Abstract: A data transfer control system receives a command packet ORB transferred through a bus BUS1 (IEEE1394), issues a command indicated by: ORB to a device connected to a bus BUS2 (ATA (IDE)/ATAPI), and orders start of a DMA transfer. The command issued based on ORB is aborted after the completion of the DMA transfer. The data transfer control system compares contents of a command packet ORB1 transferred before a bus reset with contents of a command packet ORB2 transferred after the bus reset. If the contents are different, a command issued based on ORB1 is aborted after completion of a DMA transfer. Dummy data is transferred between the data transfer control system and the device connected to the bus BUS2 until a DMA transfer is completed. Dummy data transfer is controlled by performing a dummy update on a pointer.

Abstract: Information that is transferred through a bus BUS 1 (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 BUS 1.

Abstract: A data transfer control system receives a command packet ORB (SBP-2) transferred through a bus BUS1 (IEEE1394), and issues a command included in the ORB to a device connected with a bus BUS2 (ATA (IDE)/ATAPI). The data transfer control system sets a sufficiently large fixed DMA data length irrespective of the type of the issued command, and instructs start of DMA transfer to or from the device connected with the bus BUS2. The data transfer control system aborts the DMA transfer when a device connected with BUS2 informs of completion of command processing. As the fixed DMA data length, a value greater than a storage capacity of a storage or a value greater than a data length which can be designated by a command is employed. The data transfer control system issues a command included in the ORB to a device connected with the bus BUS2 without decoding the command.