Printing to Windows LPT1.OS2 or LPT1.DOS Port

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You may be unable to print from Microsoft Windows version 3.0 or 3.1to the LPT1: port, although you can print to the LPT1.OS2 port, orLPT1.DOS port if using Windows 3.1. Some networks and print-sharingdevices may require using the LPT1.OS2 or LPT1.DOS port. For the mostpart, this should be considered a temporary workaround. If you canprint to LPT1.OS2 or LPT1.DOS and cannot print to LPT1, the reason isprobably one of the following:
  1. Windows cannot create temporary files. This could be caused by any of the following:

    1. SET TEMP points to a nonexistent directory.
    2. SET TEMP points to a directory where you don't have create, modify, or write privileges.
    3. The SET TEMP line is not typed properly.
    4. SET TEMP points to a directory with little or no disk space.
    5. The SET TEMP line does not exist and Windows is trying to create temporary files in a directory that falls into category b or d above.
    6. FAT (file allocation table) is corrupt. Using the CHKDSK/F command might correct this.
  2. Poor cabling or printer-to-computer wiring exists. Try a different cable or verify that the cable is firmly connected to the printer and computer.
When Windows prints to a port, such as LPT1:, it uses a printingmethod that allows it to detect errors on the printer. While thismethod has advantages, it is not supported by some network softwarepackages. When Windows prints to LPT1.OS2 or LPT1.DOS, a differentmethod of printing is used that does not allow Windows to check forerrors during printing. As a result, garbled output may occur duringprinting, especially when printing large files.

When Windows prints to the LPT1.OS2 or LPT1.DOS port, it prints to afile named LPT1.OS2 or LPT1.DOS. When DOS gets the request fromWindows to open the file LPT1.OS2 or LPT1.DOS, it interprets that as arequest to send data to the printer port, and it sends the data outthrough its own printing handler. Because Windows thinks that LPT1.OS2or LPT1.DOS is a DOS file, the Print Manager is not used. Windows willnot spool output to this port.

The extension .OS2 or .DOS is a dummy; any extension could be usedwith the same effect. Ports other than LPT1: can be printed to thisway. Printing to the file LPT2.XYZ causes data to be sent to a printeron the computer's LPT2: port. Although you can print to COM ports inthis manner (for example, COM1.PRN), it is not recommended because itrequires a MODE statement in MS-DOS with the proper communicationparameters.

Note: This technique is a WORKAROUND to a printer problem. It does nottruly solve the problem, although it does indicate that the problem isprobably NOT in the Windows printer driver. When possible, otherWindows troubleshooting steps should be tried to avoid futuredifficulties, even if using LPT1.OS2 or LPT1.DOS seems to solve theproblem. For more information on troubleshooting Windows printingproblems, query on the following words:
tshoot and printing
3.00 3.00a KBPrint 3.10 3.11

Article ID: 68652 - Last Review: 02/27/2014 21:01:16 - Revision: 3.0

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