PURPOSE: To perform a normal error report to high-order device by releasing the error state of a low-order device itself in case errors are generated at a processor which controls the response to the high-order device and peripheral circuit.

CONSTITUTION: When an error is generated and a main processor 4 stops its working, a microprocessor 6 detects a halt signal and loads the error information to fetch the error information of a register 7. Then a reset signal is produced to reset both the processor 4 and the register 7, and the error information fetched to a processor 6 is set to a register 5. A program counter of the processor 4 is rewritten, and a restart address is set to set the head address of an error processing routine. Then the processor 4 is restarted. Thus the processor 4 reports the generation of an error to a high-order device by the instruction supplied from the error processing routine.