public void TestLowNibble()
{
const byte input = 0xab;
var nibble = Chip.LowNibble(input);
Assert.AreEqual(0xb, nibble);
}
private string TFR(string mnemomic)
{
var data = this.GetByte(++this.address);
var reg1 = Chip.HighNibble(data);
var reg2 = Chip.LowNibble(data);
var output = $"{data:x2}\t{mnemomic}\t";
var type8 = (reg1 & (byte)Bits.Bit3) != 0; // 8 bit?
return(type8
? $"{output}{ReferenceTransfer8(reg1)},{ReferenceTransfer8(reg2)}"
: $"{output}{ReferenceTransfer16(reg1)},{ReferenceTransfer16(reg2)}");
}