LEO III completed in 1961
The first LEO III was completed in 1961. This was a solid-state machine with a ferrite core memory. It was micro-programmed and was controlled by a multi-tasking operating system.
In 1963 LEO Computers Ltd was merged into English Electric Company and this led to the breaking up of the team that had inspired LEO computers. English Electric Company continued to build the LEO III, and went on to build the faster LEO 360 and even faster LEO 326 models, which had been designed by the LEO team before the takeover.
All LEO IIIs allowed concurrent running of as many as 12 application programs through the Master program operating system. Some were still in commercial use in British Telecom until 1981. Many users fondly remember the LEO III and enthuse about some of its quirkier features, such as having a loudspeaker connected to the central processor which enabled operators to tell if a program was looping by the distinctive sound it made.
A list of LEO III installations can be found at:
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