#include<reg51.h>
#define  uint  unsigned int 
 uint  i=0;
sbit P10=P1^0;
	
	void timer1(void) interrupt 3
	{	
		TF1=0;
       	while(++i==2000)
		{
			P10=!P10;
			i=0;
		}
			
	}
	void main (void)
	{
		TMOD=0x20;
		TH1=0x00;
		TL1=0x00;
		IE=0x88;
		TR1=1;
		P10=0;
		while(1);
		
	}