DISPLAY DEVICE

PURPOSE:To synthesize and display video images generated respectively by display signal generating means in the internal and external synchronizing modes by switching a video signal from each video signal generating means with a video signal switching means and giving the result to a display means. CONSTITUTION:A synchronizing selector 5 selects an internal video signal VI or synchronizing signals SA-SC from plural display signal generators 1-3. More over, an RGB signal changeover device 6 selects one RGB signal among plural RGB signals generated from one signal from the generators 1-3. Then a synchro nizing signal selected by a selector 5 is supplied as an external synchronizing signal of the generators 1, 2 having the external synchronizing mode to synchro nize the video signal from the display signal generator in the external synchroniz ing mode and the video signal from the display signal generator in the internal synchronizing mode. The synchronizing video signal is fed to a picture tube 19 switchingly to synthesize the video images generated by the display signal generator in the external synchronizing mode and the internal synchronizing mode and to display the result.