A little history of Mac OS: Mac OS, Mac OSX and Darwin

1. As a result of the acquisition of NeXT Company, Apple obtained the design of Mach and objective-c in the NeXTSTEP architecture. Although the NeXTSTEP itself is no longer evolving, its components have been reborn in OS x. In fact, OS X can be thought of as the fusion of Mac OS Classic and NeXTSTEP, or, more precisely, the latter slowly absorbing the former. This shift is not instantaneous, and Mac OS has experienced a temporary operating system called Rhapsody, which has never been made public. However, the Rhapsody system eventually evolved into the first version of Mac OS X, and the kernel of this operating system is Darwin (Chinese name: Darwin), which we know today.

3. Within all operating systems, MAC OS X is designed and implemented to be the closest to NeXTSTEP, even more than Apple's own OS 9. The core components of OS x--cocoa, Mach, IOKit, Xcode interface Builder, and many other components come directly from NeXTSTEP. The two extreme niche operating systems--one with great GUI but poorly designed, one design is great but the GUI is very dull--the result of merging is a new operating system that is much more popular than the two combined.

   Sometimes people confuse the definition of the two nouns of OS X and Darwin and the relationship between them. Here's a clarification: OS X is a collective name for the entire operating system. As discussed in the next chapter, this operating system consists of a number of components,

   Darwin is one of those components.
   Darwin is the Unix-like core of the operating system, itself by the kernel (kernel), XNU ("X is not UNIX" abbreviation, which

   Abbreviation similar to the GNU recursive abbreviation) and run-time composition. Darwin is open source (Darwin in IOS is a transplant on ARM, this Darwin is not open source, as discussed later), and the rest of OS X, the various frameworks Apple offers, is not open source.

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There is a simple relationship between the version of OS X and the version of Darwin. In addition to OS X 10.0 for Darwin 1.3.x, the other versions are subject to the following simple formula:

If (osx.version = = 10.x.y) Darwin.version = (4+x). Y

Thus, for example, the 10.8.0 version of Mountain Lion corresponds to Darwin 12.0. Snow Leopard's 10.6.8 version corresponds to Darwin10.8. Although it may seem a bit confusing, it is at least consistent.

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A little history of Mac OS: Mac OS, Mac OSX and Darwin