MINIMOP facts for kids
MINIMOP was a special type of operating system that helped run computers made by International Computers Limited (ICL). It was designed for the ICL 1900 series of computers. Imagine an operating system as the main program that makes a computer work, like the conductor of an orchestra. MINIMOP allowed many users to work on the computer at the same time, sharing its power. This was called "Multiple Online Programming" (MOP). It often worked alongside another system called George 2, which handled tasks that didn't need immediate attention, like printing many documents at once. MINIMOP got its name because it was a smaller, simpler version of the MOP features found in George 3, which needed a much more powerful computer.
MINIMOP could run on almost all ICL 1900 computers, except for the smallest ones (the 1901 and 1902 models). It didn't need a lot of computer memory, only about 16,000 "words" (a way to measure memory back then). It also needed two special storage devices, like old-fashioned hard drives, that could hold 4 or 8 million characters of information each.
Each user had a fixed-size space to store their data. This space could be divided into smaller sections called subfiles. The system also allowed users to create "macros," which are like shortcuts for common commands, making it easier to use.
How MINIMOP Worked
MINIMOP was built as a clever program that ran on top of the ICL 1900's basic operating system, known as the executive. Think of the executive as the computer's core brain, and MINIMOP as a smart assistant running on top of it. MINIMOP could handle many tasks at once, a bit like a person juggling several balls.
When users ran their own programs, MINIMOP kept a close eye on them. If a user program tried to do something like print a document or read from a disk, MINIMOP would step in. Instead of letting the program directly access the computer's parts, MINIMOP would pretend to do it. This made sure everything ran smoothly and safely. Because computer memory was very limited back then, user programs would be temporarily moved out of the main memory when they had to wait for something (like data to be typed in) or when their turn to use the computer's main processor was over. This process is called "swapping."
The MAXIMOP Upgrade
Later on, a team at Queen Mary College in London (now Queen Mary, University of London) created an improved version called MAXIMOP. This new system worked very much like MINIMOP, so it was easy for existing users to switch. ICL, the computer company, liked MAXIMOP so much that they started giving it out to universities. Eventually, over 100 different places ended up using MAXIMOP, showing how useful and popular it was.
