PrintFil: DOSPRN and PRN2FILE - DOS print USB printer

Printfil allows printing to Windows printers, from Dos, Windows programs or Unix, Linux, legacy applications running on a Windows PC via telnet or other terminal emulator software.

Now Linux and DOS print to USB and all the newest all-in-one Windows-only printers with ease.

PRN2FILE literally mean "From PRN to FILE".

What's a FILE is something known to everybody, while PRN is an acronym used in informatics since the DOS age as it refers to something related with PRiNters, but its common meaning changed over time.

In DOS PRN was intended to mean the standard printer parallel PORT, often named LPT1 too, since at that time printers could only be connected to parallel (99% of times) and serial ports (no USB, network, firewire, bluetooth or other kind of connections were still invented at that time)

In Windows instead PRN is widely used to mean a special kind of FILE that contains the data originally designed to be sent to a printer. Creating it is pretty easy, since almost any Windows program, when printing a document, allows selecting the PRN FILE as destination instead of a physical printer.

On some situations redirecting a print job to a file on disk is desirable because, for example, the real destination printer is not available in that moment, or just because we want to read a job on screen and trash it immediately, without wasting paper and ink for an unnecessary hardcopy.

This article wants to cover both questions: "How to capture the DOS PRN PORT to a file" and "How to print a PRN FILE in Windows".

How to capture the DOS PRN PORT to a file

DOS programs are still widely used nowadays, but making changes to the old source code just to redirect a report on screen may be very hard, or totally impossible.

For this reason even in the DOS age there was an utility named PRN2FILE that was designed to automatically redirect the data sent to the PRN port to a file on disk by calling a specific DOS interrupt. To do so, it was written in a very low level machine code, so, it worked even with earlier Windows versions, but cannot work anymore on newest Windows systems.

Printfil overcomes this problem by intercepting data at the NT-Kernel level instead (the Windows kernel used since Windows NT/XP and still used in the newest Windows versions), so, it can easily capture data sent to PRN by a DOS program even if it's running on the newest Windows 10/11 or Windows Server 2016/2019/2022, even with Terminal Services enabled.

You just have to:

1) Download the free Printfil trial you can find at https://www.printfil.com/edown.htm
2) Install it on the Windows machine where the DOS program is run too.
3) At first Printfil startup the "Guided Configuration" will start automatically (or you can run it later on by right clicking the Printfil's icon in the bottom-right corner, near the Windows clock and choosing Configuration -> Guided)
4) Setup Printfil to capture the data sent to the LPT1: port (that we've said above it's an alias for PRN) and redirect it to to the FILE: printer.

That's all.

Now as soon as your DOS program will finishes printing, Printfil will capture the print job and will normally asked you for the name of the TXT file that will contain it.

If you've enabled the "Archiving print jobs" option that makes Printfil keeping a copy of each captured job without user intervention (please see https://www.printfil.com/manualen/c11.htm), no file name will be asked you after capturing the print job, but you'll automatically find the file in the Archiving directory. In this case, after FILE: in the Printfil's GUI configuration dialog is shown even the archiving path.

Alternatively, if "Preview" is enabled at Configuration -> Standard, the captured DOS print job will be shown on screen first, then you can simply click the "Create TXT" icon (the floppy) in the toolbar or the previewed job or close the window and discard the job.
If you've chosen a Windows printer as destination for Printfil instead of the "FILE:" printer, by the "Preview" window you can choose wheter you want to print the job, export it to a file on disk, or just read it and close the window.

How to print a PRN FILE in Windows

As we've said above a PRN file is a file on disk created by the Print to file option of a Windows program.

That file can be read on screen with the Windows Notepad only if you've chosen a "Generic / Text Only" printer when creating it because this way Windows normally creates a file containing a graphical print job, specifically designed to be PRINTED (not shown on screen) with the same printer originally selected when creating the file itself.

That file can be printed with a different printer model only if the printer driver originally selected was for a printer supporting a standard graphical language like HP-PCL or PostScript.

For example, if you did select a HP-PCL printer driver when creating the DOS PRN file, then that file can be printed to any HP-PCL capable printer, even if the printer is not exactly the same model selected when creating the file.

The same applies if you created the file by selecting a PostScript printer driver, but a PRN file containing PostScript data cannot be printed with an PCL capable printer, and a PRN file containing PCL data cannot be printed with a PostScript capable printer.

If instead you selected a GDI (also known as Windows-Only) printer when creating the DOS PRN file, then that file can be correctly printed only by that very same physical printer model later on.

Unfortunately, Windows allows easily creating a PRN file, but then there's no easy way to physically print it to a compatible printer.

Printfil easily overcomes this limit however. You just have to drag and drop the PRN file over the Printfil's icon on the desktop, then it will ask you to choose the destination printer on screen and Printfil will send the file there. That's all.

If you did choose to "associate DOS PRN files with Printfil" when requested during the Printfil installation, then a simple double-click on the PRN file is sufficient to print it.

Prn to file

Prn 2 file

Prn to DOS

DOS to PRN

"This program is great and we use it everyday as otherwise our stocklists cant get printed. Thank you also for your follow up service."

Stuart Paul - New Zealand

see other @SwIt Printfil awards