Donald Davies

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Donald Watts Davies
Donald-Davies Welsh computer scientist.jpg
Born(1924-06-07)7 June 1924
Died28 May 2000(2000-05-28) (aged 75)
Nationality Welsh
Alma mater Imperial College
Known for Packet switching
Scientific career
Fields Computer science
Institutions National Physical Laboratory

Donald Watts Davies, CBE, FRS [1] (7 June 1924 – 28 May 2000) was a Welsh computer scientist who was employed at the UK National Physical Laboratory (NPL). In 1965 he developed the concept of packet switching, [2] [3] which is today the dominant basis for data communications in computer networks worldwide, and implemented it in the NPL network. [4] [5] This was independent of the work of Paul Baran in the United States who had a similar idea in the early 1960s. [6] The ARPANET project, a precursor to the Internet, credited Davies for his influence. [7] [8]

Fellow of the Royal Society Elected Fellow of the Royal Society, including Honorary, Foreign and Royal Fellows

Fellowship of the Royal Society is an award granted to individuals that the Royal Society of London judges to have made a 'substantial contribution to the improvement of natural knowledge, including mathematics, engineering science and medical science'.

Welsh people nation and ethnic group native to Wales

The Welsh are a Celtic nation and ethnic group native to, or otherwise associated with, Wales, Welsh culture, Welsh history and the Welsh language. Wales is a country that is part of the United Kingdom, and the majority of people living in Wales are British citizens.

A computer scientist is a person who has acquired the knowledge of computer science, the study of the theoretical foundations of information and computation and their application.


Early life

Davies was born in Treorchy in the Rhondda Valley, Wales. His father, a clerk at a coalmine, died a few months later, and his mother took Donald and his twin sister back to her home town of Portsmouth, where he went to school. [9] He attended the Southern Grammar School for Boys.

Treorchy village in Wales

Treorchy is a village and community in Wales. Once a town, it retains the characteristics of a town. Situated in the county borough of Rhondda Cynon Taf in the Rhondda Fawr valley. Treorchy is also one of the 16 communities of the Rhondda. It includes the villages of Cwmparc and Ynyswen.

Rhondda Valley region in Wales

Rhondda, or the Rhondda Valley, is a former coal mining area in South Wales, previously in Glamorgan, and now a local government district, consisting of 16 communities built around the River Rhondda. The Rhondda is actually two valleys—the larger Rhondda Fawr valley and the smaller Rhondda Fach valley. The singular term 'Rhondda Valley' and the plural 'Rhondda Valleys' are both commonly used. In 2001, the Rhondda constituency of the National Assembly for Wales had a population of 72,443; while the National Office of Statistics described the Rhondda urban area as having a population of 59,602. Rhondda is part of Rhondda Cynon Taf County Borough and is part of the South Wales Valleys.

Wales Country in Northwest Europe, part of the United Kingdom

Wales is a country that is part of the United Kingdom and the island of Great Britain. It is bordered by England to the east, the Irish Sea to the north and west, and the Bristol Channel to the south. It had a population in 2011 of 3,063,456 and has a total area of 20,779 km2 (8,023 sq mi). Wales has over 1,680 miles (2,700 km) of coastline and is largely mountainous, with its higher peaks in the north and central areas, including Snowdon, its highest summit. The country lies within the north temperate zone and has a changeable, maritime climate.

He received a BSc degree in physics (1943) at Imperial College London, and then joined the war effort working as an assistant to Klaus Fuchs [9] on the nuclear weapons Tube Alloys project at Birmingham University. [10] He then returned to Imperial taking a first class degree in mathematics (1947); he was also awarded the Lubbock memorial Prize as the outstanding mathematician of his year.

Imperial College London public research university located in London, United Kingdom

Imperial College London is a public research university located in London, England. In 1851, Prince Albert began building his vision for a cultural area composed of the Victoria and Albert Museum, Natural History Museum, Royal Albert Hall, Royal Colleges, and the Imperial Institute. In 1907, Imperial College was established by Royal Charter, bringing together the Royal College of Science, Royal School of Mines, and City and Guilds College. In 1988, the Imperial College School of Medicine was formed through a merger with St Mary's Hospital Medical School. In 2004, Queen Elizabeth II opened the Imperial College Business School.

