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Display controller for multiple scrolling regions

  • US 4,386,410 A
  • Filed: 02/23/1981
  • Issued: 05/31/1983
  • Est. Priority Date: 02/23/1981
  • Status: Expired due to Term
First Claim
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1. In a display control system having character memory means, visual attribute generator means, a display device and a display memory, a display controller device comprising:

  • means for loading character and visual attribute data into selected display memory locations from a data bus, wherein said character data is stored in said character memory means and said attribute data is generated by said visual attribute generator means, and wherein a plurality of character and attribute data bytes form a block of data in the display memory corresponding to a row of characters as seen on the display device;

    means for assigning two or more memory location identifier bytes to each displayed row of characters corresponding to and stored adjacent said data blocks in the display memory, wherein when vertical split regions are next to be displayed each of said identifier bytes includes the display memory address of the first character in the next row of characters in a corresponding one of said vertical split regions to be displayed on the display device;

    means for storing a data byte corresponding to a preselected column on said display device wherein a vertical split region will begin;

    second means for storing a data byte corresponding to the starting address of a character row;

    third means for storing a data byte corresponding to the starting row address of a vertical split region; and

    means for determining which scan line of a character a particular display memory address corresponds to, whereby a plurality of rows of characters appearing on the display device are scrolled one scan line at a time.

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