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International Computers and Tabulators (ICT), of West Gorton, Manchester, and Park Lane, London
c.1961 ICT entered into a technical agreement with RCA. ICT also purchased RCA 301 computers and marketed them as the ICT 1500. The technical agreement with RCA provided scope for collaboration in developments and in product plans for the future.
1961 Works were at Letchworth, Croydon, Castlereagh, Dartford, Stevenage, Alderley Edge, Chertsey, Cirencester, Kirkby, Southport and Stockport.
1961 International Computers and Tabulators and GEC formed a new joint venture called I. C. T. Engineering, which was 90 percent owned by ICT and 10 percent by GEC. The new company assumed responsibility for ICT's research and design division, and for the GEC computer development department at Coventry. GEC would continue to supply most of ICT's electronics requirement; ICT would take over the majority interest in computer development
1961 Manufacturers of punched card and electronic data processing equipment; electro-mechanical tabulating machines; electronic calculators; electronic computers and computing systems. 18,600 employees. 
c.1961 The agreement with GEC on the 1301 computer ended; GEC continued to be responsible for its manufacture but essentially left the computer field.
1962 ICT acquired the computer interests of EMI and the 1100 and 2400 products, as well as a small team of hardware, software and sales staff. Also an agreement was concluded with Remington Rand to purchase and sell the 1004 in ICT's markets. Also launched the 1301.
1963 Added the business-computer division of Ferranti. The company exported computers to many countries.
1964 In the face of IBM's launch of its 360 computer, ICT was criticised for the extent and diversity of its range which included the 1301, 1500, 1100, 2400, 1004, Orion and Atlas. And then it launched the 1900 which was a great success - orders for the new line of products were on a scale entirely new to the company.
1968 English Electric Computers was merged with International Computers and Tabulators (ICT) and others to form International Computers Limited (ICL). Plessey Co and English Electric each owned 18% of the equity of ICL, with 53.5% in the hands of former shareholders of ICT and the remaining 10.5% held by the government.
1968 Queen's Award to Industry for Technological Innovation
The ICT 1201 computer used thermionic valve technology and its main memory was drum storage. Input was from 80 column punched cards and output was to 80 column cards and a printer. Before the merger, under BTM, this had been known as the HEC4 (Hollerith Electronic Computer, fourth version).
The ICT 1301, and its smaller cousin the ICT 1300, used germanium transistors and core memory. Backing store was magnetic drum, and optionally one inch, half inch or quarter inch wide magnetic tape. Input was from 80 column punched cards and optionally 160 column punched cards and punched paper tape. Output was to 80 column punched cards, printer and optionally to punched paper tape. The first customer delivery was in 1962, a 1301 sold to the University of London. One of their main attractions was that they performed British currency calculations (pounds, shillings and pence) in hardware. They also had the advantage of programmers not having to learn binary or octal arithmetic as the instruction set was pure decimal and the arithmetic unit had no binary mode, only decimal or pounds, shillings and pence. Its clock ran at 1 MHz. The London University machine still exists (January 2006) and is being reinstated to working condition by a group of enthusiasts.
The ICT 1302 used similar technology to the 1300/1301 but was a multiprogramming system capable of running three programs in addition to the Executive. It also used the 'Standard Interface' for the connection of peripherals allowing much more flexibility in peripheral configuration. The 'Standard Interface' was originally prototyped on the 1301 and went on to be used on the 1900 series.
The ICT 1500 series was a design bought in from the RCA Corporation, who called it the RCA 301. RCA also sold the design to Siemens in Germany and Compagnie des Machines Bull in France who called it the Gamma 30. It used a 6 bit byte and had core stores of 10,000, 20,000 or 40,000 bytes.
The ICT 1900 series was devised after the acquisition of Ferranti's assets which brought in the new Ferranti-Packard 6000 machine from Ferranti's Canadian subsidiary, which was considerably more advanced than the existing 130x line. It was decided to adapt this machine to use the 'Standard Interface', and it was put on the market as the ICT 1901. This was the first in a series of 190x machines, each aimed at a different segment of the market. It was launched in 1964.
By 1967 ICT, Britain's most prolific computer maker, had sold a total of 844 computers (including 400 of the still relatively new 1900 range). In comparison IBM had installed a total of 21,500 computers, including 5730 IBM System 360s, a range also launched in 1964.
In 1968 announced enhancements to the 1900 series.
At the time of the merger, EELM was in the process of making a line of large IBM System/360-compatible mainframes based on the RCA Specta 70, which was sold as the ICL System-4.
Both 1900 and System-4 were eventually replaced by the ICL 2900 Series which was introduced in 1974.