Abstract: An interactive display system includes a display terminal on which an operator may display the data contained in windows (14.1, 14.2 . . . ) on formatted application data (PS 1, PS 2 . . . ) in selected viewports (15.1, 15.2 . . . ) on the screen 13. The system is provided with storage (4), both real and virtual, into which a presentation interface service (2) loads dynamically the entire formatted data (PS 1, PS 2 . . . ) of each application (list 1, list 2 . . . ) as it is invoked by the user. A screen manager (7) maps the data contained in the defined windows into locations (16.1, 16.2 . . . ) of a programmable symbol refresh buffer (6, 8) determined by the corresponding position of viewports (15.1, 15.2 . . . ) on the screen defined by the user and through which the windows are to be viewed.

Abstract: Described is an interactive enquiry system in which a complete data base is contained at a host computer. Local terminal sub-systems are remotely connected to the host with each local sub-system containing a local data base. Each local data base is dynamically maintained so that the most frequently used pages are retained in local storage. If storage space needs to be created, the least frequently used pages are discarded from the local data base.