Abstract: A display matrix of LEDs responds to two coordinate display input signals representative of display positions each defined by a respective LED in the matrix, an input switch unit adapted for use by a disabled person being coupled to the matrix, so that the user can selectively actuate any one of a plurality of the LEDs, by a microprocessor equipped with an ROM holding the operating program for the microprocessor and an RAM in which sets of position coordinates of the matrix can be temporarily stored and recalled under the control of the user so that the user can write a message into the RAM by selecting a sequence of matrix positions corresponding to a sequence of words visibly displayed at respective LEDs and subsequently recall and display the message by selecting a read position in the matrix.