Abstract: Method and apparatus are disclosed for the serial transfer of data in a clockless manner. Data is transmitted in the form of signal state changes from a dispatcher to a receptor. The receptor is operative to translate the signal state changes into data and thereafter signal the data dispatcher that it has done so. The dispatcher is operative to transmit the next piece of data only after it has been appropriately signalled by the receptor.In accordance with another aspect of the invention, the dispatcher is capable of notifying the receptor when an end to the transmittal of data has occurred. The data receptor does not signal the dispatcher for further data when this occurs. The receptor instead signals a data sink that the previously transmitted data is available for copying. The data sink copies the data and thereafter authorizes the receptor to initiate further data receiving operations.

Abstract: A touch sensitive device includes an arrangement of conductors in combination with a pressure sensitive electrically conductive material. The conductors appear in a cross-wire matrix imprinted on the top and bottom surfaces of a rigid printed circuit board. The pressure sensitive electrically conductive material is positioned over the cross-wire matrix of spaced electrical conductors. The resulting arrangement defines a plurality of touch sensitive locations which may be used for uniquely entering information in a data entry system.

Abstract: A novel data entry system is disclosed which comprises both a touch sensitive device and a location identification device. The touch sensitive device includes a printed circuit board arrangement of conductors which define data input locations that are touch sensitive. The locations are touch sensitive by virtue of a layer of variable resistance material disposed over the printed circuit board which is highly conductive when subjected to touch pressure. The electrical conductivity of a touched location is sensed by the location identification device which thereafter provides a digital coding of the location and maintains the same until the touch pressure has been removed. The location identification device moreover prevents the double entry of data due to any variation in the touch pressure.

Abstract: A method is disclosed wherein information can be conveyed serially over a signal path in a rate-independent fashion. Three or more signal states are employed for conveying information. The disclosed method consists of attaching meanings to changes of signalling state rather than the length of time that a state is maintained. It is only required that the data source and data sink establish meanings for each change of state and that each transmitted state be maintained long enough for the receiver to detect it.