The ST was sold with either Atari's color monitor or the less expensive monochrome monitor. In fact, the Stacy (the laptop version of the Atari ST) was the first and only way to own a laptop running Mac OS at the time since Apple did not offer one until much later. The hardware was so similar to Apple's Macintosh at the time that with the addition of the Spectre GCR the ST was able to run Macintosh software faster than an actual Mac Plus at the time (since the Atari's clock speed was higher) and with a larger and higher resolution display. which refers to the Motorola 68000's 16-bit external bus and 32-bit internals. The initial ST model, the 520ST, saw limited release in April–June 1985 and was widely available in July. The Atari ST is a line of home computers from Atari Corporation and the successor to the Atari 8-bit family.