Codemasters was an independent publisher of NES games. It operated without a license from Nintendo. You can recognize a Codemasters cart by the switch on the back; in one position, its lockout defeat chip worked with USA systems; in the other, it worked with UK systems.

The mapper used in Codemasters games such as Firehawk, Micro Machines, and Linus Spacehead, is identical to Nintendo's UNROM (writes to its register switch a 16 KB bank in PRG $8000-$bfff, and CHR is RAM) except for one minor detail: only writes to $c000-$ffff have any effect. Writes to $8000-$bfff apparently do nothing; they may have been left as an expansion to support CHR ROM.

It has been assigned iNES board class 71, but most programs that use this mapper will work on an UNROM board. Note that I have not tested this information on an emulator.

(return to) iNES Mappers