🚀 go-pugleaf

lasner@watsun.cc.columbia.edu (Charles Lasner) writes:
: Please explain exactly what you were doing:  It sounds like the disk
: was created incorrectly, not that Teledisk per se is having problems.  Do 
: you have VERIFY ON in your system?  This could just be a hardware fault or
: crummy media.  If the message goes away with VERIFY OFF but the media is
: still unreadable due to CRC error after the fact, this may be more a problem

Verify is off, and the problems have occured with ADVANCED compresion in
TD.    The reason why I dont think it's my media is that it's teledisk that
is giving me the CRC error while reading the .td0.  ie: it pops up a
screen saying "CRC error while reading xxxx.td0" and stops the process.
It does this while reading the .td0 -- it hasnt begun writing to
the floppy yet. 

Originally, I discovered this bug when someone sent me about 20 .td0s
which were done using advanced compression.  About 6 had crc errors.
I got hold of the originals, and just to satisfy my curiosity, I td0'd 
the disks in question using advanced compression.  Sure enough the 
crc errors existed in my newly created td0s.  Then I tried using 
"normal compression" and there were no problems.  These were all 
3.5" 1.44mb media DOS formatted.  I am pretty certain that the
data on the disks was compressed to begin with.

Therefore, the problem is repeatable, and cannot be related to the media.  

: at will, or is it transient.  It would seem that you are saying that if you
: run the program several times, then when a copy is made without a CRC complaint
: the data is OK?  Or are there cases that *always* get an error and are 
: esentially non-recoverable?  Does the compression setting matter relative to
: the data being restored to original format?  BTW, Teledisk has no option to
: not compress as you imply.  There are only two options, to compress or to
: "advanced" compress.  The minimal compress is run-length compression, and
: possibly zeroes repeat compression only; not sure which.  The advanced is
: the full nine yards compression ala LHARC.

If there's a CRC error in the .td0, teledisk just quits at that point.
Fortunatly, Sydex provides the utility crcheck.exe.  This can, and should
be run after a creation of a .td0...

Despite all this, I still have great confidence in TD.  It has never 
failed using normal compression.  It's shareware, easy to use, widely
avail, still supported by the authors.  Cant beat that.

I will try to get hold of those "troublesome" disks and retry, just to
be verify.  I will also give Sydex a ring to see if they are aware of any 
such reports.

-andy