王爽 汇编语言第二版 问题 7.9

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,10h mov ax,0 mov cx,4h mov si,3 s0: mov bx,0 push cx mov cx,4 s: mov al,[bx + si] and al,0DFH mov [bx+si],al add bx,10H loop s pop cx inc si //准备处理下一个字节 loop s0 mov ax,4c00h int 21h code ends end start