Printers used to be connected to a computer by a printer parallel cable. As technology developed, most printers starting using a USB cable to connect to the computer. Computers now create virtual printer ports that look like old COM ports. This allows USB printers to be compatible with older software. Your computer will automatically create a virtual USB port when you connect and install a compatible printer. Windows Vista and 7 users can manually add a virtual port by using the Network printer settings.
Click the "Start" button and select "Printers and faxes." If you don't see this option, type "Printer" in the Windows Search bar and press "Enter."
Right-click on a network printer and select "Sharing."
Check the box next to "Share this printer."
Enter the name of the printer you wish to use under "Share Name."
Move to the second computer and select the "Start" button, then click the "Control Panel."
Click "Printer" option (if using Vista or above, it will be listed under "Hardware and Sound.")
Select "Add Printer."
Choose to add a printer from the Network and let it search for a list of available printers. If it doesn't find the printer, select "The printer I want isn't listed."
Select "Browse for Printer" and click "Next." You can choose the printer from pop-up list.
Press "OK" to save the printer. A virtual printer port will now be added. You can view the port by right-clicking on the printer icon, selecting "properties" and then clicking on the "port" tab.