PURPOSE: To permit the host device of a terminal controller controlling the master files of work stations to hold control information in an absolute minimum capable of version-up and to effectively use a storage area as to the master files of all the work stations.

CONSTITUTION: The host device basically stores only the master file of the latest version. Contents what kind of operation the respective work stations execute previous time and contents what kind of operation is to be executed at this are stored for respective records constituting the master file. A processing required for direct version-up is inputted from the previous version to the latest version. At the time of version-up to the latest version as to all the work stations, control information on the part is deleted.