composed for example of light emitting diodes and emit light beams through preferably triangular light exiting surfaces if a text is input to the operating memory of the computer 2 by way of the keyboard 1 the cursor 10 travels from the left to the right on the screen 3 according to the number of characters in synchronism therewith the light dot emitted by the position marker 25 or 53 moves on the form 20 which is held on the contact plate 19 by means of the clamps 21 22 23 and 24 actuation of the return key or the cursor reaching a preselected right margin marker causes the cursor 10 to return to the left margin and at the same time to jump down one line the position marker 25 or 53 moves in the same way in order to be able to transmit the cursor position to the positioning unit it is of course necessary to activate a driver program in the computer 2 the purpose of this program is to immediately report any change in the cursor position in the selection of type and in the pitch to the positioning unit by way of an interface this can be accomplished by way of an interface provided in addition to a normal computer printer interface at the printer alternatively this is accomplished by way of the normal computer printer interface at the printer as.