该程序的功能是利用BIOS的INT 14H号功能调用，将指定的数据从串行口发送出去。在发送过程中，程序不断检测通信线路状态，只有在“发送保持寄存器空”的情况下才发送下一个字符。

整个程序有主函数MAIN（）及三个函数SEND（），INIT（），LINETEST（）组成。MAIN（）是程序的入口并控制数据的发送；INIT（）函数提供对串行异步通信的初始化；SEND（）函数将指定数据逐一发送出去；LINETEST（）函数用于在发送数据前检测通信线路状态。

利用BIOS 功能调用进行串行异步通信，可以随时监测通信线路状态，只有在“发送保持寄存器空”或“接受缓冲器满”的条件下才能进行数据的发送和接收。-function of the program is to use the BIOS INT 14H, function, will be designated by the data from the serial port sent. In this process, procedures and ongoing testing communications circuits state Only in the "Send to maintain registers empty" the circumstances under which this under one character. The whole process is the main function MAIN () function and three SEND (), INIT (), LINETEST (). MAIN () is the entrance procedures and control data delivery; INIT () function to provide asynchronous serial communication initialization; SEND () function will be specified data sent out one by one; LINETEST () function to send data in the detection of pre-state communication lines. Use BIOS functions called serial asynchronous communication, it may state monitoring communications lines,