（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