loopz的问题

cx
用程序可以测试出来
DATA SEGMENT
STR1 DB " ZF=$ "
STR2 DB " SF=$ "
STR3 DB " PF=$ "
STR4 DB " CF=$ "
STR5 DB " OF=$ "
FST1 DB " ZF FIRST$ "
FST2 DB " CX FIRST$ "
DATA ENDS
CODE SEGMENT
ASSUME CS:CODE,DS:DATA
START: MOV AX,DATA
MOV DS,AX
MOV AH,2
INT 21H
LEA DX,STR1
MOV AH,9
INT 21H
MOV CX,5
MOV BX,4
SUB BX,1
JZ L1
MOV DL,'0'
MOV AH,2
INT 21H
JMP NEXT1
L1: MOV DL,'1'
MOV AH,2
INT 21H
NEXT1: LEA DX,STR2
MOV AH,9
INT 21H
JS L2
MOV DL,'0'
MOV AH,2
INT 21H
JMP NEXT2
L2: MOV DL,'1'
MOV AH,2
INT 21H
NEXT2: LEA DX,STR3
MOV AH,9
INT 21H
JP L3
MOV DL,'0