Newsgroups: comp.os.msdos.apps
Path: utzoo!utgpu!cunews!bnrgate!bigsur!bcars53!mussar
From: mussar@bcars53.uucp (G. Mussar)
Subject: Re: Meaning of "Packed File Is Corrupt" Message??
Message-ID: <1990Dec9.194401.16049@bigsur.uucp>
Keywords: packed file
Sender: news@bigsur.uucp
Organization: Bell-Northern Research, Ottawa, Canada
References: <4e61a969.20b6d@apollo.HP.COM> <1068@idcapd.idca.tds.philips.nl> <16069@ists.ists.ca>
Distribution: na
Date: Sun, 9 Dec 90 19:44:01 GMT

In article <16069@ists.ists.ca> pasquale@sgl.ists.ca (Pasquale Leone) writes:
>In article <1068@idcapd.idca.tds.philips.nl> robl@idca.tds.PHILIPS.nl (R. Luursema) writes:
>>>I get the following error message on a 286 clone when I try to
>>>run several programs: Packed File Is Corrupt
>>>
>>>The programs (games and apps) run fine on another 286 system, so
>>>I know the software is OK. 
>>>
>>>Any ideas on what might cause this message??
>>
>>Packed files are created by the Microsoft linker when using the 
>>exepack option. 
>>At load time the executable is unpacked.
>>
>>In my case, the 'Packed file corrupt' message was only given under certain
>>circumstances.
>>
>>The mystery was that it only occurred from the first command.com shell;
>>starting a second command.com, or starting from NortonCommander, or
>>
>^^^^^^^^^^^^^^^^Bingo!!
>
>The problem goes away when you lad another command.com or the Norton Commander.
>It will also go away if load more device drivers or TSR's. The reason is
>that the code in dos that unpacks the file has a bug in it. It doesn't

Acutally, the code that unpacks expects that the A20 gate is closed so that
memory references beyond the end of the last segment will wrap into the first
64K. The real problem is that the A20 gate is being left open on the 
malfunctioning system. There are utilities around to display the stat of
the A20 gate and to turn it off, however, your BIOS should be turning it
off on POST. I've heard that at least one manufacturers BIOS defaults
this A20 gate open unless you know the magic incantation to close it. Sigh.


--
-------------------------------------------------------------------------------
Gary Mussar  |Bitnet:  mussar@bnr.ca                  |  Phone: (613) 763-4937
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