#include <REGX51.H>
#define uchar unsigned char
extern void delay(unsigned int i ); 

ex51()
{
uchar code dispcode[]=
    	{ 0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,
     //字形 0   1    2    3    4    5    6    7    8   9 
          0x88,0x83,0xc6,0xa1,0x86,0x8e,0xff,0xbf,0xff};
    //字形 A   B    C   D    E    F       	-
uchar code dispbitcode[]= 
	{0x01,0x02,0x04,0x08,0x10};  
	//字位碼:數碼管1，數碼管2，數碼管3，數碼管4，LEDCOM端
  unsigned char n=0,action=1;
   while(1)
  {
     P0 = dispcode[8];
	 P2 = dispbitcode[n];     
	 delay(1000);
	 switch (action)
	 {
	   case 1: if (n<4)  n++;
	           else 
			     {action =2;
				  n =4;
				  }
				break;
	   case 2: if (n>0)  n--;
	           else 
			     {action =1;
				  n =0;
				  }
				  break;
	 }
   }
}