code: function( address, value ) {
  		if ( address & 0x8000 ) {
  			this.writeRegister( address, value );
  		} else if ( address >= 0x6000 ) {
  			// writing RAM
  			this.ramData[ address - 0x6000 ] = value;
  		}
  
  		return;
  	}
docs: Write program data.
  This is usually used to write to cartridge RAM or mapper registers. Cartridges
  don't have mappers by default, but mapperless cartridges can also not be written
  to. This method implements the most common mapper register locations.