LPT Port to USB Printer Windows 7

You may not be able to.  Most newer USB Laserjets are GDI printers which means that you have to go thru the Windows printer driver to get any output.  You can not print directly to them because they won't accept even plain text.

Here are instructions on using the 'net use' command: http://support.microsoft.com/kb/314499  This will allow you to print plain text but will Not pass on Laserjet formatting commands.  Which doesn't matter because GDI printer doesn't understand them anyway.

If your printer does not support plain text (i.e. it's a GDI printer as DaveBaldwin explained) then you can still use DOSPRN. It takes the text (and PCL commands) and feeds them through the driver, so it works with any printer that has a Windows driver. Download it from http://dosprn.com/

DOSPRN will not transfer PCL commands thru a GDI printer driver on my system, it merely prints the image for the control characters that you would see in an old ASCII chart.  I've tried it.

Good info, I hadn't seen that before.

i suggest to install a PCI to lpt card : http://www.usbgear.com/1x-LPT-PCI.html
these work better than adapter dongles
then use the dosprn  - as said above

Sorry, nobus, this is a USB printer.

We still don't know if the target LaserJet printer is a GDI printer (a.k.a. host-based or Windows printer), or one of the more traditional ones (which supports the PCL5, PCL6 and PostScript Page Description Languages).

If it is the latter (i.e. if it supports PCL), then the 'net use' technique should work (and, I think, will allow the inclusion of PCL escape sequences, as well as just plain ASCII text).

sorry - i misread the question

It is a GDI printer.

I think we have listed most of your options here.  The only question left is does your printing use PCL formatting.

Being a DOS app, it probably does. Most likely it just uses plain text, and possible some simple things like bold text. However, DOSPRN also supports ESC/P if that's what the app uses.

And, a printer model number would be nice to know...

The printer is a HP Photosmart 7520.  It can be easily be replaced if that helps.  The Dos app reports are all 132-character wide printouts originally designed to print on tractor feed paper.  The app as the ability set print strings including compressed print, portrait or landscape to an laserjet that understands print codes PCL5 or PCL6.  I am going to look into DOSPRN.  Seems I remember an app called DOS2USB or something like that.  

Thanks for all the attention.   Also, there appears to be an issue with running in compatibility mode.  My client tells me the window is too small and slow.   The ultimate solution may be to purchase a used XP box and laserjet, but really would like to move him to windows 7.

Hdhondt: Would you recommend a printer that would work with the NET USE command, and might understand PCL 5 or 6?

For a recommendation I would need more info about your requirements. Do you need colour? Duplexing? What print speed do you need? How many trays? Would you prefer a networked printer, or do you want to stick with USB (networked usually causes less trouble)? If networked, do you want wired or wireless? What is your budget?

Apart from the price and interface, none of these questions are relevant for DOS. They would only be important if you want to replace the HP. In that case, do you want an all-in-one? Is photo quality important (lasers are not as good as inkjets for photos)?

I'm only interested in getting my DOS program to print to black and white paper.  The original printer was a LJ3 or LJ4.   With USB, my client should be able to keep his other printer for use with his windows apps.   We have tech over at the clients working with us.  We are having to run the program in virtual XP mode.  We can print from there, but fonts are wrong size and no margins.  Also, can't size the screen, so it is very small.  When clicking on maximize, the window moves to top left corner of screen but doesn't get any bigger.

Have a look at the Xerox range. The Phaser 3250 is their lowest cost printer with PCL5. It runs 30 ppm; networking is optional. The Phaser 3320 is next, with WiFi and wired networking as standard.

Thinking...

There are several comments in this thread that give solutions and other help to get this working. See, for example:
 
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Sorry, didn't mean to abandon this question.  We used printfil for a while and this worked pretty good.  We are now using DOSBOX to run the application.