Mac OS

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Classic Mac OS lettering.

“Mac OS” [ mæk oʊˈɛs ] is a brand name that Apple has been using since January 1997 for the operating systems of its in-house Macintosh computers. From 1998 the “Macintosh” was officially abbreviated to “Mac”. The term is derived from Mac intosh O perating S ystem - a term that has been never used.

On the one hand, the term describes the classic Mac OS , which has been continuously developed since the system software of 1984, but was considered technically obsolete from the beginning of the 1990s.

On the other hand, the name can also be found in Mac OS X , the Unix operating system that was further developed from Rhapsody in 1998 and replaced the classic Mac OS in 2001. In 2012 it was renamed OS X - as early as 2011, Mac OS X Lion (version 10.7) was advertised as "OS X" without "Mac". Since 2016, macOS has been the name of this desktop operating system line ( macOS Sierra , version 10.12), without spaces and with a lowercase "m" - in accordance with the naming scheme of the other, derived systems iOS , tvOS and watchOS . The server version is based on the desktop version and follows its name.


In 1996, Mac OS 7.6, the Macintosh operating system originally released in 1984, was first published under this name. "System 1.0", first published in 1984 with the Macintosh 128k, was modeled on the Lisa OS operating system, which has several modern functions and was developed for the previous but economically unsuccessful computer, Apple Lisa . The Mac OS line was delivered to Macintosh and Mac computers and laptops in 1984–2002, was sold as a free upgrade and some were sold individually. In 1984 it was simply called System and from 1987 onwards it was also referred to in its entirety as Macintosh System Software .

At the beginning of the 1990s, after System 6 with the only partially modernizable System 7, it was more and more technically outdated and Apple tried to write a completely new but compatible operating system. However, when this was not yet finished in 1996, the classic “system” was renamed “Mac OS” and improved with technologies from the unfinished Copland project, while at the same time work was being carried out on the OPENSTEP operating system . Since 1999 it has also been referred to as Mac OS Classic - "classic Mac OS" - in order to clearly differentiate it from the independently developed successor Mac OS X.

At the end of 1996 Apple decided to purchase the NeXT company founded by Steve Jobs , including the modern Unix operating system OPENSTEP , which took place in January 1997. At Apple, the new operating system was further developed under the name Rhapsody until 1998 and was intended to completely replace the classic Mac OS and to run on computers that did not come from Apple itself, such as IBM-compatible PCs. Rhapsody used the new programming interface "Yellow Box" (renamed from OpenStep ) known from OPENSTEP and offered modern operating system functions such as memory protection and preemptive multitasking. Classic Macintosh programs were executed in the newly developed Blue Box , but could not make use of the modern functions.

Smooth transition

At WWDC 1998, the amalgamation of the classic Mac OS (then Mac OS 8.1) and Rhapsody to Mac OS X (pronounced “Mac OS ten”, i.e. Mac OS ten ) was announced. The strategy provided for exclusive availability for Apple computers and included the further development of Mac OS 8 (from 1999 also Mac OS 9) and the integration of the Macintosh programming interface, as far as possible, into the modern operating system Mac OS X. This was called Carbon and represented a large part of the existing interface with 6,000 of the approximately 8,000 functions. This allowed indispensable third-party manufacturers of application programs for the Macintosh platform to offer their products for the classic Mac OS as well as for the upcoming Mac OS X, since the porting effort of existing program parts to Carbon was far less than that to the new programming interface "Yellow Box" , which was renamed Cocoa on Mac OS X. Carbon, however, was in the form of CarbonLib and Mac OS version 8.1 "backported" - which allowed to "carbonized Applications" ( English carbonized applications ), the native version of the same program on both Mac OS Classic and Mac OS X.

According to the original plans, Mac OS X should have appeared in 1999, but did not appear until 2001. Mac OS 9, the last classic Mac OS, was no longer developed afterwards. To make the transition to the new operating system as smooth as possible, the Blue Box, now renamed was Classic environment , improved so classical programs on the introduced with Mac OS X Aqua - surface were shown as a window.

At the beginning, Mac OS X combined “the best of both worlds” - with Carbon it was possible for application programs such as Adobe Photoshop and Microsoft Office to become available on Mac OS X relatively quickly. Apple itself also initially took over parts of the Finder , iTunes and QuickTime from the classic Mac OS. In order to convince external developers, the Finder was even expanded with ideas from the NeXTStep / OPENSTEP Workspace Manager in Carbon. Nevertheless, Cocoa was the preferred programming interface under the new operating system, something Apple pointed out again and again. Gradually, most of the programs were ported from Carbon to Cocoa, finally the Finder in Mac OS X Snow Leopard (2009) and Adobe Creative Suite in version 5 (2010).

