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Museum of the Game® & International Arcade Museum® Forums
I have a Sega Vic Dual PCB on my bench right now that is throwing me for a loop right now. So I confirmed that I can read ROMs just fine on this but I had no video and was running into odd ram issues. I validated these things using my fluke.
The first thing I did was validated was the PROMs themselves. I have several sets on hand because I've had to do VIC dual stuff before. For this excercise I used the timing PROMs from Samurai and Wanted. My test PROMs validated just fine on my superpro. The problem I noticed though is that SRLD is always high. This is responsible for generating the clock signals used by video. I've confirmed the write signal to the 175s (this is the 15.something MHz base clock) to be fine. This is a snippit from Borderline's manual, as this is the best copy I can find of the two PROM version of the VIC hardware.
Does anyone have any insight as to why I might be encountering these issues? I believe that the 175s are good. I am just not understanding why I might be missing the clock signals here.