ABSTRACT
Timers for Periodic Notification Drivers use timers to gain control of the processor on a periodic basis in order to poll a device, to update some variables, or even to refresh the screen. Under DOS, the only way to get a periodic notification is to hook the timer interrupt, which normally occurs every 55 ms — 18.2 times per second. A DOS application also has the option of reprogramming the PC timer hardware so that the interrupt rate is faster.
