Printing to LPTx.yyy or COMx.yyy From Windows 3.0 (66070)

SUMMARY

When you print to LPTx.yyy, COMx.yyy (where "yyy" is any extension), or print to a file and subsequently copy the file to a port, the print job may be truncated.

This problem occurs primarily when you are printing graphics. To work around this problem, you must either print to a port without an extension or copy the file to the port with the /b (binary) parameter when you print to a file.

NOTE: This information does not apply to later versions of Windows.

MORE INFORMATION

When you print to a port with an extension, Windows writes the output to a file called LPTx.yyy or COMx.yyy. Since LPT and COM are reserved words for Microsoft MS-DOS, when Windows writes to a file called LPTx.yyy or COMx.yyy, MS-DOS redirects the output to the LPTx or COMx port.

You can achieve the same functionality manually by printing to a file (that is, a port called FILE) and then copying the file to LPTx or COMx.

The truncation problem occurs when one of the characters in the document formatting code or a graphic contains the ^Z (CTRL+Z) character. Because this character is the end-of-file marker for text files, the print job ends when the ^Z character is encountered.

You can workaround this problem by copying the file to the port with the /b parameter as in the following example:

COPY FILENAME.PRN LPT1: /b

The /b option lets the COPY command know the file is a binary file.

The LPTx.yyy port option in Windows does not invoke the /b parameter. Printing graphics using this parameter may cause the print job to be truncated.

To print graphics when you have a hardware problem that Windows is detecting, print to a file, then copy the file to the printer using MS-DOS with the /b switch. The steps below outline this procedure.

In the Control Panel window, choose the Printers icon. Choose the Configuration button, and select FILE: as the printer port.
Choose the print option within the Windows application from which you are trying to print.
When you are prompted for a filename, name the file using standard MS-DOS conventions. The file is then placed in the current WINDOWS directory. You can also include a full path before the filename to save the file to a path of your choice.
Exit Windows or run choose the MS-DOS Prompt icon.
Change to the WINDOWS directory, or the path specified in step 3, and type the following:
copy /b <filename> <portx>:

Microsoft has confirmed this to be a problem in Windows versions 3.0 and 3.0a. This problem was corrected and does not occur in later versions.