1. An alphanumeric terminal, comprising a text generator and a display unit with a signal input connected to the text generator and a cathode-ray tube screen arranged to display a plurality of lines with an alphanumeric information generated by an intensity modulation of a line raster on the cathode-ray tube screen in correspondence to a digitally coded information stored in the text generator, the text generator comprising an alphanumeric character generator with a data input and a test memory arranged to store the digitally coded information for generating said lines with alphanumeric information and connected to the data input of the character generator, the text memory in the text generator being divided into (a) a read memory that has a memory content arranged to produce a reproduction of an alphanumeric character set on a first portion of the cathode-ray tube screen and having a read output connected to the data input of the character generator and (b) a write-and-read memory that is arranged for a reproduction of an alphanumeric text on a second portion of the cathode-ray tube screen and having a read output connected to the data input of the character generator, a write input connected to the read output of the read memory and an enable input arranged to provide a writing operation via the write input, and the text generator further comprising an optoelectric converter with an optical input and an electrical output and a light transferring means that is connected to the optical input of the optoelectric converter and is arranged to be movable over the cathode-ray tube screen in order to be placed upon selected characters in the character set reproduced on said first portion of the cathode-ray tube screen, characterized by a mono-pulse generating circuit that comprises a retriggerable mono-pulse means having a pulse duration longer than the repetition period of the line raster on the cathode-ray tube screen and arranged to connect the electrical output of the optoelectric converter to the enable input of the write-and-read memory.