Klaus Fuchs German-born British theoretical physicist and atomic spy

Emil Julius Klaus Fuchs was a German theoretical physicist and atomic spy who, in 1950, was convicted of supplying information from the American, British, and Canadian Manhattan Project to the Soviet Union during and shortly after the Second World War. After nine years' imprisonment in Great Britain, he re-migrated to East Germany where he resumed his career as a physicist and scientific leader. While at the Los Alamos National Laboratory, Fuchs was responsible for many significant theoretical calculations relating to the first nuclear weapons and, later, early models of the hydrogen bomb.

Tube Alloys

Tube Alloys was a code name of the research and development programme authorised by the United Kingdom, with participation from Canada to develop nuclear weapons during the Second World War. Starting before the Manhattan Project in the United States, the British efforts were kept classified and as such had to be referred to by code even within the highest circles of government.

In 1955, he married Diane Burton; they had a daughter and two sons. [11]

Career history

National Physical Laboratory

From 1947, he worked at the National Physical Laboratory (NPL) where Alan Turing was designing the Automatic Computing Engine (ACE) computer. It is said that Davies spotted mistakes in Turing's seminal 1936 paper On Computable Numbers, much to Turing's annoyance. These were perhaps some of the first "programming" bugs in existence, even if they were for a theoretical computer, the universal Turing machine. The ACE project was overambitious and floundered, leading to Turing's departure. [10] Davies took the project over and concentrated on delivering the less ambitious Pilot ACE computer, which first worked in May 1950. A commercial spin-off, DEUCE was manufactured by English Electric Computers and became one of the best-selling machines of the 1950s. [10]

Alan Turing mathematician and computer scientist

Alan Mathison Turing was an English mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. Turing was highly influential in the development of theoretical computer science, providing a formalisation of the concepts of algorithm and computation with the Turing machine, which can be considered a model of a general-purpose computer. Turing is widely considered to be the father of theoretical computer science and artificial intelligence. Despite these accomplishments, he was never fully recognised in his home country during his lifetime due to his homosexuality, which was then a crime in the UK.

Automatic Computing Engine

The Automatic Computing Engine (ACE) was a British early electronic stored-program computer designed by Alan Turing.

A software bug is an error, flaw, failure or fault in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. The process of finding and fixing bugs is termed "debugging" and often uses formal techniques or tools to pinpoint bugs, and since the 1950s, some computer systems have been designed to also deter, detect or auto-correct various computer bugs during operations.

Davies also worked on applications of traffic simulation and machine translation. In the early 1960s, he worked on government technology initiatives designed to stimulate the British computer industry.

Packet switched network design

In 1965, Davies developed the idea of packet switching, dividing computer messages into packets that are routed independently across a network, possibly via differing routes, and are reassembled at the destination. Unbeknown to him, Paul Baran of the RAND Corporation in the United States was also working on a similar concept who, when he became aware of Davies's work acknowledged that they both had equally discovered the concept. [12]

Packet switching a method of grouping data which is transmitted over a digital network into packets

Packet switching is a method of grouping data that is transmitted over a digital network into packets. Packets are made of a header and a payload. Data in the header are used by networking hardware to direct the packet to its destination where the payload is extracted and used by application software. Packet switching is the primary basis for data communications in computer networks worldwide.

Paul Baran American engineer

Paul Baran was a Polish-born Jewish American engineer who was a pioneer in the development of computer networks. He was one of the two independent inventors of packet switching, which is today the dominant basis for data communications in computer networks worldwide, and went on to start several companies and develop other technologies that are an essential part of modern digital communication.

RAND Corporation non-profit organisation in the USA

RAND Corporation is an American nonprofit global policy think tank created in 1948 by Douglas Aircraft Company to offer research and analysis to the United States Armed Forces. It is financed by the U.S. government and private endowment, corporations, universities and private individuals. The company has grown to assist other governments, international organizations, private companies and foundations, with a host of defense and non-defense issues, including healthcare. RAND aims for interdisciplinary and quantitative problem solving by translating theoretical concepts from formal economics and the physical sciences into novel applications in other areas, using applied science and operations research.

