The NPL Network or NPL Data Communications Network was a local area computer network operated by a team from the National Physical Laboratory in England that pioneered the concept of packet switching. Following a pilot experiment during 1967, elements of the first version of the network, Mark I, became operational during 1969 then fully operational in 1970, and the Mark II version operated from 1973 until 1986. The NPL network, followed by the wide area ARPANET in the United States, were the first two computer networks that implemented packet switching, and were interconnected in the early 1970s. The NPL network was designed and directed by Donald Davies.


In 1965, Donald Davies, who was later was appointed to head of the NPL Division of Computer Science, proposed a national data network based on packet switching in Proposal for the Development of a National Communications Service for On-line Data Processing. After the proposal was not taken up nationally, during 1966 he headed a team which produced a design for a local network to serve the needs of NPL and prove the feasibility of packet switching.[1] The design was the first to describe the concept of an "Interface computer", today known as a router.[2]

The next year (1967) a written version of the proposal entitled NPL Data Network was presented by Roger Scantlebury at a conference at Gatlinburg of the proceedings of the Association for Computing Machinery, which described how equipment (nodes) used to transmit signals (packets) would be connected by electrical links to re-transmit the signals between and to the nodes, and interface computers would be used to link node networks to so-called time-sharing computers and other users. The interface computers would transmit multiplex signals between networks, and nodes would switch transmissions while connected to electrical circuitry functioning at a rate of processing amounting to mega-bits.[3][4][5][6][7][8] 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".[9][10][11][12][13]

Packet switching

The first theoretical foundation of packet switching was the work of Paul Baran, in which data was transmitted in small chunks and routed independently by a method similar to store-and-forward techniques between intermediate networking nodes. Davies independently arrived at the same model in 1965 and named it packet switching.[14][15] He chose the term "packet" after consulting with an NPL linguist because it was capable of being translated into languages other than English without compromise.[16] Packet switching was used to produce an experimental network using a Honeywell 516 node. According to Zakon, NPL under Davies was the earliest organisation that created a packet switching network.[3][17][9][18]


Following a pilot experiment during 1967,[19][20][21][22] Davies gave the first public demonstration of packet switching on 5 August 1968.[23] Elements of the first version of the network, Mark I, became operational during 1969 then fully operational in 1970, and the Mark II version operated from 1973.[3][4][24] The NPL team also carried out simulation work on the performance of packet networks.[25] The local area NPL network, followed by wide area ARPANET in the United States, were the first two computer networks that implemented packet switching.[26][27]

The NPL network was later interconnected with other networks, including the ARPANET in 1973.[3][28] The NPL network used a line speed of 768 kbit/s in 1967.[21][22] Influenced by this, the proposed line speed for ARPANET was upgraded from 2.4 kbit/s to 50 kbit/s and a similar packet format adopted.[29][30][31] In 1976, 12 computers and 75 terminal devices were attached,[32] and more were added. The network remained in operation until 1986, influencing other research in the UK and Europe.[33][25] Alongside Donald Davies, the NPL team included Derek Barber, Roger Scantlebury, Peter Wilkinson, Keith Bartlett, and Brian Aldous.[34]

