International Business Machines Corporation

Peter W Johnson

Peter Quarendon

Peter David Niblett

Raymond Hardiman

Harold W Tuffill

Stephen T Hall

A method for identifying a bounded area of a graphic display. The method uses the division of the display screen into nine areas then the central square is the correlation window. This window can be small, two or three pel width, or large if the application is seeking to identify a larger area. The point indicated by the operator is in the center of the correlation window. An object (bounded area) which intersects this square will register a bit. It can be seen that a bounded area will intersect the correlation window if either: (a) any part of the boundary actually passes through the window, or (b) any arbitrary point within the window is inside the area.

Interactive display system

A method and apparatus for automatically changing the display in overlapping rectangular viewport areas of a display screen of a digital display apparatus and in which each viewport area is assigned a different priority level. The method includes the steps of (a) storing in a random access store indications of the position and size of each viewport area, together with an indication of the priority level of the viewport area and (b) constructing a first matrix of (2n+1).sup.2 elements, where n is equal to the number of viewport areas, by assigning a vertical component to each vertical coordinate of each viewport area and a horizontal component to each horizontal coordinate of each viewport area, and for each element so formed storing an indication of the highest priority level of the viewports falling within the boundary formed by the coordinates defining the element.

Data display for concurrent task processing systems

A digital data display system in which the display device includes a plurality of random access stores into which character cell definitions are loaded from a remote central processing unit. A character cell may be a 9.times.16 picture element matrix and each is defined in the CPU according to the requirements of a display request received from a users application program. The system control services include a graphics manager and graphics routines which construct a character buffer and character cell definition table according to the picture to be displayed. A character cell definition that is required more than once in a picture is only included once in the definition table, the character buffer having the required number of pointers to the one definition. When the character buffer and character definition table have been constructed, they are transmitted to the display device using a data communication system. The system can be used for color or monochrome displays.

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Winchester, United Kingdom

Peter W Johnson