Telling us what the device actualyl is would be useful to help us guide you.
If you're really not sure, if you roll it over onto the back and look at the base plate, it should be written or eteched into it. You're looking for hp, Compaq, Philips, Casio or NEC model numbers.
There is a full list here:
http://www.hpcfactor.com/qlink/?linkID=9