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Display control device

  • US 5,898,442 A
  • Filed: 08/31/1995
  • Issued: 04/27/1999
  • Est. Priority Date: 09/02/1994
  • Status: Expired due to Fees
First Claim
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1. A display control device by which data stored in a video memory is displayed on the basis of a display control signals output from a CRT control device, the display control device comprising:

  • dual port memory means that allows data read and write operations to be executed simultaneously and that has a capacity to store at least one screen of first data to be displayed; and

    display control means for executing in parallel a first operation in which second data corresponding to an upper region of a display are retrieved from the first data stored in the video memory and sequentially output to said upper region of the display, a second operation in which the second data corresponding to the upper region of the display are sequentially stored in the dual port memory means and a third operation in which third data corresponding to a lower region of the display stored in the dual port memory means are sequentially output to said lower region of the display, for executing in parallel a fourth operation in which said third data corresponding to the lower region of the display are retrieved from the first data stored in the video memory and sequentially output to the lower region of the display, a fifth operation in which the third data corresponding to the lower region of the display are sequentially stored in the dual port memory means and a sixth operation in which fourth data corresponding to the upper region of the display stored in the dual port memory means are sequentially output to the upper region of the display and for alternately executing, in response to the display control signals, a first sequence comprised of the first to third operations and a second sequence comprised of the fourth to sixth operations.

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