The Mac OS operating system originated in 1984 with the introduction of the Macintosh personal computer. It was one of the first operating systems to use a graphical user interface. Early versions of Mac OS could only run one application at a time and had limited folder support. Over time, Mac OS added features like color support, larger displays, internal hard drives, and networking capabilities as new Mac models were released.

1. History of Mac OS
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Apple marketed its operating system software as "Mac OS", beginning in 1997.
On January 24, 1984, Apple Computer, Inc. (now Apple Inc.) introduced the Macintosh
personal computer, with the Macintosh 128K model, which came bundled with the Mac
OS operating system, then known as the System Software.[citation needed] 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 at Apple retail stores, and online. 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.
Contents
[hide]
• 1 Early history
o 1.1 Development
o 1.2 Release
• 2 System 1, 2, 3 & 4
• 3 System Software 5
• 4 System Software 6
• 5 System 7
o 5.1 Mac OS 7.6
o 5.2 Version history
• 6 Mac OS 8
• 7 Mac OS 9
• 8 Mac OS X

2. • 9 Timeline
• 10 See also
• 11 Notes
• 12 Further reading
• 13 External links
[edit] Early history
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[edit] 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.[citation needed]
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.
Unlike the IBM PC, which used 8 kB of system ROM for power-on self-test (POST) and
basic input/output system (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

3. Macintosh, that it quickly outshone 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.
[edit] Release
Original 1984 Mac OS desktop
The first version of the Mac OS (simply called System) 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 entirely graphical user
interface. Additional to the system kernel is the Finder, an application used for file
management, which also displays the Desktop. The two files were contained in a folder
directory labeled System Folder, which contained other resource files, like a printer
driver, needed to interact with the System.
[edit] System 1, 2, 3 & 4
System Software 0.1

4. System Software 0.3/0.5
System Software 0.7
System Software 2.0.1
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 additional 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.[1]
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
System Finder LaserWriter
Software Release Date[2] Release Information[2]
Version[2] Version[2] Version[2]
Release[2]
Mac System January 24[citation
1.0 (.97)[3] needed] 1.0 Initial Release
Software , 1984
Maintenance Release, Added
Mac System 1.1[citation May 5[citation needed],
needed] 1.1g Mountain scene, About box,
Software (0.1) 1984
Clean Up Command
Mac System 2.0 April 1985[citation 4.1 Finder Update

5. Software (0.3 needed]
& 0.5)
System
software[3] September Release for Hard Disk 20
2.1[3] 5.0[4][5]
1985[3] support[3][4][5]
[4] [5]
Mac System January Introduced with Mac Plus[citation
3.0 5.1 1.1[citation needed]
Software (0.7) 1986[citation needed] needed]
System February
3.1 5.2 1.1
Software 1.0 1986[citation needed]
Fixed problems with data loss,
System February[citation
3.2 needed] 5.3 3.1 system crashes; updated Chooser
Software 1.1 1986
and Calculator.[citation needed]
System
3.3 January 1987 5.4 3.1 Release for Macintosh II and SE
Software 2.0
System Release for Macintosh 512Ke
3.4[6] 6.1[6]
software[6] AppleShare 2.0 support[6]
System March 1987[citation
4.0 needed] 5.4 3.3 Introduced AppleShare[citation needed]
Software 2.01
Maintenance Release of System
System April 1987[citation
4.1 needed] 5.5 4.0 Software. Updated LaserWriter
Software 2.01
Driver
[edit] 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, and thus stick 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 was available for a very short time and only in some countries,
including the United States.
System
System Release Finder MultiFinder LaserWriter
Software Release Information[2]
Version[2] Date[2] Version[2] Version[2] Version[2]
Release[2]
1987
5.0 4.2 6.0 1.0 5.0 Initial Release
circa
5.1 4.3 1988 6.0 1.0 5.1 Updated LaserWriter

