>
> >
> > >
> > > >
> > > > Does anyone have any ideas on interfacing a floppy disk drive to a PIC?
 I
> > > > know it seems absurd, but there are LOTS of applications for such an
> > >  interface.
> > > >
> > >
> > > Not absurd at all. In fact I was thinking of how to interface a parallel
> > > ZIP drive to a PIC. Imagine having 100 megabytes of removable storage!!!
> >
> > Well, all the source is available, look in any slackware linux mirror, and
> > you'll find that the zip drive is supported, it's basically a scsi type
> > interface on the printer port.
>
> I'm aware. I initiated the Linux parallel ZIP project by showing that the
> ZIP drive worked under Linux's DOS emulator. Grant Guenther then used the
> I/O traces from the emulator to determine the data transfer patterns between
> the driver and the drive. This was used to write the driver.
>
> I have the code for both the kernel driver and the user level driver that
> Grant wrote. What I'm really interested in is whether or not a fast PIC can
> emulate an EPP port. If so then it's possible to get the transfer rate up
> to about 200K per second which is adequate for just about any task.
>


Hmm, I really don't see the applications for this, but anyway, soem thoughts.
I don't think the raw data rate is really a problem, you get 25 instructions
or so per data byte. (at a 20Mhz pic)
However, if you'r wanting to write incoming data, you'll need to read it
as well, at the same time, I really doubt you could do 200Khz both in and
out.
Even if you can, you'll need some cache, as no pic I'm aware of can keep
that amount of data in ram (least 1024 bytes)
Having not really examined it closely, I'd say you probably could do this
with one of the higher end pics, and some external ram.
Maybe you could use a deep FIFO to iron out data-rate fluctuations, and
eliminate the need for any cache.
If I was doing this, I'd definately prefer some sort of better processor,
maybe a z80/186 or something similar, with an address space at least as
big as the data in cache, plus, squeezing the interface code, and
dos filesystem code (minimal) would be at very best an unpleasant squeeze.



> BAJ
>


--
Ian Stirling.                        |  http://www.mauve.demon.co.uk/
AKA Caeser, Bolonewbie.              |  With information on the PDA I'm making.