Tim's own version of the Catweasel/Compaticard/whatever

From: Richard Erlacher <richard_at_idcomm.com>
Date: Wed Jul 5 17:41:08 2000

It will require no modification at all to handle those formats. It samples
the data at a harmonic of the data rate and writes it back at a harmonic
suitable for adjustment for write precompensation. Dealing with the
different modulations, as you've named, is a software post-processing task.
Likewise, if a little extra effort is put into the design, it can record,
quantitatively the location of the index/sector pulses in order to enable
reading and writing of hard-sectored diskettes. There are too many
mechanical variations to allow simple timing of the theoretical locations of
these events.

The notion of reprogramming the thing is perhaps a pregnant one, but I have
reservations about the suitability of this particular device, for want of
pins. A single or pair of 256Kx4 DRAMs might be manageable, but SRAMS would
require 30 connections and the EPP/SPP interface would require 13. Then
there are a few connections to the drive cable required. As you can see,
we're past being out of pins already. A 68-pin device would be more likely
to work. Perhaps a video DRAM would work with fewer connections.

Dick

----- Original Message -----
From: Eric J. Korpela <korpela_at_ellie.ssl.berkeley.edu>
To: <classiccmp_at_classiccmp.org>
Sent: Wednesday, July 05, 2000 11:50 AM
Subject: Re: Tim's own version of the Catweasel/Compaticard/whatever


> > The
circuit
> > wouldn't be modifiable on the fly, however, unless you consider the
multiple
> > minutes of reprogramming time and the associated physical effort "on the
> > fly."
>
> I do consider that to be on the fly.
>
> > So far, I've seen no reason to make this baby reconfigurable. What do
you
> > have in mind?
>
> FM, MFM, or GCR decom in the CPLD.
>
> Eric
>
>
Received on Wed Jul 05 2000 - 17:41:08 BST