Define the DMA controller interface.

A DMA controller interfaces along with a few peripherals which may request DMA. The controller chooses the priority of simultaneous DMA requests communicates along with the peripheral and the CPU, and gives memory addresses for data transfer. DMA controller generally used with 8088 is the 8237 programmable device.

The 8237 is actually a special-purpose microprocessor. Normally this appears as part of the system controller chip-sets. The 8237 is a 4-channel device type. All channels are dedicated to an exact peripheral device and able of addressing 64 K bytes section of memory.

8237 microprocessor