It's a black box. Approx 9 cm (3.5 in) x 14.5 cm (5.8 in) x 3 cm (1.2 in).
In large embossed letters on one side (top?) it has CMT.
On the other side (bottom?) it has a label reading: CMT Corvallis Microtechnology, inc. Model# RD512-01 Made in USA Serial# 744163 Complies with the limits for Class B...
It has a battery compartment which holds a 9v battery and a lithium cell.
It has a power jack. and an HPIL interface with 30 cm leads (i.e. *not* sockets on the box) on one end.
The other end has a 9 pin male D connector, 2 recessed push buttons (labelled On and Off and 2 LED indicators labelled on (yellow) and Bat (red).
Some things that won't help you identify it, but are kinda interesting include labels:
"Jacquie - New lithium and 9v battery fitted 16/9/94"
"Wilson wheat"
"datrec datdump ldev lsel primemp rpl rsys..."
The unit has 3 *very thin* pc boards with chips mounted both sides of other boards. It has an NEC V20 chip.
It was *probably* used with HP71's.
So what is it?