NES 2.0 Mapper 455

NES 2.0 Mapper 455 denotes the NTDEC N625836 MMC3-based multicart circuit PCB, used for a 9000000-in-1 multicart.

Extra Register ($4100, write)

A~[010. .... ..Q. .qDC] D~[...P PPBA]
               |   |||        | |||+- 0: MMC3 mode, 1: NROM mode
               |   |||        | ||+-- 0: NROM-128 mode, 1: NROM-256 mode (if A=1)
               |   |||        +-++--- PRG A16..A14 in NROM mode
               |   ||+--------------- 0: 128 KiB MMC3 inner PRG bank, 1: 256 KiB MMC3 inner PRG bank
               |   |+---------------- 0: 128 KiB MMC3 inner CHR bank, 1: 256 KiB MMC3 inner CHR bank
               +---+----------------- PRG/CHR A18..A17