Date:	Mon, 28 Jul 1997 13:27:46 +0100
From:	Matthias Paul <PAUL-MA AT reze-1 DOT rz DOT rwth-aachen DOT de>
Subject:	Re: floppy-copy errors
To:	opendos AT delorie DOT com
Reply-to:	Matthias DOT Paul AT post DOT rwth-aachen DOT de
Message-id:	<95370437CF@reze-1.rz.rwth-aachen.de>
Organization:	Rechenzentrum RWTH Aachen

On Fri, 25 Jul 1997, Bill Currie replied to Bruce A. Locke:

> > >> AD&D (two games of the series):  
> > >> Error message:  Packed File is Corrupt 
> ...
> Are they .exe files? If so, maybe opendos has problems with segment 
> relocations under certain circumstances.  I've been having 
> similar problems with IDA (interactive disassembler) complaining that 
> it's been corrupted.
> 
> My *GUESS* (wild and hairy as they come) is that maybe these problem 
> programs have negative relocations in them (I've seen some that do, 
> but mostly for the program entry point in compressed exes) and maybe 
> opendos chokes on these.
Not bad... ;-)

It's some kind of a paradoxon:

Usually (if not actually a corrupted file) the "Packed file corrupt!" 
problem can be tracked down to a file been compressed with the MS 
EXEPACK utility, which for a long time had a design flaw that caused 
this error to occur, when a program is executed in the very first 64KB 
of memory.  This was encountered first when the loadhigh features were 
implemented into DOS, freeing more conventional memory, and thus 
giving programs a TPA which starts in the lowest 64KB.

Using DR DOS 5.0+, Novell DOS, or OpenDOS, you can disable the usage 
of the so called "low memory" by typing 

 MEMMAX -L 
 
before executing any such program.  (Under MS-DOS/PC-DOS you can do 
the same on a file by file basis by using the LOADFIX command.)

If the problem disappears, a permament fix is to uncompress the 
EXEPACKed program, e.g. by various utilities from the Internet 
archives.  If I remember well, Fabrice Bellard's compressor also 
had an option to uncompress EXEPACKed files and compress them using 
his own utility.  Don't know about PKLITE right now...

Hope, this could help...

 Matthias

 
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