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Poqet PC Mailing List Digest
Volume 003, Number 057, 18 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: Mon, 15 Mar 1999 13:38:15 -0800
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In-Reply-To: <199903152111.NAA03783@xxxxxxxx>

Hi Scott,

No, the NMIs do not occur when power management is turned off.  

This reminds me . . . the Poqet can also have problems with programs that
use floating-point emulation libraries.  Whenever a floating point
operation is executed on a system that doesn't have a math coprocessor, an
interrupt is generated that uses the NMI vector.  The floating-point
emulation libraries capture the interrupt and complete the math operation
in software.  However, most floting-point emulation libraries assume that
they'll be the only one using the NMI vector, so when the Poqet uses the
NMI for power management stuff, it can get a little messy.

-- Bryan

At 01:04 PM 3/15/99, Scott Kinder wrote:
> Do these interrupts still occur when power mode is deactivated
>with the Poqet-Key combination?
>I'm having intermittent (lockup) problems with certain DOS programs and
>turning this off seems to improve things, but then I'm suddenly
>locked again.
>Thanks for the info...
>-----Original Message-----
>From: Bryan Mason <bmason@xxxxxxxx>
>To: poqetpc@xxxxxxxx <poqetpc@lists.best.com>
>Date: Friday, March 12, 1999 10:05 PM
>Subject: Re: New user / Software Compatibility
>>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
>>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.

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Date Created: 30 Nov 1996, Last Modified: 13 May 2009
Created by Bryan Mason - E-Mail: poqetpc<at>bmason<dot>com