ACD Atlas Computing Division ICF: GEC Systems

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GEC 4070 Operating System

The first GEC 4080 at Chilton system was delivered to the Atlas Computer Laboratory in the Autumn of 1974. Its role was to act as a Front End Processor to both the ICL 1906A and the IBM 360/195. GEC 2050 RJE stations in universities would be able to submit jobs to either machine. Initially it ran a core-based operating system called COS which was superseded by a disc-based operating system called DOS. By 1977, the team working on the ICF had several years experience with GEC systems albeit with a different operating system. A novel feature of both operating systems was a Nucleus, in hardware, that handled protection, low-level communication, interrupt handling and scheduling. It received the Queen's Award to Industry for its innovative design.

In 1976, GEC released OS4000, the multi-user operating system for the GEC 4000 series. It was a message-oriented operating system, that is, it consisted of a set of processes which performed tasks based on the messages it received. Although such operating systems usually appear in real-time environments, it also worked well as a general purpose operating system especially as the Nucleus provided good hardware support.