code: function() {
  		switch( this.cycles ) {
  		case 3728:
  		case 7457:
  		case 11186:
  		case 14915:
  			this.doQuarterFrame();
  			break;
  		}
  
  		switch( this.cycles ) {
  		case 7457:
  		case 14915:
  			this.doHalfFrame();
  			break;
  		}
  
  		if ( this.cycles >= 14915 ) {
  			this.cycles = 0;
  
  			if( this.frameCounterInterrupt ) {
  				this.system.cpu.requestIRQ();
  			}
  		}
  	}
docs: Tick for framecounter mode 0.