide information from the enemy, "encoding" information could also protect it from noise. About 1948, he decided that the amount of information was best expressed quantitatively in a two-value number system, using only the digits 0 and 1. John Tukey, a Princeton colleague, named these units "binary digits" (or, for short, "bits"). Almost all digital computers and communications systems use such on-off, or two-state logic as their basis of operation.Also in the 1940s, building on the work of H. Nyquist and R.V.L. Hartley, Shannon proved that there was an upper limit to the amount of information that could be transmitted through a communications channel in a unit of time, which could be approached but never reached because real transmissions are subject to interference (noise). This was the beginning of information theory, which has been used by others in attempts to quantify many sciences and technologies, as well as subjects in the humanities, but with mixed results. Before 1970, when integrated circuits were developed, Shannon's theory was not the preferred circuit-and-transmission design tool it has since become.Shannon was also a pioneer in the field of artificial intelligence, claiming that computing machines could be used to manipulate symbols as well as do calculations. His 1953 paper on computers and automata proposed that digital computers were capable of tasks then thought exclusively the province of living organisms. In 1956 he left Bell Laboratories to join the MIT faculty as Professor of Communications Science.On the lighter side, Shannon has built many devices that play games, and in particular has made a scientific study of juggling.[br]Principal Honours and DistinctionsNational Medal of Science. Institute of Electrical and Electronics Engineers Medal of Honor, Kyoto Prize.BibliographyHis seminal paper (on what has subsequently become known as information theory) was entitled "The mathematical theory of communications", first published in Bell System Technical Journal in 1948; it is also available in a monograph (written with Warren Weaver) published by the University of Illinois Press in 1949, and in Key Papers in the Development of Information Theory, ed. David Slepian, IEEE Press, 1974, 1988. For readers who want all of Shannon's works, see N.J.A.Sloane and A.D.Wyner, 1992, TheCollected Papers of Claude E.Shannon.HO -
82 Wilkes, Maurice Vincent
SUBJECT AREA: Electronics and information technology[br]b. 26 June 1913 Stourbridge, Worcestershire, England[br]English physicist who was jointly responsible for the construction of the EDS AC computer.[br]Educated at King Edward VI Grammar School, Stourbridge, where he began to make radio sets and read Wireless World, Wilkes went to St John's College, Cambridge, in 1931, graduating as a Wrangler in the Mathematical Tripos in 1934. He then carried out research at the Cavendish Laboratory, becoming a demonstrator in 1937. During the Second World War he worked on radar, differential analysers and operational research at the Bawdsey Research Station and other air-defence establishments. In 1945 he returned to Cambridge as a lecturer and as Acting Director of the Mathematical (later Computer) Laboratory, serving as Director from 1946 to 1970.During the late 1940s, following visits to the USA for computer courses and to see the ENIAC computer, with the collaboration of colleagues he constructed the Cambridge University digital computer EDSAC (for Electronic Delay Storage Automatic Computer), using ultrasonic delay lines for data storage. In the mid-1950s a second machine, EDSAC2, was constructed using a magnetic-core memory. In 1965 he became Professor of Computer Technology. After retirement he worked for the Digital Electronic Corporation (DEC) from 1981 to 1986, serving also as Adjunct Professor of Computer Science and Electrical Engineering at the Massachusetts Institute of Technology from 1981 to 1985. In 1990 he became a research strategy consultant to the Olivetti Research Directorate.[br]Principal Honours and DistinctionsFRS 1956. First President, British Computer Society 1957–60. Honorary DSc Munich 1978, Bath 1987. Honorary DTech Linkoping 1975. FEng 1976. Institution of Electrical Engineers Faraday Medal 1981.Bibliography1948, "The design of a practical high-speed computing machine", Proceedings of the Royal Society A195:274 (describes EDSAC).1949, Oscillation of the Earth's Atmosphere.1951, Preparation of Programs for an Electronic Digital Computer, New York: Addison-Wesley.1956, Automatic Digital Computers, London: Methuen. 1966, A Short Introduction to Numerical Analysis.1968, Time-Sharing Computer Systems: McDonald \& Jane's.1979, The Cambridge CAP Computer and its Operating System: H.Holland.1985, Memoirs of a Computer Pioneer, Cambridge, Mass.: MIT Press (autobiography).Further ReadingB.Randell (ed.), 1973, The Origins of Digital Computers, Berlin: Springer-Verlag.KFBiographical history of technology > Wilkes, Maurice Vincent
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