Problem Statement
What is Direct Memory Access (DMA) and what advantages does it provide over other I O methods?
Explanation
Direct Memory Access (DMA) permits devices to transfer data to or from main memory directly without continuous CPU intervention. A dedicated DMA controller requests control of the system bus, transfers a block of data, and then returns control to the CPU. The major advantages are: the CPU is freed from busy waiting for I O, overall system efficiency increases, large data transfers are more efficient, and I O throughput improves. The trade-off is increased complexity in the I O subsystem, handling of bus arbitration and ensuring coherence of data between CPU caches and memory.
