software to other manufacturers, each of which agreed to pay a flat fee for a license, and a royalty (initially ) for each clone computer they sold. This generated quick revenues for Apple during a time of financial crisis. From early 1995 through mid-1997, it was possible to buy PowerPC-based clone computers running Mac OS, most notably from Power Computing and UMAX. However, by 1996 Apple executives were worried that high-end clones were cannibalizing sales of their own high-end computers, where profit margins were highest. A total of 75 distinct Macintosh clone models are known to have been introduced during the licensee era. The following companies produced licensed Mac clones: Jobs ends the official program Soon after Steve Jobs returned to Apple in 1997, he personally tried to renegotiate licensing deals more favorable to Apple five times over the course of three weeks and in his words each time was "basically told to pound sand". This response caused him to halt negotiations of upcoming licensing deals with OS licensees that Apple executives complained were still financially unfavorable. Because the clone makers' licenses were valid only for Apple's System 7 operating system, Apple's release of Mac OS 8 left the clone manufacturers without the ability to ship a current Mac OS version and effectively ended the cloning program. Apple bought Power Computing's Mac clone business for and gave their users free Mac OS 8 upgrade disks, ending the clone era. Only UMAX ever obtained a license to ship Mac OS 8 and get Mac OS 8 upgrade disks, which expired in July 1998 (Power Computing also got Mac OS 8 disks by their acquisition by Apple). All other manufacturers had their Macintosh clone contract terminated by late 1997 and either continued their brands as PC clones or discontinued them altogether. Some of the clone manufacturers even went out of business. Reportedly, a heated telephone conversation between Jobs and Motorola CEO Christopher Galvin resulted in the contentious termination of Motorola's clone contract, and the long-favored Apple being demoted to "just another customer" mainly for PowerPC CPUs. In 1999, Jobs had discussions with Ben Rosen, Chairman and interim CEO of Compaq at the time, for the world's then-largest Wintel PC manufacturer to license Mac OS, which would have been a coup for Apple. However no agreement was reached, as Apple had second thoughts about licensing its "crown jewel", while Compaq did not want