4.1 How to set your ROM to CGB-Mode

- Write 0x80 to rombyte-offset 0x143 (=CGB mode)
   ( you can do this at link-time by setting this linkerswitch: Wl-yp0x143=0x80)

Without setting this byte most emulators will treat your program wrong (and of course the real CGB too).

0xC0 is supposed to be used for GBC-only roms, however most emulators currently do not support, this, so you can use the if(_cpu == 0x11) to make sure the game runs in color-only mode.