，DMA方式就是在一定时间段内，由DMA控制器取代CPU，获得总线控制权，来实现内存与外设或者内存的不同区域之间大量数据的快速传送。-, DMA mode is in a certain period of time, by the DMA controller to replace the CPU, access to the bus control, to achieve the memory and peripherals or memory large amounts of data between the different regions of the fast delivery.