Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!cs.utexas.edu!ut-emx!sjk
From: sjk@ut-emx.UUCP (bob)
Newsgroups: comp.sys.amiga
Subject: DMA controllers and 32bit RAM
Message-ID: <14391@ut-emx.UUCP>
Date: 22 Jun 89 22:34:57 GMT
Organization: The University of Texas at Austin, Austin, Texas
Lines: 21


Just a question I haven't been able to get a straight answer about:
What happens if you use a DMA hard disk controller, but have 32bit
expansion RAM that does not have it's own DMA controller?  It's my
understanding that there will be some problems because the controller
will be looking for 16 bit RAM, but will find 32 bit RAM in its place.
So, what happens? Does it come back saying not enough memory, does it 
revert to non-DMA transfer, does it DMA to 16 bit then upload to 32
bit via the CPU, or something completely different?  
My own system is an Amiga 1000 with LUCAS and (soon to be) FRANCES
32 bit memory board and a Toolbox expansion chassis where my hard
drive controller will go, but I suppose people with A2000's and 
a third party 68020 board (ex. Ronin) will face similar problems, as
the 2620 is the only 020 and 32 bit RAM board with its own DMA support
routines, that I know of.
FRANCE, by the way, is Brad's 32-bit memory board companion to LUCAS.
Thanks for any insight you can offer!

Scot Kleinman
sjk@astro.as.utexas.edu
Astronomy Dept. U. Texas Austin TX 78712