International Business Machines Corporation

Brian H Middleton

Stephen Graham Lawrence

Paul H Benson

John Simmons

Michael A McMorran

Martin C Pinnell

Michael L Kingdom-Hockings

Thomas E Robinson

Richard E Sheeler

A display terminal of the type which is dependent on a remote processor for its operation and for its main data storage, comprising an interactive language interpreter (24) (e.g. for BASIC), terminal processor, local storage, display and a switch for switching between a session (90) associated with the remote processor and a session (91) dedicated to servicing the interactive language interpreter (24). During an interactive language session screens of data associated with the host session may be displayed and then saved which enables host data to be processed using user programs in the interactive language.

Display terminal

A visual display unit with character overstrike capability includes a text store in which text is stored in data stream form. A formatter formats the stored text and loads character codes into a refresh buffer which together with a character generator display the characters on a raster scanned cathode ray tube. Control logic responsive to a backspace character combines the bit patterns corresponding to the characters preceding and succeeding the backspace character in a temporary store and then stores the composite bit pattern in the character generator and a pointer thereto in the refresh buffer. The control logic can be inhibited to allow the individual characters constituting the composite character to be displayed individually for editing purposes.

Visual display unit with character overstrike

A text terminal in which a text stream received on a communication link is segmented by a segmenter into chained variable-length segments which are stored in a random access text store. Each segment can contain at most one extended formatting command. Segments have slack areas to allow the subsequent insertion of text. A text editor receives keystroke signals from a keyboard and modifies the stored text stream, new segments being created as necessary for extended formatting commands or when slack areas are full. An interpreter/formatter is invoked when a received text stream has been segmented or when the stored text stream has been modified to format and map the stored text stream into a refresh buffer driving a cathode ray tube (CRT) display. The interpreter/formatter maintains a status index with condensed versions of the extended formatting commands stored in the text stream. Formatting is inhibited by the editor if it receives a keystroke requiring modification of the stored text. After editing segmented text is desegmented by a desegmenter and returned to the host along a communication link in the form in which it was received. Preferably, the terminal is implemented with a microprocessor which can also control standard data entry applications as well as text processing.

Text processing apparatus with editing of stored document at each

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.

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Winchester, United Kingdom

Brian H Middleton