计算机与计算机或计算机与终端之间的数据传送可以采用串行通讯和并行通讯二种方式。由于串行通讯方式具有使用线路少、成本低，特别是在远程传输时，避免了多条线路特性的不一致而被广泛采用。 在串行通讯时，要求通讯双方都采用一个标准接口，使不同 的设备可以方便地连接起来进行通讯。-Computer and computer or computer data transfer between the terminal can use a serial communications and parallel communications in two ways. Since the serial communication line with the use of small, low cost, especially in the long-distance transmission, the number of lines characteristic avoids inconsistencies which are widely used. In serial communications, require communicating parties have adopted a standard interface that allows different devices can be easily connected together for communication.