Apparatus for generating computer clock pulses

A circuit for generating a pair of clock pulses of opposite phases each having the same frequency as the frequency of an input signal generated by a crystal oscillator comprising means for generating a first pair of signals of opposite phases at half the frequency of the input signal generated by a crystal oscillator, means for generating a second pair of signals of opposite phases at half the frequency of the input signal generated by a crystal oscillator, means for comparing a first one of the first pair of signals with the one of the signals of the second pair of signals which is normally out of phase therewith to produce an output signal only when the two signals are in phase, means for comparing a second one of the first pair of signals with the one of the signals of the second pair of signals which is normally out or phase therewith to produce an output signal only when the two signals are in phase, means utilizing one of the output signals to lengthen the duty cycle of one of the first pair of signals of opposite phases and the other of the output signals to shorten the duty cycle of the other of the first pair of signals of opposite phases, means for producing a pair of clock pulses of opposite phases each having the same frequency as the frequency of an input signal generated by a crystal oscillator, and means responsive to the means utilizing one of the output signals to lengthen the duty cycle of one of the first pair of signals of opposite phases and the other of the output signals to shorten the duty cycle of the other of the first pair of signals of opposite phases for varying the duty cycle of the pair of clock pulses of opposite phases each having the same frequency as the frequency of an input signal generated by a crystal oscillator.