Mapper

NES cartridges can include extra hardware which allows the use of large program and graphics ROMs and extra features. This extra hardware is usually referred to as a mapper, as it is used primarily to map the relatively small CPU and PPU address spaces to a portion of the larger address space of the ROM(s) on the cartridge.

Mappers vary in how they translate addresses. The various CPU memory mapping schemes expand the maximum program size above the standard 32KB, while PPU memory mapping schemes can add new graphic features.

Most mappers fall into one of two categories: discrete logic, and ASIC based. Some discrete logic mappers are susceptible to bus conflicts.

All mappers are assigned, either individually or by groups, to either an iNES Mapper Number or a UNIF Board Name.

Programmer's reference

• Nintendo: MMC1, MMC2, MMC3, MMC4, MMC5/audio, MMC6
• Konami: VRC1, VRC2, VRC3, VRC4, VRC6/audio, VRC7/audio, VRC irqs
• Others
  • Color dream

Note

• The pinout of every mapper is available here
• Information regarding iNes mappers is located here
• For a more exhaustive resource of mappers, Disch compiled a very detailed list of mappers all in one, covering more than 50 mappers. http://www.romhacking.net/docs/%5B362%5Dmapper_docs.zip