For Mac OS X also on was from 2005 iPod , iPhone and iPad running iOS developed. Also on the Apple TV running OS TVOS comes from Mac OS X, as well as since 2014 on the Apple Watch current watchOS .

After 2007, and after switching from the PowerPC - to the Intel x86 - processor architecture disappeared the official support for classic Mac OS, as up to the (currently, as of 2017) still existing carbon in Mac OS X no longer component with classic Mac OS is directly related. Carbon has also not been further developed since 2007, has not been ported to 64-bit and carbon applications are therefore limited to 32-bit. In addition, the programming interface Carbon is missing on the derived variants iOS, tvOS and watchOS. Seen in this light, the renaming of “Mac OS X” to “OS X” in 2011 and finally to “macOS” in 2016 marks the visible end of the transition phase. With Cocoa, macOS, iOS, tvOS and watchOS are rooted in the OpenStep programming interface developed with NeXTStep, and together with new developments such as Swift, these modern interfaces and frameworks enable programming on all current Apple platforms.

Brand name "Mac OS"

Finder logo and lettering of the classic Mac OS (from 7.5.1 / 7.6).
Start logo since Mac OS X 10.2.

Mac OS is a registered trademark that designates GUI -based operating systems from Apple Inc. (previously Apple Computer Inc.) for their Macintosh computer systems.

System 7.5.1 (1995) was the first version with the familiar Mac OS logo, which replaced from then on the "Picasso" -Macintosh and how that the startup is displayed. The symbol replaced simultaneously with Mac OS X also that of the Finder . The name “Mac OS” was first used with version 7.6 (1997) for the operating system itself - from then on it was written below the symbol on the start screen in all classic Mac OS versions . Under Mac OS X 10.0 (2001), on the other hand, the well-known Happy Mac symbol was used again when booting. From Mac OS X 10.2 (2002) onwards, a gray Apple logo is shown.

Operating systems with the name "Mac OS":

With Mac OS X Lion (version 10.7 of Mac OS X) the operating system was advertised as "OS X" and the server version is already called OS X Server 1.0 (without "Mac" in the name). From OS X Mountain Lion (version 10.8) the operating system is officially called "OS X" and indicates this when you click on "About this Mac". The reason for removing “Mac” in the name is the variant of the operating system for Apple TV , iPod , iPhone and iPad in addition to the original variant for Macintosh computers. Since the operating system no longer only runs on Macs, it should no longer be called "Mac OS". A slightly modified version of Mac OS X (Tiger, version 10.4) was used for the 1st generation Apple TV, and for the iPod, iPhone and iPad as well as the 2nd generation Apple TV the operating system is called iOS (originally iPhoneOS and iPadOS) or tvOS (based on iOS) and with Darwin has the same basis and the same kernel as Mac OS X. Finally, in 2016, the name was renamed to macOS, analogous to the other operating systems, so that the original Mac OS X is now called macOS, so again with "mac" in the name, but spelled differently, and for the first time without the X, which officially stood for version 10 as a Roman number and thus clearly differentiated the modern operating system developed from Rhapsody from the classic Mac OS.


In the course of time, Apple had offered some operating systems for its own Apple computers. The first Apple computer, the Apple I , had its operating system firmly anchored in the firmware. With the Apple II from 1977 mainly text-based operating systems such as Apple DOS were used , as well as the further development of Apple SOS for the commercially unsuccessful Apple III from 1980 . Inspired by this, ProDOS appeared for the Apple II , but Apple CP / M also ran on the Apple II. With the Apple Lisa , Apple made the first commercial attempt by a computer manufacturer to market a personal computer (PC) with a purely graphical operating system - that of Xerox Systems with graphical control that were already offered in the 1970s were not PCs, but expensive business systems. The Apple Lisa, however, was far too expensive for private individuals and a commercial flop, but the Lisa OS operating system was the template for the Apple Macintosh, which appeared in 1984 and was supposed to replace the Apple II. However, it took a few years before the successful Apple IIgs with the graphic GS / OS, which was also available from 1987 , could be replaced by the Macintosh as the more successful Apple computer model.

