PURPOSE: To obtain the programmable counter easily generating a complicated output waveform which has been difficult to be realized by a conventional system.

CONSTITUTION: A counter 2 is operated by setting data of an A data register 4 and an overflow output 13 is outputted. A control circuit 6 receiving the output loads setting data of a B data register 5 to the counter 2 and the counter 2 is operated by the data. The operation of the counter 2 (overflow period) is changed by plural data registers to obtain a counter output 14 with a high degree of freedom.