RE: Alt Interrupt pin!

Yes, this has been used somewhere before I'm sure.  You'd have to write 0xFF to the counter though, the interrupt occurs when the counter rolls over from 0xFF to 0x00.  This does mean you have effectively traded the timer for another external interupt.  You could probably implement multiple external interupts with just some diode OR logic if the interrupt pulse wasn't too quick.  Just set a port as inputs, and wire a diode from each port pin to B0.  I the interrupt handler you would then read the port to decide which pin had caused the interrupt.  You could also consider using the interrupt on change feature of PORT B on the mid range devices.

Regards

Mike