Abstract: An improved track ball which can be conveniently manipulated with a single hand is disclosed. The track ball protrudes through a circular opening in a housing, with the top edge of the housing having a rounded switch. The switch can thus be manipulated with the fingers while the palm or thumb of the hand is manipulating the track ball. The housing is mounted at an angle to the side of a computer keyboard, providing for easy access. The track ball housing can be rotated to any continuous angle through two angles of rotation by the user. A tetrahedron support arrangement holds the ball in place at any angle. The same housing can be used for either the right or left sides of a keyboard by simply switching the activating point on the switch. An encoder wheel is attached by a shaft to the ball and has a number of slots extending from its center to its edge. The slots are rectangular in shape, and do not have edges along radial lines as in the prior art encoder wheels.

Abstract: The user terminals linked to the system are provided with a graphics function capable of generating particular non-elementary image components on the screen of each terminal in dependence on respective input commands. The graphic information is supplied to the user terminals in a manner integrated with the telematic services. The information is supplied after the selection of the preselected command from a command menu, and the formulation, still operating by selection, of the whole requirement, the transmission of which enables the system to produce the graphic advertising insertion associated with the retrieval effected.The proposed application has been developed for use in the supply of telematic services such as data banks, Electronic Yellow Pages, home banking, electronic mail and the like.