One of the disadvantages of the existing practice of using computers for processing geological data is the lack of output devices for outputting information in graphical form. Two main functions of graphical output devices can be distinguished: 1) recording the final results of the calculations (documentation); 2) displaying information for the purpose of operational evaluation of the results of a previous iteration stage when solving problems by the fitting method. These functions determine the technical parameters of the device: in the first case, the decisive factor is the accuracy of the graphical plotting; in the second, it is the operating speed.