Jeff,
I think you have a couple of issues here:
1. If you are using an HP2392 terminal, the second port (unless you have
physically purchased a parallel port for it) is serial only. Only the
700/92-94-96-98 terminals have a parallel printer port.
2. Doesn't the DJ820 need a bi-directional IEEE-12?? parallel cable? I
purchased for myself a DJ672 color printer two weeks ago and was required by HP
warrantee to purchase this special cable. If this is the case, I don't think
the terminal supports the bi-directional protocols.
I hope this helps you.
Marshall Medoff, ITA, Inc.
Arlington, Virginia