说明：  一、实验内容及目的 内容：AT89C51单片机的串行口经MAX232电平转换后，与PC机串行口相连。使用虚拟终端，实现上位机与下位机的通信。 目的：掌握单片机串行口的方式选择和编程方法，了解单片机与PC串行通信程序的设计方法，学会实时程序的调试技巧。
(First, the experimental content and purpose of content: AT89C51 microcontroller' s serial port via MAX232 level conversion, and the PC serial port connected. Using a virtual terminal, host computer and the next crew of the communication. Objective: Serial port control mode selection and programming methods to understand the MCU and PC serial communication program design, learn to real-time debugging skills.)