// P3口外接的鍵盤控制P1外接的LED顯示
#include <REGX51.H>


ex31( )  // C語言的主函數
{
  unsigned char LED,tmp;
  P3 = 0xff;
  LED = P3;
  while(1)
  {
     P1 = LED;	 
     tmp = P3;
	 if(tmp != 0xff) LED =tmp;
	 //delay();	 
  }
}