Abstract: Each of formula constituent elements represented in real mathematical notation is written by a user via an input device on a display screen. While confirming positions of graphic elements indicative of each of the respective inputted constituent elements with respect to the display screen, the user forms a desired formula. On the basis of types of the inputted constituent elements and their positions on the display screen, an arithmetic relationship between the formula constituent elements is automatically obtained by a computer. A computer program to solve this formula is automatically produced by the computer based on the resultant arithmetic relationship. The solutions of the formula are displayed on the display screen as numeral values and graphic representations.

Abstract: A method and apparatus for displaying on a display screen the controlling circuit in a plant controlling system for controlling a plant by a controller using a microcomputer. The display screen is segmented into a software region and a hardware region. The software circuit which is realized by software is displayed in the software region, and the hardware circuit related to the software circuit is displayed in the hardware region. The information, which is plotted during the interactive process and is displayed in the software regions, is automatically translated into a program for controlling the controller. Operation data of the plant is also given on the display screen. Desired circuit elements of the software circuit may be selected to change parameters of the circuit elements. Maintenance work can be carried out while observing the indication on the display screen without any aid of documents such as the maintenance manual or the like.

Abstract: Electronic information input via an input means is divided into first and second groups e.g. representing information which may not be modified except by a skilled operator, and information which may be modified freely. The information is stored in an information file and display elements are stored in e.g. a related information file. If a request for modification of one of the information elements is input via the input means, a judging means determines, on the basis of controlling information in a controlling information area, whether the information element belongs to the first or second group. If it belongs to the first, a display means displays one of the display elements as e.g. a warning to the operator that the information element may be modified only by a skilled operator. A password system may be provided to identify such a skilled operator.