Abstract

A portable processing device, such as a laptop computer, includes a time-of-day clock that is dynamically adjusted based upon occurrences of travel among different time zones. An itinerary is stored as a travel schedule of departure and arrival information and is used to identify anticipated multi-zone travel. When there is a coincidence between the clock and the occurrence of an anticipated multi-zone trip, the clock is automatically adjusted. The itinerary may be input via a user interface mechanism, such as a keyboard, may be entered by means of synchronization with a compatible program of a second device, or may be input via a network, such as the Internet. The determination of the relevant time zones preferably utilizes a database and most preferably utilizes an internal database of cities and time differentials among the cities. The dynamic adjustments of the time-of-day clock occur en route, without accessing externally generated signals or external devices.