Edinburgh Multiple Access System

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The Edinburgh Multi-Access System (EMAS) was a mainframe computer operating system at the University of Edinburgh. The system went online in 1971.[1]

EMAS was a powerful and efficient general purpose

multi-user system which coped with many of the computing needs of the University of Edinburgh and the University of Kent
(the only other site outside Edinburgh to adopt the operating system).

History

Originally running on the

System/370-XA architecture (the latter with help from the University of Kent, although they never actually ran EMAS-3). The National Advanced System
(NAS) VL80 IBM mainframe clone followed later. The final EMAS system (the Edinburgh VL80) was decommissioned in July 1992.

The

ICL 2900 range - an ICL 2960, with 2 MB of memory, executing about 290k instructions per second. Despite this, it reliably supported around 30 users. This number increased in 1983 with the addition of an additional 2 MB of memory and a second Order Code Processor (OCP) (what is normally known as a CPU) running with symmetric multiprocessing
. This system was decommissioned in August 1986.

Features

EMAS was written entirely in the

dynamic linking,[5] multi-level storage, an efficient scheduler,[6] a separate user-space kernel ('director'),[7] a user-level shell ('basic command interpreter'),[8] a comprehensive archiving system[9] and a memory-mapped file
architecture.

Such features led EMAS supporters to claim that their system was superior to Unix for the first 20 years of the latter's existence.[citation needed]

Legacy

The Edinburgh Computer History Project is attempting to salvage some of the lessons learned[10] from the EMAS project and has the complete source code of EMAS online for public browsing.[11]

See also

References

  1. doi:10.1093/comjnl/16.4.331
    .
  2. ^ "Archived copy". Archived from the original on 16 December 2004. Retrieved 9 October 2004.{{cite web}}: CS1 maint: archived copy as title (link)
  3. S2CID 31830708
    .
  4. S2CID 22177787
    .
  5. ^ "Index of /archive/os/emas/emas2/subsystem/doc/loader". history.dcs.ed.ac.uk.
  6. ISBN 978-3-540-06849-5
    .
  7. doi:10.1093/comjnl/18.2.122
    .
  8. doi:10.1093/comjnl/18.3.213
    .
  9. doi:10.1093/comjnl/18.2.131
    .
  10. ^ Forsyth, C. H. (2011). "More Taste: Less Greed?". history.dcs.ed.ac.uk. Department of Computer Science University of York.
  11. ^ "Index of /archive/os/emas". history.dcs.ed.ac.uk.
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