There aren't actually too many differences between GBC and DMG emulation as most of the hardware was consistent between them. The main change is around the PPU and the memory, as the GBC added some internal memory banks which are used for tile attributes and colour palettes etc. The actual changes around the graphics rendering aren't very significant other than some conditionals for GBC mode - you can see them here where `isGBC` is used: https://github.com/Humpheh/goboy/blob/master/pkg/gb/ppu.go