There were also Unix operating systems for Apple computers. Microsoft started with Xenix for Apple Lisa. In 1988 Apple itself released A / UX , a Unix System V that ran on the surface of the Macintosh's system software ( System 6 and System 7 ) and is therefore not an independent operating system.

Macintosh System Software (1984–1996)

For years Apple deliberately downplayed the existence of the operating system in order to make the Macintosh systems appear more user-friendly and to differentiate themselves from other personal computers and their operating systems. An essential part of this early system software, including the Macintosh Toolbox ( English Macintosh Toolbox ) was right in the ROM stored. In times of expensive RAM, this approach had the advantage that not all components had to be loaded into the active main memory and were still available immediately, since the programs in ROM could be called up at any time and faster than from the floppy disks and hard drives customary at the time. Also was the limited storage capacity of disks ( English floppy disks ) not occupied by parts of the operating system and could purely be used for programs and data. The first Macintosh computers came without a hard drive.

To start but a system disk was required. (Only the Macintosh Classic from 1991 was ever able to boot entirely from ROM.) The architecture of the "system software" allowed a completely graphical operating system without a command line mode. Abstürzende programs and even hardware failure such as lack of drives were graphically combinations of the user symbols ( English Icons ) Note windows, buttons, the mouse and the striking bitmap font Chicago communicated.

A side effect, probably not unintentional, was that the operating system was firmly fused with the hardware. The “system software” depended on this core system in the mainboard ROM. This fact later helped ensure that it could only be run by Apple computers or licensed clones (using Apple's proprietary ROMs). Updates to the operating system were distributed by Apple dealers through System 6 on floppy disks at cost.

The early Macintosh operating system consisted of two parts: the "System" and the " Finder ", each with its own version number and programmed in assembler and Pascal .

The classic "system" is particularly noticeable due to the lack of a command line - the user interface is completely graphical. Famous for its usability and cooperative multitasking , it has been criticized for its lack of support for memory protection ( RAM ) and its susceptibility to conflicts between operating system extensions ( e.g. device drivers ). Some extensions did not work together or only if they were loaded in a certain order.

The Macintosh originally used the Macintosh File System (MFS), which did not allow subfolders and is therefore also referred to as a flat file system . It was introduced in 1984 and replaced in 1985 by the Hierarchical File System (HFS), a (as the name suggests) hierarchical file system with a real directory tree. Both file systems are compatible, but the new HFS functions caused problems when exchanging data with other non-Macintosh file systems.

With increasing storage capacity and performance, it was at some point no longer possible to keep large parts of a modern graphic operating system in ROM or to update it. From the first PowerPC -G3 systems onwards, almost the entire operating system was saved on the hard drive. On the physical ROM of the mainboard only a part that was necessary for licensing reasons remained, without which Mac OS would still not function. The contents of the ROM are used by System 7 and Mac OS etc. a. used to find out which Macintosh model it is running on. While updates up to System 6 were free, versions from System 7 were partly sold as separate, chargeable products. These new Macintosh computers were referred to by Apple as English "New World" (translated: "New World"), while the older generation, in which essential parts of the system were still stored in ROM, called English "Old World" (translated: "Old world"). Shortly thereafter, the company switched to Open Firmware and, with the iMac (1998), the previously unofficial term “Mac” was also introduced as an official product name.

Operating system projects

The operating system of the Macintosh computers , which up until then was simply referred to as the “system” and which has been continuously developed since 1984, had some conceptual deficiencies that could only be remedied by a new development. The system did not support preemptive multitasking , multi-user operation , memory protection or dynamic memory management and was therefore considered unstable and technically obsolete. Apple had therefore started various projects over the course of time to develop a new operating system that was supposed to remedy these weaknesses and deficiencies.

Project Pink (1988–1995)

In 1988 the "Pink" project was started. Pink aimed for a fully object-oriented operating system. In mid-1991 Apple succeeded in convincing IBM of its development at the time, which is why the joint subsidiary Taligent was founded to complete Pink as TalOS. It soon became apparent, however, that the market apart from Apple did not need a new operating system, which is why Pink and TalOS were converted into the runtime environment TalAE, Taligent Application Environment, later also called CommonPoint . 1995 Apple dropped out of development completely and handed over Taligent (TalAE) completely to IBM. Thus the problem of an outdated operating system on Macintosh computers remained.

