#include <dos.h>

#define CLOCK_INT 0x01C

static void (interrupt * (CLOCK_VAL))();

static char far *p = (char far *) 0xB8000000L;

static unsigned int counter = 0;

static int sleeptime = 100;

void whatever(void);

void interrupt isr(void)
{
	(*p)++;
	if (counter++ >= sleeptime) {
		counter = 0;
		(*p) = '*';
		disable();
		setvect(CLOCK_INT, CLOCK_VAL);  /* Restore it */
		enable();
/*		whatever(); */
	}
}

void main(void)
{
	CLOCK_VAL = getvect(CLOCK_INT);  /* Memorize it */

	disable();
	setvect(CLOCK_INT, isr);  /* Change it */
	enable();

	keep(0, 600);
}