Direct Memory Access (DMA):

Technique that allows an I/O device to transfer data directly to/from main memory without CPU intervention for each word.

• DMA controller (DMAC) takes over system buses (via Bus Request BR / Bus Grant BG, cycle stealing or burst mode).
• CPU initializes DMAC with start address, word count and direction; DMAC then handles the entire block transfer.
• CPU is free to do other work; interrupted only at start and completion.

Advantage: Much faster than programmed or interrupt-driven I/O for high-speed devices (disk, display) — especially for large block transfers.