Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!udel!haven.umd.edu!ncifcrf!lhc!adm!smoke!gwyn
From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.sys.apple2
Subject: Re: DMA Compatability
Message-ID: <15955@smoke.brl.mil>
Date: 23 Apr 91 21:10:48 GMT
References: <11079@mentor.cc.purdue.edu>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 18

In article <11079@mentor.cc.purdue.edu> grochoci@mentor.cc.purdue.edu (Paul Grochocinski) writes:
>	What I have is a fully populated Apple Memory expansion card for my GS.
>The one that came with it.  Is any of the memory on this board used as DMA?

You're operating under a misconception.  The RAM itself is neither "DMA" nor
"non-DMA"; DMA refers to a method of accessing the memory by other devices.

Some RAM expansion cards for the IIGS malfunction under some types of DMA
access, which is probably where you got the notion.  I think Apple's own
expansion card has no problem when accessed via DMA.

>I have tried copying Battle Chess to the RAM and boot it from there but I
>don't notice any real difference in the timing.

Use of a "RAM disk" (emulation of a block storage device using RAM) can
speed up "disk" I/O but not computation.  Once the program is loaded it
runs at the same speed no matter where it was stored.  (There are some
minor exceptions, not worth discussing at this level.)