| 摘要 |
PURPOSE:To transfer data by using both address and data buses by connecting a data/I/O terminal of either one of 1st and 2nd memories to the address bus and connecting the other data I/O terminal to the data bus at the time of direct memory access (DMA). CONSTITUTION:At the time of DMA, a selecting means 14 selects both the 1st and 2nd memories 5-1, 5-2 and an address selecting means 14 applies the count value of a counter 17 counted up every DMA operation to the 1st and 2nd memories 5-1, 5-2 as an address signal. Connection switching means 15, 16 connect the data I/O terminal of either one of the 1st and 2nd memories 5-1, 5-2, to the address bus 6 and connect the other data I/O terminal to the data bus 7. Consequently, both the data bus 7 and address bus 6 can be used for data transfer at the time of DMA, so that the volume of transfer data per DMA can be increased without sharply changing the system. |
