Mac OS
Mac OS, which stands for
Macintosh
Operating
System, is a series of
graphical user interface-based
operating systems developed by
Apple Computer for their
Macintosh line of
computer systems. The Mac OS is often credited with popularizing the graphical user interface. It was first introduced in
1984 with the original
Macintosh 128K.
Apple deliberately played down the existence of the operating system in the early years of the Macintosh to help make the machine appear more
user-friendly and to distance it from other operating systems such as
MS-DOS, which were portrayed as arcane and technically challenging. Apple wanted Macintosh to be portrayed as a computer "for the rest of us". The term "Mac OS" didn't really exist until it was officially used during the mid-1990s. The term has since been applied to all versions of the Mac system software as a handy way to refer to it when discussing it in context with other operating systems.
Earlier versions of the Mac OS were compatible only with
Motorola 68000-based Macintoshes, while later versions were also compatible with the
PowerPC (PPC) architecture. Most recently, Mac OS X has become compatible with Intel's
x86 architecture.
The early Macintosh operating system initially consisted of two pieces of software, called "System" and "Finder", each with its own version number.
System 7.5.1 was the first to include the Mac OS logo (a variation on the original "Happy Mac"
smiley face Finder startup icon), and Mac OS 7.6 was the first to be named "Mac OS" (to ensure that users would still identify it with Apple, even when used in "clones" from other companies).
Until the advent of the later
PowerPC G3-based systems, significant parts of the system were stored in physical
ROM on the motherboard. The initial purpose of this was to avoid using up the limited storage of
floppy disks on system support, given that the early Macs had no
hard disk. (Only one model of Mac was ever actually bootable using the ROM alone, the 1991
Mac Classic model.) This architecture also allowed for a completely graphical OS interface at the lowest level without the need for a text-only console or command-line mode. A fatal software error, or even a low-level hardware error discovered during system startup (such as finding no functioning disk drives), was communicated to the user graphically using some combination of icons, alert box windows, buttons, a mouse pointer, and the distinctive Chicago bitmap font. Mac OS depended on this core system software in ROM on the motherboard, a fact which later helped to ensure that only Apple computers or licensed clones (with the copyright-protected ROMs from Apple) could run Mac OS.
The Mac OS can be divided into two families of operating systems:
* "Classic" Mac OS, the system which shipped with the first Macintosh in 1984 and its descendants, culminating with
Mac OS 9.
* The newer
Mac OS X (the "X" refers to the Roman numeral,
ten). Mac OS X incorporates elements of
OpenStep (thus also
BSD Unix and
Mach) and
Mac OS 9. Its low-level
BSD-based foundation,
Darwin, is
free software/
open source software.
"Classic" Mac OS (1984-2001)
 |
Original 1984 Mac OS desktop |
The "classic" Mac OS is characterized by its total lack of a
command line; it is a completely graphical operating system. Heralded for its ease of use, it is also criticized for its singletasking (in early versions) or
cooperative multitasking (in later versions), very limited
memory management, lack of
protected memory, and susceptibility to conflicts among "extensions" that extend the operating system, providing additional functionality (such as networking) or support for a particular device. Some extensions may not work properly together, or work only when loaded in a particular order. Troubleshooting Mac OS extensions can be a time-consuming process of
trial and error.
Mac OS originally used the
Macintosh File System (MFS), a
flat file system with only one level of folders. This was replaced by the
Hierarchical File System (HFS), which had a true
directory tree. Both file systems are otherwise compatible.
Most file systems used with DOS, Unix, or other operating systems treat a file as simply a sequence of bytes, requiring an application to know which bytes represented what type of information. By contrast, MFS and HFS gave files two different "forks". The data fork contained the same sort of information as other file systems, such as the text of a document or the bitmaps of an image file. The
resource fork contained other structured data such as menu definitions, graphics, sounds, or code segments. A file might consist only of resources with an empty data fork, or only a data fork with no resource fork. A text file could contain its text in the data fork and styling information in the resource fork, so that an application which didn't recognize the styling information could still read the raw text. On the other hand, these forks provided a challenge to interoperability with other operating systems; copying a file from a Mac to a non-Mac system would strip it of its resource fork.
The Classic OS is still supported and Classic Applications Support is shipped in addition to OS X with PowerPC (but not Intel) Macs as late as early 2006.
Mac OS X (2001-present)
Mac OS X brought Unix-style memory management and
pre-emptive multitasking to the Mac platform. It is based on the
Mach kernel and the
BSD implementation of
UNIX, which were incorporated into
NeXTSTEP, the
object-oriented operating system developed by
Steve Jobs's
NeXT company. The new memory management system allowed more programs to run at once and virtually eliminated the possibility of one program crashing another. It is also the second Macintosh operating system to include a command line (the first is the now-discontinued
A/UX, which supported classic Mac OS applications on top of a UNIX kernel), although it is never seen unless the user launches a
terminal emulator.
