NTVDM CPU 遇到无效的指令
DATAS SEGMENT
dw 2 dup (0)
DATAS ENDS
CODES SEGMENT
ASSUME CS:CODES,DS:DATAS
START:
MOV AX,DATAS
MOV DS,AX
MOV AX,0
MOV ES,AX
MOV AX,ES:[4*9]
MOV DS:[0],AX
MOV AX,ES:[4*9+2]
MOV DS:[2],AX
;保存原9号中断向量
MOV AX,CS
MOV DS,AX
MOV SI,OFFSET New_Int9
MOV AX,0
MOV ES,AX
MOV DI,200H
MOV CX,OFFSET Int9_End - OFFSET New_Int9
CLD
REP MOVSB
cli
MOV WORD PTR ES:[4*9],200H
MOV WORD PTR ES:[4*9+2],0
sti
;存入新9号中断向量
MOV CX,30
MOV DX,2000h
MOV AX,0
Latency:
CALL Delay
LOOP Latency
MOV AX,DS:[0]
MOV ES:[4*9],AX
MOV AX,DS:[2]
MOV ES:[4*9+2],AX
Delay:
SUB AX,1
SBB DX,0
CMP AX,0
JNZ Delay
CMP DX,0
JNZ Delay
ret
New_Int9:
PUSH AX
PUSH BX
PUSH CX
PUSH DX
No_A:
IN AL,60H
PUSHF
CALL DWORD PTR DS:[0]
CMP AL,9E
JNZ No_A
MOV AH,2
MOV BH,0
MOV DH,0
MOV DL,0
INT 10H
MOV AH,9
MOV AL,'A'
MOV BL,7
MOV BH,0
MOV CX,4000
INT 10H
POP DX
POP CX
POP BX
POP AX
IRET
Int9_End:
NOP
MOV AH,4CH
INT 21H
CODES ENDS
END START
我们先不说这个程序是否正确。运行时不会提示“NTVDM CPU遇到无效的指令”,而在用DEBUG调试到MOV WORD PTR ES:[4*9],200H 时就会出现NTVDM CPU这个错误,MOV WORD PTR ES:[4*9],200H 是用于修改9号中断向量表,是不是因为系统保护的原因,如果是要怎么才能修改这个中断向量。