Architecture of macOS: Difference between revisions

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{{short description|Layers of the operating system}}

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[[File:MacOS Architecture.svg|thumb|400px|Additional diagram of macOS architecture (2017 update)]]

The '''architecture of [[macOS]]''' describes the layers of the [[operating system]] that is the culmination of [[Apple Inc.]]'s decadedecades-long research and development process to replace the [[classic Mac OS]].

After the failures of their previous attempts -- Pinkattempts—Pink, which started as an Apple project but evolved into a joint venture with [[IBM]] called [[Taligent]], and [[Copland (operating system)|Copland]], which started in 1994 and was cancelled two years later -- Applelater—Apple began development of Mac OS X, later renamed OS X and then macOS, with the acquisition of [[NeXT]]'s [[NeXTSTEP]] in 1997.

Note that Mac OS X was renamed to OS X in 2012 and then again to macOS in 2016.

==Development==

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===NeXTSTEP===

{{main|NeXTSTEP}}

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NeXTSTEP used a hybrid kernel that combined the [[Mach kernel|Mach 2.5]] kernel developed at [[Carnegie Mellon University]] with subsystems from [[BSD#4.3BSD|4.3BSD]]. NeXTSTEP also introduced a new windowing system based on [[Display PostScript]] that intended to achieve better [[WYSIWYG]] systems by using the same language to draw content on monitors that drew content on printers. NeXT also included [[object-oriented programming]] tools based on the [[Objective-C]] language that they had acquired from [[Stepstone]] and a collection of Frameworks (or Kits) that were intended to speed software development. NeXTSTEP originally ran on [[Motorola]]'s [[68k]] processors, but was later ported to [[Intel]]'s [[x86]], [[Hewlett-Packard]]'s [[PA-RISC]] and [[Sun Microsystems]]' [[SPARC]] processors. Later on, the developer tools and frameworks were released, as [[OpenStep]], as a development platform that would run on other operating systems.

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===Mac OS X===

[[File:Diagram of Mac OS X architecture.svg|thumb|400px|A diagram of the Mac OS X architecture]]

At the 1998 [[Worldwide Developers Conference]] (WWDC), Apple announced a move that was intended as a response to complaints from Macintosh software developers who were not happy with the two options (Yellow Box and Blue Box) available in Rhapsody. Mac OS X would add another developer [[API]] to the existing ones in Rhapsody. Key APIs from the [[Macintosh Toolbox]] would be implemented in Mac OS X to run directly on the BSD layers of the operating system instead of in the emulated Macintosh layer. This modified interface, called [[Carbon (API)|Carbon]], would eliminate approximately 2000 troublesome API calls (of about 8000 total) and replace them with calls compatible with a modern OS.<ref name="anguish99summary">{{cite web | url=http://www.stepwise.com/SpecialCoverage/WWDC98/Summary.html | title=WWDC 98 Summary | author=Scott Anguish | date=May 1998 | publisher=stepwise.com | access-date=2006-10-13}} {{Dead link|date=October 2010|bot=H3llBot|fix-attempted=yes}}</ref>

At the same conference, Apple announced that the Mach side of the kernel had been updated with sources from the [[OSFMK]] 7.3 (Open Source Foundation's MachMK Kerneloperating system)<ref>{{cite AV media|url=https://www.youtube.com/watch?v=ggnFoDqzGMU |archive-url=https://ghostarchive.org/varchive/youtube/20211221/ggnFoDqzGMU |archive-date=2021-12-21 |url-status=live|last=Magee |first=Jim |title=WWDC 2000 Session 106 – Mac OS X: Kernel|minutes=14}}{{cbignore}}</ref> and the BSD side of the kernel had been updated with sources from the [[FreeBSD]], [[NetBSD]] and [[OpenBSD]] projects.<ref name="anguish99summary" /> They also announced a new driver model called I/O Kit, intended to replace the Driver Kit used in NeXTSTEP citing Driver Kit's lack of power management and hot-swap capabilities and its lack of automatic configuration capability.<ref>{{cite web | url=http://www.stepwise.com/SpecialCoverage/WWDC98/Thursday-IOKit.html | title=Rhapsody Core OS: Intro to the I/O Driver Architecture | author=Scott Anguish | date=1998-05-14 | publisher=stepwise.com | access-date=2006-10-13 }} {{Dead link|date=October 2010|bot=H3llBot|fix-attempted=yes}}</ref>

At the 1999 WWDC, Apple revealed [[Quartz (graphics layer)|Quartz]], a new [[Portable Document Format]] (PDF) based windowing system for the operating system that was not encumbered with licensing fees to [[Adobe Systems|Adobe]] like the Display PostScript windowing system of NeXTSTEP. Apple also announced that the Yellow Box layer had been renamed [[Cocoa (API)|Cocoa]] and began to move away from their commitment to providing the Yellow Box on Windows. At this WWDC, Apple also showed Mac OS X booting off of a [[HFS Plus]] formatted drive for the first time.

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==References==

{{reflist}}

=== Bibliography ===

* {{Cite book |last=Levin |first=Jonathan |title=*OS Internals, Volume I: User Mode |edition=v1.3.3.7 |date=September 25, 2019 |publisher=Technologeeks |isbn=978-0-9910555-6-2 |language=en}}

* {{Cite book |last=Levin |first=Jonathan |title=*OS Internals, Volume II: Kernel Mode |edition=v1.0 |date=October 16, 2019b |publisher=Technologeeks |isbn=978-0-9910555-7-9 |language=en}}

* {{Cite book |last=Singh |first=Amit |url= |title=Mac OS X Internals: A Systems Approach |date=June 19, 2006 |publisher=Addison-Wesley Professional |isbn=978-0-13-270226-3 |language=en}}

==External links==

*[https://www.apple.com/macos/ Official Website]

*{{usurped|1=[https://web.archive.org/web/20200726095434/https://gadgetraja.com/macos-mojave-a-much-better-functional-experience/ MacOS Mojave]}}

*[https://arstechnica.com/apple/2014/10/os-x-10-10/ Mac OS X Reviews]

*[http://www.osxbook.com/ Mac OS X Internals]