There is an OS-provided timer interrupt that you can hook in to, making sure your interrupt handler is called every X time units. I think it was something like

There is an OS-provided timer interrupt that you can hook in to, making sure your interrupt handler is called every X time units. I think it was something like 18 times per second by default, but changeable. I used this to slow down my computer so that old games were playable. Hooked into the interrupt, wasted cycles, and could enjoy the game. :)