INES Mapper 233

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 Here are Disch's original notes:  
 =  Mapper 233          =
 Example Game:
 ???? "42-in-1"  ????
 Sources report this mapper as "42-in-1" with description layed out below.  I did not test this,
 since I could not find a copy of the ROM in question.  The only ROM I have that's marked as
 233 is "Unknown Multicart 1", and it does *not* follow the description in this doc at all.
 There is a "Super 42-in-1"... but that is mapper 226.  226, by the way, is strikingly similar
 to the below description.  I wonder if below description really applies to 233?
  $8000-FFFF:  [MMOP PPPP]
     M = Mirroring
     O = PRG Mode
     P = PRG Page
 PRG Setup:
               $8000   $A000   $C000   $E000  
 PRG Mode 0: |            <$8000>            |
 PRG Mode 1: |     $8000     |     $8000     |
   'M' mirroring bits:
      %00 = See below
      %01 = Vert
      %10 = Horz
      %11 = 1ScB
   Mode %00 (almost, but not quite 1ScA):
     [  NTA  ][  NTA  ]
     [  NTA  ][  NTB  ]
 "Unknown Multi Cart 1"
 This ROM is a mystery.
 It consists of 32 individual mapper 0 games, each 16k PRG + 8k CHR.
 Games do not use compatible mirroring modes -- the ROM includes Ice Climber (which uses H mirroring) and
 Excitebike (V mirroring).  
 No games seem to be modified to make any kind of writes to $8000-FFFF, so I didn't find any clue as to what
 mapper registers are being written to (if any).
 There does not appear to be *ANY* game selection screen for the multicart.  I have paged through every 16k
 of PRG and they all run the individual games straight up.  So unless the mapper aligns to 8k (or smaller) pages
 on startup and there's some crap hidden in there, I don't see how these games are held together.
 Could it be that this ROM dump is bad or incomplete?  The *only* other thing I can think of is that this cart might
 be reset based (a la mapper 060) -- but that is complicated by the fact that games use conflicting mirroring modes.
 So perhaps the mapper sets the mirroring mode based on what game is selected?
 More weirdness:  games seem to have mismatching PRG/CHR pages.  Ice Climber's PRG is on page $1F, but its CHR is
 on page $17.  It seems that you need to subtract 8 from the PRG page to get the matching CHR page (and wrap where
 Even more weirdness:  despite each game only having 16k PRG, some of the games in the package normally have 32k!
 I don't know if the games were just hacked and had a bunch of stuff removed for what.
 It's possible this ROM dump is bogus and/or bad.  It might even be assigned the wrong mapper number.
 At any rate... here are the games.
 Game name          PRG page  CHR Page  Mirroring
 Galaxian              $00      $18        Horz
 10 Yard Fight         $01      $19        Horz
 DKJ Math              $02      $1A        Vert
 Antarctic Adventure   $03      $1B        Horz
 Balloon Fight         $04      $1C        Horz
 Baseball              $05      $1D        Horz
 Battle City           $06      $1E        Horz
 Binary Land           $07      $1F        Horz
 Burger Time           $08      $00        Horz
 Chack 'n Pop          $09      $01        Horz
 Clu Clu Land          $0A      $02        Horz
 Lode Runner           $0B      $03        Vert
 ?? Go / Othello ??    $0C      $04        ????
 Field Combat          $0D      $05        Horz   ** really 32k PRG? **
 Devil World           $0E      $06        Horz
 Dig Dug               $0F      $07        Horz
 Donkey Kong           $10      $08        Horz
 Donkey Kong Jr.       $11      $09        Horz
 Donkey Kong 3         $12      $0A        Vert
 Door Door             $13      $0B        Vert
 Duck Hunt             $14      $0C        Vert
 Excitebike            $15      $0D        Vert
 Exerion               $16      $0E        Horz
 F1-Race               $17      $0F        Vert
 Formation Z           $18      $10        Horz
 Front Line            $19      $11        Horz
 Galaga                $1A      $12        Horz   ** really 32k PRG? **
 Golf                  $1B      $13        Vert
 Hogan's Alley         $1C      $14        Vert
 Hyper Olympic         $1D      $15        Vert
 ?? some gun game ??   $1E      $16        ????
 Ice Climber           $1F      $17        Horz