Re: Zip Chip programming info / disk image?

["mdj" <mdj.mdj@gmail.com>]

Most of the slotted accelerators for 8-bit machines don't support DMA,
for the most
part because they're a DMA device themselves; they override the on
board 6502 using
DMA. Since you can only have one DMA device active any given time, if
can't work.

Apparently the Transwarp II supported DMA, although I'm not sure how
this is even possible; you'd have to disable the DMA of the card
itself, then either flush the cache
on the card if it's write back (probably infeasible in the amount of
setup time given for
a DMA operation in the 6502 specs) or invalidate the cache if it's
write through.

I'd imagine it's possible to build such an accelerator that gives best
of both worlds like
the GS ones do on an 8-bit machine, but that'd require utilising the
/INH line to redirect
memory access to the cache ram on the card, which would only work on
the IIe.

Anyway, I thought the unreleased Transwarp III was the one built with
rocketchip tech?
I recall the ads for the Transwarp II having more or less the same
featureset as the
Transwarp I, but a 7.12Mhz operating speed (which is apparently also
possible on a
TW I, if anyone knows how, let me know). The Transwarp III, which AFAIK
never saw
the light of day promised upgrades to potentially 12Mhz and beyond.
Transwarp II
was more of a quick upgrade to the original to compete with the Zip
8000.

I personally only have a Transwarp I, which I'd like to discontinue
using in favor of a zip 8000 since they're rather hot, and use up my
slot 3 which I'd like to have back for other
things, but have never been able to locate a zip 8000 for a reasonable
price

Matt