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    Using a uVGAIII serially as a display adapter for a home brewed 6502 computer. Is there an efficient way to implement scrolling text? My current guess is to use a portion of my computer's RAM as screen memory, and do the work there, and finally blit the whole thing to the screen.

    Is there an easier way that I am missing?

  • #2
    Hi Dan,

    Welcome to the forum.

    Yes you are right, It would be ok to use a portion of RAM as screen memory and do the work in the RAM area but you would only be able to store character spaces.A screen of 40 columns and 25 rows of text would take up 2000 bytes. You wouldn't be able to blit this to the screen but rather place the character in RAM on the screen. To speed the process up, you could just write only the characters that have changed to the screen.

    I hope this helps

    Best regards

    Paul

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    • #3
      The uVGAIII uses the SSD1963 controller.

      Whilst this doesn't support screen scrolling you can trick it into making it look like it does using the partial display capability of that chip.

      This trick will only work properly for pure text (as you need to chop the partial display at an empty pixel border, i.e. between lines of text)

      There is an example somewhere on the forum.
      Mark

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      • #4
        Hi Dan,

        The example is in this forum post. http://forum.4dsystems.com.au/forum/...ling-4dgl-prog

        It will need modifying to produce a proper text scroll as you will have to remove the top row of text before scrolling the screen.

        Best regards

        Paul

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