On January 24, 1984, Apple Computer, Inc. (now Apple Inc.) introduced the Apple Macintosh personal computer, with the Macintosh 128K model, which came bundled with the Mac OS operating system, then known as the System Software. The Macintosh is often credited with popularizing the graphical user interface. The Mac OS has been pre-installed on almost every Macintosh computer ever sold. The operating system is also sold separately from the computer. The original Mac OS was partially based on the Lisa OS, previously released by Apple for the Lisa computer in 1983 and, as part of an agreement allowing Xerox to buy shares in Apple at a favourable rate, it also used concepts from the Xerox PARC Xerox Alto which Steve Jobs and several other Macintosh team members had previewed.

Early history

Development

The Macintosh project started in early 1979 with Jef Raskin, who envisioned an easy-to-use, low-cost computer for the average consumer. In September 1979, Raskin was given permission to start hiring for the project and was, in particular, looking for an engineer that could put together a prototype. Bill Atkinson, a member of the Apple Lisa team, introduced him to Burrell Smith, a service technician who had been hired earlier that year.

In January 1981, Steve Jobs completely took over the Macintosh project. Jobs and a number of Apple engineers visited Xerox PARC in December 1979, three months after the Lisa and Macintosh projects had begun. After hearing about the pioneering GUI technology being developed at Xerox PARC from former Xerox employees like Raskin, Jobs negotiated a visit to see the Xerox Alto computer and Smalltalk development tools in exchange for Apple stock options. The final Lisa and Macintosh operating systems mostly used concepts from the Xerox Alto, but many elements of the graphical user interface were created by Apple including the menubar and pop-up menus. The click-and-drag concept was developed by Jef Raskin.

Unlike the IBM PC, which used 8 kB of system ROM for power-on self-test (POST) and basic input/output chores (BIOS), the Mac ROM was significantly larger (64 kB) and held key OS code. Much of the original Mac ROM was coded by Andy Hertzfeld, a member of the original Macintosh team. He was able to conserve some of the precious ROM space by interleaving some of the assembly language code. In addition to coding the ROM, he also coded the kernel, the Macintosh Toolbox and some of the desktop accessories (DAs) as well. The icons of the operating system, which represented folders and application software were designed by Susan Kare, who later designed the icons for Microsoft Windows 3.0. Bruce Horn and Steve Capps wrote the Macintosh Finder as well as a number of Macintosh system utilities.

Apple was very strong in advertising their newfound machine. After it was created, the company bought all 39 pages of advertisement space in the Newsweek magazine, 1984 November/December edition. Apple was so successful in its marketing for the Macintosh, that it quickly outshined its more sophisticated predecessor, the Lisa, in sales – so much so that Apple quickly developed a product called MacWorks which allowed the Lisa to emulate Macintosh system software through System 3, by which time it had been discontinued as the re-branded Macintosh XL. Many of Lisa's operating system advances would not appear in the Macintosh OS until System 7.

Release

Original 1984 Mac OS desktop

The first version of the Mac OS is easily distinguished between other operating systems from the same period because it does not use a command line interface; it was one of the first operating systems to use an completely graphical user interface. Additional to the system kernel is the Finder, an application used for file management, that also displays the Desktop.

These releases could only run one application at a time, though special application shells such as Switcher (discussed under MultiFinder) could work around this to some extent. System 1.0, 1.1, and 2.0 used a flat file system with only one kludged level of folders, called Macintosh File System (MFS); its support for folders (subdirectories) was incomplete. System 2.0 added support for AppleTalk and the newly introduced LaserWriter to use it. System 2.1 (Finder 5.0) introduced the HFS (Hierarchical File System) which had real directories. This version was specifically to support the Hard Disk 20 and only implemented HFS in RAM, startup and most floppy disks remained MFS 400K volumes. System 3.0 was introduced with the Mac Plus, officially implementing HFS and 800K startup drives and adding support for several new technologies including SCSI and AppleShare and introducing Trash "bulging" (i.e., when the Trash contained files, it would gain a bulged appearance). System 4.0 came with the Mac SE and Macintosh II, which required extra support for the first expansion slots, the Apple Desktop Bus (ADB), internal hard drives and on the Mac II, color, larger displays and the first Motorola 68020 processor.

