PURPOSE: To make it possible to back up device information in online mode using system common memory by installing a device where system common memory made of non-volatile memory is built in.

CONSTITUTION: The present system common memory built-in device consists of a communication control processing section 3, a command analysis processing section 4, a device control section 5, a system common memory section 7 made of nonvolatile memory for storing device information, and a system common memory processing section 6 for processing the system common memory 7. Thus, by using the system common memory 7 to back up device information, device information such as recording reservation for VTR of a device having no built-in non-volatile memory 7 remains as it is even in the case electric service interrupt occurs, thereby eliminating the necessity of re-setting device information.