PURPOSE: To connect both display units of digital and analog types to the personal computer which has a flat panel display internally.

CONSTITUTION: Digital video data 101, a display timing signal 104, and a clock signal 103 from a flat panel controller 1 are inputted to an analog-digital switching part 3, a D/A conversion part 2, a timing adjustment part 4, etc. The D/A conversion part 2 converts the digital video data 101 into analog video data 102, which are inputted to an analog-digital switching part 3. The analog-digital switching part 3 inputs a data format discrimination signal 105 indicating the data input format of the flat panel display 5, selects one of the digital video data 101 and analog video data 102 according to the signal, and inputs the data to the flat panel display 5 through a data bus 106.