Hi Dave,
 Thanks for the timely episode.  I am considering using a pi to serve my HP LJ-2200 printer to my home network.

The DEC LN03 uses RS-232/RS-422 for the serial connection.  You should be able to use a USB-to-serial converter.  I used an LN03 with PC clones and was able to run the serial link as fast as 19200 baud.  User manual will indicate how to set serial parameters via dip switches near the data connector.

I suggest verifying the print engine still works by printing a few test pages before trying to connect to a computer.  I think there is a small square white button on the back that initiates printing of a test page.

It is probably difficult now to get toner or replacement parts like feed rollers for the LN03.  When a nylon gear inside my LN03 fractured, I finally ditched that printer -- after about 20 years of use in a home office.

Be aware that there are a few different LN03 models.  Mine was a rare "image" printer that would only accept postscript.  The model will determine what driver and settings you need to use.

The LN03 always keeps the fuser unit hot.  This is a big power consumer and harsh to the mechanics that transport paper and the photo-sensitive band.

There used to be USB to parallel converters available for purchase.  If you can find one of those you might be able to easily connect to the matrix printer.

- Bob Evans