Question

汇编语言当AX=008FH的时候用CMP AL,0和JNL NEXT语句为什么不进行跳转？但是用小于这个数字就可以

这是一个求根号的程序 利用1+3+5+7+9=25=5^2这个原理，当求144以上时出错
CRLF MACRO
MOV DL,0DH
MOV AH,02H
INT 21H
MOV DL,0AH
MOV AH,02H
INT 21H
ENDM

DATA SEGMENT
DATA1 DB 'Input the number!','$'
DATA2 DB 'The answer is:','$'
MID DB -1
NUM DB 20
DB ?
DB 20 DUP(?)
TEN DB 10
RESULT DB 20 DUP(?)
DATA ENDS

STACK SEGMENT
STA DW 256 DUP(?)
TOP EQU LENGTH STA
STACK ENDS

CODE SEGMENT
ASSUME CS:CODE,DS:DATA,SS:STACK
START: MOV AX,DATA
MOV DS,AX

LEA DX,DATA1 ;显示输入数字
MOV AH,9
INT 21H
LEA DX,NUM ;输入数字
MOV AH,10
INT 21H
CRLF

LEA BX,NUM
MOV SI,0
MOV CX,0
ADD BX,02H
BCD: SUB DS:[BX+SI],byte ptr 30H ;ASCII变非压缩BCD码
INC SI
INC CX
CMP DS:[BX+SI],byte ptr 0DH
JNE BCD
MOV SI,0
MOV AX,0
HEX: MUL TEN
ADD AL,DS:[BX+SI]
INC SI
LOOP HEX

LEA BX,MID
MOV CX,0FFH
NEXT: ADD DS:[BX],BYTE PTR 02H ;开方运算，结果送CX
SUB AL,DS:[BX]
INC CX
CMP AL,0
JGE NEXT ；！！！就是这里！！！

LEA DX,DATA2 ;显示结果
MOV AH,9
INT 21H
MOV AL,CL
MOV AH,0
LEA BX,RESULT
MOV SI,0
ASCII: DIV TEN ;数字变ASCII码
ADD AH,30H
MOV DS:[BX+SI],AH
INC SI
MOV AH,0
CMP AL,0
JG ASCII
DISPLAY:MOV DL,DS:[BX+SI]
MOV AH,2
INT 21H
DEC SI
CMP SI,0
JGE DISPLAY
MOV AX,4C00H
INT 21H
CODE ENDS
END START

Answer 1

答案见http://zhidao.baidu.com/question/343452567.html?seed=0