Davies used the word "packets" after consulting with a linguist because it was capable of being translated into languages other than English without compromise. [13] Davies' key insight came in the realisation that computer network traffic was inherently "bursty" with periods of silence, compared with relatively constant telephone traffic. [14] He designed and proposed a national data network based on packet switching in his 1966 Proposal for the Development of a National Communications Service for On-line Data Processing. [15]

In 1966 he returned to the NPL at Teddington just outside London, where he headed and transformed its computing activity. He became interested in data communications following a visit to the Massachusetts Institute of Technology, where he saw that a significant problem with the new time-sharing computer systems was the cost of keeping a phone connection open for each user. [10] Davies was the first to describe the concept of an "Interface computer", today known as a router. [16]

His work on packet switching, presented by his colleague Roger Scantlebury, initially caught the attention of the developers of ARPANET, a US defence network, at a conference in Gatlinburg, Tennessee, in October 1967. [17] In Scantlebury's report following the conference, he noted "It would appear that the ideas in the NPL paper at the moment are more advanced than any proposed in the USA". [18] [19] Larry Roberts of the Advanced Research Projects Agency in the United States applied Davies' concepts of packet switching in the late 1960s for the ARPANET, which went on to become a predecessor to the Internet. [10] [20]

Davies first presented his own ideas on packet switching at a conference in Edinburgh on 5 August 1968. [21] At NPL Davies helped build a packet-switched network (Mark I NPL network ). It was replaced with the Mark II in 1973, and remained in operation until 1986, influencing other research in the UK and Europe. [22] [23]

Baran was happy to acknowledge that Davies had come up with the same idea as him independently. In an e-mail to Davies he wrote

You and I share a common view of what packet switching is all about, since you and I independently came up with the same ingredients. [12]

Leonard Kleinrock, a contemporary working on analysing message flow using queueing theory, developed a theoretical basis for the operation of message switching networks in his PhD thesis during 1961-2, published as a book in 1964. [24] However, Kleinrock's later claim to have developed the theoretical basis of packet switching networks is disputed by some, [25] [26] [27] including Robert Taylor, [28] Baran [29] and Davies. [30] The U.S. National Inventors Hall of Fame, which recognizes inventors who hold a U.S. patent of highly significant technology, records Donald Davies and Paul Baran as the inventors of digital packet switching. [31] [32]

Later work

Davies relinquished his management responsibilities in 1979 to return to research. He became particularly interested in computer network security. He retired from the NPL in 1984, becoming a leading consultant on data security to the banking industry. [10] Together with David O. Clayden, they designed the Message Authenticator Algorithm (MAA), an early Message Authentication Code that was adopted as international standard ISO 8731-2 in 1987. In 1987, he became a visiting professor at Royal Holloway and Bedford New College. [33]

Awards and honours

Davies was appointed a Distinguished Fellow of the British Computer Society in 1975, a CBE in 1983 and a Fellow of the Royal Society in 1987. In 2007, Davies was inducted into the National Inventors Hall of Fame, [31] and in 2012 he was inducted into the Internet Hall of Fame by the Internet Society. [34] A blue plaque commemorating Davies was unveiled in Treorchy in July 2013. [2]


Davies was survived by his wife Diane, a daughter and two sons. [35]

