王爽汇编第二册:将每个单词的前四位改为大写字母

1  问题描述

2 汇编代码

assume cs:codesg,ss:stacksg,ds:datasg
stacksg segment
  dw 0,0,0,0,0,0,0,0
stacksg ends
datasg segment
 db '1.display#######'
 db '2.brows#########'
 db '3.replace#######'
 db '4.modify########'
datasg ends
codesg segment
 start:mov ax,stacksg
       mov ss,ax
       mov sp,16
	   mov cx,4
	   mov si,datasg
	   mov ds,si
	   mov si,0
  s1:  push cx
       mov cx,4
       mov bx,0
   s2: mov al,[si+bx+2]
       and al,11011111b
	   mov [si+bx+2],al
	   add bx,1
       loop s2
       pop cx
       add si,16
	   loop s1
	   mov ah,9
	   int 21h
codesg ends
end startassume cs:codesg,ss:st