Star Trek Project (1992-1993)

As early as 1985, after Steve Jobs left Apple after a dispute with John Sculley , the idea for a project was born to port the Apple operating system to x86 hardware. But in 1992, the project codenamed "was Star Trek was" resumed after Novell had approached Apple to a competitive operating system for the first time then commercially successful graphical PC operating system Windows 3.0 from Microsoft to develop.

At the time, Novell, along with Netware, was the leading developer of network systems and software and saw itself endangered by the success of Windows . As early as 1991, Novell had taken over the DR DOS operating system developed by Digital Research including the GEM graphical user interface and wanted to develop it further into a modern graphical operating system with GEM as an alternative to Windows and a Netware client supplied with DR DOS (later Novell DOS). But under Digital Research, GEM had already been the reason for a lawsuit by Apple because it looked too similar to the Macintosh operating system. To avoid a repetition of such an action, we contacted Apple to instead the operating system on the Intel x86 - architecture to ported . John Sculley, Apple's CEO in 1991, agreed. Even Intel was interested and contributed 486 PCs for the development team at.

From the summer of 1992, only 18 developers ported System 7 to x86, and a fully functional prototype was available by the end of October. At Apple, they were amazed to see their own operating system run on an IBM-compatible PC . Since large parts of it were written in assembler (for the Motorola 68000 used in Macintosh computers ), almost the entire operating system had to be reprogrammed. Only the finder and many parts that were written in Pascal could still be used with just a few changes. The result was source code compatible on x86 : Programs that had been written for the Macintosh (and its "System" operating system on the m68k architecture) would have been recompiled on x86 - but hardware- related programming had to be completely rewritten.

At Apple the situation arose on the one hand that they also wanted to sell hardware and had just formed an alliance with IBM and Motorola for the development of PowerPC . An x86 operating system would have competed in-house. On the other hand, PC makers were unwilling to pay a good price for the operating system if it were sold preinstalled on a new PC. Microsoft had signed a contract with the manufacturers of PCs under which a certain amount had to be paid to Microsoft for every PC sold - regardless of which operating system was preinstalled. But the software developers were also cautious, because they did not know how much porting effort it would have taken to make their programs fit for the x86 instruction set. In many programs, functions for acceleration were written in 68k assembler near the hardware .

In 1993 there was also a change at the top of Apple and Michael Spindler became the new CEO. An austerity program was implemented under him and, although the team was increased to 50 programmers after the working prototype of “Star Trek”, the entire project was finally discontinued in June 1993.

Project Raptor (1993-1994)

In March 1988 Apple managers and developers met to discuss the successor to System 6 . All the ideas for the next operating system were written on index cards : on blue index cards were ideas that could be implemented with the existing operating system as a further development. This became System 7 in "Project Blue" 1991 . Ideas for a new next-generation operating system that had to be rewritten were written on pink index cards. This later became TalAE in “Project Pink”, but it did not contain a stable kernel. All ideas that were considered realistic for the next generation but one at the earliest were written on red index cards. These ideas were taken up again after the end of “Star Trek” in the “Raptor” project - the actual “Project Red”.

"Raptor" was stopped after a year because Apple lacked both the financial and human resources.

Copland project (1994–1997)

Copland was the project name for a completely rewritten operating system from Apple , which should succeed System 7 ; instead, the latter was further developed to Mac OS 8 . The project was named after the contemporary composer Aaron Copland . Apple planned to equip the first PowerPC- based Macintosh computers with the Copland operating system in 1994 . The goal was a system that is based on a microkernel (Apple likes to call it a nanokernel) and that finally masters preemptive multitasking and memory protection . The whole system should be multi-user capable and, unlike System 7, work natively on the PowerPC processor.

Copland was launched in March 1994. Initially, a release date was planned for late 1995, which was later postponed to mid-1996 and late 1997. In November 1995 a beta version for software developers was released. The Copland development, on which around 500 developers were working and which cost more than 250 million dollars in total, was not finished at this point and hopelessly behind schedule. Apple had to put off Macintosh users and developers with the aged System 7. At the same time, Microsoft enjoyed great success with Windows 95 , and the first serious Linux distributions appeared on the market. Inspired by Microsoft's amalgamation of MS-DOS and Windows 3.11 to form Windows 95, which took less than a year to develop, Apple decided in 1997 to stop Copland and move as many functions as possible into a revised System 7 integrate. The first innovations from the Copland project were already incorporated into version 7.6 of Mac OS. Many more have been integrated into Mac OS 8.0.

