hey
This sounds like a Digital BA-11 of some sort. It
could be something
as early as a pdp 11/20, 11/05, 11/34, 11/35, or as late as a 11/24
or 11/44 -- possibly others.
I think the toggle switches on the front need to be set right and the
terminal settings need to be guessed at to talk over serial. The pics
probably don't reveal much but they're easier than describing it.
http://www.xmission.com/~bmidgley/front.jpg
http://www.xmission.com/~bmidgley/back.jpg
I don't have the inclination to tear it open.
--
Brad