#include<reg52.h>
#define uchar unsigned char
uchar i=1;
main()
{ P0=0xff;
  EA=1;
  EX0=1;
  IT0=0;
  while(1);
}
voidINT0 () interrupt 0
{switch(i)
  { case 1:P0=0xfe;break;
    case 2:P0=0xfd;break;
    case 3:P0=0xfb;break;
    case 4:P0=0xf7;break;
    case 5:P0=0xef;break;
    case 6:P0=0xdf;break;
    case 7:P0=0xbf;break;
        case 8:P0=0x7f;break;
   }
   i++;
   if(i==9)
   {EA=0;EX0=0;}
  }