without MMU you have to trust your tasks, but yes technically all you need is timed interrupts. so if you go the no mmu route, you could even list 6502 and z80

without MMU you have to trust your tasks, but yes technically all you need is timed interrupts. so if you go the no mmu route, you could even list 6502 and z80, as in "I rarely do multithreading, but if I do I do it without MMU" ;-) or at least have an MPU, which is what some microcontrollers have to protect multitasking.