6. Driver and new version of
circa
Apple HD SC Setup
[edit] System Software 6
System Software 6.0.8
Main article: System 6
System Software 6 (also referred to simply as System 6) was a consolidation release of
the Mac OS, producing a complete, stable, and long-lasting operating system. Two major
hardware introductions requiring additional support under System 6 were 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
confusion caused by the often considerable differences between earlier Systems.[7]
System Finder MultiFinder LaserWriter
Release Date[2] Release Information[2]
Version[2] Version[2] Version[2] Version[2]
April, 1988[citation
6.0 needed] 6.1 6.0 5.2 Initial Release
September
Release for Macintosh IIx
6.0.1 19[citation needed], 6.1.1 6.0.1 5.2
(1988)
1988
Late 1988[citation
6.0.2 needed] 6.1 6.0.1 5.2 Maintenance Release
March 7[citation Release for Macintosh IIcx
6.0.3 needed] 6.1 6.0.3 5.2
, 1989 (1989)
September
Release for Macintosh
6.0.4 20[citation needed], 6.1.4 6.0.4 5.2
Portable and IIci (1989)
1989
March 19[citation Release for Macintosh IIfx
6.0.5 needed] 6.1.5 6.0.5 5.2
, 1990 (1990)
October 15[citation Not released because of
6.0.6 needed] 6.1.6 6.0.6 5.2
, 1990 AppleTalk bug [8]
Official release for
October 16[citation
6.0.7 needed] 6.1.7 6.0.7 5.2 Macintosh LC, IIsi and
, 1990
Classic (1990)
6.0.8 April, 1991[citation 6.1.8 6.0.8 7.0 Updated printing software to

7. needed] match software of System
7.0
Late 1991/Early 6.1.8[citation Limited maintenance release
6.0.8L 6.0.8[citation needed] 7.0[citation needed]
1992[citation needed] needed]
for Pacific customers
[edit] System 7
The neutrality of this section is disputed. Please see the discussion on the talk
page. Please do not remove this message until the dispute is resolved. (December
2007)
Main article: System 7
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 page swapping 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 to the Motorola 68030 CPU. 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[9]
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. The original Macs used the Motorola 68000 CPU which could address only 16
MB of memory. 24 Bits is all that is needed to address the 16MB memory space. This
was a hardware limitation, not a system software design fault. The 68020/68030/68040
CPUs have 32-bit address buses and can address up to 4 GB of physical memory. As
Apple moved to the 68030 CPU it needed to allow the use of more than 16 MB of
memory. Thus the transition to 32-bit clean ROMs and software had to be implemented.
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"

8. 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.[citation needed] 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 (which can be turned off), 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.
[edit] Mac OS 7.6
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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.
[edit] Version history
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challenged and removed. (June 2008)
• System 7.0 (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

9. • 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 7.1.2P (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 6400/200)
• 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 7.1P
• System 7.1P1
• System 7.1P2
• System 7.1P3 (last release with new features)
• System 7.1P4
• System 7.1P5
• System 7.1P6
[edit] Mac OS 8
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Main article: Mac OS 8

10. 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's goal of terminating third-party manufacturers' licenses to
System 7 and shutting down the Macintosh clone market.[citation needed] 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.[citation needed]
Mac OS 8.1 saw the introduction of an updated version of the Hierarchical File System
called HFS Plus, which fixed many of the limitations 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

11. • Mac OS 8.6 (included a new nanokernel for improved performance and
Multiprocessing Services 2.0 support, added support for the PowerPC G4
processor)
[edit] Mac OS 9
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article by adding citations to reliable sources. Unsourced material may be
challenged and removed. (June 2008)
Main article: Mac OS 9
Mac OS 9 was released on October 23, 1999. It was generally a steady evolution from
Mac OS 8. Early development releases of Mac OS 9 were numbered 8.7. Mac OS 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.
Mac OS 9 also added some transitional technologies to help application developers adopt
some Mac 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 Mac OS X as well. Other
changes were made in Mac OS 9 to allow it to be booted in the "classic environment"
within Mac OS X. This is a compatibility layer in Mac OS X (in fact a Mac OS X
application, originally codenamed 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
Mac OS 8/9 appearance and do not gain the Mac 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
[edit] Mac OS X

12. Main article: History of Mac OS X
Mac OS X (pronounced /mæk oʊ ɛs tɛn/)[10] is the line of graphical operating systems
developed, marketed, and sold by Apple Inc. which succeeded the original Mac OS,
which had been Apple's primary operating system since 1984. Unlike the earlier
Macintosh operating system, Mac OS X is a Unix-based operating system[11] built on
technology developed at NeXT from the second half of the 1980s until early 1997, when
Apple purchased the company.[12]
The first version was Mac OS X Server 1.0 in 1999, which retained the earlier Mac
operating system's "platinum" appearance and even resembled OPENSTEP in places. The
desktop-oriented version, Mac OS X v10.0, followed in March 2001 sporting the new
Aqua user interface. Since then, six more distinct "end-user" and "server" versions have
been released, most recently Mac OS X v10.5 in October 2007. Releases of Mac OS X
are named after big cats. For example, Apple calls Mac OS X v10.5 "Leopard," while its
previous release was called "Tiger."
Versions of Mac OS X:
• 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)
• Mac OS X v10.6 (Snow Leopard)
[edit] Timeline