[comp.sys.ibm.pc.misc] Meaning of "Packed File Is Corrupt" Message??

angelini@apollo.HP.COM (Bob Angelini) (12/04/90)

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??

Bob Angelini

kabra437@pallas.athenanet.com (Ken Abrams) (12/05/90)

In article <4e61a969.20b6d@apollo.HP.COM> angelini@apollo.HP.COM (Bob Angelini) writes:
>
>I get the following error message on a 286 clone when I try to
>run several programs: Packed File Is Corrupt
>
Surprising as it may seem, you can do TOO good a job of conserving RAM.
I don't remember all the gory details but executables produced with 
certain compilers that include an "EXE packer" would produce this message
IF the program is loaded starting below the first 64K segment of RAM.
Assuming that you have 640K to start with, if a CHKDSK shows 576K or
more available then this might be the problem.  You need to do something
to eat up a little extra RAM to allow these programs to run.  Adding a
few more BUFFERS in your CONFIG.SYS file is probably the easiest way.

few more BUFFERS
-- 
========================================================
Ken Abrams                     uunet!pallas!kabra437
Illinois Bell                  kabra437@athenanet.com
Springfield                    (voice) 217-753-7965

murli@bobcat.ent.ohiou.edu (murli-ramakrishnan-ISE-272-90-2726) (12/05/90)

I had the same problem on one of my computers. I think it might be because of a hard disk  bad sector, I used pc tools diskfix and the software runs ok now
Murli
Ohio University

robl@idca.tds.PHILIPS.nl (R. Luursema) (12/06/90)

In article <4e61a969.20b6d@apollo.HP.COM> angelini@apollo.HP.COM (Bob Angelini) 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??
>
>Bob Angelini


I stumbled once also over this problem...

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 problem was tracked down to A20 GATE signal. This signal enables
Addressline 20 from the cpu to the outside world (memory). When A20 is
DIS-abled, the system mimicks the 8088/86 1 Mb address-space roll over.
This (hardware-) signal is a combination of two sources on the system I 
worked on. One is from the keyboard controller chip (8042) and is
generally used by protected mode (control) programs. The other is 
from a hidden/proprietary system IO port.
The first source is for compatibility and is rather slow, the second
is BIOS internal and fast.

The 'packed file corrupt' only occurred after some utility left the
fast A20 gate in the wrong state (A20-enabled).

The mystery was that it only occurred from the first command.com shell;
starting a second command.com, or starting from NortonCommander, or
running from a debugger made the problem go away.

Since the program is already unpacked when loaded by the debugger (it
did cot complain while loading), the problem could not be traced
using a debugger  :-(

What I still don't know is WHY the unpacking (code added to the program
by the linker) code is sensitive to the enabling/disabling of A20?

Is there somebody on the net who can enlighten me?

Rob.
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pasquale@sgl (Pasquale Leone) (12/08/90)

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
work if the program is loaded into an area of memory that starts
in the first 64k. If you load more device drivers, TSR's another command.com
etc you will have occupied the first 64k and the problem goes away.
I got this answer from the DesqView manual for DesqView 2.26 (or maybe it was
from the qram or qemm manual). The reason it is of interest to them is
that Qram for example can load all TSR's etc into high ram thus giving
you lots of lower memory; too much in fact.

I hope this was enlightening(sp?).

pasquale@sgl.ists.ca