以AT89S51单片机为核心器件，组成一个定时数字钟系统，系统显示器由四位数字型数码管组成，分别显示小时和分钟，能够随时对当前时间进行调整，并能构随时输入定时时间，在定时时间到时会有提示音提示时间已到。(Using AT89S51 microcontroller as the core device, a digital clock timing system, the system displays a four bit digital type digital tube, respectively, show the hours and minutes, can adjust the current time, and the input time at any time in the regular time, there will be time to prompt tone.)