the flcd 26 the output data from the memory data register 50 instead of the output data from the video memory 41 the data either 34 1 34 s or 34 0 34 s outputted by the memory data register 50 have been inputted therein by means of the data bus driver 52 when an entire frame refresh cycle is started the lines constituting the display frame are sequentially rewritten into 34 1 34 s or 34 0 34 s when the display frame is entirely rewritten into 34 1 34 s or 34 0 34 s that is entirely refreshed the flcd 26 displays an entirely black or white frame the information processing system switches off the power source for a period long enough to allow completion of refreshment of the entire display panel of the flcd 26 after a power off request has been made thus the flcd 26 retains the entirely black or white state even after the power source has been switched off according to these embodiments because the entire display frame of the flcd is rewritten into an entirely black or white frame before the power source is switched off the display panels of the flcd latently retains the entirely black or white frame even after being switched off due to the bistability of flcs ferroelectric liquid crystals although in the above described embodiments the display frame is rewritten by using entirely black or white image data before the power source is switched off a pre stored image data may be used instead more specifically image data is stored in a backed up memory by for example scanning a desired image when a power.