INES Mapper 061

 Here are Disch's original notes:  
 ========================
 =  Mapper 061          =
 ========================
 
 Example Game:
 --------------------------
 20-in-1
 
 
 Registers:
 ---------------------------
 
   $8000-FFFF:  A~[.... .... M.LO HHHH]
     H = High 4 bits of PRG Reg
     L = Low bit of PRG Reg
     O = PRG Mode
     M = Mirroring (0=Vert, 1=Horz)
 
 
 PRG Setup:
 ---------------------------
 
 PRG Reg is 5 bits -- combination of 'H' and 'L' bits.
 
                $8000   $A000   $C000   $E000  
              +-------------------------------+
 PRG Mode 0:  |            <$8000>            |
              +-------------------------------+
 PRG Mode 1:  |     $8000     |     $8000     |
              +---------------+---------------+