Architecture of Mac OS X
Encyclopedia
Mac OS X
is the culmination of Apple Inc.'s decade-long search for an operating system
to replace the original Mac OS
. After the failures of their previous attempts; Pink, which started as an Apple project but evolved into a joint venture with IBM
called Taligent
, and Copland
, which started in 1994 and was cancelled two years later, Apple began development of their most recent operating system (Mac OS X) with the acquisition of NeXT
's NEXTSTEP
.
with subsystems from 4.3BSD. NEXTSTEP also introduced a new windowing system based on Display PostScript
that intended to achieve better WYSIWYG
systems by using the same language to draw content on monitors that drew content on printers. NeXT also included object-oriented programming
tools based on the Objective-C
language that they had acquired from Stepstone
and a collection of Frameworks (or Kits) that were intended to speed software development. NEXTSTEP originally ran on Motorola
's 68k
processors, but was later ported to Intel's x86, Hewlett-Packard
's PA-RISC
and Sun Microsystems
' SPARC
processors. Later on, the developer tools and frameworks were released, as OpenStep
, as a development platform that would run on other operating systems.
the core system to the PowerPC
architecture and adding a redesigned user interface based on the Platinum user interface from Mac OS 8
. An emulation layer called Blue Box
allowed Mac OS applications to run within an actual instance of the Mac OS and an integrated Java platform. The Objective-C developer tools and Frameworks were referred to as the Yellow Box
and also made available separately for Microsoft Windows
. The Rhapsody project eventually bore the fruit of all Apple's efforts to develop a new generation Mac OS, which finally shipped in the form of Mac OS X Server
.
At the 1998 Worldwide Developers Conference
(WWDC), Apple announced a move that was intended as a response to complaints from Macintosh software developers who were not happy with the two options (Yellow Box and Blue Box) available in Rhapsody. Mac OS X would add another developer API to the existing ones in Rhapsody. Key APIs from the Macintosh Toolbox
would be implemented in Mac OS X to run directly on the BSD layers of the operating system instead of in the emulated Macintosh layer. This modified interface, called Carbon
, would eliminate approximately 2000 troublesome API calls (of about 8000 total) and replace them with calls compatible with a modern OS.
At the same conference, Apple announced that the Mach side of the kernel had been updated with sources from version 3 of the Mach kernel and the BSD side of the kernel had been updated with sources from the FreeBSD
, NetBSD
and OpenBSD
projects. They also announced a new driver model called I/O Kit
, intended to replace the Driver Kit used in NEXTSTEP citing Driver Kit's lack of power management and hot-swap capabilities and its lack of automatic configuration capability.
At the 1999 WWDC, Apple revealed Quartz
, a new Portable Document Format
(PDF) based windowing system for the operating system that was not encumbered with licensing fees to Adobe
like the Display PostScript windowing system of NEXTSTEP. Apple also announced that the Yellow Box layer had been renamed Cocoa
and began to move away from their commitment to providing the Yellow Box on Windows. At this WWDC, Apple also showed Mac OS X booting off of a HFS Plus
formatted drive for the first time.
The first public release of Mac OS X released to consumers was a Public Beta
released on September 13, 2000.
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
is the culmination of Apple Inc.'s decade-long search for an operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
to replace the original Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
. After the failures of their previous attempts; Pink, which started as an Apple project but evolved into a joint venture with IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
called Taligent
Taligent
Taligent was the name of an object-oriented operating system and the company dedicated to producing it...
, and Copland
Copland (operating system)
Copland was a project at Apple Computer to create an updated version of the Macintosh operating system. It was to have introduced protected memory, preemptive multitasking and a number of new underlying operating system features, yet still be compatible with existing Mac software...
, which started in 1994 and was cancelled two years later, Apple began development of their most recent operating system (Mac OS X) with the acquisition of NeXT
NeXT
Next, Inc. was an American computer company headquartered in Redwood City, California, that developed and manufactured a series of computer workstations intended for the higher education and business markets...
's NEXTSTEP
NEXTSTEP
NeXTSTEP was the object-oriented, multitasking operating system developed by NeXT Computer to run on its range of proprietary workstation computers, such as the NeXTcube...
.
NEXTSTEP
NEXTSTEP used a hybrid kernel that combined the Mach 2.5 kernel developed at Carnegie Mellon UniversityCarnegie Mellon University
Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....
with subsystems from 4.3BSD. NEXTSTEP also introduced a new windowing system based on Display PostScript
Display PostScript
Display PostScript is an on-screen display system. As the name implies, DPS uses the PostScript imaging model and language to generate on-screen graphics...
that intended to achieve better WYSIWYG
WYSIWYG
WYSIWYG is an acronym for What You See Is What You Get. The term is used in computing to describe a system in which content displayed onscreen during editing appears in a form closely corresponding to its appearance when printed or displayed as a finished product...
systems by using the same language to draw content on monitors that drew content on printers. NeXT also included object-oriented programming
Object-oriented programming
Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...
tools based on the Objective-C
Objective-C
Objective-C is a reflective, object-oriented programming language that adds Smalltalk-style messaging to the C programming language.Today, it is used primarily on Apple's Mac OS X and iOS: two environments derived from the OpenStep standard, though not compliant with it...
language that they had acquired from Stepstone
Stepstone
Stepstone, originally named Productivity Products International , was a software company founded in 1983 by Brad Cox and Tom Love, best known for releasing the original version of the Objective-C programming language....
and a collection of Frameworks (or Kits) that were intended to speed software development. NEXTSTEP originally ran on Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
's 68k
68k
The Motorola 680x0/m68000/68000 is a family of 32-bit CISC microprocessors. During the 1980s and early 1990s, they were popular in personal computers and workstations and were the primary competitors of Intel's x86 microprocessors...
processors, but was later ported to Intel's x86, Hewlett-Packard
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
's PA-RISC
PA-RISC
PA-RISC is an instruction set architecture developed by Hewlett-Packard. As the name implies, it is a reduced instruction set computer architecture, where the PA stands for Precision Architecture...
and Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
' SPARC
SPARC
SPARC is a RISC instruction set architecture developed by Sun Microsystems and introduced in mid-1987....
processors. Later on, the developer tools and frameworks were released, as OpenStep
OpenStep
OpenStep was an object-oriented application programming interface specification for an object-oriented operating system that used a non-NeXTSTEP operating system as its core, principally developed by NeXT with Sun Microsystems. OPENSTEP was a specific implementation of the OpenStep API developed...
, as a development platform that would run on other operating systems.
Rhapsody
On February 4, 1997, Apple acquired NeXT and began development of the Rhapsody operating system. Rhapsody built on NEXTSTEP, portingPorting
In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed...
the core system to the PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
architecture and adding a redesigned user interface based on the Platinum user interface from Mac OS 8
Mac OS 8
Mac OS 8 is an operating system that was released by Apple Computer on July 26, 1997. It represented the largest overhaul of the Mac OS since the release of System 7, some six years previously. It puts more emphasis on color than previous operating systems...
. An emulation layer called Blue Box
Classic (Mac OS X)
Classic, or Classic Environment, was a hardware and software abstraction layer in Mac OS X that allowed applications compatible with Mac OS 9 to run on the Mac OS X operating system...
allowed Mac OS applications to run within an actual instance of the Mac OS and an integrated Java platform. The Objective-C developer tools and Frameworks were referred to as the Yellow Box
Cocoa (API)
Cocoa is Apple's native object-oriented application programming interface for the Mac OS X operating system and—along with the Cocoa Touch extension for gesture recognition and animation—for applications for the iOS operating system, used on Apple devices such as the iPhone, the iPod Touch, and...
and also made available separately for Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
. The Rhapsody project eventually bore the fruit of all Apple's efforts to develop a new generation Mac OS, which finally shipped in the form of Mac OS X Server
Mac OS X Server
Mac OS X Server is a Unix server operating system from Apple Inc. The server edition of Mac OS X is architecturally identical to its desktop counterpart, except that it includes work group management and administration software tools...
