INES Mapper 230
Here are Disch’s original notes:
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= Mapper 230 =
========================
Example Game:
--------------------------
22-in-1
Reset Driven:
---------------------------
The mapper has 2 main modes: Contra mode, and multicart mode. Performing a Soft Reset switches between
them.
Notes:
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This multicart has an odd PRG size (not power of 2). This is because there are 2 PRG chips.
The first is 128k and contains Contra, the other is 512k and contains the multicart.
A soft reset changes which chip is used as well as other stuff relating to the mode
Registers:
---------------------------
Contra Mode $8000-FFFF: [.... .PPP]
Multicart Mode $8000-FFFF: [.MOP PPPP]
M = Mirroring (0=Horz, 1=Vert)
O = PRG Mode
P = PRG Page
Note:
Mirroring is always Vert in Contra Mode.
PRG Setup:
---------------------------
$8000 $A000 $C000 $E000
+---------------+---------------+
Contra Mode: | $8000 | { 7 } | <--- use chip 0
+-------------------------------+
Multi Mode 0: | <Reg> | <--- use chip 1
+-------------------------------+
Multi Mode 1: | Reg | Reg | <--- use chip 1
+---------------+---------------+
chip 0 = 128k PRG (offset 0x00010-0x2000F)
chip 1 = 512k PRG (offset 0x20010-0xA000F)