4 ms·
In 1987 I published a preemptive multitasking for 6502[1] (Apple II). If I remember properly (it's only been 30 years or so), the stack is fixed at $100, so all
by alain94040 11y ago
In 1987 I published a preemptive multitasking for 6502[1] (Apple II). If I remember properly (it's only been 30 years or so), the stack is fixed at $100, so all you need to do on a context switch is save the stack somewhere else and restore it. That's 256 bytes to move around. I used the mouse card as an interrupt source (video refresh) to get a regular source of interrupts.
[1] I can't find any trace online, except for some weird Word document of what must have been the original README file.