Switching to a different "thread" would also switch to a different stack though (although that would be kinda tricky on a 6502 where the stack is hardwired to t

Switching to a different "thread" would also switch to a different stack though (although that would be kinda tricky on a 6502 where the stack is hardwired to the $100 page). Actual multithreading on an 8-bit CPU is a bit of an esoteric topic though, usually one only has to deal with interrupt service routines running concurrently :)