Subject: Re: Bounce buffers for ISA dma
To: Mark P. Gooderum <>
From: Greg A. Woods <>
List: current-users
Date: 11/29/1994 12:18:04
[ On Mon, November 28, 1994 at 15:07:29 (-0600), Mark P. Gooderum wrote: ]
> Subject: Re: Bounce buffers for ISA dma 
> I know the feeling.  But this ground has been covered before...
> The bounce support in isa/dma.c is only for devices that use the
> motherboard DMA controller for their DMA.  This would include things
> like the floppy controller and driver (anything that takes a drq and
> actually uses it).  Bus-mastering controllers don't use the
> DMA controller and don't have a drq(/arq) channel assigned to them, so
> they aren't helped by this fix.  Thus, ISA bus-mastering devices, like
> IDA IDE controllers, the AHA-154x's, etc have the 16M limit still.

DRAT!  A lot of old ISA equipment could be put into service on low-I/O
servers, workstations, etc. (i.e. low-I/O once you eliminate the need to
do paging by adding enough memory), if this could be made to work.  This
isn't so important to me, since I live in a city where we can get new
systems cheaper than most anywhere else in the world, but for folks
elsewhere, I can surely sympathize with their frustrations over older,
limited, equipment.

						Greg A. Woods

+1 416 443-1734			VE3TCP		robohack!woods
Planix, Inc. <>; UniForum Canada <>