MkLinux (1996-1999)

The Research Institute of the Open Software Foundation (OSF) created a Mach 3.0 microkernel based on Linux for the Intel 486 architecture. Because Apple still lacked a modern operating system, the company sponsored the development and ported MkLinux to the Power Macintosh platform. In May 1996 Apple released "MkLinux Developer Release 1" for the Power Macintosh. It was not until 1999 that Apple withdrew from MkLinux development.

During the development of Rhapsody and then finally Mac OS X (see section “Development of Mac OS X” ), the existing Mach 2.5 kernel from OPENSTEP was also updated to Mach 3 - and improved with parts of the Mach 3 from MkLinux. MkLinux was a not insignificant preparatory work for the modernization of OPENSTEP and thus the development of Mac OS X.

Gershwin project (1997)

After Copland was discontinued, the operating system project "Gershwin" was started at Apple. It was supposed to correct what had gone wrong at Copland as part of a new development. However, Gershwin was nothing more than a project name and an idea, because there was no real development.

In retrospect, however, Copland can be seen as the idea for Mac OS 8 and Gershwin as the idea for Mac OS 9, since some of the functions that were intended have found their way into the real operating systems with these designations.

Macintosh Clones (1994-1996)

In December 1994, the then CEO Michael Spindler opened a market for authorized Macintosh clones. The contract stipulated that other manufacturers could sell Macintosh-compatible computers that could run System 7. The hope was that through the sale of cheaper “ Mac Clones ” the sales figures would increase further. Under the contract, Apple earned a flat rate of $ 50 with every clone sold. However, it did not work out because, on the one hand, the now competitive PC operating system Windows 95 came onto the market in 1995 - and Apple no longer offered the only easy-to-use graphical user interface with System 7 - and, on the other hand, the clones resulted in lower sales in their own market . In 1995 4.5 million Macs were sold, down from 4 million in 1996 and 2.8 million in 1997.

In January 1997, NeXT was acquired by Apple and Steve Jobs was appointed as interim CEO. One of his first activities was to end the cloning program. Since Apple had control of the operating system, it was renamed Mac OS 7.6 from version 7.6 and attempts were made to limit the clones to the low-priced segment under $ 1,000 and to increase the license costs per PC sold. When the Macintosh clone manufacturers did not accept the new conditions, the planned Mac OS 7.7 was quickly released as Mac OS 8.0 . That suddenly ended the market for Macintosh clones, as the contract specifically licensed "System 7" (including Mac OS version 7, including Mac OS 7.6).

Mac OS (1997-2001)

The reason why the successor to System 7.5.5 was renamed " Mac OS 7.6 " are the Macintosh clones and the changed strategy at Apple that became apparent from the end of 1996: users should associate the system more with Apple than before - even if you used a clone from another manufacturer. The contract with the Macintosh clone manufacturers is also the reason why Mac OS 8.0 came onto the market so early. In fact, Mac OS is a further version of “System”, “System Software” or “Macintosh System Software” - from version 7.6 onwards, however, with developments from the never completed Copland operating system , which were integrated into the existing “system” after its end.

Since Apple was already working on the successor operating system, the transfer of Copland technology in versions 8.0 to 9.2.2 was consistently continued. This and the porting of new developments (such as CarbonLib and the better integration into the Classic environment) paved the way for Apple's next operating system incarnation, which was also to be called “Mac OS”: Mac OS X.

Acquisition of a successor operating system

At Apple, sales continued to decline until the end of 1996. Industry insiders knew that Apple had little time, as System 7 was hopelessly out of date and the PC with Windows 95 was technically superior and commercially more successful.

After Apple failed to replace its outdated operating system with its own new development, the management feverishly looked for a modern alternative that they either wanted to license or buy. In addition to BeOS , which was soon to become a favorite, Windows NT 4.0 was also considered. Even the revival of TalOS ( Project Pink ) was considered. At the same time, the programmers were given the task of transferring as many functions of the failed Copland operating system as possible to Mac OS.


The Be Incorporated was actually occurred as a manufacturer of hardware and operating system had together with the BeBox designated personal computers with PowerPC - architecture sold. But the real value of the company wasn't the BeBoxes, but the operating system: BeOS already ran on Apple's Power Macs and offered everything that Apple had wanted to achieve with Copland; it was technically up to date and already fully functional.

When Apple entered into negotiations with Be Inc. to buy BeOS, Jean-Louis Gassée , then CEO of Be, was very sure that Apple - economically with its back to the wall - would have no other option than BeOS to buy. He drove the price up because he had something Apple badly needed.

