Overview

This website provides information about the ICL 2900 series of computers; I worked on one of these for about ten years. It includes history, images, anecdotes, and (eventually) software.

This was created because there is very little detailed information about these systems; any books contain only vague information with little material in any depth. However, a good overview can be found in John Buckle's book (see the Documents section)

History

International Computers Limited (ICL) was formed in June 1968, from the merger of English Electric Computers (EE) and International Computers and Tabulators (ICT), with some additional financial input from Plessey and the government of the time. EE had already absorbed Elliott Automation and LEO Computers, and these in turn had previously absorbed a number of other companies. The merger had been under discussion for some time, but was eventually pushed through by Anthony Wedgwood Benn, a Labour minister, who made them “an offer they couldn't refuse”.

Both companies were wedded to their respective current products. For EE this was the System 4 (similar to the IBM 360), and for ICT it was the 1900 series (developed from the Ferranti Packard (Canada) FP6000). A condition of the merger was that a new range of computers would be developed by ICL, and it was hoped that this would provide some compatibility with System 4 and 1900, in order to retain current customers. Various options were considered, including developments of existing systems, but eventually it was decided that a new architecture would be developed, this being dubbed the Synthetic Option.

The new systems were to be compatible across the complete range, and were known internally as New Range. The marketing name that was settled on was the somewhat unoriginal 2900 series. The systems in the range were numbered 29XY, where X and Y varied; note that systems named 290Y were not technically New Range systems, as they emulated the 1900 series; the smaller 290Y machines were later replaced by the ME29 system. These smaller systems are not covered here; the term '2900 series' should be taken to refer to all but the 290Y systems.

Over the years, a number of different models were produced. The early systems were the so-called 'P-series', based on small scale and medium scale integrated circuits (SSI and MSI). To cut costs, these were soon replaced by the 'S-series', which were eventually based on large scale integration (LSI) and very large scale integration (VLSI). ICL was in financial trouble at this point, and reduced the range to S3 only. More details of these are given below.