The Edinburgh Multi Access System

Overview

This page provides information about the Edinburgh Multi-Access System, which I worked on for about 8 years. Its primary purpose is to provide supporting information for my lecture The Edinburgh Multi Access System, first given to the Computer Conservation Society.

The Lecture

The following direct material is available:

Full video of the lecture. This link skips the Chair's initial comments which are not germane to the lecture.
If you are just interested the the resurrection of EMAS, skip to 1:00:50 (one hour and 50 seconds in). For ease of access, use this link.
Just the slides for the lecture

Acknowledgements

The lecture would not have been possible without the help (over the last 40 or so years) of a large number of people.

I would like to thank anyone who was part of the EMAS team; thank you for your splendid work. I may not have met all of you, but your names are familiar to me from reading documentation (and source code!)

I am particularly grateful to those at Edinburgh with whom I had the pleasure of working (and eating and drinking). These are just a few of the people I worked with a lot, or to whom I owe a great deal; implicit thanks to anyone whom I have left out. Those marked with an asterisk (*) are sadly no longer with us; there may be more in that category of whom I am not aware. They include:

Colin Adams, Gordon Brebner, Mike Brown, Gordon Burns*, Scott Currie, Tony Gibbons*, Brian Gilmore, Bill Hay, Stephen Hayes, John Henshall*, George Howat, Bill Laing, Colin McArthur, Colin McCallum*, Roderick McLeod, Geoff Millard*, Brian Murdoch, John Murison, David Rees, Sandy Shaw*, Felicity Stephens, Peter Stephens*, Peter Robertson, Nick Shelness, John Wexler*, Harry Whitfield, Alex Wight, Keith Yarwood*

References

There are many references, including all of the documents in the repository mentioned below in the Links section. The most important ones are linked here. Some are published papers, and others are gleaned from rescued internal reports.

EMAS (or EMAS-1)

The Edinburgh Multi Access System: This is the original paper on EMAS.
The EMAS Director: This explains the Director, and its function in implementing the filing system.
The Standard EMAS Subsystem: This concerns the usual user interface to EMAS, although other subsystems can be used.
The EMAS Archiving Program: This important component provided offline storage for files, helping to keep the main filing system clear of rarely used files.
Edinburgh Multi Access System User Manual: The preliminary user manual issued when EMAS first offered a full service.
EMAS User's Guide: The User's Guide for the system. There is a small update here.

EMAS 2900 (or EMAS-2)

The EMAS 2900 Operating System: This is the principal paper on the second implementation of EMAS, on the ICL 2900.
An Experiment In Doing It Again, But Very Well This Time: The famously named paper on the process of re-implementing EMAS on the ICL 2900.
The Kernel of the EMAS 2900 Operating System: This paper describes the paging system, and (inter alia) the interaction between components such as the Director, Local Controller and Global Controller.
EMAS 2900 User's Guide: The User's Guide for EMAS 2900; some commands are changed or enhanced.
Introduction to EMAS: A simple introductory guide to the system.
The ICL 2900 Series: Probably the only actual book published about the ICL 2900. Rather superficial in places, no doubt because of legal issues; however, it is still interesting and informative.

EMAS-3

EMAS-3 User's Guide: The User's Guide for EMAS-3; many commands are changed or enhanced.
Mail on EMAS-3: The manual for using electronic mail of EMAS-3. Much of this also applies to EMAS 2900.

Miscellaneous

EMAS 2900: Concepts: A particularly useful document, describing the history of EMAS until about 1981. There is also a good overview of its inner workings.
The IMP language and compiler: EMAS was implemented almost entirely in the IMP programming language, based on Atlas Autocode. This describes the language, and the workings of its compiler.
Edinburgh IMP Language Manual: Describes the version of IMP used on EMAS, which was also available on EMAS 2900.
The IMP80 Language: Describes the slightly revised version of IMP used later on EMAS 2900, and on EMAS-3.
Atlas Autocode Reference Manual: An early manual on Atlas Autocode, which is a direct ancestor of the IMP language.
Atlas Autocode Mini Manual: An abbreviated manual for Atlas Autocode, which is a direct ancestor of the IMP language.

Anecdotes

Some EMAS and ICL 2900 related anecdotes are here: