此设计是利用接口RS-232C来实现两机通讯。通过8250芯片来控制COM1和COM2端口来传输和接收数据。（在IBM-PC中，COM1与COM2都是RS-232C接口）-This design is the use of interface RS-232C to achieve the two-computer communication. Through the 8250 chip to control COM1 and COM2 port to transmit and receive