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

From: Richard Erlacher <richard_at_idcomm.com>
Date: Fri Jul 7 20:42:47 2000

----- Original Message -----
From: <CLASSICCMP_at_trailing-edge.com>
To: <classiccmp_at_classiccmp.org>
Sent: Friday, July 07, 2000 4:25 PM
Subject: Re: Re[2]: Tim's own version of the Catweasel/Compaticard/whatever


> >You write about this experiment with considerable confidence in your
result,
> >considering that you haven't any conventional hardware for dealing with
this
> >stuff. There must be something about your results that gives you the
> >confidence to proceed. What might that be? Are you getting verifiable
> >results, i.e. data that makes sense like ascii files, etc?
>
> Yes, ASCII (and EBCDIC, remember I'm recovering floppies originally
written
> in the early 70's) files that make sense.
>
> I think, Dick, that sometimes you make this seem harder than it is. Many
> of the data formats are readable (in hardware) with something as simple as
> a one-shot and a UART.
>
I remember some of those, and some actually worked at least some of the
time. OTOH, I'm not too familiar with the problem of unreadable diskettes.
In fact, I still have and (can) use the first floppies I ever owned. Aside
from the couple of truckloads of 8" diskettes I hauled to the dumpster
because they'd been wet, I believe I've still got every one I owned in 1985
when I quit using CP/M. The 8" diskettes I used with the APEX OS on a
homebrew 6502 are all still readable, and the I can't remember the last time
I had one I couldn't read once I figured out which machine wrote it.
Moreover, I've never had to attack the problem of reading floppies for a
machine that isn't in the lab or available somewhere. I'd never go to the
trouble you've gone to in order to read old files unless someone was footing
the bill. To me it's a daunting problem because of the time and efforr that
would have to be invested in developing a tool.

I had to get an Apple][ and a PC in order to find out about diskette
problems. Fortunately there were hard disks available.

I once had an NBI word processor that used those old MEMOREX drives that
used hard sectored floppies with the sector holes around the outside. When
there were sectors with error flags set, you just had to look at the text
file and could see which word had the wrong character in it.
>
> >Sampling and recording the analog signal might prove disappointing. The
> >data will be much harder to recognize in its analog form, particularly on
> >the inner tracks on a noisy diskette or drive.
>
> True, but the analog circuit would also be easy to simulate
electronically.
> Just a few coupled linear and nonlinear differential equations!
>
yes, but the you still have to make sense of it. It depends on what your
goal is.
>
> Tim.
>
>
Received on Fri Jul 07 2000 - 20:42:47 BST