Z80 has a non-maskable (NMI) interrupt line that will break whatever code is currently executing without allowing the software to opt out (EI/DI instructions), and then jump to a hardcoded page zero location, I believe it is address 0x66.
This line is typically tied in popular Z80 machines to the vertical blanking generator (frame refresh - 50/60Hz). Presumably, the OS would then schedule the tasks in a round robin fashion and most tasks will cooperate and yield control quicker to allow a not too choppy experience.
This line is typically tied in popular Z80 machines to the vertical blanking generator (frame refresh - 50/60Hz). Presumably, the OS would then schedule the tasks in a round robin fashion and most tasks will cooperate and yield control quicker to allow a not too choppy experience.