Answer:
Programmed I/O refers to the method where the processor is responsible for manually controlling the transfer of data to or from a device. In this method, the processor waits for the input or output operation to be completed before moving on to the next task.
In interrupt-driven I/O, the device itself notifies the processor when it is ready for input or output operations. This method reduces the amount of waiting time for the processor since it can continue executing other tasks while waiting for the device to complete.
Direct Memory Access (DMA) is a technique that allows devices to transfer data to or from memory without involving the processor. This method is used to reduce the burden on the processor and speed up the data transfer process. The DMA controller takes over the bus and directly transfers data between the device and memory. During this process, the processor is free to perform other tasks, increasing overall system performance.