INES Mapper 075

iNES Mapper 075 is used to represent the Konami VRC1 mapper.

 Here are Disch's original notes:  
 ========================
 =  Mapper 075          =
 ========================
 
 
 aka:
 --------------------------
 VRC1
 
 
 Example Games:
 --------------------------
 Tetsuwan Atom
 Ganbare Goemon! - Karakuri Douchuu
 
 
 
 Registers:
 --------------------------
 
 Range,Mask:   $8000-FFFF, $F000
 
   $8000:  [.... PPPP]   PRG Reg 0 (8k @ $8000)
   $A000:  [.... PPPP]   PRG Reg 1 (8k @ $A000)
   $C000:  [.... PPPP]   PRG Reg 2 (8k @ $C000)
 
   $9000:  [.... .BAM]   Mirroring, CHR reg high bits
      M = Mirroring (0=Vert, 1=Horz)
      A = High bit of CHR Reg 0
      B = High bit of CHR Reg 1
 
   $E000:  [.... CCCC]   Low 4 bits of CHR Reg 0 (4k @ $0000)
   $F000:  [.... CCCC]   Low 4 bits of CHR Reg 1 (4k @ $1000)
 
 
 PRG Setup:
 ---------------------------
       $8000   $A000   $C000   $E000  
     +-------+-------+-------+-------+
     | $8000 | $A000 | $C000 | { -1} |
     +-------+-------+-------+-------+
 
 
 CHR Setup:
 ---------------------------
 
   CHR regs are 5 bits wide.  The low 4 bits of each reg are set by $E000 and $F000, and the high bit is taken
 from the appropriate bits of $9000.
 
       $0000   $0400   $0800   $0C00   $1000   $1400   $1800   $1C00 
     +-------------------------------+-------------------------------+
     |       $9000.1 + $E000         |       $9000.2 + $F000         |
     +-------------------------------+-------------------------------+