PURPOSE: To prevent the interruption of a comparator from being ceased even if the value of a clock comparator register varies during scanning operation by confirming and setting, etc. the contents of a TOD (Time of DAY) timer and a clock comparator register by a coincidence circuit.

CONSTITUTION: This system performs data processing by using a scan loop system and the coincidence circuit 3 compares the contents of the TOD timer 1 with the contents of the clock comparator register 2 wherein a desired value is set by the instruction of the timer; when they coincide with each other, an FF4 is set to start a microprogram. Further, a scan control circuit 5 which scans the register 3 and another register 6, etc., is provided, and the FF4 is set when its scanning operation is completed to start a microprogram interruption.