Metal Max 2 Kai (Japan) - Glitch on the text box

[wwark]

Save state:
https://github.com/MiSTer-devel/GBA_MiSTer/files/4130173/Metal.Max.2.Kai.Japan.zip

• Activate turbo mode fixed this issue
• The glitches are not present in the Rev1 of this game.

Thanks,

[paulb-nl]

This game reads the VCOUNT register at rom address 800174E at the beginning of every line in an HBlank IRQ. The CPU sometimes reads the VCOUNT register too early (in the HBlank of the previous line) so the game does not get the value it expects.

Could be that the HBlank IRQ starts too early.

[RobertPeip]

Thank you for debugging this.
I fear the current way the core is made can lead to minor inconsistencies of the timing.
I will work on an improved version at some point that solves such issues.

[paulb-nl]

Thanks Robert. That would be great!