Disclosed is an information processing system in which a high-order apparatus and a low-order apparatus are connected so as to be capable of bidirectional communicating. The low-order apparatus stores control command information of the low-order apparatus in a ROM and, in response to a request from the high-order apparatus, transmits the control command information to the high-order apparatus to store the information in a memory of the high-order apparatus. Using the control command information corresponding to the low-order apparatus stored in the memory, the high-order apparatus transmits print data to the low-order apparatus and controls the operation of the low-order apparatus.