If a program (such as a terminal emulator) connects to that port, it will get the stream from the mainframe through the connection. Whatever it sends to the connection will go to the next program...
如果程序(例如终端模拟器)连接到该端口，就会通过该连接得到来自主机的流。
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In June Cosco, the biggest Chinese state-owned shipping company, won a tender to build and operate a new container terminal at the port of Piraeus.
Early network Bridges, protocol converters, and routers were simple dedicated hardware units typically configured through a terminal directly connected to a serial port on the unit itself.