Abstract: In a network control system connecting terminal units providing at least a chat function to make communication with the other terminal units on a real time basis while connecting the keyboard and executing mutual communication between the terminal units, the terminal unit which becomes the transmitting side describes the mode corresponding to the function to be executed and sets a communication code corresponding to such mode within a communication command to be transmitted. The transmitting terminal indexes a connection timing table and also connects or disconnects the line for communication to the distant terminal unit on the basis of contents of the connection timing table in order obtain cost-effective application of the communication network.

Abstract: A distributed data base system is formed by terminal units connected in a public network or a private network. Each terminal unit stores respectively the real data and a temporary center for storing the one or a plurality of control information among various pieces of control information, such as contents corresponding to each real data, keyword or command assigned to data. Moreover, check information set up for acquiring security is provided as the one of the terminal unit. A terminal unit utilizing data obtains identification information of terminal units storing relevant real data by inputting contents, commands or keywords by accessing the center and reading or extracting the necessary real data through the network from a terminal unit having real data based on such identification information but is capable of restricting users (terminal units) which are allowed to read the open data in accordance with the degree of importance of the data.