INES Mapper 243

 Based on Disch's original notes:  
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 =  Mapper 243          =
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 Example Games:
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 Honey
 Poker III 5-in-1
 
 
 Registers:
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 Range,Mask:   $4020-4FFF, $4101
 
   $4100:  [.... .AAA]   Address for use with $4101
 
   $4101:   Data port
      R:2 -> [.... ...H]  High bit of CHR reg
      R:4 -> [.... ...L]  Low bit of CHR reg
      R:5 -> [.... .PPP]  PRG reg  (32k @ $8000)
      R:6 -> [.... ..DD]  Middle bits of CHR reg
      R:7 -> [.... .MM.]  Mirroring
          %00 = Horz
          %01 = Vert
          %10 = L-shaped; see below
          %11 = 1ScB
 
 
 Mirroring:
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 Mirroring mode %10 is not quite 1ScB:
 
   [  NTA  ][  NTB  ]
   [  NTB  ][  NTB  ]
 
 
 CHR Setup:
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 8k CHR page @ $0000 is selected by the given 4 bit CHR page number ('HDDL')