编写一个交通灯控制程序，实现东西路口与南北路口状态灯的转换和紧急处理。采用8253芯片计数，输出1S的时钟脉冲，并使用8255接口芯片控制LED亮灭，同时让8279芯片显示倒计时，键盘控制紧急处理按键，以此实现交通灯指挥控制系统。-Write a traffic light control program, the conversion of the things the intersection with the north and south of the intersection status lights and emergency treatment. 8253 count output 1S the clock pulse, and use the 8255 interface chip to control the LED light off, while the 8279 display the countdown, keyboard control emergency processing keys, command and control systems in order to achieve the traffic lights.