Abstract: 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.

Abstract: 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.