Changes in early Macintosh operating systems are best reflected in the version number of the Finder, where major leaps are found between 1.x, 4.x, 5.x, and 6.x.

System 1

Main Article: System 1.0

System 1.0 (actually 0.97), Finder 1.0 (January 1984)

System 1.1, Finder 1.1g (May 1984)

System 2

System 2.0, Finder 4.1 (April 1985)

System 2.1, Finder 5.0 (September 1985)

System 3

System 3.0, Finder 5.1 (January 1986)

System 3.2, Finder 5.3 (June 1986)

System 3.3, Finder 5.4 (January 1987)

System 3.4, Finder 6.1

System 4

System 4.0, Finder 5.4 (March 1987)

System 4.1, Finder 5.5 (April 1987)

System Software 5

System Software 5 (also referred to as simply System 5) added MultiFinder, an extension which let the system run several programs at once. The system used a co-operative multitasking model, meaning that time was given to the background applications only when the running application yielded control. A clever change in system functions that applications were already calling to handle events made many existing applications share time automatically. Users could also choose to not use MultiFinder, andthereforestick with using a single application at a time as in previous releases of the system software.

System Software 5 was also the first Macintosh operating system to be given a unified "Macintosh System Software" version number, as opposed to the numbers used for the System and Finder files.

System Software 5.0 (System 4.2, Finder 6.0, MultiFinder 1.0)

System Software 5.1 (System 4.3, Finder 6.0, MultiFinder 1.0)

System Software 5 was available for a very short time and only in some countries, including the United States.

System Software 6

Main article: System Software 6
System Software 6 running two applications and a desktop accessory.

System Software 6 (also referred to as simply System 6) was a consolidation release of the Mac OS, producing a complete, stable, and long-lasting operating system. Two major hardware introductions requiring extra support under System 6 were the the 68030 processor and 1.44MB SuperDrive debuting with the Macintosh IIx and Macintosh SE/30. Later it would include support for the first specialized laptop features with the introduction of the Macintosh Portable. From System 6 forward, the Finder would have a unified version number closely matching that of the System, alleviating much of the perplexity caused by the often considerable differences between earlier Systems.

System Software 6.0 (System 4.4, Finder 6.1, MultiFinder 1.1 - the version numbers of the System and MultiFinder files were changed to 6.0 just before the public release)

System Software 6.0.1

System Software 6.0.2

System Software 6.0.3

System Software 6.0.4

System Software 6.0.5

System Software 6.0.6

System Software 6.0.7

System Software 6.0.8 (indistinguishable to System 6.0.7, but configured with System 7.0 printing software for printer sharing with System 7)

System Software 6.0.8L (only for Macintosh Classic, Classic II, PowerBook 100, Macintosh LC, LC II)

System 7

Main article: System 7
Screenshot of System 7.5.3 Revision 2

On May 13, 1991 System 7 was released. It was the second major upgrade to the Mac OS, adding a significant user interface overhaul, new applications, stability improvements and many new features. Its introduction coincided with the release of and provided support for the 68040 Macintosh line.

Perhaps the most significant feature of System 7 was virtual memory support, which previously had only been available as a third-party add-on. Accompanying this was a move to 32-bit memory addressing, necessary for the ever-increasing amounts of RAM available. Earlier versions of Mac OS had used the lower 24 bits for addressing, and the upper 8 bits for flags. This had been an effective solution for earlier Macintosh models with very limited amounts of RAM, but it became a liability later. Apple described code that assumed the 24 + 8-bit addressing as being "not 32-bit clean", and most such applications would crash when 32-bit addressing was enabled by the user.

One notable System 7 feature was the built-in co-operative multitasking. In System Software 6, this function was optional through the MultiFinder. System 7 also introduced aliases, similar to shortcuts that were introduced in later versions of Microsoft Windows. System extensions were enhanced, by being moved to their own subfolder; a subfolder in the System Folder was also created for the control panels. In System 7.5, Apple included the Extensions Manager, a previously third-party program which simplified the process of enabling and disabling extensions.

