MPOS
(Frankly I know very little of this. I installed a couple just before I left BCL)
New Operating System for the Molecular designed to support new hardware in particular, but with some very clever features added for both programmers and users benefits.
One in particular, which was seen as revolutionary, was the ability to stow the job you were working on to disk, and then work on something quite different. You could then return to the 'stowed' job on your own or anothers terminal.
Knowing more about the OS, albeit LOS, this isn't difficult to achieve. The entire memory partition for the task being stowed would be saved (probably) in the spool file. A new utility to show stowed jobs, and an extension to the command handler to perform the stow.)