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

By: Prof. Fazal Rehman Shamil
Last modified on May 8th, 2020

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

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 the CPU.

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.

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Prof. Fazal Rehman Shamil
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