In DMA-based I/O,
A) CPU is relieved from data transfer and is interrupted after every word has been transferred to initiate the next word transfer.
B) cycle stealing can slow down the CPU computation, but off-loading the data-transfer work to a DMA controller generally improves the total system performance.
C) interrupt mechanism is not used.
D) data is transferred to/from a single block of memory, but not to/from multiple blocks.

Question

Quizplus · Accepted Answer

DMA-based I/O offloads the data-transfer work to a dedicated DMA controller, which can operate in parallel with the CPU. This can improve the overall system performance. DMA transfers can occur without interrupting the CPU, using cycle stealing to sneak in memory access during CPU wait states. Therefore, option A is incorrect. Option C is incorrect because interrupt mechanism is used in DMA-based I/O. Option D is incorrect because DMA can transfer data to/from multiple blocks of memory.

In DMA-Based I/O