bbb.asm

交通灯控制

data segment
io8255a equ 28ah
io8255b equ 28bh
portc1 db 24h,44h,04h,44h,04h,44h,04h ;六个灯可能
db 81h,82h,80h,82h,80h,82h,80h ;的状态数据
db 0ffh ;结束标志
data ends
code segment
assume cs:code,ds:data
start:
mov ax,data
mov ds,ax
mov dx,io8255b
mov al,90h
out dx,al ;设置8255为C口输出
mov dx,io8255a
re_on: mov bx,0
on: mov al,portc1[bx]
cmp al,0ffh
jz re_on
out dx,al ;点亮相应的灯
inc bx
mov cx,200 ;参数赋初值
test al,21h ;是否有绿灯亮
jz de1 ;没有,短延时
mov cx,2000 ;有,长延时
de1: mov di,9000 ;di赋初值9000
de0: dec di ;减1计数
jnz de0 ;di不为0
loop de1
push dx
mov ah,06h
mov dl,0ffh
int 21h
pop dx
jz on ;没有,转到on
exit: mov ah,4ch ;返回
int 21h
code ends
end start