trafficlight.asm

这是一个用汇编编写的

iport equ 5400h-280h;

code segment
assume cs:code
start:

    mov  dx,iport+283h   ;          初始化8255
    mov  al,10010000b    ;
    out  dx,al;

go:
    mov dx,iport+282h           ;指向C口    从C口输出 ？？？？？？？？？？
    mov  al,00100100B  ;1
    out  dx,al

    mov bl,20h;
    call delay;        调延时5秒子程序


    mov dx,iport+282h
    mov  al,01000100B  ;2
    out  dx,al

    mov bl,12h;
    call delay;            调延时3秒子程序

    mov dx,iport+282h
    mov  al,10000001B  ; 3
    out  dx,al 

    mov bl,20h;
    call delay;        调延时5秒子程序

    mov dx,iport+282h
    mov  al,10000010B  ;4
    out  dx,al
                      ; 调延时3秒子程序
    mov bl,12h;
    call delay;

    mov dx,iport+282h
    mov ah,01h;
    int 16h;
    jz  go;                 没有键按下
    

exit: mov ah,4ch;
      int 21h;

delay proc
      mov dx,iport+28bh;
      mov al,00110101b;
      out dx,al;
      
      mov dx,iport+288h;
      mov al,00h
      out dx,al
      mov al,50h
      out dx,al
      
      mov dx,iport+28bh;
      mov al,01110111b;
      out dx,al;
      
      mov dx,iport+289h;
      mov al,00h
      out dx,al
      mov al,bl   ;
      out dx,al


      mov dx,iport+280h;
  h:
      xor al,al;
      in al,dx;
      and al,01h;
      cmp al,01h;

      je h;          
      ret
delay endp


code ends
    end start