An IEEE 1394-compliant communication bus connects a printer and host computer so as to allow communication. The configuration ROM of the printer stores information about devices mountable on the apparatus. The host computer accesses the configuration ROM via the communication bus to acquire information in a Feature Directory. The Feature Directory stores information about optional devices connectable to the printer. Information about the printer is displayed based upon information acquired from the Feature Directory. This allows the user to easily grasp information about devices mountable on the apparatus.