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
-------------------------------------------------------------------------------
The information in this article applies to:
- Microsoft Windows versions 3.1, 3.11
-------------------------------------------------------------------------------
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
======================================================================
Keywords :
Technology : kbWin3xSearch kbZNotKeyword3 kbWin310 kbWin311
Version : WINDOWS:3.1,3.11
=============================================================================