| 摘要 |
PURPOSE:To transfer the data even in case of the refreshing in a DMA transfer between an input output control device and a local memory device by providing a buffer register which temporarily stores the data at an input output control device. CONSTITUTION:In a DMA transfer from a main memory device 3 to a local memory device 9, a DMA controller 13 receives a DMA transfer request signal 20 from the device 9, and then, the controller outputs a holding request signal 21 to a CPU29. When the request is received, a holding permitting signal 22 is outputted, the data of the device 3 are read, transferred and stored through a data bus 23, etc., to a buffer register device 15. The data stored at the device 15 are written to a local memory 18, after confirming that a status signal 30 of a memory control device 17 is investigated and refreshing is not executed by the device 14. In case of a DMA transfer from the device 9 to the device 3, a buffer register device 16 is used, the transfer is executed by the same procedure, and in case of the refreshing, the data transfer can be executed. |
