How the internet was made possible

Now used by more than one in four of the world’s population, the internet is the phenomenon of our age. The NPL Technology of the Internet Gallery traces the history of communication technologies from the telegraph to today’s high speed internet and explains Packet Switching, the underlying technology of modern data communications.

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The Gallery provides hands-on emulations of a user’s access to a network of 40 years ago and shows examples of the hardware employed, video interviews with former members of Donald Davies’ packet switching development team at NPL, a video of how packetswitching works and a demonstration of ‘Traceroute’ technology which shows the origin and routing of internet traffic accessing the Museum website.

The birth of Packet Switching

Following the end of World War II, Alan Turing left Bletchley Park to work at the National Physical Laboratory (NPL) developing his ideas for a stored program digital computer. This work resulted in the Pilot Model ACE, later followed by the full-scale ACE computer.

To use the facilities of ACE, researchers at the NPL Teddington site had either to book one of the limited time-slots available or place their programs and data, on punched cards or paper-tape, with instructions in a queue for the computer operators. Later cables were laid from the computer to buildings where there were most users, but still the process was tedious and required booking slots.

Donald Davies, a member of the ACE computer project from the beginning, worked on a solution and conceived the idea of a ‘network’ of inter-connected data terminals where the data was broken up into small chunks, later named ‘packets’, which would avoid the problem of short messages getting stuck behind long messages. This contrasted with the then conventional method of delivering the data in a continuous stream. Davies’ ideas were first presented in public in the US at the ACM symposium, in Gatlinburg, 1967, and in the UK at the IFIP Congress, 1968, in Edinburgh.

The world adopts Packet Switching

In 1967, NPL’s ideas about packet switching were adopted by the US Department of Defense and the following year, a project called the ARPANET, the forerunner of the internet, was launched and its first link was established between the University of California and Stanford Research Institute in 1969.

The first international ARPANET connection was made between London and Norway in 1973. In 1978 the first International Packet Switched Service (IPSS) was developed and by the 1990s it had been adopted worldwide.

The launch of the NPL Gallery in December 2009 brought together four members of Donald Davies’ original packet switching team: Roger Scantlebury, Peter Wilkinson, Brian Aldous and Keith Bartlett. They appear on video in the gallery recalling their experiences. Donald Davies’ widow, also present at the launch, said that Donald would have been “surprised, embarrassed, pleased and proud” at the recognition he has since received.