Don't worry, I didn't give up - I will not be beat. I have just been collecting recon with rant's inbetween...
dp and ddp are very very timing sensitive when it comes to vbl and sprite buffering, I mean, just a couple cycles off and it will do one of 3 things:
1: go out of sync with sprite:tile layer (usually when getting close to the 2 frames of reaction time)
2: go between 2-4 frames of reaction time
3: explode!
if you get it exactly right, it will react in 2 frames with no bad side effects. that being said, our dp / ddp now reacts in 2 frames. with no side effects. tonight I'll do the ultimate playtest.
p.s. fba doesn't use drivers from mame
best regards,
- dink