The Atari ST is a line of personal computers from Atari Corporation and the successor to the Atari 8-bit family. The initial model, the 520ST, saw limited release in April - June 1985 and was widely available in July. It is the first personal computer to come with a bitmapped color GUI, using a version of Digital Research's GEM from February 1985. The 1040ST, released in 1986 with 1 MB of RAM, is the first with a cost-per-kilobyte of less than US$1.
The Atari ST is part of a mid-1980s generation of computers with 16 or 32-bit processors, 256 KB or more of RAM, and mouse-controlled graphical user interfaces. This includes the Macintosh, Amiga, Apple IIGS, and Acorn Archimedes. "ST" officially stands for "Sixteen/Thirty-two", which refers to the Motorola 68000's 16-bit external bus and 32-bit internals. The system was designed by a small team led by Shiraz Shivji.
The ST was sold with either Atari's color monitor or a less expensive monochrome monitor. Color graphics modes are only available on the former while the highest-resolution mode needs the monochrome monitor. Some later models could display the color modes on a TV.