ICL VME
Mainframe operating system developed by ICL
VME (Virtual Machine Environment) is a mainframe computer operating system developed by the UK company International Computers Limited (ICL, now part of the Fujitsu group). Originally developed in the 1970s (as VME/B, later VME 2900) to drive the then new ICL 2900 Series mainframes, it is now named OpenVME, incorporates a Unix subsystem, and runs on ICL Series 39 and Trimetra mainframe computers, and industry-standard x86-64 servers.
Origins
The development program for the New Range system started on the merger of International Computers and Tabulators (ICT) and English Electric Computers in 1968. One of the fundamental decisions was that it would feature a new operating system. A number of different feasibility and design studies were carried out within ICL, the three most notable being:
VME/B (originally System B), targeted at large processors such as the 2970/2980 and developed in Kidsgrove, Staffordshire and West Gorton, Manchester
VME/K (originally System T), targeted at the mid-range systems such as the 2960 and developed at Bracknell after the original design for these small processors, System D, was dropped. VME/K was developed and introduced to the market but was eventually replaced by VME/B
VME/T, which was never actually launched, but warrants a mention as it was conceived to support "fault tolerance", and predated the efforts of the successful American startup company Tandem Computers in this area.
The chief architect of VME/B was Brian Warboys, who subsequently became professor of software engineering at the University of Manchester. A number of influences can be seen in its design, for example Multics and ICL's earlier George 3 operating system; however it was essentially designed from scratch.
VME/B was viewed as primarily competing with the System/370 IBM mainframe as a commercial operating system, and adopted the EBCDIC character encoding.
History
When New Range was first launched in October 1974, its operating system was referred to as "System B".
Begin with the source’s own compact description: “ICL VME” is mainframe operating system developed by ICL. The dossier treats that line as a proposition to test through Mainframe, operating and system, not as a finished interpretation.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Mar 30, 2026. The linked authority identifier is Q4052546. 1 of 2 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1968 and 1974.
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This entry incorporates text from “ICL VME” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.