How can I redirect LTP or COM port to USB for printing from MS-DOS?

by on November 12, 2011

Q: LPT or COM redirected to USB
When redirecting a printer port from a MS-DOS based program to a USB printer should you only redirect the COM ports, COM1 or COM2 rather than the LPT ports, LPT1 or LPT2, since the COM ports are serial ports and the USB port is a serial port (Universal Serial Bus)? Such as explained in the following article:
How to print to a network printer from an MS-DOS-based program in Windows XP
as explained on web site:

The reason I ask is because as soon as I did it I got a Printhead error on my USB printer and I eventually had to replace it. I am reluctant to try it again until I’m sure. Or was the printhead failure I experienced just a coincidence that would have happened anyway?


One Response to “How can I redirect LTP or COM port to USB for printing from MS-DOS?”

    I received this email from Snagglegaster via and I do believe it to be correct, although I haven’t been able to get my Generic Cadd program to print out via the net use command probably because it is geared for printing characters and not points defined by x and y coordinates, which is what Generic Cadd DOS print drivers do. Snagglegaster’s email:

    “Peohguy, the net use command doesn’t care about the physical interface of the printer you want to use, and there is no way it could ever damage a printer. So, the first thing I would suggest would be deleting the current net use printer redirection by using the /delete switch. See for details. To remove the current redirection, you have to open a command prompt, and type the “net use” command followed by the same string you used to enable printer redirection except that you will replace the “/persistent: yes” switch with “/delete” (no quotations) and that will remove the current port redirection.

    Next, make sure that your printer is a shared device and give it a short and simple share name like “lex”. Now double check your program and see which printer port it prefers to use. A lot of old DOS software only prints to LPT1, though some can handle LPT2 as well. Anyway, set the program’s output to the appropriate port and exit the program. Then open a command prompt and type “net use lptX \\computername\printersharename /persistent:yes” substituting the appropriate device names and omitting the quotation marks. Hit the enter key. If you typed the command correctly, you should get a confirmation and you are good to go. The same method works for printers connected via hardware print servers and virtual print servers; not just USB ports.”