| 摘要 |
PURPOSE:To use plural input/output control sections by setting a transmission/ reception parameter to a control register in an input/output control section to apply direct memory access from the input/output control section so thereby improving the efficiency of a program. CONSTITUTION:When no bus access exists by direct memory access DMA from an input/output controller 13, the bus access from a microprocessing unit 11 is permitted unconditionally. When the bus access from both the units 13 and 11 exists, the DMA from the units 13, 11 is controlled by a DMA control section 15 so that the DMA can use alternately a common bus 14. Since the transmission/ reception of the DMA is switched by the unit 13, the content of the control register is brought into the ''receiving state'' at a high speed while the unit 13 receives end information transmitted from an I/O circuit 2 in succession to the end of transmission of the data. |
