International Computers Ltd.

International Computers Limited (ICL) was a British computer hardware, computer software and computer services company that operated from 1968 until 2002. It was formed through a merger of International Computers and Tabulators (ICT), English Electric Computers (EEC) and Elliott Automation in 1968. The company's most successful product line was the ICL 2900 Series range of mainframe computers.

In later years, ICL diversified its product line but the bulk of its profits always came from its mainframe customers. New ventures included marketing a range of powerful IBM clones made by Fujitsu, various minicomputer and personal computer ranges and (more successfully) a range of retail point-of-sale equipment and back-office software. Although it had significant sales overseas, ICL's mainframe business was dominated by large contracts from the UK public sector, including Post Office Ltd, the Inland Revenue, the Department for Work and Pensions and the Ministry of Defence. It also had a strong market share with UK local authorities and (at that time) nationalised utilities including the water, electricity, and gas boards.

The company had an increasingly close relationship with Fujitsu from the early 1980s, culminating in Fujitsu becoming sole shareholder in 1998. ICL was rebranded as Fujitsu in April 2002. The ICL brand is still used by the former Russian joint-venture of the company, founded in 1991.

Origins

International Computers Limited was formed in 1968 as a part of the Industrial Expansion Act of the Wilson Labour Government. ICL was an initiative of Tony Benn, the Minister of Technology, to create a British computer industry that could compete with major world manufacturers like IBM; the formation of the company was the last in a series of mergers that had taken place in the industry since the late 1950s.

The main portions of ICL were formed by merging International Computers and Tabulators (ICT) with English Electric Computers, the latter a recent merger of Elliott Automation with English Electric Leo Marconi computers, which itself had been a merger of the computer divisions of English Electric, LEO and Marconi. Upon its creation, the British government held a 10% stake in the company and provided a $32.4 million research-and-development grant spread across four years.

International Computers and Tabulators (ICT)

ICT was itself the result of a merger of two UK companies that had competed with each other throughout the 1930s and 1940s during the punched card era: British Tabulating Machine Company (BTM) and Powers-Samas. ICT had thus emerged with equipment that would process data encoded on punched cards with 40, 80 or 160 columns, compared to the 64 or 80 columns used by IBM and its predecessors.

In 1962, ICT delivered the first ICT 1300 series computer, its first transistor machine and also the first to use core memory. A small team from Ferranti's Canadian subsidiary, Ferranti-Packard, visited the various Ferranti computer labs and saw their work on a next-generation machine. On their return home they quickly produced the Ferranti-Packard 6000, developing the machine, compilers and an operating system (before these were common) and putting it on the market by 1963. A feature of the Executive operating system was its ability to multitask, using dynamic memory allocation enabled with a magnetic drum as an intermediate random access device. The machine went on to have some success and sold in small numbers in Canada (Saskatchewan Power Corporation retired serial number 0004 in early 1982) and the United States.

In 1964, ICT purchased the computer division of Ferranti in another government-forced merger. Ferranti had been building a small number of scientific machines based on various university designs since the 1950s. None of these could be considered commercially successful, however, and Ferranti always seemed to be slow bringing its designs to market.

Meanwhile, ICT management in England was looking to rejuvenate their line-up; their latest developments, the ones used to develop the FP 6000, were still not on the market. Management looked at the FP 6000 as well as licensing the RCA Spectra 70. In the end it was decided to go with the FP 6000 as the basis for a small line of small-to-midrange machines. The result was the ICT 1900 series, which would eventually go on to sell into the thousands.

The 1900 Series, which derived from the Canadian Ferranti-Packard 6000, competed successfully in the UK with the IBM System/360 range from the mid-1960s to the mid-1970s. The design was based on a 24-bit word, divided up into 6-bit characters. Lower case and control characters were provided for by "shift" characters. The early machines (1904/1905 with hardware floating point) had only 15-bit addressing. Later machines (1904E, 1905E, 1906A) had extended addressing modes, up to 22 bits.

The operating systems (Executives) were

*E4BM – the original for the FP 6000 (known internally as the FP1)
*E4RM – a significantly rewritten version of E4BM, with parts of the operating system overlaid to save space.
*E6BM – a rewritten version of E4BM for the later machines with 22 bit addressing.
*E6RM – a rewritten version of E4RM overlay software for the later machines with 22 bit addressing.

A later development was GEORGE3, remembered with great affection by a generation of British programmers.

A series of smaller machines were developed by the ICL Stevenage operation, consisting initially of the 1901 / 1902 / 1903 systems running E3 series executives (e.g. E3RM) and versions of the GEORGE operating system (initially GEORGE1). Later developments were the 1901A / 1902A / 1903A with their own Executives and GEORGE2.

At a time (in the 1960s and 1970s) when IBM/360 series programs had to be recompiled to run in different machine and/or operating system environments, one significant feature of the 1900 series was that programs would function unaltered on any 1900 system, without the need for recompilation. Unfortunately ICT, and later ICL, were unable to capitalise on this advantage to make significant inroads into IBM's customer base.

English Electric LEO Marconi (EELM)

During the same period, LEO was struggling to produce its own machines that would be able to compete with IBM. Its parent company,