编写程序控制8255A可编程并行接口芯片，使红、绿、黄发光二极管按照十字路口交通信号灯的规律交替发光。当按下任意键则停止运行，返回DOS。-Preparation of program control 8255A programmable parallel interface chip, the red, green, Huang Faguang diode in accordance with the laws of the crossroads traffic lights alternately luminous. When the Press any key to stop running and return to DOS.