However, since these new features put higher demands on system resources, Mac OS X only officially supported the
PowerPC G3 and newer processors, and now has even higher requirements (the additional requirement of built-in
USB (
10.3) and later
FireWire (
10.4)). Even then, it runs somewhat slowly on older G3 systems for many purposes.
As of 2005, every update to Mac OS X since the original
public beta has had the atypical quality of being perceptibly more responsive than the version it replaced, the opposite to the trend of most operating systems. As noted by John Siracusa of
Ars Technica:
"For over three years now, Mac OS X has gotten faster with every releaseâ€"and not just "faster in the experience of most end users", but faster on the same hardware. This trend is unheard of among contemporary desktop operating systems."[
1]
This could, however, be attributed to the relative immaturity of the OS, and the speed gains have diminished as OS X has matured. Some reports regarding Mac OS X 10.4 suggested that it seemed similar to version 10.3 in responsiveness, or even slower at times.
Power PC builds of Mac OS X include a compatibility layer for running older Mac applications, the
Classic Environment. This runs a full copy of the older Mac OS, version 9.1 or later, in a Mac OS X process. PowerPC-based Macs ship with OS 9.2 as well as OS X. OS 9.2 must be installed by the userâ€"it is not installed by default on all new hardware revisions released after the release of Mac OS X 10.4. Most well-written "classic" applications function properly under this environment, but compatibility is only assured if the software was written to be unaware of the actual hardware, and to interact solely with the operating system. The Classic Environment does not work in the Intel version of OS X.
Users of the original Mac OS generally upgraded to Mac OS X, but a few criticized it as being more difficult and less user-friendly than the original Mac OS, for the lack of certain features that had not been re-implemented in the new OS, or for being slower on the same hardware (especially older hardware), or other, sometimes serious incompatibilities with the older OS. Because drivers (for printers, scanners, tablets, etc.) written for the older Mac OS are not compatible with Mac OS X, and due to the lack of OS X support for older Apple machines, a significant number of Macintosh users have continued using the older OS. By 2005, it is reported that almost all users of systems capable of running Mac OS X are doing so, with only a small percentage still running the classic Mac OS.
In June 2005,
Steve Jobs announced at his
Worldwide Developers Conference keynote that Apple computers would be transitioning from PowerPC to
Intel processors. At the same conference, Jobs announced Developer Transition Kits that included beta versions of Apple software including Mac OS X that developers could use to test their applications as they ported them to run on Intel-powered Macs. In January 2006, Apple released the first Macintosh computers with Intel processors, an
iMac and the
MacBook Pro, and in February 2006, Apple released a
Mac Mini with an Intel Core Solo and Duo processor. Continuing the trend of switching Apple's entire product line to the Intel chip, Apple released the
MacBook on
May 16,
2006. To ease the transition for early buyers of the new machines, Intel-based Macs include an emulation technology called
Rosetta, which allows them to run (at reduced speed) pre-existing Mac OS X native application software which was compiled only for PowerPC-based Macintoshes.
Some features of the "classic" Mac OS are carried forward and implemented natively in Mac OS X, including:
; ColorSync :
ColorSync is a technology for matching colors between the screen and a printer.
Finder : The Finder is the interface for browsing the filesystem and launching applications.; MacRoman :
MacRoman is the character encoding used in classic Macintosh systems. Mac OS X's standard character encoding is
Unicode, in its
UTF-8 and
UTF-16 forms, but
HFS volumes using MacRoman encoding are still supported.
PlainTalk : PlainTalk is a speech synthesis and speech recognition technology providing Mac OS with a spoken language interface for controlling the computer. The proprietary noise-cancelling microphone interface bearing the same name was phased out with the introduction of the Blue and White Power Macintosh G3s in 1999.; QuickDraw :
QuickDraw was the first imaging model to provide mass-market
WYSIWYG capabilities. Although mostly obsolete on Mac OS X, due to the use of
Quartz, QuickDraw still works on
Mac OS X 10.4. Apple has deprecated QuickDraw, meaning it may not work in future versions.
QuickTime : QuickTime provides support for audio-visual editing and playback, virtual reality motion, and streaming of multimedia content over a network. The Quicktime file format and streaming technology has been adopted in some MPEG 4 standards relating to multimedia content delivery via DVD or by streaming over the Internet to computers and cell phones. The iTunes music store also uses Quicktime.; TrueType :
TrueType is a very successful scalable font technology which was eventually ported to Microsoft Windows and later integrated into the OpenType font standard.
Obsolete technologies
Many technologies of the "classic" Mac OS are no longer used on OS X, including:
; Chooser : The
Chooser is a tool for enabling
AppleTalk, and accessing and selecting network resources such as
printers. It was derived from the Choose Printer
Desk Accessory found in early versions of the Mac OS.
