Atari's answer to
ASCII, providing fewer international
characters and a new set of fairly useful
graphical characters.
The Atari 8-bit computers, including the Atari 400 and Atari 800/Atari 800XL, all supported this character set. At 2400 baud, you could make some fairly elaborate animations akin to Bambi Meets Godzilla; these were also known as Lebreak movies, for a popular editor/player.
The character set can be seen at http://www.infos.cz/raster/atari/chars/atascii.htm.