INES Mapper 231
Here are Disch’s original notes:
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= Mapper 231 =
========================
Example Game:
--------------------------
20-in-1
Registers:
---------------------------
$8000-FFFF: A~[.... .... M.LP PPP.]
M = Mirroring (0=Vert, 1=Horz)
L = Low bit of PRG
P = High bits of PRG
PRG Setup:
---------------------------
Note that 'L' and 'P' bits make up the PRG reg, and the 'L' is the low bit.
$8000 $A000 $C000 $E000
+---------------+---------------+
| $8000 AND $1E | $8000 |
+---------------+---------------+