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Apparatus for overlaying a displayed image with a second image

  • US 5,099,331 A
  • Filed: 02/28/1990
  • Issued: 03/24/1992
  • Est. Priority Date: 09/04/1987
  • Status: Expired due to Term
First Claim
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1. A display system, comprising:

  • display means for providing a visual display;

    a first frame buffer, connected to the said display means, for storing data representative of a primary image to be displayed by said display means;

    a data source, for providing data corresponding to an overlay image;

    a second frame buffer, connected to said date source, for storing data presented by said data source;

    a first addressing means, connected to said first frame buffer, for presenting address and control signals thereto;

    a second addressing means, connected to said second frame buffer, for presenting address and control signals thereto;

    a data bus, connected between said first and second frame buffers, for communication data therebetween, so that the contents of said second frame buffer containing said overlay image may be communicated to said first frame buffer for writing thereinto;

    wherein said second frame buffer comprises a bank of dual-port random access memories, said dual-port random memories each including;

    a serial input, connected to said data source, for receiving serial input data therefrom;

    an array of randomly addressable memory cells;

    a random access port for presenting the contents of the memory cell selected by said second addressing means.

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