对微机系统的串行口内环测试

代码说明：

  编写程序对微机系统的串行口进行自发自收内环测试，从键盘键入发送数据，屏幕显示接收数据。这是用未来汇编程序编写的关于微型计算机的程序，是我上学时所写的一份实验报告。(The program is programmed to automatically test the serial port of the microcomputer system, input data from the keyboard, and receive data on the screen. This is a microcomputer program written in the future assembler. It is an experiment report written by me when I was at school.)