|Source model||Closed source (with open source components)|
|Initial release||System Software 1|
(24 January 1984)
|Latest release||macOS Monterey |
(25 October 2021)
|Latest preview||macOS Monterey (build 21C5045a) |
(1 December 2021)
|Supported platforms||x86_64, ARM64 (previously 68k, PPC and i386)|
|Kernel type||Hybrid (XNU)|
macOS is a series of operating systems developed by Apple for their Macintosh platform. macOS is the second-most commonly used operating system after Microsoft Windows. It first became publicly available in 1984 with the release of the Macintosh 128k.
The classic Mac OS was originally written for the Motorola 68k architecture. The 68k architecture was used from 1984 to 1994, after which Apple transitioned to PowerPC. PowerPC would be used until the classic Mac OS's discontinuation in 2002. Classic Mac OS was based on a simple kernel design, which eventually became too limited and crash-prone for applications. In response, Apple bought NeXT and used NeXTSTEP as a base to develop Mac OS X. In 2006, Apple switched to Intel-based x86 processors in Macs. Support for PowerPC in Mac OS X was dropped in 2009.
At WWDC 2020, Apple declared that they would switch over to the Apple Silicon SoC in future Mac computers.
The Classic Mac OS can run standalone, and under Mac OS X using the Classic system layer. Only certain versions of Mac OS 9 can run under the Classic system layer, and the layer itself was dropped after Mac OS X Tiger.
PearPC is a useful emulator that can run PowerPC builds of Mac OS X under Windows or other x86 operating systems. PCE and Mini vMac are able to run 68k builds of Mac OS, QEMU is also capable of running earlier PPC builds of MacOS, and VirtualBox and VMware Fusion can run x86/64 builds of Mac OS X.
Timeline[edit | edit source]
Classic[edit | edit source]
The original Macintosh System Software is based on the Lisa OS and UI concepts from Xerox PARC. It uses a monolithic architecture but lacks support for memory management, protected memory, access controls, and conflict-free extensions. Only one application at a time could be supported under System Software until version 5 when MultiFinder was introduced. In 1997, Apple rebranded the Macintosh System Software to Mac OS. Mac OS would continue to be developed until the introduction of Mac OS X, after which Apple only delivered minor updates to the classic Mac OS. The final minor updates were designed to ease the transition to OS X. Carbon, an API introduced with Mac OS 8, works as the transitional API for classic Mac OS and Mac OS X applications.
|Name||Versions||Release date(s), Notes||Codenames|
|System Software 1||1.0-1.1h||Released in January 1984-April 1984; uses the 68k architecture|
|System Software 2||2.0-2.1||Released in April 1985-September 1985|
|System Software 3||3.0-3.3||Released in January 1986-June 1987|
|System Software 4||4.0-4.1.1||Released in January 1987-July 1989|
|System Software 5||5.0-5.1||Released in October 1987-February 1988|
|System Software 6||6.0-184.108.40.206||Released in 1988-1992|
|Mac OS 7||7.0-7.6.1||Released in 1991-1997; first version to officially run on PowerPC (added on version 7.1.2)||Big Bang, Superbeta, Cube-E, Shuswap, Capone, Jirocho, Mozart, Son of Buster, Unity, Zeus, Gory, Harmony, Ides.|
|Mac OS 8||8.0-8.6||Released in 1997-1999; version 8.5 removed support for 68k||Copland, Tempo, Bride of Buster, Sequoia, Snowman, South Park, Allegro, Horatio, Veronica, Sarah.|
|Mac OS 9||9.0-9.2.2||Released in 1999-2001; version 9.2 requires a PowerPC G3 processor||Sonata, Minuet, Fortissimo, Moonlight, Limelight, LU1.|
UNIX-based[edit | edit source]
macOS (formerly known as Mac OS X until 2012, or OS X until 2016) is the current incarnation of Mac OS. The first version released was Mac OS X Server in 1999. Unlike the classic Mac OS, it is based on NeXTSTEP and uses its frameworks and architectures. In 2012, Apple began to use the OS X moniker to brand Mac OS X alongside their other operating systems (watchOS, tvOS, iOS). In 2016, Apple began to use the macOS moniker to brand OS X alongside their other operating systems (watchOS, tvOS, iOS).
|Name||OS version||Darwin version||Codename(s)||Notes|
|Mac OS X Server 1.x||N/A||Rhapsody 5.3 - 5.6[note 1]||Rhapsody||Released in March 1999|
|Mac OS X Public Beta||N/A||1.2.1||Kodiak||Released in September 2000; introduced the Aqua interface|
|Mac OS X Cheetah||10.0||1.3.1||Cheetah||Released in March 2001|
|Mac OS X Puma||10.1||1.4.1 / 5||Puma||Released in September 2001|
|Mac OS X Jaguar||10.2||6||Jaguar||Released in August 2002|
|Mac OS X Panther||10.3||7||Pinot||Released in October 2003|
|Mac OS X Tiger||10.4||8||Merlot (PPC), Chardonay (Intel)||Released in April 2005; first version to officially run on Intel (added in 10.4.1)|
|Mac OS X Leopard||10.5||9||Chablis||Released in October 2007; removes support for PowerPC G3 processors|
|Mac OS X Snow Leopard||10.6||10||Snow Leopard||Released in August 2009; removes support for PowerPC Macs|
|Mac OS X Lion||10.7||11||Barolo||Released in July 2011; removes support for PPC-only applications via Rosetta; removes support for x86 processors|
|OS X Mountain Lion||10.8||12||Zinfandel||Released in July 2012; removes the 32-bit kernel and 32-bit EFI bootloader|
|OS X Mavericks||10.9||13||Cabernet||Released in October 2013|
|OS X Yosemite||10.10||14||Syrah||Released in October 2014; refreshed UI design|
|OS X El Capitan||10.11||15||Gala||Released in September 2015|
|macOS Sierra||10.12||16||Fuji||Released in September 2016; removes support for non-SSE4 Intel CPUs|
|macOS High Sierra||10.13||17||Lobo||Released in September 2017|
|macOS Mojave||10.14||18||Liberty||Released in September 2018|
|macOS Catalina||10.15||19||Marzipan||Released in October 2019; removes support for 32-bit applications|
|macOS Big Sur||11||20||Golden Gate||Released in November 2020; refreshed UI design again; first version to run on Apple Silicon.|
|macOS Monterey||12||21||Star||Released in October 2021|
Notes[edit | edit source]
- Mac OS X Server 1.x is a direct descendant of the NeXTSTEP/OPENSTEP codebase and is not based on Darwin.