The DE8681 Demonstration Board is a reference design for the CMX868 V.22 bis modem IC. On the main "socket modem" section it also contains the line interface components and a Flash PIC C. Attached to the main section are two break-off sections which contain a 9-pin D type socket for PC serial communications, a Flash PIC programming connector, an RJ11 line connector and various LEDs for indicating signal activity. AT Commands are used to control the demonstration board via a standard terminal emulator program running on a host PC. Interfacing to the Demonstration Board can be via socket pins on the socket modem section, or via the connectors provided on the break-off sections. The board can be operated at 3V or 5V dc, which must be provided by an external, regulated power supply. The PCB has been laid out for both CTR21 and FCC68 compliant DAA designs. However the components fitted are for the simplified FCC68 design. Instructions are given for users who wish to fit the CTR21 components. Hardware has been provided on the socket modem section for CLI Type 1, but a PIC firmware upgrade will be required to enable this function, which may be available at a later date. With this is mind, the socket modem has been provided with a Flash PIC Microcontroller that can be serially programmed in circuit via the RS232 connection. 2004 CML Microsystems Plc