What is I/O control method?

An I/O control method is the way the CPU manages data transfer between itself and an input/output device. It decides who starts the transfer and who moves the data.

There are three main methods:

• Programmed I/O: the CPU runs a program that checks the device status again and again and moves each word itself.
• Interrupt-initiated I/O: the device sends an interrupt signal when it is ready, so the CPU can do other work meanwhile.
• Direct Memory Access (DMA): a DMA controller moves blocks of data between the device and memory without the CPU handling each word.