DMA

What is DMA?
DMA is an essential feature of all modern computers, as it allows devices to transfer data without subjecting the CPU to a heavy overhead. Otherwise, the CPU would have to copy each piece of data from the source to the destination, making the CPU unavailable for other tasks. This situation is aggravated because access to I/O devices over a peripheral bus is generally slower than normal system RAM. With DMA, the CPU gets freed from this overhead and can do useful tasks during data transfer (though the CPU bus would be partly blocked by DMA).