code: function() {
  		this.prgRead = new Uint8Array( 0x8000 );
  		this.prgRead.set( this.prgData.subarray( 0, 0x2000 ) );
  
  		this.chrRead = new Uint8Array( 0x2000 );
  		this.chrRead.set( this.chrData.subarray( 0, 0x2000 ) );
  
  		mappers.init( this );
  	}
docs: Init mapper data and logic.
  NESNES copies data around to a dedicated typed array to emulate mapper
  behavior. See also loadChrBank and loadPrgBank.