利用定时计数器，设计一个电子时钟，从左到右依次显示时分秒。有两种方法实现，一种是在中断程序中计数，产生时分秒计数，送到显示缓冲区。另一种是中断程序每一秒清除一个位变量，而主程序通过监视位变量的变化来知道每秒的时间。 -The use of regular counters, design of an electronic clock, minutes and seconds from left to right is displayed. There are two ways to realize one is in the interruption of proceedings counting, when the minutes and seconds count, to the display buffer. Another procedure is interrupted every second to clear a bit variable, while the main program by monitoring the change of variable-bit-per-second of time to know.