#include<reg52.h>
sbit speaker=P1^4;
void delay(int x,int y) ;
main()
{
	while (1)
	{
		speaker=1;
		delay(1,20);
		speaker=0;
		delay(1,20);
	}

}
void delay(int x,int y)
{ 
unsigned int a,b; 
for(a=x;a>0;a--) 
for(b=y;b>0;b--); 
}