See also


  1. ^ Pelkey, James (2007), "NPL Network and Donald Davies 1966 - 1971", Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968-1988, retrieved 13 April 2016 
  2. ^ 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. 
  3. ^ a b c d C. Hempstead, W. Worthington. Encyclopedia of 20th-Century Technology. Routledge 8 Aug 2005, 992 pages, (edited by C. Hempstead, W. Worthington),. Retrieved 2015-08-15. 
  4. ^ a b A Hey, G Pápay. The Computing Universe: A Journey through a Revolution. published by Cambridge University Press 8 Dec 2014, 424 pages, ISBN 0521766451. Retrieved 2015-08-16. (source: Roger Scantlebury - p.201)
  5. ^ B. Steil, Council on Foreign Relations. Technological Innovation and Economic Performance. published by Princeton University Press 1 Jan 2002, 476 pages,ISBN 0691090912. Retrieved 2015-08-15. 
  6. ^ Oxford Dictionaries - word definition - relay & word definition - node published by Oxford University Press [Retrieved 2015-08-16]
  7. ^ J. Everard - VIRTUAL STATES (p.14) published by Routledge 28 Feb 2013 (reprint), 176 pages, ISBN 1134692757 [Retrieved 2015-08-16]
  8. ^ F.E. Froehlich, A. Kent. The Froehlich/Kent Encyclopedia of Telecommunications: Volume 1 - Access Charges in the U.S.A. to Basics of Digital Communications (p.344). published by CRC Press 14 Nov 1990, 552 pages, ISBN 0824729005, Volume 1 of Encyclopedia of Telecommunications. Retrieved 2015-08-16. 
  9. ^ a b 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. 
  10. ^ "Oral-History:Donald Davies & Derek Barber". Retrieved 13 April 2016. the ARPA network is being implemented using existing telegraphic techniques simply because the type of network we describe does not exist. It appears that the ideas in the NPL paper at this moment are more advanced than any proposed in the USA 
  11. ^ Naughton, John (2015). "8 Packet post". A Brief History of the Future: The origins of the Internet. Hachette UK. ISBN 1474602770. they lacked one vital ingredient. Since none of them had heard of Paul Baran they had no serious idea of how to make the system work. And it took an English outfit to tell them. 
  12. ^ Barber, Derek (Spring 1993). "The Origins of Packet Switching". The Bulletin of the Computer Conservation Society (5). ISSN 0958-7403. Retrieved 6 September 2017. Roger actually convinced Larry that what he was talking about was all wrong and that the way that NPL were proposing to do it was right. I've got some notes that say that first Larry was sceptical but several of the others there sided with Roger and eventually Larry was overwhelmed by the numbers. 
  13. ^ Abbate, Jane (2000). Inventing the Internet. MIT Press. p. 37. ISBN 0262261332. Although he was aware of the concept of packet switching, Roberts was not sure how to implement it in a large network. 
  14. ^ Scantlebury, Roger (25 June 2013). "Internet pioneers airbrushed from history". The Guardian. Retrieved 1 August 2015. 
  15. ^ "Packets of data were the key...". NPL. Retrieved 1 August 2015. 
  16. ^ Harris, Trevor, Who is the Father of the Internet? The case for Donald Watts Davies, p. 6, retrieved 10 July 2013 
  17. ^ T. Vickers. Alan Turing's Automatic Computing Engine: The Master Codebreaker's Struggle to Build the Modern Computer. published by OUP Oxford 14 Apr 2005, 576 pages, (edited by B. J. Copeland), ISBN 0191625868. Retrieved 2015-08-15. 
  18. ^ R.H. Zakon. The Internet Encyclopedia, G – O. published by John Wiley & Sons 2004, 840 pages,(ed. by H. Bidgoli), ISBN 0471689963, Volume 2 of The Internet Encyclopedia. Retrieved 2015-08-16. 
  19. ^ Elliott, Geoffrey (2004). Global business information technology : an integrated systems approach. Financial Times Prentice Hall. p. 425. ISBN 9780321270122. 
  20. ^ Winston, Brian (2002). Media,Technology and Society: A History: From the Telegraph to the Internet. Routledge. p. 327. ISBN 1134766327. 
  21. ^ a b K.G. Coffman & A.M. Odlyzco. Optical Fiber Telecommunications IV-B: Systems and Impairments. published by Academic Press 22 May 2002, 1022 pages, Optics and Photonics, ISBN 0080513190, (edited by I. Kaminow & T. Li). Retrieved 2015-08-15. 
  22. ^ a b "The History of the Internet". The History of Computing Project. 19 March 2001. Retrieved 13 April 2016. 
  23. ^ "The accelerator of the modern age". BBC News. 5 August 2008. Retrieved 19 May 2009. 
  24. ^ "UK National Physical Laboratory (NPL) & Donald Davies". Living Internet. Retrieved 13 April 2016. 
  25. ^ a b C. Hempstead; W. Worthington (2005). Encyclopedia of 20th-Century Technology. Routledge. 
  26. ^ Roberts, Lawrence G. (November 1978). "The Evolution of Packet Switching". Retrieved 9 April 2016. 
  27. ^ "Donald Davies". thocp.net ; "Donald Davies". internethalloffame.org. 
  28. ^ M. Ziewitz & I. Brown (2013). Research Handbook on Governance of the Internet. Edward Elgar Publishing. p. 7. ISBN 1849805040. Retrieved 2015-08-16. 
  29. ^ Abbate, Jane (2000). Inventing the Internet. MIT Press. p. 38. ISBN 0262261332. 
  30. ^ "Brief History of the Internet". Internet Society. Retrieved April 9, 2016. 
  31. ^ Roberts, Dr. Lawrence G. (May 1995). "The ARPANET & Computer Networks". Retrieved 13 April 2016. 
  32. ^ "The National Physical Laboratory Data Communications Netowrk". 1974. Retrieved 5 September 2017. 
  33. ^ Packet Switching
  34. ^ "Technology of the Internet". The National Museum of Computing. Retrieved 3 October 2017. 

Further reading

External links