To propose a new model for mobile.computing to avoid many problems of a portable computer apparatus.

A system to have access to data stored in a vehicle based on a key 40 makes it possible that the vehicle becomes a very important link as the platform of mobile computing while keeping safety of the data. Plural stratums of key.codes 44a, 44b, 44c make it possible that all users have an access right to all vehicle functions and also have an access right to a different memory partition 76 to store the data. The partition 76 can be used to store data containing a password, a preferred setting and driving record data, which are peculiar to the user. The data are enciphered by the key.code and can be safely protected, even if the memory.system is removed from the vehicle or the vehicle is stolen.