Direct memory access (DMA) Defination ,description

•Direct memory access (DMA) is a feature of modern computer systems that allows certain hardware subsystems to read/write data to/from memory without microprocessor intervention, allowing the processor to do other work.

•Used in disk controllers, video/sound cards etc, or between memory locations.

•Typically, the CPU initiates DMA transfer, does other operations while the transfer is in progress, and receives an interrupt from the DMA controller once the operation is complete.

•Can create cache coherency problems (the data in the cache may be different from the data in the external memory after DMA)