MiSTer FPGA Forum

I was watching the Joonas Javanainen Gameboy talk and he mentioned all the CPU revisions and how in some cases it can actually effect some games. Donkey Kong Land 3 for example.

So I was curious, what GB/GBC CPU was referenced and implemented on the MiSTer core? Is there just one set of behavior implemented for both GB and GBC modes or is the CPU reconfigured when you change modes. For example when running OG GB games does the CPU behaves like an early Rev DMG CPU, or is it just the GBC CPU running in BC mode? For best accuracy I would think implemented both an Original DMG CPU specifically for GB games and a GBC CPU for GBC games would be best of both worlds and provide most authentic results.

Here is the video I referenced and timestamped.

https://youtu.be/GBYwjch6oEE?t=595

Edit: Looks like behavior is different between running OG GB games via Original Gameboy or GBC modes as Donkey Kong Land 3 correctly shows the pixel glitches only in GBC mode. Very cool

There is not a specific CPU revision implemented but there are basically 3 behaviors. DMG, DMG in CGB mode and CGB game. Although I do look at Furrtek's DMG-CPU-B schematics to try and figure out the logic.

https://github.com/furrtek/DMG-CPU-Inside

I didn't know about that difference with Donkey Kong Land 3 but the cause has only been implemented recently. The difference is that CGB still fetches sprites even if they are disabled.