public final int registerRead(int regNum) {
		switch (regNum) {
		case 0  : return b;
		case 1  : return c;
		case 2  : return d;
		case 3  : return e;
		case 4  : return (short) ((hl & 0xFF00) >> 8);
		case 5  : return (short) (hl & 0x00FF);
		case 6  : return LowLevelData.unsign(addressRead(hl));
		case 7  : return a;
		default : return -1;
		}
	}