Information that is transferred through a bus BUS1 (conforming to IEEE 1394) is downloaded into a rewrite area storing device information (such as GUID or config ROM) and data transfer control program information (such as a SBP-2 firmware program), and rewriter processing is performed to write the information into the rewrite area. When it is detected that no device is connected to a bus BUS2 (conforming to ATA/ATAPI or IDE), the rewriter processing starts. The detection of whether or not a device is connected to BUS2 is based on the result of an access to a register of the device. In a download mode, the information is written into the rewrite area by transferring data to and from a PC connected to BUS1.