DxROM

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The generic designation DxROM refers to cartridge boards made by Nintendo that use the seemingly-identical Namco 108, 109, 118 or 119 mappers. Nintendo did not manufacture the Famicom counterparts. The iNES format assigns Mapper 206 to DxROM.

The following DxROM boards are known to exist:

Board PRG ROM CHR ROM Comments
DEROM 64 KiB 32,64 KiB ROM Nintendo's clone of Tengen's 800002 and Namco's 3413 and 3414
DE1ROM 128 KiB 64 KiB Nintendo's clone of Tengen's 800030 and Namco's 3406
DRROM 128 KiB 64 KiB Nintendo's clone of Tengen's 800004, with four-screen mirroring.

Tengen initially tried to get around Nintendo's publication restrictions by manufacturing all parts of the games themselves. They were eventually prohibited from continuing, but Nintendo only re-released a subset of all the games that Tengen brought to the US.

Namco published a wide number of differently-numbered Famicom counterparts. Some of them have significantly different behavior and have had their own mappers allocated.

Board PRG ROM CHR ROM Comments
3401 32 KiB 32 KiB
3405, 3415 128 KiB 32 KiB
3406, 3416 128 KiB 64 KiB
3407, 3417, 3451 32 KiB 16,32 KiB PRG A13, A14 connected directly to CPU, no PRG banking available
3413 64 KiB 32 KiB
3414 64 KiB 64 KiB
3425 128 KiB 32 KiB CHR A15 controls CIRAM A10
3433, 3443 128 KiB 128 KiB PA12 controls CHR A16
3446 128 KiB 128 KiB 2K banks using regs 2-5
3453 128 KiB 128 KiB Bit 6 of written value controls CIRAM A10; PA12 controls CHR A16

Otherwise, the Namco 108 family is just a subset of MMC3