这是一个51单片机与PC的通信系统：利用3*4小键盘输入0~9的一串数字（不大于5），通过8051自带的串口发送给PC并显示在系统的6位LED上；单片机接收上位机的输入并显示在LED上。8051串行口经232电平转换后，与PC机串行口相连。PC机使用串口调试应用程序V2.2.exe，实现上位机与下位机的通讯。-This is a 51 microcontroller and PC communication system : use 3 * 4 0 small keyboard input of a bunch of nine-figure (no more than 5), by 8051, bringing their serial sent to the PC and display system in the six LED; SCM receiving PC input and displayed on the LED on. 8,051 by 232 serial port-level conversion, and the PC serial port connected. PC using serial debugging applications V2.2.exe achieve PC and the next crew communications.