Article ID: 131976 - Last Review: November 1, 2006 - Revision: 2.1

How to Disable Detection of Devices on Serial Ports

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This article was previously published under Q131976

SUMMARY

This article explains how to modify the Boot.ini file to disable the detection of devices on COM ports.

When you start Windows NT, NTDETECT searches for the pointing device (usually a mouse). In the course of this process, data is sent to the serial (COM) ports. If a serial mouse is detected, Windows NT disables the port so a device driver for the mouse can load instead. If a device is not detected, Windows NT disables the port. A disabled COM port does not display any information in Control Panel Ports.

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MORE INFORMATION

To disable the detection of devices on COM ports in Windows NT:

Make a backup copy of the Boot.ini file.
Remove the hidden, system, and read-only attributes from the Boot.ini file.
Using a text editor (such as Notepad) open the Boot.ini file.
Add the /NoSerialMice option to the end of each entry in the [operating systems] section of Boot.ini. See the example below for more information.
Save Boot.ini and quit Notepad.
Restore the hidden, system, and read-only attributes to the Boot.ini file.
Shutdown and restart Windows NT.

The following is a sample of the Boot.ini file:

   [boot loader]
   timeout=3
   default=multi(0)disk(0)rdisk(0)partition(1)\WINNT35

   [operating systems]
   multi(0)disk(0)rdisk(0)partition(1)\WINNT35="Windows NT Workstation
      Version 3.51" /NoSerialMice

   multi(0)disk(0)rdisk(0)partition(1)\WINNT35="Windows NT Workstation
      Version 3.51 [VGA mode]" /basevideo /sos /NoSerialMice

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NoSerialMice Syntax

/NoSerialMice          - Disables the detection of serial mice on
                         all COM ports.

/NoSerialMice:COMx     - Disables the detection of serial mice on
                         COM x, where x is the number of the port.

/NoSerialMice:COMx,y,z - Disables the detection of serial mice on
                         COM x, y and z.

NOTE: The /NoSerialMice option is not case sensitive.

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