实验十二

编写0号中断的处理程序，使得在除法溢出发生时，在屏幕中间显示字符串"divide error!"

中断处理程序

assume cs:code
code segment
start:
mov ax,cs
mov ds,ax
mov si,offset do0; 设置源地址
mov ax,0
mov es,ax
mov di,200h; 设置目的地址
mov cx,offset do0end-offset do0; 设置传输长度
cld
rep movsb

mov ax,0
mov es,ax
mov word ptr es:[0*4],200h; 修改中断向量表，使其指向我们设置的地址
mov word ptr es:[0*4+2],0

mov ax,4c00h
int 21h

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; 指向屏幕中间
mov cx,13

s:
mov al,ds:[si]
mov es:[di],al
inc si
add di,2
loop s

mov ax,4c00h
int 21h

do0end:
nop
code ends
end start

测试程序

assume cs:code
code segment
start:
mov ax,1000h
mov bh,1
div bh
code ends
end start