{TAIL ~ The subtrahend} is stored in {HEAD ~ the A register} and the minuend in the B register 
{ TAIL ~ The subtrahend } is stored in { HEAD ~ the A register } and the minuend in the B register
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH