Editing MacOS version history (section)

==Development==

===Development outside Apple===
[[File:Unix history-simple.svg|thumb|400px|A diagram of the relationships between Unix systems including the ancestors of macOS]]
After [[Apple Inc.|Apple]] removed [[Steve Jobs]] from management in 1985, he left the company and attempted to create the "next big thing", with funding from [[Ross Perot]]<ref>{{cite book|last=Isaacson|first=Walter|author-link=Walter Isaacson|year=2011|title=Steve Jobs|url=https://archive.org/details/stevejobs00isaa|url-access=registration|page=[https://archive.org/details/stevejobs00isaa/page/227 227]|publisher=[[Simon & Schuster]]|isbn=978-1-4087-0374-8}}</ref> and himself. The result was the [[NeXT Computer]]. As the first workstation to include a [[digital signal processor]] (DSP) and a high-capacity optical disc drive, NeXT hardware was advanced for its time, but was expensive relative to the rapidly commoditizing workstation market. The hardware was phased out in 1993; however, the company's [[object-oriented operating system]] [[NeXTSTEP]] had a more lasting legacy as it eventually became the basis for Mac OS X.

NeXTSTEP was based on the [[Mach kernel]] developed at CMU (Carnegie Mellon University)<ref>A Practical Guide to Linux Commands, Editors, and Shell Programming, 3rd edition, by Mark G. Sobell, page 2</ref> and [[Berkeley Software Distribution|BSD]], an implementation of [[Unix]] dating back to the 1970s. It featured an [[object-oriented]] programming [[Software framework|framework]] based on the [[Objective-C]] language. This environment is known today in the Mac world as [[Cocoa (API)|Cocoa]]. It also supported the innovative [[Enterprise Objects Framework]] database access layer and [[WebObjects]] application server development environment, among other notable features.{{Citation needed|date=February 2021}}

All but abandoning the idea of an operating system, NeXT managed to maintain a business selling WebObjects and consulting services, only ever making modest profits in its last few quarters as an independent company. NeXTSTEP underwent an evolution into [[OPENSTEP]] which separated the object layers from the operating system below, allowing it to run with less modification on other platforms. OPENSTEP was, for a short time, adopted by [[Sun Microsystems|Sun]] and [[Hewlett-Packard|HP]].

However, by this point, a number of other companies — notably Apple, IBM, Microsoft, and even Sun itself — were claiming they would soon be releasing similar object-oriented operating systems and development tools of their own. Some of these efforts, such as [[Taligent]], did not fully come to fruition; others, like [[Java platform|Java]], gained widespread adoption.{{Citation needed|date=February 2021}}

On February 4, 1997, [[Apple Inc.|Apple Computer]] acquired NeXT for $427 million, and used OPENSTEP as the basis for [[Mac OS X]], as it was called at the time.<ref>{{cite book | title=Apple Confidential: The Real Story of Apple Computer, Inc | url=https://archive.org/details/appleconfidentia00linz | url-access=registration | last=Linzmayer | first=Owen W. | year=1999| publisher=No Starch Press | isbn=9781886411289 }}</ref> Traces of the NeXT software heritage can still be seen in macOS. For example, in the [[Cocoa (API)|Cocoa]] development environment, the [[Objective-C]] library classes have "NS" prefixes, and the HISTORY section of the manual page for the <code>defaults</code> command in macOS straightforwardly states that the command "First appeared in NeXTStep."{{Citation needed|date=February 2021}}

===Internal development===
Meanwhile, Apple was facing commercial difficulties of its own. The decade-old [[classic Mac OS|Macintosh System Software]] had reached the limits of its single-user, [[co-operative multitasking]] architecture, and its once-innovative user interface was looking increasingly outdated. A massive development effort to replace it, known as [[Copland (operating system)|Copland]], was started in 1994, but was generally perceived outside Apple to be a hopeless case due to political infighting and conflicting goals. By 1996, Copland was nowhere near ready for release, and the project was eventually cancelled. Some elements of Copland were incorporated into [[Mac OS 8]], released on July 26, 1997.

