There are car navigation systems known in the related art that have multiple functions including a function for displaying a road map of an area around the current vehicle position, a function for determining through an arithmetic operation a recommended route from a start point to a destination and a function for providing route guidance based upon the determined recommended route.
Such a car navigation system includes an arithmetic processing unit constituted with a microprocessor and the like and a display device such as an LCD at which the road map, the recommended route and the like are displayed. In addition, an audio system, a television set achieved by using an LCD and the like may be installed in the vehicle.
It is desirable that the arithmetic processing units and display devices used in these systems be combined with a high degree of efficiency.