Task Switching Environment (TSE) v1.5 || Michael Vincent & Robin Kay || 3616 bytes
This operating system is like Ion, with more libraries (for programmers), but it allows you stop a program whenever and restart where it has stopped. But there are threes problems : it is slower than Ion to display the programs list, it takes more memory, and you must unarchive programs to run them. Finally, this program works only with a 83+.