4-in-1 multicart (UNROM/ANROM)

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Components

PRG: 512 kiB ROM

CHR: 8 kiB RAM

Bus conflicts: no

gG | GAME
---+----------------
00 | Trog
10 | Duck Tales I
01 | Marble Madness
11 | Captain Skyhawk

Registers

$6000-$7FFF: UNROM/ANROM banking type & game number

7  bit  0
---- ----
TgGP
||||
|||+------------ protection:    0 - off, 1 - contents of this register cannot be changed until console reset
|++------------- selects one of four 128 kB games; g is lower address line: PRG-A18 = G, PRG-A17=g 
+--------------- banking style: 0 - UNROM: $8000-$bfff 16 kB switchable CBA bank, $c000-$ffff fixed to last bank, PPU vertical mirroring
                                1 - ANROM: $8000-$ffff 32 kB switchable BA bank, PPU single screen mirroring

$8000-$FFFF: bank select (when in UNROM mode)

7  bit  0
---- ----
      CBA
      |||
      +++------------ UNROM bank (when in UNROM MODE)

$8000-$FFFF: bank select (when in ANROM mode)

7  bit  0
---- ----
   M   BA
   |   ||
   |   ++------------ ANROM bank (when in ANROM MODE)
   +----------------- one screen mirroring
  
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