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Q87450: MSD Utility Incorrectly Identifies UART Chip

Article: Q87450
Product(s): Microsoft Windows 95.x Retail Product
Version(s): WINDOWS:3.1,3.11
Operating System(s): 
Keyword(s): 
Last Modified: 01-OCT-1999

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The information in this article applies to:

- Microsoft Windows versions 3.1, 3.11 
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SUMMARY
=======

When you use the Microsoft Diagnostic Utility (MSD) shipped with Windows 3.1 to
identify local COM ports on a personal computer, MSD will erroneously report a
16550AF under "UART Chip Used" when in fact there is no UART (universal
asynchronous receiver transmitter) chip or COM port installed at that address.
This occurs when a utility, such as SETCOM.COM, or a debug script has been used
to create a COM port address in the BIOS data segment for a non-existing COM
port.

Other defaults reported by MSD for the non-existing COM port are:

  Baud Rate: 1
  Parity: Space
  Data Bits: 8
  Stop Bits: 2
  Carrier Detect (CD): Yes
  Ring Indicator: (RI): Yes
  Clear To Send (CTS): Yes

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

The 16550AF chip is a UART chip with a 16-byte character buffer to reduce
interrupt overhead and errors during high-speed serial transmissions.

Additional query words: 3.10 3.11 communications comm serial modem

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Keywords          :  
Technology        : kbWin3xSearch kbZNotKeyword3 kbWin310 kbWin311
Version           : WINDOWS:3.1,3.11

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