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4.0 Graphics

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6502Nerd edited this page Nov 16, 2020 · 2 revisions

Graphics introduction

dflat offers a few commands to deal with the following type of graphics handling;

  • Low resolution screen handling
  • High resolution screen handling
  • Software sprite system

Fundamentals

The Oric computer uses serial attributes, meaning that codes below ASCII 32 are not displayed by the video processor, but used to create certain effects, including changing the foreground (ink) and background (paper) colour. This is great for memory use - there is only the screen memory buffer and no separate buffer needed for colour information. The downside is that changing colour takes up 1 screen position. The impact of this is that by default the left two columns of the Oric screen are reserved for the paper and ink colour attributes.

The Oric has two fundamental modes of operation - low resolution and high resolution

  • low resolution is a 40x28 text area, each position is a displayable character or attribute
  • high resolution is a 240x200 pixel area, plus a 40x3 text area

The following commands work only on the text area (40x28 in low resolution, 40x3 in high resolution);

  • ink colour:<int> the colour to set the foreground (0-7)
  • paper colour:<int> then colour to set the background (0-7)

When the paper or ink are set, it only takes effect on screen being cleared, or blank lines due to scrolling. To clear the screen;

  • cls
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