Abstract: A method for controlling a data set-up system in a display device comprises the steps of: maintaining an off-mode when electric power is supplied to the display device in order to store operation mode data in a memory; reading out predetermined identification information indicating a storage state of the operation mode data in the memory in the off-mode; comparing reference identification information, indicating a storage state of the operation mode data stored in a microcomputer in which the display device is normally operated, with the identification information in the off-mode data; and controlling operation of the display device according to a result of the latter comparison. With the above method, and with a data set-up system performing functions corresponding to the above steps, breakdown of a circuit due to damage in operation mode data is prevented.