DxROM
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