macOS (formerly Mac OS X)

The modern Mac operating system is now termed macOS, after an entire generation of OS X and its many variants (10.1, 10.2, and the current 10.4) having initially been given feline code names - Cheetah, Jaguar, Panther, Tiger, Leopard, these days turned into grander monikers like El Capitan, Sierra, etc.

It is essentially a current-day version of NeXTSTEP with the Aqua interface wrapped around it - that is to say, a BSD-like UNIX system running on top of the Mach microkernel.

The best currently available online reference to its internals is Amit Singh's What Is Mac OS X?, which I recommend heartily to anyone coming from mainstream UNIX systems like Linux and BSD - it explains most of the rationale and heritage of Mac OS X in a exceptionally clear and well written fashion, and draws appropriate comparisons as it goes along.

Amit has also recently published a must-have book on Mac OS X, and made available a vastly extended version of its initial chapter covering Mac OS X's precursors and history.

O'Reilly also has a great book for people coming to Mac OS X from other UNIXes called Mac OS X for Unix Geeks:






Mach and Mach-O

Neat Stuff:

This page is referenced in: