Q1:	MOV AL, 1h	; AL: 1
	SUB AL, 2h	; AL: (AL) - 2

meaning AL: 1h - 2h = FFh

Result: CF = 1, SF = 1, ZF = 0, OF = 0	
	
	0000 0001
	0000 0010 (-)
	---------
		?
-------------		
Q2:	MOV AH, 1h	; AH: 1
	SUB AH, 1h	

meaning AH: 1h - 1h = 0h

Result: CF = 0, SF = 0, ZF = 1, OF = 0	

-------------
Q3:	MOV AL, 1h	; AL: 1
	ADD AL, FFh	; AL: (1+FF)	

meaning AL: 1h + (-1h) = 0h

	0000 0001
	1111 1111 (+)
	---------
		
Result: CF = 1, SF = 0, ZF = 1, OF = 0	


-------------
Q4:	MOV AL, 80h	; AL: 1
	SUB AL, 1h	; AL: 7F (80h-1h)	

meaning AL: 80h - 1h = 7Fh [(-128) - 1 = -129]

	1000 0000
	0000 0001 (-)
	---------
	0111 1111 = 7F
		
Result: CF = 0, SF = 0, ZF = 0, OF = 1	


-------------
Q5:	MOV AL, 7Fh  	; +127	
	ADD AL, 2h	; plus 2 -> out of range
	

Result: AL: 81h
	CF: 0   SF: 1  ZF: 0   OF: 1
	
	
-------------
Q6:	MOV AL, FFh	
	SUB AL, 2 	; FFh - 2h = ?
			; FFh + (-2) = (-3)
	
	1111 1111
	0000 0010 (-)
--------------------
        1111 1101
        
        1111 1111
 (-2)	1111 1110 (+)
 --------------------
     (1)1111 1101 = FD      
        
        
Result: AL: FDh
	CF: 0   SF: 1  ZF: 0   OF: 0
	
	
------------------
Q7:	MOV AL, FFh
	ADD AL, 2
	

AL: 1 (-128 to 127)
CF: 1 	SF: 0	ZF: 0	OF: 0


=====================================================

Conclusion:


(A) CF = ?   (0/1)

	ADD op1, op2

	(unsigned) op1
	(unsigned) op2 +
	-----------------
	 (1) xxxx xxxx     --> CF = 1
	 (0) xxxx xxxx	   --> CF = 0

	
	SUB op1, op2
	
	if (op1 < op2)	--> CF = 1
	else		--> CF = 0

 (B)
     OF = ?
     
     	ADD/SUB op1, op2	;  if the result (signed operation)
     				; 	is out of [-128, 127]	--> OF = 1
     				;  else				--> OF = 0