说明：  （1）利用单片机定时器中断和定时器计数方式实现秒、分定时。 （2）通过LED显示程序的调整，熟悉8155与8051，8155与LED的接口技术
((1) the use of single-chip timer interrupt and the timer means counts seconds, minutes from time to time. (2) through the adjustment of LED display program, familiar with the 8155 and 8051,8155 and LED Interface Technology)