The Apple menu, home only to desk accessories in System 6, was made more general-purpose: the user could now make often-used folders and applications - or anything else they desired - appear in the menu by placing aliases to them in an "Apple Menu Items" subfolder of the System Folder. AppleScript, a scripting language for automating tasks, was also introduced with System 7. 32-bit QuickDraw, supporting so-called "true color" imaging, was also included as standard; it was previously available as a system extension. TrueType, an outline font standard, was also introduced with System 7.

The Trash, under System 6 and earlier, would empty itself automatically when shutting down the computer or, if MultiFinder were not running, when launching an application. System 7 reimplemented the Trash as a special hidden folder, allowing files to remain in it across reboots until the user deliberately chose the "Empty Trash" command.

System 7.1 was mainly a bugfix release, with a few minor features added. System 7.1 was not only the first operating system to cost money (all previous versions were free or sold at the cost of the floppies), but also received a "Pro" sibling with extra features. System 7.1.2 was the first version to support PowerPC-based Macs. System 7.1 also introduced the System Enablers as a method to support new models without updating the actual System file. This led to extra files inside the system folder (one per new model supported) that some users found unpleasing.

System 7.5 introduced a large number of "high level" additions, considered by some to be less well thought-out than they could have been. Many of the new features were based on shareware applications that Apple bought and included into the new system. On the newer PowerPC machines, System 7.5 was plagued by stability problems due partly to a new memory manager (that can be turned off, by the way), and poor OS handling of errors in PowerPC code (all PowerPC exceptions map to Type 11). These growing pains did not afflict the 68k-architecture machines.

Mac OS 7.6

Mac OS 7.6.1 performing various tasks.

Stability improved in PPC Macs with Mac OS 7.6, which dropped the "System" moniker as a more-trademarkable name was needed in order to license the OS to the growing market of third-party Macintosh clone manufacturers. Mac OS 7.6 required a 68030 CPU and 32 bit clean ROMs, and so dropped support for many of the early Macs, including the Mac Plus and Mac II. Mac OS 7.6.1 finally introduced proper error handling for PowerPC code, so that errors in PowerPC code did not always force an immediate reboot.

Although the version number was subsequently changed to 8.x and 9.x, the internal core of the OS (except the nanokernel, which was replaced by a new one that support Multiprocessing Services 2.x in Mac OS 8.6) remained basically the same.

Version History

System 7.0 (released in late 1991; integrated MultiFinder always enabled)

System 7.0.1 (introduced with LC II and Quadra series)

System 7 Tuner (update for both 7.0 and 7.0.1)

System 7.1

System 7.1 Pro (version 7.1.1, combined with PowerTalk, Speech Manager & Macintalk, Thread Manager)

System 7.1.2 (first version for Macs equipped with a PowerPC processor)

System 7.1.2 (only for Performa/LC/Quadra 630 series, very quickly replaced by 7.5)

System 7.5

System 7.5.1 (System 7.5 Update 1.0 - the first Macintosh operating system to call itself "Mac OS")

System 7.5.2 (first version for Power Macs that use PCI expansion cards, usable only on these Power Macs and PowerBooks 5300 and Duo 2300)

System 7.5.3 (System 7.5 Update 2.0)

System 7.5.3L (only for Mac clones)

System 7.5.3 Revision 2

System 7.5.3 Revision 2.1 (only for Performa 6400/180 and 6400/120)

System 7.5.4, released very briefly and withdrawn within hours. Replaced by 7.5.5

System 7.5.5 Last to support non-32 bit clean Macs, including all with less than a 68030 CPU.

Mac OS 7.6 (name formally changed because of the experimental clone program, although System 7.5.1 and later used the "Mac OS" name on the splash screen)

Mac OS 7.6.1 Proper PowerPC error handling introduced.

Performas used to have their own, exclusive operating system before they were merged into System 7.5.

System 7.0.1P

System 7.1P1

System 7.1P2

System 7.1P3 (last release with new features)

System 7.1P4

System 7.1P5

System 7.1P6

Mac OS 8

Main article: Mac OS 8
Mac OS 8.1 desktop

Mac OS 8 was released on July 26, 1997, shortly after Steve Jobs returned to the company. It was mainly released to keep the Mac OS moving forward during a difficult time for Apple. Initially planned as Mac OS 7.7, it was renumbered "8" to exploit a legal loophole to accomplish Jobs' goal of terminating third-party manufacturers' licenses to System 7 and shutting down the Macintosh clone market. 8.0 added a number of features from the stillborn Copland project, while leaving the underlying operating system unchanged. A multi-threaded Finder was included, enabling better multi-tasking. The GUI was changed in appearance to a new shaded greyscale look called Platinum, and the ability to change the appearance themes (also known as skins) was added with a new control panel. This capability was provided by a new "appearance" API layer within the OS, one of the few significant changes.

