
========================
=  Mapper 227          =
========================


Example Game:
--------------------------
1200-in-1


Notes:
---------------------------
This mapper has 8k CHR-RAM, and also has the ability to write protect it's CHR-RAM!


Registers:
---------------------------

  $8000-FFFF:  A~[.... ..LP  OPPP PPMS]
    L = Last PRG Page Mode
    P = PRG Reg
    O = Mode
    M = Mirroring (0=Vert, 1=Horz)
    S = PRG Size


Setup:
---------------------------

When 'O' is set, CHR-RAM is write protected (writes have no effect).  'O' also changes the PRG mode.

Note there is funky ANDs and ORs going on below depending on the modes:


                  $8000   $A000   $C000   $E000  
                +---------------+---------------+
O=1, S=0:       |       P       |       P       |
                +-------------------------------+
O=1, S=1:       |             < P >             |
                +-------------------------------+
O=0, S=0, L=0:  |       P       |   P AND $38   |
                +---------------+---------------+
O=0, S=1, L=0:  |   P AND $3E   |   P AND $38   |
                +---------------+---------------+
O=0, S=0, L=1:  |       P       |   P  OR $07   |
                +---------------+---------------+
O=0, S=1, L=1:  |   P AND $3E   |   P  OR $07   |
                +---------------+---------------+


