ICL Direct Machine Environment facts for kids

Direct Machine Environment, or DME for short, was a special computer system used in the 1970s. It helped big computers called mainframes from a company named International Computers Limited (ICL) work better. DME was like a special program that let older computer programs run on newer ICL 2900 Series computers.

Why DME Was Created

In the 1970s, many companies used large computers and had teams of people who wrote special programs for them. When ICL made new, more advanced computers (the ICL 2900 Series), these companies faced a problem. Their old programs, made for the ICL 1900 or System 4 computers, wouldn't work on the new machines right away.

ICL created DME to solve this. It allowed customers to buy the new ICL 2900 computers but still use their old programs. This gave them time to create new programs that would work perfectly with the new system, called VME.

Running Old and New Programs Together

For a while, some companies would switch between using DME (for old programs) and VME (for new programs) on the same computer. This meant they couldn't run both at the same time. Sometimes, teams working on new programs had to wait for the computer to finish running older programs.

To fix this, ICL developed something called Concurrent Machine Environment, or CME. CME allowed the new VME system to run DME at the same time. This meant that old programs from the 1900 or System 4 series could run on the ICL 2900 or Series 39 computers right alongside the newer VME programs. It made things much more efficient for businesses.