Port 3D9  -  Color/VGA Color select register

        Text modes:
                xxx1 xxxx  Intensity of background
                xxxx 1111  Screen/border IRBG

        Graphics modes:

                xx1x xxxx  0=green, red and brow palette
                           1=cyan, magenta and white palette
                xxx1 xxxx  1=enable palette intensity
                xxxx 1111  IRBG for background+border