A display pattern preparing system for forming picture element series data for formation and display of picture images by raster scanning. "Figure" or "Configuration" of a pattern is disassembled to be normalized. An fixed pattern memory stores, as a registered configuration data, the length of a segment by which a fixed pattern of a prescribed configuration and area crosses a scanning line in the primary direction of scanning. An analogous pattern memory stores, as parameters, a reference position data representative of a reference point for a portion of an analogous pattern through which the analogous pattern overlaps the scanning line, the analogous pattern being defined as a pattern whose configuration is analogously variable, a distance data representative of the length of the portion of the analogous pattern, and a change ratio data representative of a ratio at which the reference point changes in the auxiliary direction of scanning. The data of the fixed pattern and analogous pattern memories are read out for preparation of a position data for display of a pattern designated by the read-out data. The position data is transmitted to display units.

A lighting model processing system for a computer graphics workstation's shading function includes multiple floating point processing stages arranged and operated in pipeline. Each stage is constructed from one or more identical floating point processors. The lighting model processing system supports one or more light sources illuminating an object to be displayed, with parallel or perspective projection. Dynamic partitioning can be used to balance the computational workload among various of the processors in order to avoid a bottleneck in the pipeline. The high throughput of the pipeline system makes possible the rapid calculation and display of high quality shaded images.

A visual display system and method for use in converting calligraphic symbology information into raster scanned symbology. The system simultaneously generates and displays calligraphic and raster matrix imagery utilizing the same set of software instructions. The imagery is displayed upon a single, hybrid calligraphic/raster matrix display or separate raster matrix and calligraphic displays. A programmable calligraphic symbology generator utilizes digital stroking techniques that successively generates addressing for a matrix arrayed memory and determines the attributes of both the raster matrix generated and calligraphic generated symbology. The information is stored in a single or a plurality of matrix arrayed memories according to desired symbol attributes and system performance.

A system for writing cursors on a raster scanned television screen that uses the microprocessor in a display controller to produce blocks of data defining the parameters of vectors that compose the cursor. The blocks are put in a first-in first-out memory during a vertical blanking inerval or during active picture time. Each block specifies where writing of a cursor segment is to start and stop on a horizontal scan line and it also specifies a repeat count that indicates the number of lines on which the segment is to be written. Each block contains a delta value to indicate how much, if any each segment is to be displaced left or right from line to line so vertical and angulated vertical vectors can be produced. The blocks are read out of the memory consecutively by a circuit that converts the segment start and stop data to pixel counts. Pixel counters determine the writing start and stop points. When the number of horizontal lines on which segments are written equals the repeat count, the next block is processed.

An object-oriented software architecture interacts with "real" input/output devices exclusively through "virtual" input/output devices. Since all human interface with the operating system is performed through such virtual devices, the system can accept any form of real input or output devices. The lowest level of the operating system converts input from any physical device to virtual form and converts virtual output into suitable physical output. Any number of physical devices can be connected to, removed from, or replaced in the system without disrupting the system.