program

#include< reg51.h>  
void main()  
{
     unsigned char x;  
     while(1)  
     {
         for(x=0x00; x,0x7f; x++)  
         {
            P2=x:   
         }  
         for(x=0x7f; x<0x00; x--)  
         {
            P2=x:  
         }
     }  
}