DOCUMENT:Q143126
TITLE   :Windows NT Incorrectly handles Dongle support
PRODUCT :Microsoft Windows NT
PROD/VER:4.00
OPER/SYS:WINDOWS
KEYWORDS:kb3rdparty ntdriver

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The information in this article applies to:

 - Microsoft Windows NT Workstation version 4.0
 - Microsoft Windows NT Server version 4.0
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SYMPTOMS
========

An application that uses a third-party parallel port device known as a
dongle will fail to function properly on Windows NT 4.0.


CAUSE
=====

Windows NT 4.0 incorrectly handles initialization of the parallel ports, 
keeping third-party virtual device drivers from trapping any I/O. This 
problem only occurs when Windows NT runs on an Intel x86 or compatible system.


RESOLUTION
==========

Microsoft has updated Ntvdm.exe to correct the problem.

This update is available from Microsoft support channels or directly from the 
following Internet location:

   ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/nt40/
   hotfixes-postSP1/ntvdm-fix

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT version 4.0. A 
supported fix is now available, but is not fully regression-tested and 
should be applied only to systems experiencing this specific problem. Unless 
you are severely impacted by this specific problem, Microsoft recommends that 
you wait for the service pack release containing this fix. Contact Microsoft 
Technical Support for more information on the availability of this fix.

KBCategory: kb3rdparty
KBSubcategory: ntdriver
Additional reference words: prodnt vdd dongle 4.00



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