For Apple, however, BeOS was not complete; if only because there was no compatibility with existing Macintosh applications. One result of the efforts to establish this compatibility is SheepShaver : a virtualization environment or a PowerPC emulator for BeOS, which made it possible to virtualize the classic system from 7.5.2 on BeOS or to emulate it on non-PowerPC architectures and existing ones Applications can therefore continue to be used.

Ultimately, there was no agreement on the price of BeOS. Apple looked for new options and found them in Apple co-founder Steve Jobs and his new company NeXT . Be Inc. came away empty-handed and was finally dissolved, its intellectual property passed to Palm Inc., which has since been bought and dissolved itself.


NeXTSTEP screenshot

NeXT , the computer and software company founded by Steve Jobs , had a working modern operating system and initially sold it together with hardware, later as a pure software product individually, but was unsuccessful in the market. Apple, on the other hand, had a loyal customer base but no modern operating system. After Steve Jobs phoned Gil Amelio and reportedly advised him not to use BeOS, both companies agreed on a takeover of NeXT by Apple. This was announced in December 1996 and implemented in early 1997. Steve Jobs himself first became an advisor to Gil Amelio, and shortly afterwards became interim CEO of Apple.

In addition to the revised computer designs heralded by the new CEO, such as the iMacs (1998) and the iBooks (1999), work was immediately carried out on converting the NeXT operating system, the original NeXTStep, renamed OPENSTEP from version 4 in 1996, into the Mac OS successor .

Mac OS X development

Rhapsody (1997-2000)

The OPENSTEP operating system , which was called NeXTStep up to version 3.3 from 1995, was further developed under the project name “ Rhapsody ” . With OPENSTEP, Apple received the long-awaited stable Mach kernel and was able to achieve some of the goals aimed at in the Copland project on the basis of Rhapsody.

When Mac OS 8 was released, Rhapsody was already being worked on. The new on BSD based operating system had first to the PowerPC - architecture of the Macintosh to be ported. Originally it was supposed to keep the typical NeXTStep look, but then got the look of Mac OS 8 in the Platinum design.

Apple had big plans for Rhapsody: As early as January 1997, Apple announced the upcoming operating system as the successor to Mac OS 7.6 and assumed that Mac OS users would migrate directly to Rhapsody. In May 1997, Apple turned to developers: Software programmed for Rhapsody can be compiled for other operating systems without any problems if the underlying OPENSTEP- compatible framework " Yellow Box " is installed.

Yellow Box was the programming interface (API) that was taken over from OPENSTEP and developed from NeXTstep together with Sun Microsystems as OpenStep. With GNUstep there was already an implementation of the OpenStep interface for Linux, while Sun had ported OpenStep to Solaris. However, since Sun had developed its own cross-platform interface with Java, the end of OpenStep on Solaris was in sight. Since NeXT had already ported OpenStep to Windows itself, Yellow Box in a Windows version was also given to developers during the Rhapsody development, who could use it to develop their programs for both Rhapsody and Windows.

Rhapsody as the operating system should appear both for Apple's own PowerPC-based computers and for Intel PCs. Because native applications are programmed first had, included Rhapsody one hand, already known from OPEN STEP programs, on the other hand variant PowerPC was a than in the blue box called Virtual Machine supplied, which was intended for a virtualized running Mac OS 8 for existing Macintosh applications. The blue box was missing on the Intel version.

In 1998 this open multi-platform strategy was finally coming to an end. Apple had to accept the real facts that the announced operating system was not accepted on the market in this form. On the one hand, the Yellow Box API contained the Display Postscript taken over from OpenStep, which had to be licensed by Adobe. The cost of several thousand dollars per license stood in the way of an inexpensive multi-platform API that Yellow Box was supposed to be. On the other hand, the manufacturers of software written for the Macintosh were not ready to completely reprogram their programs for Rhapsody. Switching from the Macintosh API to the Yellow Box API was tantamount to a radical system change, for which large parts of the existing source code would have had to be rewritten. From this point of view, Rhapsody was actually another NeXTStep or OPENSTEP, which only had the appearance and the desktop in common with Mac OS. Thirdly, there was no real market for the Rhapsody operating system on PCs, as almost all newly sold PCs came with a Windows operating system for good reason. Due to the Microsoft contracts, PC sellers were bound to pay license costs to Microsoft with every PC sold - even if a different operating system, e.g. B. Rhapsody, would have been sold pre-installed. Rhapsody was finished as "Rhapsody 1.0" for the processor architectures PowerPC and Intel, but the publication was literally canceled at the last moment.

