Microware OS9 implemented preemptive multitasking on the motorola 6809 without an MMU back in 1980. You don't have memory protection without an MMU, but you ca

Microware OS9 implemented preemptive multitasking on the motorola 6809 without an MMU back in 1980. You don't have memory protection without an MMU, but you can have preemptive multitasking.