> What is happening to TMR0 during the execution of the ISR? Once
> it rolls over, does it continue to cycle automagically or does it get
> held until you return from the interupt?  In other words, does the
> amount of code that is executed inside the ISR affect the overall
> interupt timing

As noted yesterday to another question, TMR0 does not stop. It
jus' keeps rollin' along, except when the system clock is stopped
or if TMR0 is assigned as a T0CKI counter. Time spent in the
ISR or any routine is also elapsing in any active timers

> I also never heard an answer on...can I enable both TMR0 and
> PORTB0 interupts at the same time?

Of course. Once in the ISR you'll have to poll IRQ flags to find out
what caused the interrupt. Be aware of any interrupt sources that
may go live during the ISR - you should check for pending IRQs
before you leave the ISR. Even if GIE is off, IRQ flags still get set
(which is how you can poll for events without causing an interrupt)

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