INES Mapper 115

iNES Mapper 115 is an MMC3 clone used by Carson (卡聖), which uses "NT" model numbers for its games. Some games formerly assigned as mapper 248 (such as Bao Qing Tian/Justice Pao) should be emulated with this mapper 115.

 Here are Disch's original notes:  
 ========================
 =  Mapper 115          =
 ========================
 
 Example Game:
 --------------------------
 Yuu Yuu Hakusho Final - Makai Saikyou Retsuden
 
 
 Notes:
 ---------------------------
 MMC3 variant.  For info on MMC3, see mapper 004.
 
 Regs at $6000-7FFF means no PRG-RAM
 
 
 Registers:
 ---------------------------
 
 Range,Mask:   $6000-7FFF, $6001
 
   $6000:  [O... PPPP]
     O = PRG Mode
     P = 16k PRG Page
 
   $6001:  [.... ...C]
     C = CHR Block select
 
   $8000-FFFF:  Same as MMC3
 
 
 CHR Setup:
 ---------------------------
 
  'C' selects a 256k CHR block for all the CHR selected by the MMC3.  You can think of this as a CHR-OR of
 $000 or $100 depending on 'C'.
 
 
 PRG Setup:
 ---------------------------
 
        $8000   $A000   $C000   $E000  
       +-------------------------------+
 O=0:  |              MMC3             |
       +-------------------------------+
 O=1:  |     $6000     |     MMC3      |
       +---------------+---------------+
 
 Normal MMC3 PRG setup applies.  If the O mode bit is set, then $8000-BFFF no longer reflects the typical MMC3
 setup, and instead has a 16k page selected by $6000.