@bloodline
I'm not sure exactly how detailed of an answer you're looking for so, here's a general wash...
The Amiga 2000, 3000, and 4000 all had an internal video slot that a card could use to intercept the video signal and manipulate it. This is how we get Amiga only graphics cards, and scan-doublers, and the like without needing external hardware on those machines.
the A1200 of course doesn't have any of those expansion slots on it, and therefore needs the expansion bus extended out to give it Zorro-II slots and (sometimes) a video slot.
you can find a pinout listing of the A4000 video slot here
http://www.l8r.net/technical/t-videoslot.shtml@Everyone else
Thanks for the help guys, I now have a couple of places at least to send him looking.