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Mac OS is Apple Computer's operating system for Apple Macintosh computers. Mac OS was the first commercially successful operating system which used a
graphical user interface - although early versions
did not use that, or any, name. The Macintosh team included Bill
Atkinson, Jef Raskin and Andy Hertzfeld.
There are a variety of views on how the Macintosh was developed, and where the underlying ideas originated. While the
connection between the Macintosh and the Alto project at Xerox PARC has been
established in the historical record, the earlier contributions of Ivan
Sutherland's Sketchpad and Doug Engelbart's On-Line System are no less
significant. See History of the GUI, and Apple v. Microsoft.
The Mac OS can be divided into two families of operating systems:
- An older and now unsupported "classic" Mac OS (the system that shipped with the first Mac in 1984 and its descendants,
culminating with Mac OS 9)
Classic Mac OS
The "classic" Mac OS is characterized by its total lack of a command
line; it is a 100% graphical operating system. Heralded for its ease of use, it is also criticized for its almost total lack
of memory management, cooperative multitasking, and susceptibility to extension
conflicts. "Extensions" are program modules that extend the operating system, providing additional functionality (such as a
networking) or support for a particular device. Some extensions are prone not to work properly together, or only when loaded in a
particular order. Troubleshooting Mac OS extensions can be a time-consuming process.
The MacOS also introduced a new type of filesystem, which contained two different "forks" for a file. It was innovative at the
time for separating out structured data into the resource fork, and raw
data in the "data fork" -- for example, most application files would consist of a resource fork with no data fork, whereas a text
file would either only have a data fork or -- a special feature of the Macintosh -- it would have styling information in the
resource fork, with the data fork still containing plain old text, undisturbed by interfering style information. Regardless of
the many assets of this arrangement, it became quite a challenge to interoperate with other operating systems which did not
recognize such a system.
The term "Mac OS" was not officially used until 1996 with the release of Mac OS 7.6 -
prior to that the Macintosh operating system software was simply known as "The System", or by its version number, e.g. System 6
or System 7. Another common term was "the Toolbox".
Apple deliberately played down the existence of the operating system in the early years of the Mac to help make the machine
appear more user-friendly and to distance it from other systems such as MS-DOS, which
were portrayed as arcane and technically challenging. Apple wanted Mac to be portrayed as a system that would "just work" when
you turned it on.
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, with the goal having not been met. Although a direct port was never released, it did eventually become possible to
run the classic Mac OS on x86 PCs by using third-party Macintosh emulators, such
as vMac and Basilisk II.
By the late 1990s, it was clear the useful life of this 1980s-era technology was coming to an end, with other more stable
multitasking operating systems being developed.
Mac OS X
Mac OS X remedied this situation, bringing Unix-style memory management and pre-emptive multitasking. Vastly improved memory management allowed more programs to run at once
and virtually eliminated the possibility of one program crashing another. It is also the first Mac OS to include a command line,
although it is never seen unless a separate "terminal" program is launched. However, since these new features put higher demands
on system resources, Mac OS X is only officially supported on PowerPC G3 and
newer processors. Even then, it runs poorly on older G3 systems for many purposes. Mac OS X has a compatibility layer for running
older Mac applications, the Classic Environment (known to
programmers as "the blue box"). This runs a full copy of the older Mac OS 9.x as a Mac OS X process. 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.
Mac OS Technologies
- QuickDraw: the imaging model which first provided mass-market WYSIWYG
- Finder: the interface for browsing the filesystem and launching applications
- MultiFinder: the first version to support simultaneously running multiple
apps
- Chooser: tool for accessing network
resources (e.g., enabling AppleTalk)
- ColorSync: technology for ensuring appropriate color matching
- Mac OS memory management: how the Mac managed
RAM and virtual memory before the
switch to UNIX
- PowerPC emulation of Motorola 68000: how the Mac handled the architectural transition from CISC to RISC (see Mac
68K emulator)
- Desk Accessories: small "helper" apps that could be run
concurrently with any other app, prior to the advent of MultiFinder or System
7.
- PlainTalk: speech
synthesis and speech recognition technology
- Mac-Roman : Character set
Mac OS X References
Software
See List of Macintosh software
See also: Mac OS history, OS Advocacy
External links
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