程序详细功能介绍：AT89S51单片机的P0.0－P0.3接四个发光二极管L0－L3，P2.0－P2.3接了四个按键K0－K3，编程将按键的状态反映到发光二极管上。（按住按键，对应的灯亮，松开按键，对应的灯灭）。 L0对应显示K0状态, L1--K1 , L2--K2 ,L3--K3-Features program details: AT89S51 MCU P0.0-P0.3 four light-emitting diodes then L0-L3, P2.0-P2.3 next four keys K0-K3, programming will be reflected in key state the light-emitting diodes. (Hold down the button, the corresponding lights, release the button, the corresponding lights out). K0 state corresponding L0 show, L1- K1, L2- K2, L3- K3