CIRCUIT CONNECTING PRIVATE EXCHANGER AND DIGITAL TELEPHONE

a first central processing unit for controlling a communication memory access to a private switching system main processor and communication with a digital telephone; a first decoder for generating a control signal which enables each of corresponding units; a second central processing unit for comprehensively controlling each board when a plurality of interface boards are mounted; an inter-processor communication unit for enabling data communication between the second central processing unit and the first central processing unit in the interface board; a memory having RAM and ROM; a communication unit to the digital telephone for processing a data signal and a voice signal from the digital telephone and for transmitting output data from the first central processing unit to the digital telephone; a second decoder for receiving address data from the second central processing unit for generate a control signal according to channel assignment; and a channel assigning unit for assigning a voice 1 channel and a data 1 channel among N channels to transmit the voice and data through the digital telephone.