Apple gave in to pressure from third-party manufacturers to create a programming interface compatible with Mac OS applications for the upcoming operating system. As a consequence, the product name "Rhapsody" and the Yellow Box were discarded for other platforms. Steve Jobs announced at MacWorld on July 8, 1998 that Rhapsody would be released as Mac OS X Server 1.0 exclusively for the Power Macintosh - and as a pure server operating system.

Because Apple was still unable to offer a complete, modern desktop operating system in 1998, all existing developments and technologies were integrated as well as possible into the existing classic Mac OS operating system. In order to bridge the time until the completion of the successor operating system Mac OS X - "Mac OS Version 10" - the classic Mac OS was refined further, but new developments were also incorporated in preparation. So was u. a. CarbonLib made available for Mac OS version 8.1 or higher, the “old” operating system improved with parts of the Copland kernel from Mac OS 8.5 and the keychain known from OPENSTEP was integrated in Mac OS 9. Sherlock introduces the search function developed for Copland in Mac OS 8.5, later also in Mac OS X 10.2 . (On Mac OS X Tiger , Spotlight replaced search with Sherlock.)

Meanwhile, Mac OS X was being worked on at full speed.

Mac OS X (2000-2012)

The development of Mac OS X arose as a result of the failure of Rhapsody and began in 1998. The name for the new operating system makes it clear that it is a Mac OS.

With the Blue Box , Rhapsody offered the possibility of using existing Mac OS applications on the new operating system, but these did not benefit from the advantages of the modern kernel (memory protection, preemptive multitasking), since they were actually based on a virtualized classic Mac OS was running. Since porting the existing programs to the Yellow Box would have meant too much effort, Apple was forced to port the Macintosh programming interface to Mac OS X: it was called Carbon and contained all those Macintosh API calls that did not include memory protection and preemptive multitasking Stood away. With Carbon, existing applications only had to be modified slightly in order to benefit from the modern kernel from Rhapsody, which was renamed XNU . The porting effort of existing Macintosh applications was kept within limits and also made it possible for Apple to integrate existing programs into Mac OS X. So were QuickTime and the Finder on Mac OS X Carbon programs, while new developments such as iTunes and Safari in the of Yellow Box in Cocoa written renamed new API.

So that programs adapted to the Carbon API did not only run on Mac OS X, Carbon was also ported to Mac OS 8.1 in the form of the CarbonLib, so that the new interface (which differs in details from the Macintosh API) also works for classic Mac OS applications could be used. Applications that ran on both Mac OS X and classic Mac OS with CarbonLib were called "carbonized applications", which roughly translates as "carbonized applications". CarbonLib, however, required a PowerPC processor, as did Mac OS itself from version 8.5. Applications for the 68k processor rely on the classic Macintosh API and continue to run on Mac OS up to the last version 9.2.2 in a transparent emulation.

The X in the name of Mac OS X showed both - as a Roman number for 10 - the successor to Mac OS 9 and the compatibility with it, as well as the new unix-like character of the new generation of operating systems ("Uni x "). With Developer Preview 3 (January 2000) Aqua , a newly written graphical user interface based on ideas from OPENSTEP , was introduced. This created an unmistakable, independent look and feel that still characterizes Mac OS X today. In the course of this, the expensive display postscript was replaced by the free display PDF .

The kernel of Mac OS X is XNU , which on the one hand alludes to Unix (" X  is N ot U nix "), on the other hand it can be interpreted as "Mac OS  X Nu Kernel" - because Apple had tried with the NuKernel in the Copland project , to develop a Mach-3-based modern microkernel yourself. XNU was now a stable microkernel, but was still based on Mach 2.5 under OPENSTEP. During the Rhapsody development, the Mach 3 concept was adopted for the kernel, but not completely, which makes XNU a hybrid kernel based on the FreeBSD kernel. In addition, the user land has been updated from 4.3BSD-Reno under OPENSTEP to 4.4BSD-Lite under Rhapsody. For Mac OS X, because it is based directly on Rhapsody, the only difference is that the kernel has been given the name XNU and Carbon is a Macintosh API.

