王爽汇编语言第二版学习笔记之实验13(2)

程序：
assume cs:code
code segment
start:
     mov ax,0b800h
     mov es,ax
     mov di,160*12+16*2
     mov bx,offset s-offset se
     mov cx,80
s:
     mov byte ptr es:[di],'!'
     add di,2
     int 7ch
se:
     nop
     mov ax,4c00h
     int 21h
code ends
end start
7ch中断例程：
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 do0end-offset do0
     cld
     rep movsb
     
     mov ax,0
     mov ds,ax
     mov word ptr ds:[7ch*4],200H
     mov word ptr ds:[7ch*4+2],0H
     
     mov ax,4c00h
     int 21h
     
do0:
     dec cx
     jcxz ok
     push bp
     mov bp,sp
     add [bp+2],bx
     pop bp
ok:
     iret
     
do0end:
     nop
     
code ends
end start