7 Jul
2000
7 Jul
'00
1:42 p.m.
----- Original Message -----
From: <CLASSICCMP(a)trailing-edge.com>
To: <classiccmp(a)classiccmp.org>
Sent: Friday, July 07, 2000 4:25 PM
Subject: Re: Re[2]: Tim's own version of the Catweasel/Compaticard/whatever
written
electronically.
>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 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 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.