The current
DMA structure used by
Intel systems is as follows:
DMA Assignment
--------------------------------
0 RAM refresh, sometimes used by sound cards
1 Usually available for add-on peripherals
2 Floppy controller
3 ECP printer port, Bernoulli Box (rare these days)
4 The DMA COntroller uses this address
5 Most sound cards
6 Usually available for add-on peripherals
7 Usually available for add-on peripherals
Any high-volume I/O functions cause the load on the CPU to spike. Using DMA channels helps to reduce the overall CPU load.