Datasheet

Mac OS 10.5 is another evolutionary step in the OS X product line. Apple claims it has more than

300 enhancements. One of the more significant enhancements, though most likely unperceivable

to most users, is that the product is now a 64-bit Universal OS that is capable of running 32-bit

software without recompilation. What does this mean in layman’s terms? Mac OS X 10.5 can be

installed on both Intel and PowerPC CPU-based Macs and will continue to run your existing Mac

OS X application.

Mac OS X is capable of addressing up to a whopping 16 exabytes of virtual memory.

An exabyte is equivalent to 1,024 petabytes, and a petabyte is equivalent to 1,024

terabytes — that’s a lot of memory.

Core Technologies of Mac OS X

The most important thing to know about Mac OS X is that it is based on open standards. This is

because at the heart of OS X is Unix, which has played a major role in the development of the

Internet. Because Unix is so Internet-centric, OS X can be integrated in virtually any computing

environment. In fact, the X in Mac OS X represents the X in Unix. But fear not; although Mac OS X

is a Unix operating system, its operation does not require the mastery of complex Unix command

syntax. As Apple publicizes, the command line is there for those who would like to use it, but it

isn’t required for day-to-day operations. You can make as much or as little use of it as you want.

If OS X were compared to an automobile, you would see a similarity in that both are composed

of many parts. All these parts have very distinct functions, and yet all make up a greater whole.

Metaphorically speaking, the intention of Apple was to design a vehicle akin to a Formula 1 racing

car. When the engineers at Apple set out to build OS X, they pulled together world-class technolo-

gies in an effort to build the most advanced consumer operating system the world has ever seen.

The following sections take a closer look at these parts.

Darwin

The foundation of OS X is Darwin, which is an open source community/Apple joint effort. Though

Darwin is a complete OS in and of itself, the primary objective of the Darwin project was to build

an industrial-strength Unix-based operating system core that would provide greater stability and

performance compared to all existing iterations of the Mac OS. Reviewing Darwin in detail is

beyond the scope of this book. Instead, we review some of Darwin’s more marketed features.

Mach microkernel

At the center of Darwin is the Mach microkernel based on FreeBSD 5.x, the foundation that pro-

vides basic services for all other parts of the operating system. Mach was developed at Carnegie-

Mellon University, and its history is closely tied with BSD Unix (Berkeley Software Distribution).

It is Mach that gives OS X the features of protected memory architecture, preemptive multitasking,

and symmetric multiprocessing.

NOTE

Getting to Know Mac OS X

Part I

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