Direct Memory Access (DMA) and Programmed Input/Output (PIO) interface in operating systems (OS)

Direct Memory Access (DMA) and Programmed Input/Output (PIO) interface in operating systems (OS)

In this tutorial, we will learn about the followings;

  1. Direct Memory Access (DMA) 
  2. Programmed Input/Output (PIO) interface

Direct Memory Access (DMA) 

Direct Memory Access is a memory access technique in which any device can access the main memory without the involvement of the CPU.

According to Figure 1, if any device wants to load on the main memory (RAM), then it can be loaded without the involvement of CPU.

Direct Memory Access DMA in operating systems OS
Figure: Direct Memory Access DMA in operating systems OS

Programmed Input/Output (PIO) interface

Another way to access the memory is the Programmed Input/Output (PIO) interface. In this kind of memory access, all the data from devices travel to the CPU memory, commonly known as registers.

The programmed I/O is the simplest I/O technique for the exchanges of data and instructions between external devices and the CPU.