Deleting COM Ports from a Windows NT Installation (101730)

This article was previously published under Q101730

Microsoft Windows NT and Windows NT Advanced Server support up to 256 COM ports on each workstation. Use the Ports application in the Windows NT Control Panel to add ports. However, Windows NT does not provide a graphical interface to remove ports after adding them. To remove a COM port, you must use the Registry Editor utility.

Perform the following five steps to remove a COM port from a Windows NT or Windows NT Advanced Server workstation:

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.

1. Start the Registry Editor (REGEDT32.EXE)
2. Find the following key:
   

   \HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services \Serial\Parameters

3. The Parameters key has several subkeys such as Serial10000, Serial10001, and so on. Each of these subkeys corresponds to a COM port. To determine the COM port to which each applies, check the corresponding DosDevices value.
4. After you determine the COM port to remove, choose the appropriate Serial<xxxxx> subkey and choose Delete from the Edit menu.
5. Close the Registry Editor, and then shut down and restart your system.

NOTE: In Windows NT 3.5 you can delete COM ports from Control Panel Ports.