ISDN communications terminal apparatus

A communications service control apparatus for an Integrated Services Digital Network (ISDN) matching communications terminal apparatus comprising:

• a RISC core unit for performing central processing function;
• a reset and clock control unit which receives a reset signal from the outside, initializes each control unit, receives a clock signal from the outside, frequency divides the received clock signal, and provides the frequency divided clock signal to each unit that needs a clock signal;
• a memory control unit for generating a control signal for reading data from and writing data to a memory;
• a bus arbiter for controlling rights for using a bus among controllers connected to an extended system bus;
• a timer and interrupt controller for receiving a reference clock signal provided by the reset and clock control unit, generating an appropriate timing signal indicated by a program, and processing internal and external interrupts occurring when the program is executed;
• a bus bridge unit for transferring a data signal, an address signal, a control signal in accordance with the timing signal of each bus between an extended system bus and an extended peripheral bus;
• an input/output control unit for processing one or more input/output signals of a keypad, a Liquid Crystal Display (LCD), and a Light-Emitting Device (LED);
• a D channel control unit for transferring D channel data, including call control protocol data, between the RISC core unit and a channel data multiplexer;
• a B channel control unit for transferring B1 channel data and B2 channel data between the RISC core unit and a B channel switch;
• a tone module and voice codec unit for generating tone or melody data, transferring the generated data to a handset through a voice codec, and transferring a voice signal provided by the handset to the B channel switch;
• said B channel switch for controlling B channel data paths of the B channel control unit, the tone module and voice codec unit, and a time division multiplexer;
• said channel data multiplexer for transferring data between the ISDN transceiver and the B channel switch and the D channel control unit;
• and
• an ISDN transceiver unit for transferring data between the ISDN lines or the network termination apparatus and a channel data multiplexer.