View source for MMC3 + NROM multicart

[[File:MMC3+NROM_farid_components.jpg|thumb]] [[File:MMC3+NROM_farid_top.jpg|thumb]] [[File:MMC3+NROM_farid_bottom.jpg|thumb]] [[File:MMC3+NROM_farid_schematics.png|thumb]]

==Overview==
*PRG: 512kB ROM1 + 32kB ROM2
*CHR: 512kB ROM
*Mirroring: H or V (selected by software)
*Bus conflicts: no

All MMC3's PRG & CHR registers are available at $8000-$ffff for the whole time.
There is no WRAM at $6000-$7fff but additional register (which can be protected
from writes using MMC3's $a001 just like it protects WRAM).

After power up & soft/hard reset, this is cleared and ROM2 is selected (for $8000-$ffff).

 [011. ...R .wMG GPPP] REG $6000-$7fff (address bits are latched)
          |  ||| ||||
          |  ||| |+++- selects inner 16KB PRG when in NROM mode
          |  ||+-+---- selects outer 128KB PRG & 128KB CHR (in any mode)
          |  |+------- 0: NROM mode, 1: MMC3 mode
          |  +-------- 1: protect whole $6000-$7fff register from further changes
          +----------- 0: selects ROM2, 1: selects ROM1 and protects this single bit from further changes

==PRG banking==
 condition         | $8000-$9fff | $a000-$bfff | $c000-$dfff | $e000-$ffff | notes
 ------------------+-------------+-------------+-------------+-------------+--------
 R=0               |  one 32 KB PRG from ROM2 (mapped to first 32 KB)      | NROM32 
 ------------------+-------------+-------------+-------------+-------------+--------
 R=1 & M=1         |   four CPU banks just as in MMC3 (from outer bank GG) | MMC3
 ------------------+-------------+-------------+-------------+-------------+--------
 R=1 & M=0 & GG=0  |        GGPPPP             |         GGPPPP            | NROM16
 ------------------+-------------+-------------+-------------+-------------+--------
 R=1 & M=0 & GG!=0 |         GGPPP0            |         GGPPP1            | NROM32
 ------------------+-------------+-------------+-------------+-------------+--------

==CHR banking==
CHR banking works in the same manner like in MMC3.

==Mirroring==
Mirroring works in the same manner like in MMC3.

==Notes==
More info about this multicart can be found here: http://forums.nesdev.org/viewtopic.php?t=7926&start=15

[[Category:Mappers]]