1.txt

最掉汇编程序

code segment 
     assume cs:code
start:
      mov dx,028bh  ;将初始化程序片段写入控制寄存器, 
      mov al,089h  ;8255控制寄存器端口地址28BH,A口的地址288H,C口的地址28AH
      out dx,al
      mov dx,028ah 
 l0:  in  al,dx     ;监听C端口
      cmp al,00h
      jz  l0
      cmp al,01h
      jz  l1  
      cmp al,02h
      jz  l2
      cmp al,04h    ;当C端口对应其中编码时跳转
      jz  l3
      cmp al,08h
      jz  l4
      cmp al,010h
      jz  l5
      cmp al,020h
      jz  l6
      cmp al,040h
      jz  l7
      jmp finish
l1:  and al,07fh
      mov dx,0288h
      out dx,06h
      jmp pd
 l2:  and al,07fh
      mov dx,0288h
      out dx,05bh
      jmp pd 
 l3:  and al,07fh
      mov dx,0288h     ;把编码对应的信号送到A口输出
      out dx,04fh
      jmp pd 
 l4:  and al,07fh
      mov dx,0288h
      out dx,066h
      jmp pd  
 l5:  and al,07fh
      mov dx,0288h
      out dx,06dh
      jmp pd  
 l6:  and al,07fh
      mov dx,0288h
      out dx,07dh
      jmp pd 
 l7:  and al,07fh
      mov dx,0288h
      out dx,07h
      jmp pd

 pd:  mov dx,0ffh    ;判断是否按下空格
     mov ah,06h
      int 21h
      cmp dl," "
      jz  l0 

finish: mov ah,4ch
      int 21h
code ends
    end start