;*********************************************
;编写程序,使得在除法溢出时,在屏幕中显示字符串
;”divide error!”然后返回dos
;*********************************************
assume cs:code, ss:stack
stack segment
db 128 dup(0)
stack ends
code segment
start:
mov ax, cs
mov ds, ax
mov si, offset do0 ;ds:si指向源地址
mov ax, 0
mov es, ax
mov di, 200h ;es:di,0000:2000指向目标地址
mov cx, offset do0end-offset do0 ;cx中存放传输长度
cld ;设定传输方向为正
rep movsb ;将中断处理程序do0放到内存中
mov word ptr es:[0*4], 200h
mov word ptr es:[0*4+2], 0 ;设置中断向量表为0000:0200
int 0 ;调用0号中断
do0:
jmp short do0start
db “divide errors!”
do0start:
mov ax, cs
mov ds, ax
mov si, 202h ;设置ds:si指向字符串
mov ax, 0b800h
mov es, ax
mov di, 12*160+36*2 ;设置es:di指向显存空间的中间位置
mov cx, 9
s:mov al, [si]
mov es:[di], al ;写入显存
inc si
add di, 2
loop s
mov ax, 4c00h
int 21h
do0end:nop
code ends
end start