Atlas Computer

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Ferranti: the Company

Ferranti were a long established family business (started 1882) involved in large transformers, domestic appliances, etc. After the 1939-45 war, Sir Vincent de Ferranti encouraged the company to get into new technologies which led to the collaboration with Manchester University in the area of digital computers.

By 1951, the Manchester University-Ferranti team had produced the Mark 1, the first commercial computer. Over the period 1951 to 1959, Ferranti had about 25% of the UK computer market at the top end of systems delivered. A breakdown of systems originating from the Ferranti West Gorton plant over the period is:

Model Dates Number
Mark 1 1951-52 2
Mark 1* 1953-57 7
Pegasus I 1956-61 26
Pegasus II 1959-62 12
Mercury 1957-61 19
Perseus 1959 2
Sirius 1960-63 16
Orion 1963-65 10
Atlas I 1963-64 3
Atlas II 1964-65 3
Total 1951-65 100

The main competitors were Elliott Brothers (32%), Leo (16%) and English Electric (15%). Elliott's smaller machines such as the 401 had sold in quite large numbers.

Lord Halsbury, head of NRDC, had set up an advisory panel on electronic computers in 1949 but had got little support from some of the more obvious companies, Power-Samas, British Tabulating Machines and GEC. NRDC helped fund the Mark 1* which was produced by Ferranti with little support from the University as they were already working on a new machine, the Mark II or MEG which eventually became Mercury.

Ferranti Mercury 1024 40-bit words 512 40-bit data 1024 20-bit instructions Load Integer: 180 microseconds Integer Multiply: 300 microseconds Fixed Point Divide: milliseconds!


By 1960 about 240 computers had been installed in the UK with the largest being the IBM systems of the Atomic Energy Authority.

ATLAS STRETCH 7090 Rest UK Atlas Computer Laboratory AWRE Aldermaston AERE Risley ATLAS STRETCH Word Length 48 64 Cycle (microsecs) 2.00 2.18 Memory 48K 64K Virtual Yes No Index Registers 127 16 Look Ahead Levels 1 4 Disc 98Kwords 2Mwords Tape Decks 16 Ampex 16 7-Track


By 1953, Manchester University had started looking at transistor technology for a third generation system, initially called MUSE, to rival the fast computer, Stretch, being developed by IBM. This eventually became the Atlas computer keeping with the naming tradition of Ferranti machines. In December 1962 when the Manchester University Atlas was completed, it could claim to be the most powerful and flexible computer in the world with only Stretch being in competition for that title. Only two Atlas I systems were sold: the Chilton/NIRNS machine and one to London University

By 1963, Ferranti had developed the Atlas II in collaboration with Cambridge University. The machine at Cambridge was called Titan. A second system was installed along side the Stretch at Aldermaston.

In 1963, Ferranti sold its mainframe computer business to ICT for £1.5M in cash and 1.9 million ordinary shares which gave Ferranti a 10.6% stake in ICT.

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