TOUCH SENSITIVE SCREEN SYSTEM

A position signalling system employs a plurality of touch sensitive screens each of which generate analog signals representing the co-ordinates of a position when touched. A selection means is provided to select the screens rapidly in sequence. The analog output signals from the selected screen are fed to analog-to-digital converters. The sequence of selection proceeds rapidly from screen to screen until a screen is detected that is being touched whereupon the selection sequencing pauses to permit the analog-to-digital conversion to be carried out and the resulting digital values to be read out to a computer system. Upon readout of the digital values to the computer system, the screen selection sequencing is again permitted to proceed. Means are provided to indicate whether a selected screen that is being touched was touched the last time the same screen was selected.