For the first time, Apple published the part, which is open source, as a separate project under the name Darwin . The hope was that independent and free developers would be found who would work on the basis of the operating system, from which Mac OS X would ultimately also benefit. However, only a few of the early Darwin versions were released as a distribution, most of which had to be installed under Mac OS and which were only available from Apple for the PowerPC. However, Darwin has remained the core for Mac OS X and the iOS based on it .

The Blue Box has also been further developed and integrated into Mac OS X as a classic environment . However, no Mac OS operating system was included, so that an existing (pre-installed) must be used or a separately purchased Mac OS 9 must be installed in order to be able to use the Classic environment.

On September 13, 2000, Apple released the public beta of Mac OS X, which was now version number 10.0. This should clarify the successor to Mac OS 9. On May 24, 2001, the final version was finally released as Mac OS X 10.0 , codenamed "Cheetah."

At the end of 2000, the first Power Macs were shipped with Mac OS 9 and Mac OS X 10.0 preinstalled , but Mac OS 9 remained the standard operating system. As of 2001, with Mac OS X 10.0.3, Mac OS X was the standard system. A supplied Mac OS 9.1 or 9.2 could be installed by the user. The last version of the classic Mac OS was version 9.2.2.

The Classic environment is included up to Mac OS X Tiger (10.4, 2005; 10.4.11 is the last update at the end of 2007). In contrast to the Blue Box, the windows of the “classic” Mac OS programs running under this system can be moved freely, the desktop background of the Mac OS is hidden. This compatibility environment also enables the execution of 68k programs because this option is included as a transparent emulation in Mac OS for PowerPC and also works in virtualization. The Classic environment could only be used on PowerPC-based Macs and was discontinued with Mac OS X Leopard (10.5, 2007).

Mac OS X has also been UNIX certified since Leopard .

OS X (2012-2016) and macOS (from 2016)


With Lion (10.7; from 2011), the last version (10.7.5) of the new generation of operating systems was published in October 2012 with “Mac OS” in the original spelling in full name. This has already been advertised as "OS X Lion". Its successor Mountain Lion (10.8; from July 2012) was officially called "OS X" - the "Mac" in the name was omitted.


Mac OS X from version 10.4 (Tiger, 2005) forms the basis for Apple's Apple TV , which was created in 2006, and the mobile systems iPhone , iPod , iPad and Apple Watch : tvOS (from 2006), iOS and iPadOS (from 2007 and 2019) and watchOS (from 2014). In accordance with their names, the operating system for computers has been called "macOS" since 2016 from version 10.12 .

Web links

Wikibooks: Mac OS Compendium  - Learning and Teaching Materials

Individual evidence

  2. Ten years of Mac OS X - the best of both worlds ; Retrieved July 10, 2016.
  3. a b Mac OS X - History ,, accessed: July 20, 2010
  4. Owen W. Linzmayer: Apple Confidential 2.0: The Definitive History of the World's Most Colorful Company . No Starch Press, 2004, ISBN 978-1-59327-010-0 , chap. 19 , p. 229–232 ( [accessed October 3, 2017]).
  5. Amit Singh: Mac OS X Internals: A Systems Approach . Addison-Wesley Professional, 2006, ISBN 978-0-13-270226-3 , pp. 2 ( full text in Google Book Search).
  6. a b Apple’s Copland Project: An OS for the Common Man , Tom Hormby, November 8, 2005,, accessed: July 21, 2010
  7. Hopeful project: Copland , APPLE HISTORY - CHAPTER # 10, - PAGE 2,, accessed: July 21, 2010
  8. Amit Singh: Mac OS X Internals: A Systems Approach . Addison-Wesley Professional, 2006, ISBN 978-0-13-270226-3 , pp. 1680 ( limited preview in Google Book search).
  9. Low End Mac: Apple Squeezes Mac Clones Out of the Market , Dan Knight, January 25, 2014, accessed October 22, 2015
  10. Low End Mac: System 7.5 and Mac OS 7.6: The Beginning and End of an Era , Tyler Sable, June 27, 2014, accessed October 22, 2015
  11. Christian Persson: Apple buys Next - Steve Jobs returns. In: Heise online . December 21, 1996 . Retrieved March 9, 2016.
  12. Carsten Meyer: Apple builds on Mach kernel. In: Heise online . February 3, 1997 . Retrieved March 9, 2016 .; Quote: "The hesitation in choosing the kernel clearly shows that Apple was probably mainly interested in OPENSTEP's object technology when purchasing Next Inc.".
  13. ^ Cocoa and the Death of Yellow Box and Rhapsody (English); accessed on May 24, 2016.