| 摘要 |
PURPOSE:To attain DMA transfer under multi-task environment by allowing a bank memory device to select a stored memory block and applying an address obtained by converting an address on an address bus on the basis of the stored value to the selected memory block. CONSTITUTION:At the time of starting an I/O control device, 2 an OS switches a bank memory 3, maps another memory block (one of memory blocks 13-15) on an address space and starts another task assigned to the memory block. When the device 2 starts the DMA transfer of data to a bank memory window under said status, an address converting circuit 11 executes address converting operation and the switching operation of the memory blocks 13-15 in accordance with a set value and writes the data transferred from the device 2 in a prescribed memory block out of the memory blocks 13-15. Since the DMA transfer of data from the device 2 is executed independently of the memory block in the bank memory which is selected by the CPU, DMA transfer can be attained even under the multi-task environment. |
