说明：  微机实验 1、编写程序：使用8253的计数器0和计数器1实现对输入时钟频率的两级分频，得到一个周期为1秒的方波，用此方波控制蜂鸣器，发出报警信号，也可以将输入脚接到逻辑笔上来检验程序是否正确。 2、使用8253，编写一个时钟程序。
(Microcomputer Experiment 1, the preparation process: 8253 counter 0 and counter two of the input clock frequency divider, a period of 1 second square wave, the square wave control buzzer alarm signal, but also logic input pin to pen up the inspection program is correct. 2, 8253, to write a clock program.)