#include <reg52.h>
 //=========================
 // delay function
 //=========================
 void delay(int del_val)
 {
	int i,k;
	   for(i=0;i<=del_val;i++)
	   for(k=0;k<=50;k++);
 }

 //=== main program =========
 void main()
 {	
	int count,patt;
	while(1)
	{	  
	   patt=0x1;	// 00000001
	   for(count=0;count<=8;count++)
	   {	  		
 	     P2=~patt;
 	     patt=patt<<1;
	     delay(1000);
	   }
	  patt=0x80;	// 10000000
	  for(count=0;count<=8;count++)
	  {
	     P2=~patt;
	     patt=patt>>1;
 	     delay(1000);
	  }
	}	
 } // end of main program