说明：  利用8255并行接口芯片和6位数码管显示分和秒，分秒的数字之间用数码管上的小数点隔开。要求秒钟显示从00-59，分钟显示从00-59，60秒后，分钟要进1。
(8255 parallel interface chip to use digital display and 6 minutes and seconds, minutes and seconds between the figures on the decimal point with a separate digital control. Requirements from 00-59 seconds to display, minute display from 00-59,60 seconds, minutes to get into one.)