Programming implementation: 8255 A port of A pick up the 8 leds, PC5 by one switch, detection switch state, if the switch (high level, namely PC3=1), all eight lights (low level, PA=00 h); Switch press (low level, namely PC3=0), eight light-emitting diodes (leds) on (high level, PA=0 FFH), assuming that 8255 a port PA, PB, PC, control port address respectively 30 h, h, h, 33 h,