1 Dec
2006
1 Dec
'06
7:46 p.m.
Here's an interesting one. I have
several disk images for the
Tandy 2000 that had been made with TeleDisk. One of the images is bad for
some reason (must be truncated; won't get past track 30; complains that
target disk drive is not ready when it reaches T30). The original disk is
not available.
I've done the basic troubleshooting on the drive and media
(other images made with same new floppy diskette and drive work fine;
swapped drive and media) to eliminate them from the failure tree.
Even though TeleDisk seems to write to track 30 just fine, the
disk is unusable. This is odd because it's an MS-DOS format (although 80T
9S) so all of the directory and media parameter info is at the front of the
disk rather than the back.
Is there anything I can do with this partial disk image to
retrieve at least some of the info?
I know this won't help you with this problem, however I'd like to point out that
this is exactly the reason I created ImageDisk - ImageDisk is a replacement
for TeleDisk that has an open and documented disk image format, utilities for
extracting/merging tracks, converting to/from raw binary, and many options
to help accomodate those times when you need to do exceptional data recovery.
Full source code to the main program and utilties is also available. The whole
point behind ImageDisk is to give you the information and tools you need to
attempt data recovery by "any and all other means" if you find yourself in a
situation like this.
Regarding your teledisk image - is it possible that the original disk was copy
protected, or for some other reason had a non-standard format? - If for
example, there were a single-density track in the middle of it (say on track
30) - MANY PC's would be unable to recreate the disk and might exhibit
symptoms similar to what you describe. Chuck wrote a very useful TESTSD
program which helps identify PCs which can do SD - I have it posted on my
site. I've also found that for some formats it can help a lot to slow the drive
slightly - This is common in Cromemco formats - probably not the case with
a DOS format, but it is a Tandy variation and you never know - worth a
try.
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