Atari 8-bit computers: Difference between revisions

Revision as of 07:17, 18 August 2005

Revision as of 18:27, 19 August 2005

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=== Standard modes ===

While the ANTIC and GTIA chips allowed a variety of graphics modes to be combined, and different playfield widths to be used, the Atari's Operating System provided a basic set of graphics modes. TheseIn most cases, these were exposed to Atari BASIC via the "GRAPHICS" command, and to some other languages, via similar system calls.

*40x24 text modes

**1 color of text, with each character's 8x8 pixels the same size as those in 320x192 graphics mode, with the same hue restriction. Characters with the high-bit on were represented in inverse-video.

**"Lowercase with descenders" mode, which was not available through GRAPHICS, only as part of custom display lists. In this mode characters were 10 pixels high and occupied either the upper or lower 8 pixels of that height.

**Colored text, where every two bits represents a colored pixel (characters were 4x8 pixels that were the same size as those in 160x192 graphics mode). Characters with the high-bit on were displayed using a 5th color palette registered where the 4th would normally be used.

**Colored text, where every four bits represents a colored pixel (characters were 2x8 pixels that were the same size as those in 80x192 graphics mode and had the same color limitations). This mode was not directly available through GRAPHICS but required setting GTIA flags in text mode.

*20x24 text mode

**1 color of text, with each character's 8x8 pixels the same size as those in 160x192 graphics mode. Characters with various bits enabled or disabled (which would normally appear as 'control-characters', lower-case characters, or inverse-video) were displayed with different colored pixels.