DOCUMENT:Q100372  19-OCT-1993  [W_NT]
TITLE   :Detecting Windows NT Serial Ports
PRODUCT :Windows NT
PROD/VER:3.10
OPER/SYS:WINDOWS
KEYWORDS:

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The information in this article applies to:
 
 - Microsoft Windows NT operating system version 3.1
 - Microsoft Windows NT Advanced Server version 3.1
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WARNING: Using Registry Editor incorrectly can cause
	 serious, system-wide problems that may require you to
	 reinstall Windows NT to correct them. Microsoft cannot
	 guarantee that any problems resulting from the use of
	 Registry Editor can be solved. Use this tool at your own
	 risk.

 
Windows NT manages serial (COM) ports somewhat differently from the
way Windows 3.1 does. In Windows 3.1, you can observe and configure
all the COM ports from Ports in Control Panel. In Windows NT, only
unused COM ports are displayed in Control Panel. For example, if a
mouse is connected to COM1, COM1 is not available in Control Panel,
nor is it listed. To check a COM port and perform any trouble-shooting
steps, you need to use Registry Editor.
 
Finding Serial Ports in Registry Editor
---------------------------------------
 
To determine what is using a COM port, from Registry Editor go to the
following hive and subkey:
 
   \HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System
   \MultifunctionAdapter\0\SerialController\...
 
Note: If you have an EISA type machine, MultifunctionAdapter will be
EisaAdapter.
 
Each COM port is stored in one of the numbered subkeys. If you have
two COM ports, COM1 and COM2, you would find them stored under 0 and
1, respectively.
 
If a mouse is using a COM port, you will find a PointerPeripheral
subkey under the serial ports subkey. For example: If you have a mouse
on COM1, you would see the following:
 
   ...\SerialController\0\PointerPeripheral
 
If PointerPeripheral is absent, then the serial port is in use by some
other device.
 
Additional Differences in Windows NT Control Panel
--------------------------------------------------
 
You might notice an additional difference in Windows NT Control Panel.
If you select a COM port, choose Settings, and then choose Advanced,
the following message may be displayed in a dialog box:
 
   There are no user configurable Advanced I/O parameters for this
   COM port.
 
This means that Windows NT has obtained all the information it needs
for the port from NTDETECT.COM (or OSLOADER.EXE on RISC-based
computers). This ensures that redundant or incorrect information is
not entered.
 
Additional reference words: 3.10 winnt
KBCategory:
KBSubCategory: HRDWR

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Copyright Microsoft Corporation 1993.