_(MIA) Redhog's (KangaroOS | http://k35.ryd.student.liu.se/index.frame.html), an operating system implementing multitasking by providing a _(VM) to each process; processes can also have subprocesses that they can schedule at their liking. There is a lot of documentation and some sourcecode available, currently completely in assembler, and building under _(DOS) (scroll down the left frame to get to the _(OS) pages proper).
