The purpose of this thesis is to develop the interfacing subsystem to the existing Thai terminal emulation program. The program can work remotely by using Hayes compatible modem. Also the program can work through network with TCP/IP protocol which is standard for computer and communication. The program still operates with Hercules or EGA/VGA video adaptor card using graphic mode and works with RS232C standard. It can operate with network interface card in the microcomputer under packet driver and DOS operating system.