A system for displaying alphanumeric characters in airports, train stations or cinemas. The system comprises a small robot (1) on a rail (2) that can move along a stack of cards (3) on which alphanumerical characters are printed. The robot (1) is able to pick-up any card, place it on a mobile holding means (4). By repeating this operation words, numbers or codes can be formed. The holding means (4) is mobile in order to be in such a position as to exchange cards or in a position to display the composed information. The system provides for simplified pick-up, placing and retrieving operation and does not expose the hardware of the system to the public.