10 Oct
2007
10 Oct
'07
5:16 p.m.
Can we see hex of the 32 bytes of some of the
directory entries,
preferably with a LARGE file?
IIRC, Cromemco used at least 3 different ways of handling extended entries
for large files.
Do you have access to how many records per block?
How many blocks per extent?
(Is the block number stored as 8 or 16 bits?)
Sorry, I haven't delved back into the CDOS/CPM filesystem yet - It's been
years, and I haven't found a good technical description yet (any pointers?)
I have put ImageDisk images up at: www.dunfield.com/pub/index.htm
You can use my IMDV (IMageDisk View) utility to browse through the sectors.
Can you use ImageDisk or TeleDisk to copy the sector
contents, to produce
a "copied" disk that has readable sector 1s?
Nope - the copy behaves exactly like the originals. Reads fine with IMD/TD,
but 22disk has trouble - Since 22disk also reports file mislinks, it's possible
that it's looking somewhere that isn't (I don't know if the Cyl1, Side1, Sec1
indication is real or logical - if logical, it might refer to a physical sector
that doesn't exist... Chuck?)
IIRC, some CDOS variants (there were several) had a
skew, resulting in
some other sectors on the disk being hard to get at.
If the Cromemco machine is still in existence, they don't seem to mind
disks that have reasonable gaps, so long as you get the flag in the "boot
sector" to show the correct disk size.
I've always had trouble with Cromemco disks - I find that slowing the drive
to about 290 rpm makes a huge difference in being able to read the disks.
The original machine used to create the disks is long gone, although I can
get a Cromemco machine setup if necessary - I don't relise the thought if
transferring files from a few hundred disks by serial tranfer, which is
why I would really like to get a PC based solution working...
I probably won't have access to any of my stuff in
the next week or two,
but I can eventually get my notes of the CDOS interleave pattern(s).
Thanks, anything would help. The CDOS manual has some tables at the back,
but I don't know how complete or accurate they are for all versions.
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