INES Mapper 080

iNES Mapper 080 represents most boards using Taito's X1-005 mapper IC, which provides something somewhere between the MMC6 and the Namcot 108 in sophistication.

In comparison to to the Namcot 108, it:

• has the ability to bankswitch ROM from $C000-$DFFF
• has mirroring control
• has 128 extra bytes of RAM, optionally battery-backed

In comparison to the MMC6, it

• has the ability to bankswitch three different 8 KiB slices of PRG ROM simultaneously
• does not have an IRQ
• cannot swap which pattern table is 2×2KiB and which is 4×1KiB
• has only 128 extra bytes of RAM

If the pinout is correct, CPU A7 is ignored and the control registers should also be present at $7E7x.

See also: Taito X1-017, Taito X1-005 with alternate mirroring control, BootGod's forum post

 ========================
 =  Mapper 080          =
 ========================
 
 
 Example Games:
 --------------------------
 Kyonshiizu 2
 Minelvaton Saga
 Taito Grand Prix - Eikou heno License
 
 
 Notes:
 ---------------------------
 Regs appear at $7EFx, I'm unsure whether or not PRG-RAM can exist at $6000-7EFF
 
 Fudou Myouou Den is often marked to use this mapper -- however it uses mapper 207.
 
 
 Registers:
 ---------------------------
 
   $7EF0-7EF5:  CHR Regs
 
   $7EF6:       [.... ...M]  Mirroring
     0 = Horz
     1 = Vert

   $7EF8,7EF9:  Internal RAM permission ($A3 enables reads/writes; any other value disables)
  
   $7EFA,7EFB:  PRG Reg 0 (8k @ $8000)
   $7EFC,7EFD:  PRG Reg 1 (8k @ $A000)
   $7EFE,7EFF:  PRG Reg 2 (8k @ $C000)

   $7F00-7FFF:  128 Bytes of RAM, mirrored once.
 
 
 CHR Setup:
 ---------------------------
 
        $0000   $0400   $0800   $0C00   $1000   $1400   $1800   $1C00 
      +---------------+---------------+-------+-------+-------+-------+
      |    <$7EF0>    |    <$7EF1>    | $7EF2 | $7EF3 | $7EF4 | $7EF5 |
      +---------------+---------------+-------+-------+-------+-------+
 
 PRG Setup:
 ---------------------------
 
       $8000   $A000   $C000   $E000  
     +-------+-------+-------+-------+
     | $7EFA | $7EFC | $7EFE | { -1} |
     +-------+-------+-------+-------+