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Mac OS X is the newest of Apple Computer's Mac OS line of operating systems. Although it is officially designated as simply "version 10" of the Mac OS, it has a history largely independent of the earlier Mac OS releases.
Development outside of Apple
Internal development Meanwhile, Apple was facing commercial difficulties of its own. The decade-old Mac OS had reached the limits of its single-user, co-operative multitasking architecture, and its once-innovative user interface was looking increasingly "dated." A massive development effort to replace it, known as Copland, was started in 1994, but was generally perceived outside of Apple to be a hopeless case due to political infighting. 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 in 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 an emulator — known as the Blue Box — for running "classic" Macintosh applications. The result was known by the code name 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 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, and asked him to resign. The board convinced Jobs to lead the company on an interim basis. Jobs was, in essence, given carte blanche by the Apple board to return the company to profitability. When Jobs announced at the World Wide Developer's Conference that what developers really wanted was a modern version of the Mac OS, and that's what Apple was going to deliver, it was met with thunderous applause. Over the next two years, major effort was applied to porting the original Macintosh APIs to Unix libraries known as ''Carbon''. Mac OS applications could be ported to Carbon without the need for a complete re-write, while still making them full citizens of the new operating system. Meanwhile, applications written using the older toolkits would be supported using the "Classic" Mac OS 9 environment. Included support for C, C++, Objective-C, Java, and Python furthered developer comfort. During this time the lower layers of the operating system (the Mach kernel and the BSD layers on top of it) were re-packaged and released under an open source license known as Darwin. The Darwin kernel provides an extremely stable and flexible operating system, which rivals many other Unix implementations, and takes advantage of the contributions of programmers and independent open-source projects outside of Apple; however, it sees little use outside the Macintosh community. During this period, the 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 OS X-specific "Cocoa" APIs to the Java language. While the first release of the new OS — Mac OS X Server 1.0 — used a modified version of the Mac OS GUI, all versions following used a new theme known as Aqua. The development of this part of the OS was delayed somewhat by the switch from OpenStep's Display PostScript engine to one that was license free, known as Quartz. Aqua was a fairly radical departure from the Mac OS 9 interface, which was an evolution of the original Macintosh Finder. Aqua incorporated full color scalable graphics, anti-aliasing of text and graphics, simulated shading and highlights, transparency and shadows, and animation. A key new feature was the Dock, an application launcher which took full advantage of these capabilities. Despite this, Mac OS X maintained a substantial degree of compatibility with the traditional Mac OS interface and Apple's own 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. Releases
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