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A Technical History of National Physical Laboratories (NPL) Network Architecture - A Design Timeline


Proposed Construction
In Service Disconnected



  • In the UK, the Ministry of Defense is created to spur productivity and efficiency in industries in need of restructuring or modernization, above all- computing
  • Paul Baran of the Rand Corporation publishes the On Distributed Communications series, introducing the system concept and requirements for his distributed communication network- which includes the idea of message switching.


  • November: Davies proposes the idea of a national message switching network focusing on the other needs of real-time computing
  • December: Davies writes Proposal for the Development of a National Communciation Service for On-Line Data Processing. The first paper to propose the network with technical detail.


  • March: Davies presents his network ideas publicly for the first time to an audience of people active in computing, telecommunications and the military. Afterwards, a man from the British Ministry of Defense, Arthur Llewellyn, reveals to Davies that packet switching had already been invented in 1964 by Baran
  • June: Davies presents his own network and packet switching ideas in Proposal for a Digital Communication Network. First time the word "packet" was used in print.
  • July: Memorandum written by Davies that proposed to build a network on the NPL site. This is the starting point of the group.


  • April: Scantlebury and Barlett writes A Protocol for Use in the NPL Data Communications Network. First occurence of the word protocol in print to be used in context of telecommunications.
  • August: Davies, Barlett, Scantlebury and Wilkinson wrote A Digital Communications Network for Computers Giving Rapid Response which was the first public presentation of NPL's work.
  • Autumn: The National Physical Laboratory begins to build the modest packet-switched network called the Mark I, UK's early experimental version of the ARPANET.


  • August: Davies invited to present Communication Network to Serve Rapid Response Computers at the IFIP Congress of 1968 in Edinburg.
    Barlett presented Transmission Control in a Local Network. This is the first time packet switching ideas were presented at a major international conference.


  • The Mark I first goes live.


  • June:Donald Davies' team at NPL introduces an upgraded version of the network called the Mark II to official replace the Mark I.


  • The Mark II ends its term of service at NPL.




Written by the THINK Protocols team, CS Dept, UT Austin
Please direct comments to Chris Edmondson-Yurkanan.

This document was last modified on Tuesday, 11-Jun-2002 10:18:03 CDT.