Re: Final question about my PC-Transporter...

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

<pubpc1@library.ucla.edu> wrote:

> suomynona@suomynona.tseug.edu (suomynona) wrote:
> >In article <19970122215831243351@dempson.actrix.gen.nz>,
> >dempson@actrix.gen.nz (David Empson) wrote:
> >> 
> >> Paul Dunkel <pdunkel@cc.hut.fi> wrote:
> >> 
> >> > I don't run any PC-emulations, so do I have any use for my
> >> > PC-Transporter? I mean, now it's only as a ram-card, but doeas any
> >> > program really use it?
> >
> >It can also support an AppleDisk 3.5 drive, which is a big plus for
> >][e owners. Caution, don't use the UniDisk 3.5! You might fry both the
> >drive and the PCT card in the process.
> 
> Would it also be possible to use its math co-processor in
> Apple mode?  I am thinking of a SANE patch that would use
> the FPU on the PCT as an I/O device, much like the way the
> FPE and Number Cruncher works.

I'm sure it is possible, but it wouldn't be easy.

I very much doubt that the 8087 can be accessed directly from the Apple
II side.  It is set up for use as a coprocesor of the V30, and is
dependent on the opcode fetches, etc. of the main processor.

This means that to use the FPU, it would be necessary to upload some
8086 code into the card to control the FPU, and communicate with it.
This code would have to include a rudimentary BIOS (at least enough to
initialize the PC hardware) and support code running on the Apple II
side to implement I/O devices required by the PC.

Someone would have to do some extensive disassembly of the PC
Transporter software to find out how to do this.

I suspect it is not possible to do this and still retain the device
driver support of the PC Transporter (thus you would lose /RAMAEPC and
any connected drives).


All of this assumes that the FPU is actually installed on the card, of
course.  I have only ever seen two PCTs (including mine) and neither has
an FPU.

> Although the old chip probably won't help in the case of a
> Zipped or Xwarped GS, for unaccelerated machines it may be
> of use.

Even with a fast accelerator, an FPU should be faster than SANE.  The
overhead of communicating with it would even things out somewhat.

-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, New Zealand