Direct Memory Access
DMA is used when low latency and/or high bandwidth is required. (disk IO, video output or low latency data acquisition)
Software DMA: starts with normal interrupts, the ISR sets the device resisters and initiate I/O, processor returns to normal operation, on completion of I/O device inform the processor.
Hardware DMA: the above can be implemented in hardware
Burst DMA: when buffers are put in I/O devices (disk)
- Low latency asynchronous I/O can not use burst DMA.