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lgblgblgb / xemu

Emulations (running on Linux/Unix/Windows/macOS, utilizing SDL2) of some - mainly - 8 bit machines, including the Commodore LCD, Commodore 65, and the MEGA65 as well.
https://github.com/lgblgblgb/xemu/wiki
GNU General Public License v2.0
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MEGA65: VIC-III (!) palette precision problem compared to the hardware #259

Closed lgblgblgb closed 3 years ago

lgblgblgb commented 3 years ago

As it turned out in #256 , I have some palette precision problems when using "legacy" (VIC-III) palette registers, in terms of actual values represented in VIC-IV palette. Maybe other problems as well. Since it's kind of different topic than just reading back pixels in issue #256 , let's open a new issue on this specific topic.

New findings: palette handling in Xemu is somewhat wrong, by writing legacy VIC-III palreg with value $F (for example) results in $FF for Xemu for the real VIC-IV palreg (my idea was to allow to use the whole brightness spectrum via VIC-III as well). However it seems, on MEGA65 it's only done with writing the most significant nybble to set.

lgblgblgb commented 3 years ago

Now actual RGB values seems to be kinda identical with MEGA65 with the commit above. This also changed the palette slightly, which is not a problem, since it means it should be closer to MEGA65 now anyway ;)