.
Mac OS X
Worldwide Developers Conference
The Apple Worldwide Developers Conference, commonly abbreviated WWDC, is a conference held annually in California by Apple Inc. The conference is primarily used by Apple to showcase its new software and technologies for developers, as well as offering hands-on labs and feedback sessions...
(WWDC), Apple announced a move that was intended as a response to complaints from Macintosh software developers who were not happy with the two options (Yellow Box and Blue Box) available in Rhapsody. Mac OS X would add another developer API to the existing ones in Rhapsody. Key APIs from the Macintosh Toolbox
Macintosh Toolbox
The Macintosh Toolbox is a set of application programming interfaces with a particular access mechanism. They implement many of the high-level features of the Mac OS. The Toolbox consists of a number of "managers," software components such as QuickDraw, responsible for drawing onscreen graphics,...
would be implemented in Mac OS X to run directly on the BSD layers of the operating system instead of in the emulated Macintosh layer. This modified interface, called Carbon
Carbon (API)
Carbon is one of Apple Inc.'s procedural application programming interfaces for the Macintosh operating system. It provides C programming language access to Macintosh system services...
, would eliminate approximately 2000 troublesome API calls (of about 8000 total) and replace them with calls compatible with a modern OS.
At the same conference, Apple announced that the Mach side of the kernel had been updated with sources from version 3 of the Mach kernel and the BSD side of the kernel had been updated with sources from the FreeBSD
FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
, NetBSD
NetBSD
NetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...
and OpenBSD
OpenBSD
OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...
projects. They also announced a new driver model called I/O Kit
I/O Kit
The I/O Kit is an open-source framework in the XNU kernel that helps developers code device drivers for Apple's Mac OS X and iOS operating systems...
, intended to replace the Driver Kit used in NEXTSTEP citing Driver Kit's lack of power management and hot-swap capabilities and its lack of automatic configuration capability.
At the 1999 WWDC, Apple revealed Quartz
Quartz (graphics layer)
Quartz specifically refers to a pair of Mac OS X technologies, each part of the Core Graphics framework: Quartz 2D and Quartz Compositor. It includes both a 2D renderer in Core Graphics and the composition engine that sends instructions to the graphics card...
, a new Portable Document Format
Portable Document Format
Portable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....
(PDF) based windowing system for the operating system that was not encumbered with licensing fees to Adobe
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...
like the Display PostScript windowing system of NEXTSTEP. Apple also announced that the Yellow Box layer had been renamed Cocoa
Cocoa (API)
Cocoa is Apple's native object-oriented application programming interface for the Mac OS X operating system and—along with the Cocoa Touch extension for gesture recognition and animation—for applications for the iOS operating system, used on Apple devices such as the iPhone, the iPod Touch, and...
and began to move away from their commitment to providing the Yellow Box on Windows. At this WWDC, Apple also showed Mac OS X booting off of a HFS Plus
HFS Plus
HFS Plus or HFS+ is a file system developed by Apple Inc. to replace their Hierarchical File System as the primary file system used in Macintosh computers . It is also one of the formats used by the iPod digital music player...
formatted drive for the first time.
The first public release of Mac OS X released to consumers was a Public Beta
Mac OS X Public Beta
The Mac OS X Public Beta was an early beta version of Apple Computer's Mac OS X operating system Cheetah. It was released to the public on September 13, 2000 for US$29.95...
released on September 13, 2000.
External links
- Apple: Mac OS X — The official page for Mac OS X.
- What is Mac OS X? (kernelthread.com) — An overview of the Mac OS X operating system architecture
- Mac OS X (arstechnica.com) — Comprehensive reviews of Mac OS X (all versions)
- Mac OS X Internals The web page associated with the book.