PURPOSE: To specify a fault factor by securely extracting control information developed in the internal memory of the SCSI peripheral device without requiring any special interface means when a fault occurs in the SCSI peripheral device.

CONSTITUTION: If the fault occurs in the peripheral device 1 equipped with SCSI interface as general input/output interface, an operation means 1b provided on the peripheral device 1 is operated and then an interruption having high priority is generated by the interruption of a SCSI control device to saves the contents of the registers of the SCSI control device in the memory; and the SCSI device of the peripheral device 1 is initialized and conversion to an initiator is performed. Then an interruption having a lower level than the interruption of the SCSI control device is generated to search for another peripheral device on the same SCSI bus 2 and internal information on the peripheral device 1 where the fault occurs is transferred to another peripheral device 3 such as a printer device.