| 摘要 |
PURPOSE:To make efficient the DMA processing, by comparing a data stored in a resister with a transfer data in a direct memory access DMA porcessing device, and selecting an address pointer ADP. CONSTITUTION:In a peripheral processor 2 storing data to a memory 3 via a DMA processor 1, the data are already stored in data registers DRs 10, 11 of the device 2 and ADPs 14-16. When the device 2 makes a DMA request signal line 4 active, the device 1 detects this signal fetches a transfer data to comparison circuits 12, 13, and compares it with the content of the DRs 10, 11. When the circuit 12 coincides with the DR10 and the circuit 13 with the DR11, a selecting circuit 17 selects the ADPs 14 and 15 addresses the memory 3 via an address bus 6 and writes in the transfer data via a data bus 5. If the DR and the content of the comparison circuits are not in agreement the circuit 17 selects the ADP16 to address the memory 3. Since the ADPs are selected according to the content of data, the efficiency of DMA processing is increased. |
