What is Direct Memory Access (DMA)? How disk controllers and memory communicate

Having the CPU co-ordinate communication between heavily used I/O devices like disks reduces CPU throughput as it waits for data transfer to complete. Direct Memory Access or DMA is a method of transferring large blocks of data between disk controllers and memory that frees up the CPU to accomplish other tasks one the transfer is initialized. The CPU must provide basic info to start transfer, but then is free to do other work until it receives an interrupt to notify it of the completion of the data transfer. This optimization results in big gains in CPU throughput and reduced latency.
This video is part of a full semester course in Computer Organization and Architecture. You can see all of the topics in the course here: • Computer Organization ...
This video is part of the I/O topic with in the course, the video prior to this one is an introduction to I/O, discussing the challenges inherit to connecting extremely varied devices to the CPU. You can see it here: • Introduction to Input ...
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If you have not seen the Little Man Computer (LMC) series of videos, they explore how a computer works at it most fundamental level. You can find them here:
* A recommended introduction to Little Man computer video here: • Little Man Computer Ex...
* A "Hello LMC" video where we do a smaller program and talk more in-depth about the instruction cycle and basic instructions: • Little Man Computer (L...
* And an intermediate step where we introduce branching and explore recreating conditional statements with LMC: • Little Man Computer (L...
* Finally we explore iteration, labels and advanced LMC: • Little Man Computer (L...
Here are presentation slides that can be used as a supplement to follow along and as a future reference for this content: drive.google.c...

[@bhanuchanderbalusa3327]

I really found the differences between programmed io, interrupted io and DMA from your videos. You gave simple and real examples for clear understanding. Thank you so much for this

[@mth32871]

Excellent explanation. I just wish it was longer and more in depth, but it is amazing at just how much understanding I gained about this topic from such a short video. Thank you.

[@CodingCoach]

Glad you enjoyed it!

[@walidabdallaoui920]

This was pretty useful. Thank you

[@CodingCoach]

Glad it was helpful!