Re: Zip Chip programming info / disk image?

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

RedskullDC <RDC@oz.org> wrote:

> One thing that doesn't appear to be covered is whether it co-exists
> with DMA capable devices?
> Does it actually work with DMA devices?

No. The Zip Chip is totally incompatible with any DMA device, because it
doesn't have access to the slot signals which indicate that a DMA cycle
is taking place.

By comparison, the ZipGS _is_ compatible with DMA, because it is a
slotted card and can see DMA cycles from other cards.

As far as I recall, this can also be extended to other Apple II
accelerators. The TransWarp GS is also DMA comptabile, but my
recollection is that no accelerator for 8-bit models is DMA compatible,
even those which have access to the slot connector.

> P.S. I have both a Rom1 and 3 GS. Anyone have any info on
> the ZIP-GS, or does it adhere to a similar programming scheme?

I have a copy of the programming documentation for it (on paper, no
handy scanner). I believe it is an extension of the general logic of the
Zip Chip, with a fair amount of additional logic required for the added
complexity of the IIgs.

-- 
David Empson
dempson@actrix.gen.nz