Solved

Question about DMA

Posted on 1998-02-15
2
643 Views
Last Modified: 2013-12-27
Hi, I am doing a Operation System Homework problem. However, I just have no idea about this problem (I can't find the answer in the book.)  I wonder if someone here can explain it for me?

The question is:
In virtually all systems that include DMA modules, DMA access to main memory is given higher priority than processor access to main memory. Why?


Thanks,
0
Comment
Question by:kelly_host
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 2

Accepted Solution

by:
Stonewal earned 50 total points
ID: 1806318
Because it is called "Direct Memory Access"? or because it has no use for the CPU and only needs room to work?

That was off the wall   hehehehe
0
 
LVL 12

Expert Comment

by:Otta
ID: 1806319
It's a matter of "priorities".
The hard-drive is physically "spinning",
and is either sending data from the
hard-drive into RAM, or needs to copy
data from RAM onto the hard-drive,
and it needs access to RAM *RIGHT* *NOW*,
i.e., at the highest priority.
The CPU must "wait" for the accesses to be
done; then, the CPU can fetch the next instruction to be executed.
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Administrator Tools 2 76
Any differences between redirected files & offline files? 4 76
BOSD APC_INDEX_MISMATCH - who's the culprit ? 4 60
z/OS IO Benchmark 3 69
I. Introduction There's an interesting discussion going on now in an Experts Exchange Group — Attachments with no extension (http://www.experts-exchange.com/discussions/210281/Attachments-with-no-extension.html). This reminded me of questions tha…
Windows 10 is here and for most admins this means frustration and challenges getting that first working Windows 10 image. As in my previous sysprep articles, I've put together a simple help guide to get you through this process. The aim is to achiev…
This is used to tweak the memory usage for your computer, it is used for servers more so than workstations but just be careful editing registry settings as it may cause irreversible results. I hold no responsibility for anything you do to the regist…
Hi friends,  in this video  I'll show you how new windows 10 user can learn the using of windows 10. Thank you.

738 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question