Wonder Boy - minor sprite issue

big10p

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I got 3 of them !! None working though or I could test to make sure its not a factory upgrade fault. Very possible and people just not noticed maybe ?

Dave.
Anything is possible, I guess. I'm pretty sure this version is the wboy2 romset in MAME which doesn't have the issue, but I don't know if this is meaningful, or not.
 

TheDaddy

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Wboy2 (I think) was used on multiple boards including the original ones that are not factory upgrades from Up 'n Down (As far as I know). The architecture of the boards are different and the logic is not the same so its possible , shot in the dark though as I am just guessing as such. Dont want you going to far down the rabbit hole Alice ! looking for something thats on all boards (If that makes sense)

Dave.
 

big10p

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I had a look at the Up n Down schems today, and used it to SLICE around, but didn't find anything obviously faulty. There's also a few ICs underneath the daughter board that I can't access to SLICE.

Looking at the schem, there's a couple of customs used in the sprite circuit, so I can't do much with those.

I did notice that the 4 data lines of one of the sprite RAMs used in the circuit are also piped through a nand gate that connects back to a custom, to a pin labelled OBJEND.

1000001701.png

Could this be used to signal when a sprite scan line has ended, or something?

I think this is just going to be a 'bug' I'm going to have to live with, but now I've spotted it, it's really distracting while playing. Lol
 

big10p

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Yes, it still does it in cocktail mode. It's just on the other side of the sprite for player 2, as everything is up-side down (if you see what I mean).

It seems to be affecting all 'end pixels' that are followed by a blank/transparent pixel in the scan line. Probably didn't explain that very well. lol. It's weird.
 
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