Start and target point entered for navigation systems.

Relevant street map data placed in a data memorycontain street identities and street point coordinates associated with house numbers. After each entry of a starting or destination point the road identifier and house number are entered. The data memory is searched for the identifier then the located and entered house numbers are compared. If coincidence occurs the coordinates are transferred to a read/write memory. If coincidence does not occur the data entered are temporarily stored with those of adjacent house numbers. The coordinates of the entered point are then determined by interpolation and transferred to the read/write memory.