Question

How does the cpu interface with the device to coordinate the transfer?

Answer 1

The CPU initiates a DMA operation by writing values into special registers that can be .independently accessed by the device. The device initiates the corresponding operation once it .receives a command from the CPU. When the device is finished with its operation, it interrupts .the CPU to initiate the completion of the operation

Answer 2

Direct memory access (DMA) is used for high-speed I/O devices in order to avoid increasing the CPU's execution load.