Code fragment using Clock Monitor interrupt */

#include <hc11.h>

/* Use of Clock Monitor -- set CME bit of OPTION register      *
 * Get Clock Monitor Fail interrupt if E-clock falls below     *
 * 10 kHz, interrupt vector FFFC-FFFD                          */

main()
{
    OPTION = 8;    /* Enable Clock Monitor */

	/* Set up interrupt vectors */

	while(1)
	{
	    .
		.
		.
	}
}

#pragma interrupt_handler cme_isr

void cme_isr(void)
{
    /* Code to deal with clock speed too low */
}