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

Motivation and Historical Background

NPL was originally founded in 1900 and a Mathematical Division was formed with it at the end of World War II to research into computing machinery and methods. In 1960, the group was renamed to the Autonomics Division and was led by R. H. Tizzard. Early works of the division included the ACE computer proposed by A. M. Turing and Duece computer in 1946 and 1952, respectively. Donald Davies joined NPL in 1947 at the young age of 23 and by 1960 was promoted to the position of Deputy Superintenedent of the division. In 1961, a standard interface project was led by D. L. A. Barber under Davies to "rationalize the connection of devices to computers for process control and communication." This project is noted as the mark for bringing NPL into researching in the telecommunications area. (Campbell-Kelly 222)

The concept of a 'store and forward' was inspired by time sharing technologies and the 'inadequacy of data communications facilities for interactive systems' in the 1960's. Donald Davies envisioned the possibility of matching time sharing systems' performance with interactive system if very short message sizes were matched the store and forward techniques. In November of 1965, Davies wrote 'Remote on-line data processing and its communication needs' that described this new concept for the first time. It included ideas about how the existing telephony infrastructure can support this digital data network. A longer document, 'Proposal for development of a nation communication service for on-line data processing was written in December that year to elaborate on the earlier paper. The new paper included estimations and calculations on possible delay times of the 'store and forward' system. Davies distributed this paper to a small group of people who he felt would be interested in this type of technology, but the response was not 'enthusiastic'. In the months to follow, he gave a lecture at the National Physical Laboratory called 'The future digital communication network' that described the design in more detail. Davies gave a few more lectures in the subsequent years. It was not until 1967 that he made his first open publication in the ACM Symposium on Operating System Principles at Gatlinburg. And it was not until the 1968 IFIP Congress in Edinburg his idea was proposed to a larger audience in a paper entitled 'Communication networks to serve rapid response computers.' In less than 7 years after Davies' first described his packet switching concept, a local network began operations. Finally in 1973, the network was in full operations.(Davies)

The idea of packet switching implemented on a public data network would help to resolve the issue of incompatibilities between computers sharing information.(Davies)Davies also noticed that the telegraph system's message switching techniques were anaglous to the communication networks. But instead of transmitting an an entire message, shorter broken-up 'packets' can be sent to eliminate the delay faced by telegraph networks.

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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 10:18:02 CDT.