INES Mapper 225

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 Here are Disch's original notes:  
 ========================
 =  Mapper 225          =
 ========================
 
 Example Games:
 --------------------------
 52 Games
 58-in-1
 64-in-1
 
 
 Registers:
 ---------------------------
 
   $5800-5803:  [.... RRRR]  RAM  (readable/writable)
                 (16 bits of RAM -- 4 bits in each of the 4 regs)
   $5804-5FFF:    mirrors $5800-5803
 
   $8000-FFFF:  A~[.HMO PPPP PPCC CCCC]
     H = High bit (acts as bit 7 for PRG and CHR regs)
     M = Mirroring (0=Vert, 1=Horz)
     O = PRG Mode
     P = PRG Reg
     C = CHR Reg
 
 
 CHR Setup:
 ---------------------------
 
                $0000   $0400   $0800   $0C00   $1000   $1400   $1800   $1C00 
              +---------------------------------------------------------------+
 CHR Mode 0:  |                             $8000                             |
              +---------------------------------------------------------------+
 
 
 PRG Setup:
 ---------------------------
 
                $8000   $A000   $C000   $E000  
              +-------------------------------+
 PRG Mode 0:  |            <$8000>            |
              +-------------------------------+
 PRG Mode 1:  |     $8000     |     $8000     |
              +---------------+---------------+

Nestopia does not implement the 4 × 4 bit RAM, and FCEUX ceased to support it between 2.1.5 and 2.2.1

See also