assume cs:code
code segment
;编写中断例程的安装程序
start: mov ax,cs
mov ds,ax
mov si,offset dot
mov ax,0
mov es,ax
mov di,200h
mov cx,offset dotend-offset dot
cld
rep movsb
;设置中断例程的中断向量
mov ax,0
mov es,ax
mov word ptr es:[7ch*4],200h
mov word ptr es:[7ch*4+2],0
mov ax,4c00h
int 21h
;编写中断例程
dot: mov ax,0b800h
mov es,ax
mov ax,160
mul dh
mov bx,ax
mov ax,2
mul dl
add bx,ax
mov al,cl
mov cx,0
s: mov cl,[si]
jcxz ok
mov es:[bx],cl
mov es:[bx].1,al
inc si
add bx,2
jmp s
ok: iret
dotend:
nop
code ends
end start