http://en.wikipedia.org/wiki/Software-driven_graphics_modes_for_the_Atari_8-bit_computers\' target=_blank>
http://en.wikipedia.org/wiki/Software-driven_graphics_modes_for_the_Atari_8-bit_computers40×24 graphics mode — 4 colors (2 bpp)
80×48 graphics modes — Either 2 colors (1 bpp), or 4 colors (2 bpp)
160×96 graphics modes — Either 2 colors, or 4 colors
160×192 graphics modes — Either 2 colors, or 4 colors
320×192 graphics mode — 2 colors (1 bpp). The pixels were a shade of the playfield color, and could not be different hue. (In practice on NTSC models, this actually resulted in 4 possible colors on a standard TV screen: black, white, blue, and brown, the last two colors being caused by using pixels in only even or only odd columns — thus the blue and brown regions were effectively in 160×192 resolution).
80×192 graphics modes (GTIA chip only)
9 colors from the color palette registers
All 15 Atari hues, but only of one brightness (plus black)
All 16 Atari shades, but only of one hue
These were only the modes the OS setup by default. As described above, the ANTIC chip used a display list and other settings to create these modes. The actual hardware could be programmed to display up to 384 pixels wide by putting the hardware in wide or overscan mode and up to 240 pixels tall by creating a custom display list.