How many DMA channels are there?
There are 8 direct memory access (DMA) channels in all, represented by the numbers 0 through 7. The older original IBM PC had only 4 DMA channels (0 to 3) capable of 8-bit transfers of data, while the 1984 IBM AT had 7 DMA channels. Modern processors now have 8 DMA channels with a much faster 32-bit data transfer capability. Except for DMA4, all DMA channels are used for communicating with input/output devices.