DATA TRANSFER CONTROL SYSTEM

摘要

PURPOSE:To omit an adaptor which is set between a slave device and a bus having different data widths by setting the data width of a master device which performs the DMA transfer in accordance with the data width of the slave device at the destination of transfer by means of the software. CONSTITUTION:A CPU1 starts the DMA transfer to a master device 2 when the DMA transfer is desired for data between an I/O device 6 and a slave device 3 or 4 in a program execution mode. In this case, the information on the maximum data width of the device 3, for example, at the destination of the DMA transfer is informed by means of a mode setting command. Then the started device 2 sets its own maximum data width at the value equal to or smaller then the maximum data width of the device 3 indicated by the mode setting command regardless of the data width of a system bus 5. Then the DMA transfer of data is carried out between the device 6 and the device 3.