An oscillator is provided to control the processing of binary digits. If such bits comprise video information which construct characters on a display monitor, then by varying the frequency of the oscillator the number of bits or pulses during visible portions of the scan time is controlled. The oscillator includes a register, counter, comparator logic, and speed correction circuitry. The oscillator itself has a disable input which in combination with the other elements provides an output signal that may also be started or stopped synchronously.