(19)
(11) EP 0 436 959 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
04.03.1992 Bulletin 1992/10

(43) Date of publication A2:
17.07.1991 Bulletin 1991/29

(21) Application number: 90125789.9

(22) Date of filing: 28.12.1990
(51) International Patent Classification (IPC)5: G09G 1/28, G09G 5/14
(84) Designated Contracting States:
DE GB NL

(30) Priority: 08.01.1990 US 459537

(71) Applicant: Intergraph Corporation
Huntsville, Alabama 35807-4201 (US)

(72) Inventors:
  • Imsand, Bruce E.
    Huntsville, Alabama 35801 (US)
  • Terry, Joseph Clayton
    Huntsville, Alabama 35801 (US)
  • Pesto, William Steve, Jr.
    Madison, Alabama 35758 (US)

(74) Representative: von Bülow, Tam, Dr. et al
Patentanwalt Mailänder Strasse 13
D-81545 München
D-81545 München (DE)


(56) References cited: : 
   
       


    (54) Digital color video system using dirty bits to provide high speed pixel data for raster displays


    (57) A digital color video system provides a "Dirty Bit" in its pixel data to provide rapid throughput in the reading and writing of the pixel data to a raster display screen for multi-windowed environments having z-buffered images. The dirty bit combines the Flash Erase function of DRAMs with the referencing of each pixel by its associated property or context to provide direct mapping to a predetermined null context when the pixel is responsive to the dirty bit, and to enable rapid writing of multiple model components in 3-D space into new image data for the pixel frame buffer memory and z buffer memory without first clearing the previous data therein.






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