Study on Expansion of Sigle-Chip Computer's Serial Port

In a system which takes single-chip computer as the croe,the serial communication is a common-used manner.MCS-51 series single-chip computers have only one serial port.In order to realize the connection with many peripheral equipments,we must expand the sigle-chip computer's serial port.By using serial port's expansion chip GM8125,the design expands single-chip computer AT89C52's serial port into five subserial ports and achieves their communication in the form of single passage and multipassage.