PURPOSE: To prevent an increase in load on a program even if the number of channels increases, by determining the entry address of a processing program on the basis of a set value outputted from an interruption control part.

CONSTITUTION: An encoding circuit 4, when one of interruption signals Ii0WIi7 is made effective, selects one with top priority and encodes the selected signal to output three bits EA0WEA2. Simultaneously, the circuit 4 inputs an interruption information signal Ii to an interruption control circuit 3. An address sent from the circuit 3 is the same. At this time, the outputs EA0WEA2 of the circuit 4 are inserted into part of a data bus 6, so microcomputer 1 is capable of implementing a branch to the entry bus for a processing program which corresponds to an interruption corresponding to each circuit.