Re: Apple II accelerator card.

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <40oiul$55d@news.globalx.net>,
Jeremy Rand <jeremy@gate.globalx.net> wrote:
> 
>   I have a CVTech card and it is fully compatible with my HS SCSI in
> DMA mode.

Now I'm getting rather confused.  There have been conflicting reports
in recent articles - some people say that they can't get DMA to work
with this combination of cards, and other people say they can.

Are there two versions of the CVTech RAM card, perhaps?

Does it depend on the installed RAM configuration?

My gut feeling is that the CVTech card cannot be DMA compatible if you
have mixed RAM types, i.e. 1MB-wide chips on the CVTech card and
256KB-wide chips on the piggyback card.  It also cannot be fully DMA
compatible if you have more than 4MB of RAM in total (the Apple HS
SCSI card should avoid attempting to do DMA beyond the 4MB point,
which usually avoids any problem).
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand