Question 16117 – I/O-Devices

Explanation: Both the methods of programmed I/O and Interrupt-driven I/O require the active intervention of the processor to transfer data between memory and the I/O module, and any data transfer must transverse a path through the processor.
DMA or direct memory access allows the peripherals to directly communicate with each other using the memory buses, removing the intervention of the CPU. Hence it is the fast mode of IO transfer compared to all other methods. In polling, the processor wastes countless processor cycles by repeatedly checking each IO device if it needs attention.