INES Mapper 226

Here are Disch’s original notes:
======================== = Mapper 226 = ========================

 Example Games:
 --------------------------
 76-in-1
 Super 42-in-1

 Registers:
 ---------------------------

 Range, Mask:  $8000-FFFF, $8001

   $8000:  [PMOP PPPP]
      P = Low 6 bits of PRG Reg
      M = Mirroring (0=Horz, 1=Vert)
      O = PRG Mode

   $8001:  [.... ...H]
      H = high bit of PRG

 PRG Setup:
 ---------------------------

 Low 6 bits of the PRG Reg come from $8000, high bit comes from $8001

                $8000   $A000   $C000   $E000  
              +-------------------------------+
 PRG Mode 0:  |             <Reg>             |
              +-------------------------------+
 PRG Mode 1:  |      Reg      |      Reg      |
              +---------------+---------------+

The original describing document states the 2s bit of the register at $8001 disables CHRRAM writes. No games seem to rely on it, though. It also says that the mapper hardware is made of a 74LS74A, 74LS273, 74LS139, 74LS02, and 74LS153.

The multicart reportedly relies on the value of uninitialized memory to determine exactly how many games are available.

The multicart clears both registers on soft reset.