21 Feb
2008
21 Feb
'08
7:30 p.m.
> other useful tools that work well are
"rawrite" or rawcopy.
> though if you must use dos to read floppies, I always prefer teledisk,
> however it uses a proprietary format teledisk compresses so it makes the
> images smaller, and it also has handlers for errors, etc.
>
> if you use linux/bsd, you can simply put the disk in the drive and use dd
> like: dd if=/dev/fd0 of=/home/myhome/outputfile.iso
> (modify the path as needed)
Interesting stuff, I've used rawrite for my first
linux installation way back
in 1999, as the system I had to install it to then didn't boot from a
CD. :-)
dd, rawread, rawwrite etc. will only work with diskettes which have a format
that the linux driver understands - There are *MANY* variations on the soft-
sector disk format, and programs like ImageDisk and TeleDisk will analyze the
disk to determine how it's formatted, read that format and record metadata
in the image file so that it can be exactly recreated. dd and others will
typically just report an error if an expected sector header is encountered.
At this point I have some image files that were
apparently created with the
ImageDisk program, and while I can use a file viewer (F3 in mc :-) to see
the innards of the file I'm not sure what the original format was, and am
running into a bit of a problem with non-contiguous files. The images in
question are for the Bigboard II, so it's possible they might even be for an
8" format, and I sure don't have one of those hooked up to any linux box.
Any hints on getting past this to where I can extract the files into something
I can fiddle with would be much appreciated. I'm basically looking at
assembly source, mostly, and would likely want to end up with something on
a 5.25" format. Only suggestion I've gotten so far is to set up a dos box,
which I suppose I could do, but I'd rather avoid that if I can, space here
being a little short at the moment.
The disk may have physical and/or logical interleave, which will make sectors
within a track appear to be broken up, as well as file allocation which may
also "break up" the data in a logically contiguous file and spread it around
the disk.
If it has physical interleave, IMDU will show you this in a detail track
listing. The IMDV viewer will also allow you to page through the data and
account for physical interleave (the sectors appear in logically ascending
order). Unfortunately, logical interleave is known only to the CP/M BIOS
which deals with the disk. And file allocation is known to CP/M itself.
I do have a preliminary utility I wrote to extract CP/M files from ImageDisk
CP/M images - Worked very well for me in extracting some CDOS files, however
I didn't get much interest in it so I never bothered to expand it into a
general purpose utility - it is configurable however - I can make it available
if you want to play with it. You will need to figure out the right parameters
for Bigboard disks (the tables for Chucks 22disk might be helpful).
Regards,
Dave
--
dave06a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.classiccmp.org/dunfield/index.html