Using COM1.OS2 or COM1.PRN Ports in Windows 3.0 (68756)


The information in this article applies to:

  • Microsoft Windows 3.0
  • Microsoft Windows 3.0a
This article was previously published under Q68756

SUMMARY

When using COM1.OS2 or COM1.PRN as a workaround for printing problems with Microsoft Windows version 3.0, you must configure the serial port through the AUTOEXEC.BAT file. The statement

MODE COMn[:]bb[,x[,y[,z]]]

must be added to the AUTOEXEC.BAT file, where the following is true:

"n" is the name of the communications port.
"bb" is the number of bits per second to be received or sent.
"x" is the type of parity.
"y" is the number of data bits.
"z" is the number of stop bits.

In addition, you must add the following line to the [PORTS] section of the WIN.INI file

[PORTS]
COMn.PRN=
...

where "n" is the name of the communications port.

NOTE: Using the COMn.PRN workaround is not recommended, as explained in the "MODE Statement" section below.

MORE INFORMATION

The function of the MODE COMn statement is to set the parameters of the communications port that define the speed and form of the data transmitted through the port. When using a COM port in Windows, these settings are taken care of by the Control Panel. When using the COM1.OS2 and COM1.PRN workarounds in Windows, the print job is sent to the MS-DOS COMn device, which requires the serial port be reconfigured for it to work correctly with every print job.

Printing to a port such as LPT1.OS2, LPT2.OS2, or COM1.PRN is a TEMPORARY workaround or troubleshooting step. If Windows can print to these ports, and not the normal Windows port, you could have any of the following problems:
  • Windows cannot create temporary files.
  • The printer cable is defective.
  • The printer-to-computer connection is loose or not connected properly.
  • Corrupted installation of Windows.

MODE Statement

Printing to COMn.PRN ports requires a MODE statement at the MS-DOS level. If this statement gets changed or deleted, Windows won't print to the COM port. Testing printing to a serial printer from MS-DOS, using a COM port, may not work with some printers (such as PostScript printers). As a result, using the COMn.PRN workaround is not recommended.

For example:

MODE LPT1=COMn.PRN (where n=1,2,3, or 4)

For more information on printing to ports, such as COM1.PRN and LPT1.OS2, query on the following words:

LPT1.OS2 and LPT1.PRN

Modification Type:MinorLast Reviewed:7/7/2005
Keywords:KB68756
©2004 Microsoft Corporation. All rights reserved.