Edinburgh Multiple Access System facts for kids
The Edinburgh Multi-Access System (EMAS) was a special type of computer program called an operating system. It ran on large computers called mainframe computers at the University of Edinburgh in Scotland. EMAS started working in 1971.
This system was very powerful and could handle many users at the same time. It helped meet most of the computing needs for the University of Edinburgh. Another university, the University of Kent, also used EMAS.
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How EMAS Started and Grew
EMAS first ran on a big computer called the ICL System 4/75. This computer was designed similarly to the IBM 360. Later, EMAS was rebuilt to work on newer computers called the ICL 2900 series of mainframes. This new version was known as EMAS 2900 or EMAS-2. It was used until the mid-1980s.
Near the end of its life, an even newer version, EMAS-3, was made. It could run on other large computers like the Amdahl 470 and IBM System/370-XA. The very last EMAS system, at the University of Edinburgh, was turned off in July 1992.
EMAS at the University of Kent
The University of Kent started using EMAS in December 1979. They had a smaller ICL 2900 computer, an ICL 2960. Even with only 2 megabytes of memory, it could reliably support about 30 users at once! In 1983, they added more memory and another processor. This made the system even better. The Kent system was turned off in August 1986.
What Made EMAS Special?
EMAS was written using a special computer language called Edinburgh IMP. Only a few very important parts used a more basic language called assembler. EMAS had many features that were very advanced for its time.
Some of these cool features included:
- Dynamic linking: This allowed programs to share parts of code easily.
- Multi-level storage: It managed different types of computer memory very well.
- Efficient scheduler: This helped the computer decide which tasks to work on next.
- Separate user-space kernel: This part, called the 'director', helped keep user programs separate and safe.
- User-level shell: This was a 'basic command interpreter' that let users type commands to control the computer.
- Comprehensive archiving system: It had a great way to save and store old files.
- Memory-mapped file architecture: This made it easier and faster for programs to use files.
Because of these advanced features, many people who used EMAS believed it was better than Unix for a long time.
EMAS's Lasting Impact
The Edinburgh Computer History Project is working to learn from the EMAS project. They have made the complete source code of EMAS available online for anyone to look at. This helps people understand how these early computer systems worked.
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