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From: Martin Str|mberg <ams AT speedy DOT ludd DOT ltu DOT se>
Subject: Re: Problems with timer interrupt chaining and SmartDrv
Newsgroups: comp.os.msdos.djgpp
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Date: 20 Dec 2004 20:49:09 GMT
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To: djgpp AT delorie DOT com
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Eli Zaretskii <eliz AT gnu DOT org> wrote:
>> From: Martin Str|mberg <ams AT speedy DOT ludd DOT ltu DOT se>
>> Date: 18 Dec 2004 11:09:24 GMT
>> 
>> Eli Zaretskii <eliz AT gnu DOT org> wrote:
>> > It sounds like you are assuming that DMA is faster than PIO.  That was
>> > so once, long ago, mainly with floppy drives, but is no longer true
>> > since ATA interfaces conquered the PC land.  Nowadays, PIO is faster
>> > than DMA, so AFAIK DMA is no longer used in disk I/O.
>> 
>> For DOS maybe, not for a multitasking system.

> Do you mean DMA is used on multitasking systems?  Or do you mean PIO
> is only faster on DOS, not on multitasking systems?

> If the latter, please explain.

The former. And since DOS isn't multitasking it doesn't gain anything
from the possiblity of the CPU doing something else but waiting for
IO.


Right,

						MartinS