Path: utzoo!attcan!uunet!crdgw1!rpi!uwm.edu!cs.utexas.edu!tut.cis.ohio-state.edu!n8emr!bluemoon!jerryk
From: jerryk (Jerry Kindall)
Newsgroups: comp.sys.apple2
Subject: Re: DMA, Octoram
Message-ID: <F1V3P1w163w@bluemoon.UUCP>
Date: 25 Sep 90 23:49:02 GMT
References: <5600@mace.cc.purdue.edu>
Sender: bbs@bluemoon.UUCP
Organization: Blue Moon BBS (614) 868-9980 & 9982 & 9984
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Re: Memory card DMA compatibility.
 
NO IIgs memory card is DMA compatible over 4 megabytes.  The design of the 
IIgs restricts DMA compatibility to the first 4 megs of the address space. 
(On a ROM 03, that would indeed be the first meg on the motherboard and 
three megs from a RAM card).  On the other hand, peripherals such as the 
Apple II High Speed SCSI Card and the RamFAST/SCSI card KNOW that they 
can't do DMA above 4 megs, so they don't even bother trying.  There is no 
need to set a RAM disk to keep these cards from trying to DMA into higher 
banks of memory, because the people who designed the cards knew all about 
the DMA limitations of the IIgs.

Jerry Kindall / Quality Computers
osu-cis!n8emr!bluemoon!jerryk