comment            ;
 实验六 
;            
              assume    cs:code,ds:data,ss:stack
       stack  segment
              dw        8 dup(0)
       stack  ends
        data  segment
              db        '1. dispaly      '
              db        '2. brows        '
              db        '3. replace      '
              db        '4. modify       '
        data  ends
        code  segment
      start:
              mov       ax,data
              mov       ds,ax
              mov       bx,0        ;初始化ds:bx指向数据

              mov       ax,stack
              mov       ss,ax
              mov       sp,10h      ;初始化栈段
              
              mov       cx,4        ;外循环控制变量
          s:
              push      cx          ;外循环变量入栈
              mov       si,0        ;利用[bx+si+idata]指向要操作的字符，
                                    ;中bx控制行，si控制列，idata是常量偏移，相当于操作二维数组
              mov       cx,4        ;内循环控制变量
         s0:
              mov       al,[bx+si+3]            ;把字符放入al中
              and       al,11011111b            ;与运算把字符变成大写
              mov       [bx+si+3],al            ;把字符写回内存
              inc       si          ;si加一指向下一个字符
              loop      s0
              
              add       bx,16
              pop       cx          ;外循环变量出栈
              loop      s
;退出
              mov       ax,4c00h
              int       21h
        code  ends
              end       start