Desk Accessories : Desk Accessories were small "helper" applications that could be run concurrently with other applications, prior to the advent of the multi-tasking MultiFinder and System 7. Mac OS X version 10.4 introduced a similar feature called Dashboard.; Mac OS memory management : The
Mac OS memory management describes how the Macintosh managed
RAM and
virtual memory before the switch to the
Unix-based Mac OS X. It has been defunct since Mac OS X, but most of the
APIs are still available via the
Carbon compatibility layer.
MultiFinder : MultiFinder was a version of the Finder with support for simultaneous processes. It became a part of the Finder in System 7.; PowerPC emulation of the Motorola 68000 : The
PowerPC emulation of the Motorola 68000 refers to the way in which the Macintosh handled the architectural transition to the PowerPC microprocessor. The emulator could run older software (including parts of the OS) which had not been recompiled to run natively on the PowerPC processor. The 68k emulator remained in Mac OS through version 9, and most old 68k application software still works within the Classic environment of Mac OS X.
GeoPort : Geoport Technology allows the Macintosh to run fax, data, and voice telephony services using an interface device called a GeoPort. Unlike true modems, the GeoPort device is merely an interface adapterâ€"the modem is implemented in software, an approach that some say burdens the CPU and slows the computer.; OpenDoc : Co-developed with IBM,
OpenDoc allowed bits of software, known as "parts" to interact within a framework application known as an "editor." Apple discontinued development on OpenDoc in 1997 in favor of the
OpenStep technology now know as Cocoa, acquired in the merger with NeXT Computer.
QuickDraw GX : An enhanced printing, screen display and typography system building on the Classic Mac OS QuickDraw system. The technology was introduced with System 7.5, but was initially plagued with bugs and lack of third party support. Though most of the bugs were eventually worked out, it was, like OpenDoc, abandoned in favor of OpenStep technology. The TrueType font engine was isolated and retained, and the rest of Quickdraw GX was removed from Mac OS 8.5 and later OS versions. Mac OS X provides capabilities superior to Quickdraw GX in its PDF-based Quartz graphics engine.One interesting historical aspect of the classic Mac OS was a relatively unknown secret prototype Apple started work on in 1992, code-named "Project Star Trek". The goal of this project was to create a version of Mac OS that would run on
Intel-compatible
x86 personal computers. It was short lived, being cancelled only one year later in 1993 due to political infighting, although its team was able to get the
Macintosh Finder and some basic applications, like
QuickTime, running smoothly on a PC. It ran on MS-DOS' rival DR-DOS and was generally faster than its 680x0 counterparts.
Fourteen years after project Star Trek, as
Apple transitions to the Intel processor, the current version of Mac OS (v10.4) runs smoothly on x86 architecture.
Although the Star Trek software was never released, third-party Macintosh
emulators, such as
vMac,
Basilisk II, and Executor, eventually made it possible to run the classic Mac OS on Intel-based PCs. These emulators were restricted to emulating the
68000 series of processors, and as such couldn't run versions of the Mac OS that succeeded 8.1, which required PowerPC processors. Recently, the
PearPC emulator has appeared, which is capable of emulating the PowerPC processors required by newer versions of the Mac OS (like
Mac OS X). Unfortunately, it is still in the early stages and, like many emulators, tends to run much slower than a native OS would.
Another PowerPC emulator is
SheepShaver, which has been around since
1998 for the
BeOS platform, but in
2002 was
open sourced with porting efforts beginning to get it to run on other platforms. Although it is capable of emulating a PowerPC processor, it can only emulate up to
Mac OS 9.0.4 because it does not emulate a
memory management unit.
Other examples include
ShapeShifter (by the same programmer that conceived
SheepShaver), Fusion and iFusion. The latter ran classic Mac OS with a PowerPC "coprocessor" accelerator card. Using this method has been said to equal or better the speed of a Macintosh with the same processor, especially with respect to the
m68k series due to real Macs running in
MMU trap mode, hampering performance.
Several computer manufacturers over the years have made
Macintosh clones capable of running Mac OS, notably
Power Computing and
Umax. These machines normally ran various versions of classic Mac OS. Steve Jobs ended the clone licensing program after returning to Apple in 1997.
In 1988, Apple released its first UNIX based OS, named
A/UX.
This was an
operating system that seamlessly integrated the Mac OS look and feel with the power and flexibility of UNIX. Since it was before the advent of PowerPC and therefore had to run on the Motorola 68000 processor, it was not very competitive for its time. A/UX had most of its success in sales to the
Federal government of the United States, where UNIX was a requirement that Mac OS could not meet.
*
Mac OS history*
Mac OS X history*
Mac OS X Server*
List of Macintosh software*
Operating system advocacy*
Comparison of operating systems*
folklore.org a site with anecdotes by the creators of the first Macintosh
*
Mac OS X official site
