C51 press the keyboard K1, P2 port LED to circulation of flowing water light from left to right (at the same time there are two lights), and in digital tube display cycles,
Press the keyboard K2, P2 port LED to circulation of flowing water light from right to left (at the same time there are two lights), and in digital tube display cycles (and counting),
Press the keyboard K3, completely destroyed,
Press the keyboard K4, all bright, programming