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Poqet PC Mailing List Digest
Volume 003, Number 054, 13 Mar 1999

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  1. Re: New user / Software Compatibility by Bryan Mason <bmason@xxxxxxxx>

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Re: New user / Software Compatibility by Bryan Mason <bmason@xxxxxxxx>


From: Bryan Mason <bmason@xxxxxxxx>
Subject: Re: New user / Software Compatibility
Date: Fri, 12 Mar 1999 19:00:12 -0800
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In-Reply-To: <199903100046.QAA05968@xxxxxxxx>

If I remember correctly, older versions of PKWare products used the
"string" assembly instructions of the 8086/88 to move data around.  The
8086/88 had a problem where if an NMI occurred while these instructions
were being executed, unexpected results could occur and the machine could
lock up.

That wasn't a problem on most IBM-PC/XT's and compatibles, because the NMI
was used really only to signify parity errors.  If you got a parity error,
the system would halt, so it wasn't a problem that the system would lock up
if you were doing a string instruction and an NMI occurred because of a
parity error.

The problem was that the Poqet PC used NMIs extensively for its power
management routines.  So the chances were pretty high that you would get an
NMI during an execution of a string instruction in PKZip, PKUnzip, or PKLite.

I know that Poqet asked PKWare to change their code, and they stopped using
the string instructions in PKLite -- I guess they also made the change in
PKZip/PKUnzip as well.

-- Bryan

At 04:46 PM 3/9/99, Scott Kinder wrote:
>PKUNZIP.EXE version 2.04g works perfectly on the Poqet!
>I was using version 2.01 (don't know how I ended up with that
>version!). This is one of the most popular compression/
>decompression (pkzip/pkunzip) utilities around. 
>
>It can be found at http://www.pkware.com/ 
>
>Thanks to Bill and Alain for setting me straight!
>
>Regards,
>Scott
>




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