Macintosh clones

Several computer manufacturers over the years have made Macintosh clones capable of running Mac OS, notably Power Computing, UMAX and Motorola. These machines normally ran various versions of classic Mac OS. Steve Jobs ended the clone-licensing program after returning to Apple in 1997.

In 2008, a manufacturing company in Miami, FL called Psystar Corporation, announced a $399 clone that comes with a barebones system that can run Mac OS X v10.5. Threatened with legal battles, Psystar originally called the system OpenMac and have since changed it to Open Computer.

A/UX

In 1988, Apple released its first UNIX-based OS, A/UX, which was a UNIX operating system with the Mac OS look and feel. It was not very competitive for its time, due in part to the crowded Unix market. A/UX had most of its success in sales to the U.S. government, where UNIX was a requirement that Mac OS could not meet.