Ok so I have resolved my sprite issues with my short Ghost Hunt game running on Pac-Man hardware. I'll explain more about that in the thread about that.
Now that I have the sprites working correctly I can explain a bug I think I've found in the Pac-Man driver
I've done a video of my code running in Mame 0.171 (I also tested this in 0.174 and it has the same wrong behaviour) and on my Midway Pac-Man board.
here's the video:
Basically when a sprite is partially off the bottom of the screen (Y values less than $10) the hardware draws the missing parts at the top of the screen, basically wrapping the sprite. Unfortunately it appears in mame that the driver is ignoring the x and y flip bits (bits 1 and 0 of the sprite number register - that's the first byte in each sprites info values) so if the sprite is flipped vertically (bit 1 is set in the sprite number regsiter) it is drawn at the bottom of the screen ok but the wrap at the top is rendered as if the bit is clear.
This renders properly on the Pac-Man board.
If anyone knows how to report this to the Mame dev team can you let me know how please.
Thought this might be interesting as this bug would not have surfaced as the sprites never wrap the top and bottom of the screen on Pac-Man because of the maze layout and the horizontal wrap as 32 pixel locations that don't render on screen at all, so you would never see a wrap problem.
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