Abstract: A display device (1;31), capable of providing visual displays (2) from electrical input signals, is controlled by means of a presentation application program adapted to convert data files representing images to be displayed into electrical input signals for the display device. Instructions are transmitted to said presentation application program from a portable telecommunications device (5;75) having an information access program for accessing a global information network, and a communication application program for communication with said information access program, and for controlling the presentation application program, is executed. In this way the display device can be controlled from the portable telecommunications device instead of a PC. A user does not have to carry a PC to the presentation location, and the need to struggle with a good deal of setting up before a presentation can be shown is avoided.