说明：  汇编程序，附加proteus仿真电路，8251的应用。8251具有同步/异步的接受/发送功能。它能将并行输入的8位数据变换成逐位输出的串行信号；也能将串行输入数据变换成并行数据，一次传送给处理机。广泛应用于长距离通信系统及计算机网络
(Assembler, additional proteus simulation circuit, 8251 application. 8251 has synchronous / asynchronous receiving / sending function. It can transform 8-bit data of parallel input into serial signal of bit by bit output, and it can also transform serial input data into parallel data, which can be transmitted to the processor at one time. It is widely used in long distance communication system and computer network)