There is provided a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers to be controlled, and a magnetic head and magnetic recording andor reproducing system using the same. After a titaniumtitanium nitride film is formed along an inner surface of the contact hole, a photo-resist film is applied. With the auto back-lit feature, the brightness adjusts automatically making the screen easy to read in all light conditions. The arbitrator may include notification and call back mechanisms for sending messages relating to an access request and a granting of access for a remote station.