INES Mapper 074

iNES Mapper 074 is a MMC3 clone used in Eastern games. It's identical to iNES Mapper 192 and used for the same reason, except that only pages 8 and 9 are RAM. If the NES 2.0 header is present, 74 and 192 should be emulated identically, as NES 2.0 specifies CHR RAM size elsewhere.

Some games will be mis-headered as m074 but should really be m192 and will either need to be changed to the correct mapper, or changed to the correct amount of CHR RAM and handled by unified code.

We could consider deprecating one of these mappers and re-specifying it to support either CHR RAM size.

 Here are Disch's original notes:
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 =  Mapper 074          =
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 aka:
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 Pirate MMC3 variant
 
 
 Example Games:
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 Di 4 Ci - Ji Qi Ren Dai Zhan
 Ji Jia Zhan Shi
 
 
 Notes:
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 This mapper is a modified MMC3 (or is based on MMC3?).
 
 In addition to any CHR-ROM present, there is also an additional 2k of CHR-RAM which is selectable.  CHR pages
 $08 and $09 select CHR-RAM, other pages select CHR-ROM
 
 Apart from that, this mapper behaves exactly like your typical MMC3.  See mapper 004 for details.