From:	damon AT WRONG DOT redshift DOT com (Damon Casale)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Using DMA for hard disk access?
Date:	Fri, 02 Mar 2001 16:39:24 GMT
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On Fri, 02 Mar 2001 12:54:26 +0200, "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
wrote:

>> >Keep in mind that while DMA moves data from the disk to memory or
>> >back, the system bus is not available.  Therefore, you will have bus
>> >contention with any other device that goes through the bus.  VGA, for
>> >example.
>> 
>> Would plain memory access (regardless of what it is) be going through
>> the same bus?
>
>It depends.  On most modern motherboards, the main memory doesn't go
>through the system bus, AFAIK.

Hmm!  Interesting.

>> >> I'm not entirely sure how to tell the hard drive what sectors I want
>> >> to read or write, but I _think_ I know how to use the DMA I/O ports.
>> >> Where would I look for more detailed info on this?
>> >
>> >In case you didn't see it, the DJGPP FAQ has something about using DMA
>> >in section 18.13.
>> 
>> Yup, saw that already.  Thanks tho.  :-)
>
>You should probably study some good book about DMA programming in
>conjunction with PC and disk I/O.  The Undocumented PC is one of my
>favorites.

Just ordered that one from Amazon.com.  Thanks for the tip, tho.  ^_-

Damon Casale, damon AT WRONG DOT redshift DOT com (remove the obvious)
Did the memory forget to take the bus?  ;-)

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