PR-8210

PR-8210 support for Dexter is "finished" but remains untested on Cliff Hanger and MACH 3 hardware (the two main targets).

Warren recently tested it on his Cobra Command conversion for Cliff Hanger boardset and discovered that the picture number from the video signal is apparently completely ignored.  The way that the game decides when a seek has finished is to watch for the PR-8210 to drop the video signal and then restore it.  In other words, it appears that all PR-8210's drop the video signal during seeks (and maybe all laserdisc players in general do this and we've just never noticed!).  If this is true, then it introduces a mystery as to what exactly needed to be different about the PR-8210 player for MACH 3.

Anyway, the gist of it is that Cobra Command (Cliff Hanger conversion) is now tested and working with Dexter.

Our next target is to test with MACH 3 because we know for sure that it definitely reads the picture number from the video stream.  We know this because MAME and Daphne both emulate MACH 3 and provide this behavior.  Cliff Hanger also reads the picture number from the video stream (verified by the same reason).