See also


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  1. Needham, R. M. (2002). "Donald Watts Davies, C.B.E. 7 June 1924 – 28 May 2000". Biographical Memoirs of Fellows of the Royal Society . 48: 87–96. doi:10.1098/rsbm.2002.0006.
  2. 1 2 Emily Gorton (26 July 2013). "Blue plaque to honour Welsh computing pioneer Donald Davies". The Independent . Retrieved 26 January 2016.
  3. Harris, Trevor, Who is the Father of the Internet? The case for Donald Watts Davies , retrieved 10 July 2013
  4. Scantlebury, Roger (25 June 2013). "Internet pioneers airbrushed from history". The Guardian. Retrieved 1 August 2015.
  5. "Packets of data were the key...". NPL. Retrieved 1 August 2015.
  6. "Donald Watts Davies". Internet Guide. 2010.
  7. "Pioneer: Donald Davies", Internet Hall of Fame
  8. Berners-Lee, Tim (1999), Weaving the Web: The Past, Present and Future of the World Wide Web by its Inventor, London: Orion, p. 7, ISBN   0 75282 090 7
  9. 1 2 The History of Computing Project – Donald Davies Biography
  10. 1 2 3 4 5 6 Cambell-Kelly, Martin (Autumn 2008). "Pioneer Profiles: Donald Davies". Computer Resurrection (44). ISSN   0958-7403.
  11. "Obituary", The Guardian, 2 June 2000
  12. 1 2 Harris , p. 9
  13. Harris , p. 6
  14. Dettmer, R. (16 July 1998). "Almost an Accident". IEE Review. 44 (4): 169–172. ISSN   0953-5683.
  15. Davies, D. W. (1966), Proposal for a Digital Communication Network (PDF), National Physical Laboratory
  16. Roberts, Dr. Lawrence G. (May 1995). "The ARPANET & Computer Networks" . Retrieved 13 April 2016. Then in June 1966, Davies wrote a second internal paper, "Proposal for a Digital Communication Network" In which he coined the word packet,- a small sub part of the message the user wants to send, and also introduced the concept of an "Interface computer" to sit between the user equipment and the packet network.
  17. Isaacson, Walter (2014). The Innovators: How a Group of Hackers, Geniuses, and Geeks Created the Digital Revolution. Simon & Schuster. p. 237. ISBN   9781476708690.
  18. J. Gillies, R. Cailliau (2000). How the Web was Born: The Story of the World Wide Web. Oxford University Press. pp. 23–25. ISBN   0192862073.
  19. "Oral-History:Donald Davies & Derek Barber" . Retrieved 13 April 2016.
  20. Abbate, Jane (2000). Inventing the Internet. MIT Press. p. 38. ISBN   0262261332.
  21. Luke Collins, "Network pioneer remembered", Engineering & Technology, IET, 6 September 2008
  22. Packet Switching
  23. C. Hempstead; W. Worthington (2005). Encyclopedia of 20th-Century Technology. Routledge.
  24. Kleinrock, Leonard (1961), "Information flow in large communication nets", RLE Quarterly Progress Report (1)
  25. Alex McKenzie (2009), Comments on Dr. Leonard Kleinrock's claim to be "the Father of Modern Data Networking" , retrieved 23 April 2015 "...there is nothing in the entire 1964 book that suggests, analyzes, or alludes to the idea of packetization."
  26. Isaacson, Walter (2014). The Innovators: How a Group of Hackers, Geniuses, and Geeks Created the Digital Revolution. Simon & Schuster. p. 245. ISBN   9781476708690. This led to an outcry among many of the other Internet pioneers, who publicly attacked Kleinrock and said that his brief mention of breaking messages into smaller pieces did not come close to being a proposal for packet switching
  27. Harris
  28. "Birthing the Internet: Letters From the Delivery Room; Disputing a Claim". New York Times. 22 November 2001. Retrieved 10 September 2017. Authors who have interviewed dozens of Arpanet pioneers know very well that the Kleinrock-Roberts claims are not believed.
  29. Katie Hefner (8 November 2001), "A Paternity Dispute Divides Net Pioneers", The New York Times, The Internet is really the work of a thousand people," Mr. Baran said. "And of all the stories about what different people have done, all the pieces fit together. It's just this one little case that seems to be an aberration.
  30. Donald Davies (2001), "A Historical Study of the Beginnings of Packet Switching", Computer Journal, British Computer Society, I can find no evidence that he understood the principles of packet switching.
  31. 1 2 "Inductee Details - Donald Watts Davies". National Inventors Hall of Fame. Retrieved 6 September 2017.
  32. "Inductee Details - Paul Baran". National Inventors Hall of Fame. Retrieved 6 September 2017.
  33. "Donald W. Davies, 75, Dies; Helped Refine Data Networks". New York Times. 4 June 2000. Retrieved 4 September 2017.
  34. 2012 Inductees, Internet Hall of Fame website. Retrieved 24 April 2012
  35. "Obituary: Data Pioneer Donald Davies Dies", Internet Society (ISOC), 31 May 2000