A programmable high resolution timing system includes a selectable modulus prescaler counter. In one embodiment a high frequency clock is coupled to a prescaler counter which provides an output signal every predetermined number of clock pulses. The prescaler is coupled to a period counter which provides a period signal after a predetermined number of prescaler output signal pulses. The prescaler and period counter are coupled to a memory which stores data corresponding to the selected modulus of the prescaler and the number of counts by which the period counter output signal is to be delayed. The period resolution is thus made substantially equal to the resolution of the high frequency clock by varying the prescaler modulus at programmable intervals.