80C51单片机所做的数字时钟，已测试过，绝对可用。（利用一个控制器对多路电器进行控制，同时又可以进行时钟校准和定点打铃。它可以执行不同的时间表（考试时间和日常作息时间）的打铃，可以任意设置时间。）-Made digital clock 80C51 microcontroller, has been tested, absolutely free. (Using a controller to control multiple appliances, while the clock can be calibrated and fixed-point ring a bell. It can perform different schedule (time of examination time and daily routines) and rang the bell, you can arbitrarily set the time.)