| 摘要 |
PURPOSE:To reduce the load of a host device and to improve the performance of a system by surveying validity/invalidity of a SCSI bus disconnection designated by a command from the host device and previously controlling a DMA at the time of the invalidity of the disconnection. CONSTITUTION:In a SCSI host adapter circuit 2 for connecting the host device 1 having no direct memory access restarting function and a slave device connected to a SCSI (Small Computer System Interface) bus 4, when the host device 1 designates the invalidity of the SCSI bus disconnection, a direct memory access starting processing part 21 is provided, which previously executes a direct memory access starting processing preceding to a direct memory access request generated from the slave device 3. Thereby, at the time of a data phasing of the slave device 3, transfer of data, is started immediately so that, the load of the host device is reduced and the performance is improved. |
