1.asm

assume cs:code,ds:data,ss:stack

stack segment
   dw 0,0,0,0,0,0,0,0
stack ends

data segment
   db '1. display       '
   db '2. brows         '
   db '3. replace       '
   db '4. modify        '
data ends

code segment   
start: mov ax,data
       mov ds,ax
       mov ax,stack
       mov ss,ax
       mov sp,8
       mov cx,4   ;循环4行	
       mov bx,0

       s:push cx
	 mov si,0
	 mov cx,4
       s0: mov al,[bx+3+si]
	   and al,11011111b
           mov [bx+3+si],al
           inc si
	   loop s0
           add bx,16
	   pop cx
	   loop s  
 
	   
	  mov ax,4c00h
	  int 21h
code ends
end start