Production of the Mac is based on a vertical integration model in that Apple facilitates all aspects of its hardware and creates its own operating system that is pre-installed on all Macs. This is in contrast to most IBM PC compatibles, where multiple vendors create hardware intended to run another company's software. Apple exclusively produces Mac hardware, choosing internal systems, designs, and prices. Apple does use third party components, however; current Macintosh CPUs use Intel's x86 architecture. Previous models used the AIM alliance's PowerPC and early models used Motorola's 68k. Apple also develops the operating system for Macs, currently Mac OS X 10.5 "Leopard". The modern Mac, like other personal computers, is capable of running alternative operating systems such as Linux, FreeBSD, and Microsoft Windows, the latter of which is considered to be the Mac's biggest competitor.