Dad has just bought a Tomtom 1000. According to Tomtom page, you get 90 day map update. However how does when this 90 day time start? If he doesn't connect it to a PC / install software, and create a account could he leave it say 3 years and then do the update? (get latest map) Or does it have RTC and the unit knows it's been used for >90 days.