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Q149279: FIX: Garbage in Input Buffer When InBufferSize > 2048

Article: Q149279
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0
Operating System(s): 
Keyword(s): kbVBp kbVBp400bug kbOSWin98fix kbGrpDSVB kbDSupport
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SYMPTOMS
========

Using the MSCOMM control, the contents of the input buffer may be corrupted when
read by an application. This problem can occur if the InBufferSize property is
greater than 2048 bytes and if the ParityReplace property holds some value other
than an empty string ("").

RESOLUTION
==========

To avoid this problem, reduce the value of the InBufferSize property to
something less than 2048 bytes. Alternatively, the ParityReplace property can be
set to "", an empty string. This will disable all parity checking and remove the
problem. In addition, because Windows NT does not have this problem, utilizing
NT instead of Windows 95 or Windows 3.x may also be an option.

STATUS
======

Microsoft has confirmed this to be an issue in the Microsoft products listed at
the beginning of this article. This problem has been fixed in Microsoft Windows
98.


MORE INFORMATION
================

Due to a problem with the Windows 3.x and Windows 95 operating systems and a
resulting conflict with the MSCOMM control, when parity checking is enabled,
characters in the input buffer can be corrupted. The character specified in the
ParityReplace property ends up replacing characters in the input buffer. For
example, if ParityReplace is set to "?" (the default), then:

  "Hello VB World" might be replaced by "He?l?o V??W?rld"

In this case, the problem is actually not with the MSCOMM control, but rather
with Win3.x and Win95 operating systems. The problem does not occur on Windows
NT.

Additional query words:

======================================================================
Keywords          : kbVBp kbVBp400bug kbOSWin98fix kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : WINDOWS:4.0
Issue type        : kbbug
Solution Type     : kbfix

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