APPARATUS FOR INDIVIDUALLY MATCHING SERIES INTERFACE OF DATAPROCESSING SYSTEM TO DATA TRANSMISSION SPEED OF COMMON COMMUNICATION PATH USER OF

摘要

An arrangement, for adapting the serial interface of a data processing system to the data speed of a communication partner, has a recognition circuit for recognizing the transmission speed wherein signals from the communication partner having the unknown transmission speed are inputted to a frequency counter of the recognition circuit and the resulting count provided to a microprocessor which calculates an adjustment division signal N from the counting results. The adjustment divison signal N is inputted to a frequency divider of a phase lock loop (PLL) circuit of an adjustment circuit to provide a divided clock frequency signal which is compared with a divided reference frequency signal by the PPL circuit so that the frequency of a voltage control oscillator of the PLL circuit is adjusted until the divided clock frequency signal and divided reference frequency signal are equal. The adjusted voltage control oscillator signal is inputted to the microprocessor from which a matching data transmission speed equal to the data transmission speed of the communication partner is calculated.