摘要：Earlier this year Apple officially released OS X, its new operating system. OS X now comes preinstalled on all Macs, although by default you still boot into MacOS 9.x. But soon OS X will be the default. OS X is not an incremental upgrade, it is a completely new operating system. It has a layered architecture. The lowest layer is Darwin, which consists of the Mach 3.0 kernel and a version of BSD 4.4. Thus OS X is, among other things, a certified and POSIX compliant Unix. Darwin is (certified) Open Source, and it can be downloaded from the Apple servers. One surprising consequence of the above is that soon Apple will be the largest distributor of Unix, and that soon OS X will be the most popular Unix on the planet, although most users will be blissfully unaware of this fact.