Apple sold 1.2 million copies of Mac OS 8 in its first two weeks of availability and 3 million within six months. In light of Apple's financial difficulties at the time, there was a large grassroots movement among Mac users to upgrade and 'help save Apple'. Even some pirate groups refused to redistribute the OS.

Mac OS 8.1 saw the introduction of an updated version of the Hierarchical File System called HFS Plus , which fixed many of the boundaries of the earlier system (HFS Plus continues to be used in Mac OS X). There were some other interface changes such as separating network features from printing (the venerable, and rather odd Chooser was at last headed for retirement), and some improvements to application switching. However, in underlying technical respects, Mac OS 8 was not very different from System 7.

Mac OS 8.5 focused on speed and stability, with lots of old 68k code replaced by modern code native to the PowerPC. It also improved the appearance on the system, although the theming feature was cut late in development.

Mac OS 8.0 (first version to require a 68040 processor, dropping support for the remainder of the Macintosh II series and other 68030 Macs)

Mac OS 8.1 (last version to run on a 68K processor, added support for USB on the Bondi iMac, added support for HFS+)

Mac OS 8.5 (first version to run only on a PowerPC processor, added built-in support for Firewire on the PowerMac G3)

Mac OS 8.5.1

Mac OS 8.6 (included a new nanokernel for improved performance and Multiprocessing Services 2.0 support, added support for the PowerPC G4 processor)

Mac OS 9

Main article: Mac OS 9

Mac OS 9 was released on October 23, 1999. It was typically a steady evolution from Mac OS 8. Early development releases of Mac OS 9 were numbered 8.7. MacOS 9 added improved support for AirPort wireless networking. It introduced an early implementation of multi-user support (though not considered a true multi-user operating system by modern standards). An improved Sherlock search engine added several new search plug-ins. Mac OS 9 also provided a much improved memory implementation and management. AppleScript was improved to allow TCP/IP and networking control. Mac OS 9 also made the first use of the centralized Apple Software Update to find and install OS and hardware updates. Other new features included its on-the-fly file encryption software with code signing and Keychain technologies, Remote Networking and File Server packages and much improved list of USB drivers.

OS 9 also added some transitional technologies to help application developers adopt some OS X features before the introduction of the new OS to the public, again easing the transition. These included new APIs for the file system, and the bundling of the Carbon library that apps could link against instead of the traditional API libraries - apps that were adapted to do this can be run natively on OS X as well. Other changes were made in OS 9 to allow it to be booted in the "classic environment" within OS X. This is a compatibility layer in OS X (in fact an OS X application, known in developer circles as "the blue box") that runs a complete Mac OS 9 operating system, so allowing applications that have not been ported to Carbon to run on Mac OS X. This is reasonably seamless, though "classic" applications retain their original OS 8/9 appearance and do not gain the OS X "Aqua" appearance.

Mac OS 9.0

Mac OS 9.0.2

Mac OS 9.0.3

Mac OS 9.0.4

Mac OS 9.1

Mac OS 9.2

Mac OS 9.2.1

Mac OS 9.2.2

Mac OS X

Main article: History of Mac OS X

While its name is similar to its predecessors from Apple, Mac OS X is largely independent. It is primarily based on a UNIX core known as Darwin, while older versions are based on a proprietary core (the same basic core was in use from System 1 up to Mac OS 9).

Versions of Mac OS X include:

Mac OS X v10.0 (Cheetah)

Mac OS X v10.1 (Puma)

Mac OS X v10.2 (Jaguar)

Mac OS X v10.3 (Panther)

Mac OS X v10.4 (Tiger)

Mac OS X v10.5 (Leopard)

Other

A/UX

Apple DOS

Apple GS/OS

Apple Lisa

Apple ProDOS

Apple SOS