The DMA controller (1)

• The DMAC is an auxiliary processor, which can be instructed by PCI devices to transfer data between the RAM and I/O devices

• Once activated by the CPU, the DMAC is able to continue the data transfer on its own

• The DMAC is mostly used by disk drivers and other slow devices that transfer a large number of bytes at once

• Its setup time is high, not appropriate for transfering small amount of data