王爽《汇编语言》第十二章实验，执行时出错，且在debug下单步执行也有问题，求解
assume cs:code
code segment
start: mov ax,cs
mov ds,ax
mov si,offset do0
mov ax,0
mov es,ax
mov di,200h
mov cx, offset do0ends - offset do0
cld
rep movsb
mov ax,0
mov es,ax
mov word ptr es:[0*4],200h
mov word ptr es:[0*4+2],0h
mov ax,1000h
mov dx,1
mov bx,1
div bx
mov ax,4c00h
int 21
do0: jmp short do0start
db "divide error!"
do0start: mov ax,cs
mov ds,ax
mov si,202h
mov ax,0b800h
mov es,ax
mov di,12*160+36*2
mov cx,13
s: mov al,[si]
mov es:[di],al
inc si
add di,2
loop s
mov ax,4c00h
int 21
do0ends:nop
code ends
end start
错误信息：
------解决方案--------------------
最后的 int 21 应该是 int 21h 吧