Re: asm.e questions
----- Original Message -----
From: Bernie Ryan <bwryan at PCOM.NET>
To: <EUPHORIA at LISTSERV.MUOHIO.EDU>
Sent: Sunday, October 24, 1999 1:11 PM
Subject: Re: asm.e questions
> On Sun, 24 Oct 1999 12:29:37 -0500, Kat <KSMiTH at PELL.NET> wrote:
>
> >
> >True DMA on a motherbd with only ISA slots?
> >
> >Kat
>
> Then how do you think the floppys work on your motherbord ?
> The dma controller is on the motherboard.
>
I've never seen a DMA with a floppy. I know there is chip to handle the DMA,
it's been on motherbds at least since the ZX80 in one form or another. But
you couldn't tell the hard drives to DMA to a memory location inside your
program. On the early motherbds with PCI slots, not all the slots supported
DMA *from* sound cards, hd cards, etc,, because they couldn't get that
chip's attention to shut it off. What he needs to do is set the hd as a buss
*master* , not under the control of that chip. When the hd is running buss
master dma, the dma chip on the motherbd does one job, the cpu does another
job, and the card doing pci buss mastering does it's job. For instance, you
could have the motherbd chip doing an ems page swap, the cpu running your
app, and the hd dropping data into xms somewhere.
Kat
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