Abstract: In a transaction processing system in which a plurality of terminal devices are connected to a common transmission line to carry out transactions on the basis of the contents of transaction slips read out by the terminal devices, a transaction can be continued even when misreading or reject is detected in the results of reading of a transaction slip. When misreading or reject is detected, data read out from the transaction slip are transferred to a specified terminal devices to be corrected, complemented, confirmed, etc., and, after approval of the transaction, the transaction is executed.

Abstract: In a system for the transaction operation with terminal units connected to a central unit through the communication line, the transaction operation by use of an ineligible terminal unit is prevented. An illegality preventive information is provided for each terminal unit and stored in each terminal unit and the central unit. When the terminal unit transmits transaction data to the central unit, it also transmits the illegality preventive information registered in it. The central unit carries out the transaction process when the received illegality preventive information coincides with or has a certain relationship to the registered information.

Abstract: A portable terminal device is adapted to effect transaction operation by transmitting and receiving data to and from a central unit. When transaction data is entered, the transactions including the current transaction are accumulated, and when the accumulated transaction exceeds a predetermined limit determined by a preset transaction limiting data, the transaction based on the input data is inhibited.

Abstract: In a system having a central unit, a terminal control equipment and terminal devices connected through communication lines, a transaction operation by an unauthorized terminal device is prevented.Unauthorized use prevention information is registered to each of the terminal devices and the unauthorized use prevention information of the respective terminal devices is registered to the terminal control equipment. The terminal device, when it transmits transaction data to the terminal control equipment, transmits the unauthorized use prevention information of its own. The terminal control equipment compares the received unauthorized use prevention information with the registered unauthorized use prevention information of the corresponding terminal device and, if they are in a predetermined relation, permits the transaction operation.