OPUS the GEC Computers Multi-access system


Comprehensive technical manual covering


Job Control Language

User Command Specifications

OPUS, released in Autumn, 1975, is the principal GEC involvement in multi-access operation and is a packaged system based on the OS 4000 operating system, together with a selection of elements from the GEC hardware catalogue. It is now a proven mainline multi-terminal, timesharing system. which can support system development and run applications programs simultaneously. OS400 now is generally issued in the OPUS form.

OPUS supports up to 32 time-sharing terminals. They can be running interactively or they may be devoted to specific background batch jobs - like RJE, for which emulator packages are becoming available, or printer spooling. The principal OPUS/OS4000 languages are:

Babbage: a high-level assembler. reportedly easy to use and to some extent compensating for the limitations of the register facilities of the; 4000. Commands largely follow English-language terms (IF ... THEN, RETURN, CALL). To some extent it follows the fashionable notions of structured programming; certainly it encourages a modular structure, with chapters linked into processes which form an application system.

Fortran: a Fortran IV to ANSI 1968 standards. A single-pass compiler, it produces non-optimised object code. GEC has an extensive library of run-time and applications routines for it.

Coral 66: a highly-rated implementation of the official blue book definition of this language. Used widely by MoD installations of the 4000.

Algol: full implementation of Algol 60, compatible with that for ICL 4100 and 1900 systems.

APL: recently-announced interpreter containing ,em>all the features of other commercially-available advanced APL systems,/em>. Features considerable reporting and debugging facilities; file support includes indexed sequential.

Basic: the usual language for OPUS users. Apparently a fairly good implementation, with several of the normal enhancements including matrix-handling, string-handling. chaining and filing.

RPG 2: a compiler which broadly follows the de facto standard laid down by IBM System/3.

Cobol: not yet available; when it appears it should be a considerable boost to the commercial aspirations of the 4000. The compiler is being written by North Staffordshire Polytechnic and was scheduled for completion originally in Autumn, 1978. It is due to appear later this year. or perhaps during 1980.

We are extremely grateful to both Dawn and Kim Wakefield for the kind donation of the collection of their late father Richard Wakefield

Reference Number / ISBN :

Date Published : 1976
Publisher : GEC
Format :






This exhibit has a reference ID of CH15843. Please quote this reference ID in any communication with the Centre for Computing History.

OPUS the GEC Computers Multi-access system

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