Mac OS X

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Mac OS X

(operating system)
/mak oss ten/ Version 10 of the Macintosh Operating System, based on FreeBSD unlike prevoius versions. Apple released the kernel of Mac OS X Server as "darwin", under an open source license. Mac OS X incldues a code framework called the "Core Foundation" and an "Application Kit" framework for GUI and widgets strongly derived from NEXTSTEP.
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Mac OS X

(Mac OS 10) The current operating system from Apple for the Mac family. Starting in the fall of 2016, Version 10.12 uses the rebranded "macOS" moniker and not OS X. See macOS and Sierra.

OS X Server was introduced in 1999, and the client version came out in 2001. Based on Unix and featuring an entirely redesigned user interface, OS X was a major departure from the previous OS 9 system. For the first time, the rich set of Unix commands became available to all Mac developers (A/UX was an earlier Unix OS for the Mac but was not widely used).

OS X added protected memory, pre-emptive multitasking, multithreading and symmetric multiprocessing (SMP) to the Mac world. The heart of OS X is the open source, POSIX-compliant Darwin kernel, which includes an enhanced BSD 4.4 operating system and Mach 2.5 microkernel. See HFS.

Legacy Software
Prior to Mac OS X 10.5 (Leopard), OS X ran legacy OS 9 and earlier applications via its Classic software, which was a full copy of OS 9 that ran as an OS X process. Classic was not preloaded on new Macs, but was available for installation from the system disks.

In 2006, Apple switched from the PowerPC to the Intel platform, and Classic support was dropped in the Intel version of OS X. However, PowerPC applications could run on Intel Macs via an emulator (see Rosetta).

Programming Environments
There have been five programming interfaces (APIs) for writing Mac OS X applications. Cocoa is the native OS X interface, derived from OpenStep. Carbon is used for applications that can run on both OS X and earlier Mac OS machines, and Classic is the API prior to Mac OS X. Programs can also be developed in Java and BSD. See OpenStep and Cocoa.

Faster Cats!
Mac OS X versions were internally code-named after jungle cats. Starting with Version 10.2 (Jaguar), the animals became the official product name until Version 10.9 (see below). See Rhapsody and Bonjour.
macOS Version  Place
  10.15  2019     Catalina
  10.14  2018     Mojave
  10.13  2017     High Sierra
  10.12  2016     SierraOS X Version   Place
  10.11  2015     El Capitan
  10.10  2014     Yosemite
  10.9   2013     MavericksOS X Version   Jungle Cat
  10.8   2012     Mountain Lion
  10.7   2011     Lion
  10.6   2009     Snow Leopard
  10.5   2007     Leopard
  10.4   2005     Tiger
  10.3   2003     Panther
  10.2   2002     Jaguar
  10.1   2001    Puma (code name)
  10.0   2001    Cheetah (code name)
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The piece of malware known as the Flashback Trojan is the most advanced and most successful Mac OS X malware ever discovered, and it is still ( affecting 38,000 Macs one year after Apple released a software update to halt the spread of the worm.