Eldon 2 Multi Access System at Leeds University

Speaker: David Holdsworth
Date: Thursday 21th March 2024
Time: 14:30

25 Copthall Ave, London EC2R 7BP and
Via the Internet using ZOOM.


About the seminar

This is the story of developing the English Electric KDF9 Time-Sharing system into a multi-access terminal system. The bulk of the implementation of Eldon2 started in October 1967, and the system started offering a live service in the following March. The talk will describe how the system was designed to offer interactive program development facilities to teletype users (there were 32 connected) and yet continue to run CPU-intensive jobs in the background. This happened on a machine with 192 kbytes of core store and a disc drive with a 300 millisecond seek time. The system ran the main computing service at Leeds until it was switched to be a student facility in about 1972. During this time its facilities underwent considerable expansion. Although 32 terminals were connected, it was generally reckoned that it was not worth staying logged on if more than 28 users were logged on. The system was taken up by the National Physical Laboratory, who added a second KDF9. The Leeds University system ran until about 1976, and the NPL system was finally shut down in 1980. This talk will be personal recollections of my earliest work at Leeds.

About the speaker

David Holdsworth studied physics at Oxford University and took first and second degrees there in 1964 and 1968.

He has worked in computing at Leeds University since 1967, both as lecturer in the academic department and mainly in systems development in the computer centre under its several names. He was at one time its Acting Director. In the 1990s and early 2000s he worked on preservation of digital material and was involved with OAIS and NASA.

Since his retirement in 2001 he has worked with the CCS on preserving software.

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