;内存数据区有大小写混合英文ASCII码字母10个,将其转换为全部
;大写和全部小写,在屏幕上分三行显示这三种字母.
data segment
h1 db 'AbCdEfghIj$'  ;加上$共11个字符
h2 db 11 dup(?)      ;加上$共11个字符
h3 db 11 dup(?)      ;加上$共11个字符
data ends
stack segment para stack 'stack'
db 100 dup(?)
stack ends
code segment
assume cs:code,ds:data,ss:stack
start:mov ax,data
      mov ds,ax
      mov ax,stack
      mov ss,ax
;     mov dx,offset h1
      lea dx,h1
      mov ah,9
      int 21h
      call z1
      mov si,0
      mov cx,10
loop1:mov al,h1[si]
      cmp al,61h
      jb x1             ;al小于61h(为大写字母)转移
      mov [h3+si],al
      sub al,20h
      mov [h2+si],al
      jmp x2
x1:   mov h2[si],al     ;h2放大写字母
      add al,20h
      mov h3[si],al     ;h3放小写字母
x2:   inc si
      loop loop1
      mov bl,24h        ;可换为 mov bl '$'
      mov h2[si],bl
;     mov dx,offset h2
      lea dx,h2
      mov ah,9
      int 21h
      call z1
      mov h3[si],bl
      mov dx,offset h3
;     lea dx,h3
      mov ah,9
      int 21h
      mov ah,4ch
      int 21h
z1    proc
      mov dl,0dh
      mov ah,2
      int 21h
      mov dl,0ah
      mov ah,2
      int 21h
      ret
z1    endp
code  ends
      end start