Re: Questions on Accelerators and RamWorks III

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

On Nov 3, 5:26 am, dog_...@macgui.com (D Finnigan) wrote:
> The last piece of desired equipment for my "dream" IIe system is an
> accelerator card. Before I pry open my wallet, I'd like to have some
> questions satisfied.
>
> First, I've done some research on various accelerators. From what I've read,
> not all of them "accelerate" the 64 KB AUX RAM area on a IIe, while others
> do. Ideally, since I'd be using a RamWorks III card, I'd like to know if
> there are any accelerators which can accelerate all banks of RAM.

For Ramworks compatibility, you need a Transwarp or newer accelerator.
None of them can accelerate more than 1mb of Ramworks memory. The Zip
uses a fairly standard tagged RAM cache. The Transwarp uses one of its
64k banks for caching the Ramworks, and I *think* it simply
invalidates the cache when a bank switch occurs. Simple enough to
determine with a test program if you care enough.

The Transwarp II is the clear pick of the bunch, but they're almost
pure unobtainium.

The best accelerator you're likely to *find* is a Zip 8000. However,
Zip Chips are notoriously unreliable and you'll find that people are
loathe to part with them.

Michael and I did some limited objective testing of a Zip vs a
Transwarp a few years back (thread should be easy to find). The Zip is
a *clear* winner. Subjectively I'd say there's not that much
difference, so unless you're running a huge assembly job (which may
well be IO bound anyway) either one provides a substantial improvement
over stock.

The Transwarp has some advantages over the Zip: being card based it's
more reliable, and relatively easy to repair. It doesn't exhibit that
annoying pause on ctrl-reset that the Zip Chips have. Lastly you can
install a 65816 part in place of its stock R65C02 and run Merlin-16
which is both more feature rich and considerably faster. Merlin-8
makes extensive use of SWEET16 internally, so the switch to 16 bit has
a large performance improvement. The 16 bit full screen editor is also
much nicer than the 8 bit version.

Disadvantages are: current draw (make sure your power supply is
fresh), you lose a slot (although slot 3 isn't useful for much else),
and of course, performance.

> Furthermore, I'd like to know if there are any incompatibilities with
> accelerators and mass storage systems such as the FocusDrive. I suspect that
> since the Focus does not use IDE, there are none. But I'd like to confirm.

I think you mean DMA... Seriously, DMA on an 8 bit Apple II isn't
really much of a win, since ProDOS 8 forces all disk access to be "one
block at a time". The accelerator will more than compensate you, and
from experience I can tell you that a Focus on a Transwarped or Zipped
IIe is *wicked* fast.

> Lastly, would an accelerator affect the timing of a clock card, such as the
> Timemaster II H.O.? Again, I suspect not, but I'd like to ask anyway.

It won't. BTW, the Timemaster II has a 1024Hz interrupt generator, so
combined with an accelerator you can do millisecond resolution
instrumentation.

> In closing, if anyone has suggestions for what I should get, please tell.
> I'll be posting a WTB advertisement in the csa2.marketplace newsgroup
> shortly.

I suspect it'll be more a case of taking what you can get, than being
picky. Since virtually all 8 bit software was designed to run well on
a stock machine, any accelerator gives a substantial subjective
improvement over stock speed. If you happen to get one of the faster
ones, good for you, but if someone offers you a Transwarp I'd
recommend picking it up.

Matt