After considering the purchase of [[BeOS]] — a multimedia-enabled, multi-tasking OS designed for hardware similar to Apple's, the company decided instead to acquire NeXT and use [[OPENSTEP]] as the basis for their new OS. [[Avie Tevanian]] took over OS development, and Steve Jobs was brought on as a consultant. At first, the plan was to develop a new operating system based almost entirely on an updated version of OPENSTEP, with the addition of a virtual machine subsystem — known as the ''Blue Box'' — for running "classic" Macintosh applications. The result was known by the code name [[Rhapsody (operating system)|Rhapsody]], slated for release in late 1998.

Apple expected that developers would port their software to the considerably more powerful OPENSTEP libraries once they learned of its power and flexibility. Instead, several major developers such as [[Adobe Systems|Adobe]] told Apple that this would never occur, and that they would rather leave the platform entirely. This "rejection" of Apple's plan was largely the result of a string of previous broken promises from Apple; after watching one "next OS" after another disappear and Apple's market share dwindle, developers were not interested in doing much work on the platform at all, let alone a re-write.

===Changed direction under Jobs===
Apple's financial losses continued and the board of directors lost confidence in CEO [[Gil Amelio]], asking him to resign. The board asked [[Steve Jobs]] to lead the company on an interim basis, essentially giving him ''[[wikt:carte blanche|carte blanche]]'' to make changes to return the company to profitability. When Jobs announced at the [[Apple Worldwide Developers Conference|World Wide Developer's Conference]] that what developers really wanted was a modern version of the Mac OS, and Apple was going to deliver it{{Citation needed|date=February 2009}}, he was met with applause.

Over the next two years, a major effort was applied to porting the original Macintosh API to Unix libraries known as ''[[Carbon (computing)|Carbon]]''. Mac OS applications could be ported to Carbon without the need for a complete re-write, making them operate as native applications on the new operating system. Meanwhile, applications written using the older toolkits would be supported using the "Classic" Mac OS 9 environment. Support for [[C (programming language)|C]], [[C++]], [[Objective-C]], [[Java (programming language)|Java]], and [[Python (programming language)|Python]] were added, furthering developer comfort with the new platform.{{Citation needed|date=February 2021}}

During this time, the lower layers of the operating system (the [[Mach (kernel)|Mach kernel]] and the BSD layers on top of it<ref>A Practical Guide to Linux Commands, Editors, and Shell Programming, 3rd edition by Mark G. Sobell, page 2</ref>) were re-packaged and released under the [[Apple Public Source License]]. They became known as [[Darwin (operating system)|Darwin]]. The Darwin kernel provides a stable and flexible operating system, which takes advantage of the contributions of programmers and independent open-source projects outside Apple; however, it sees little use outside the Macintosh community.{{Citation needed|date=December 2017}}

During this period, the [[Java (programming language)|Java programming language]] had increased in popularity, and an effort was started to improve Mac Java support. This consisted of porting a high-speed Java [[virtual machine]] to the platform, and exposing macOS-specific "Cocoa" APIs to the Java language.{{Citation needed|date=February 2021}}

The first release of the new OS — [[Mac OS X Server 1.0]] — used a modified version of the Mac OS GUI, but all client versions starting with Mac OS X Developer Preview 3 used a new theme known as [[Aqua (user interface)|Aqua]]. Aqua marked a significant shift from the Mac OS 9 interface, which had seen minimal changes since the original Macintosh OS. It introduced full-color scalable graphics, text and graphic anti-aliasing, simulated shading and highlights, transparency, shadows, and animation. A new feature was the Dock, an application launcher which took advantage of these capabilities.

Despite this, Mac OS X maintained a substantial degree of consistency with the traditional Mac OS interface and Apple's own [https://web.archive.org/web/20110805043358/http://developer.apple.com/library/mac/#documentation/UserExperience/Conceptual/AppleHIGuidelines/Intro/Intro.html Apple Human Interface Guidelines], with its pull-down menu at the top of the screen, familiar keyboard shortcuts, and support for a single-button mouse. The development of Aqua was delayed somewhat by the switch from OpenStep's [[Display PostScript]] engine to one developed in-house that was free of any license restrictions, known as [[Quartz (graphics layer)|Quartz]].{{Citation needed|date=February 2021}}