note:
mov, push, pop and other transfer instructions, the execution result has no effect on the flag register!
ZF flag: if the result is 0 , ZF is 1; if it is not 0, ZF is 0; (zero flag)
PF sign: if the number of 1 is even, pf=1; if it is odd, then pf=0;
SF flag: if the result is negative , SF is 1; if the result is non-negative, SF is 0
CF flag: It is a flag bit that is meaningful for unsigned number operations [see if there is a carry]
OF flag: a flag bit that is meaningful for signed number operations [see if there is overflow]
Monitoring point 11.1:
sub al, al al = 0h ZF = 1 PF = 1 SF = 0
al is 0h, the result is 0, so ZF is 1 for true, there are 0 even numbers, so PF is 1, and the result is non-negative, so SF is 0. When we calculate the data as an unsigned number, the value of the SF bit has no meaning.
mov al,1 al=1h ZF=1 PF=1 SF=0
mov means that the transfer instruction has no effect on the flag register, and the flag register does not change.
push ax ax=1h ZF=1 PF=1 SF=0
Push means that the transfer instruction has no effect on the flag register, and the flag register does not change.
pop bx bx=1h ZF=1 PF=1 SF=0
pop means that the transfer instruction has no effect on the flag register, and the flag register does not change.
add al,bl al=2h ZF=0 PF=0 SF=0
The binary value of 2h is 0010, the result is not 0, ZF is 0, and the odd number is 1, PF is 0, SF is 0
add al,10 al=12h ZF=0 PF=1 SF=0
The binary value of 12h is 10010. This is an 8-bit register so the value is 0010. If the result is not 0, ZF is 0, and even number 1 is PF 1, and SF is 0.
mul al ax=144h ZF=0 PF=1 SF=0
The binary value of 144h is 101000100. This is a 16-bit register, so the value is 01000100. If the result is 0, ZF is 0, and even number 1 is PF 1, and SF is 0.
Monitoring point 11.2
