HP48 - InVision48 projector

[Cricket]

I have a newly acquired overhead display unit that looks just like the one pictured by Joe Horn that came with cables for the 38G and the 48GX. The 48 cable plugs in the card slot and the 38G cable is a female 10 pin and plugs in the 38G. So far I have had success in getting the 38G to work, but have had no success with the 48. This is really why I was hunting info on this subject. The overhead unit I have is said to be a F1212A Overhead Display Unit and it bears the HP name and Logo. One more thing, the end of my cable that plugs to the overhead is a 8 pin circular plug that is similar to a Mouse Cable plug. I hope this helps.
Personally I could use some help locating some documentation on how to operate the projector if it exists. I am going to heed Joe's suggestion and try slot #1 on my GX.