Lists or changes the COM port mappings to be compatible with MS-DOS applications.

For examples of how to use this command, see Examples.


change port [<PortX>=<PortY> | /d <PortX> | /query]


Parameter Description


Maps COM <PortX> to <PortY>.

/d <PortX>

Deletes the mapping for COM <PortX>.


Displays the current port mappings.


Displays help at the command prompt.


  • Most MS-DOS applications support only COM1 through COM4 serial ports. The change port command maps a serial port to a different port number, allowing applications that do not support high-numbered COM ports to access the serial port. Remapping works only for the current session and is not retained if you log off from a session and then log on again.

  • Use change port without any parameters to display the available COM ports and their current mappings.


  • To map COM12 to COM1 for use by an MS-DOS-based application, type:

    change port com12=com1
  • To display the current port mappings, type:

    change port /query