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AddThis Social Bookmark Button Mac OS X Terms and Definitions

by Michael J. Norton and Derrick Story

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A brand new operating system certainly demands a whole new set of terms to describe it. Mac OS X is a bold departure for Apple. It's based on FreeBSD, 4.2BSDLite, and Mach 3.0, with much of the early work taken from NetBSD. In other words, Apple is blending the power and stability of the Unix world with the beauty and design of its own.

Here are the key terms you'll need to know to become fully conversant with the Mac OS X.

Aqua - The new graphical interface for Mac OS X, with a colorful translucent feel. Aqua introduces an interleaved window layering scheme, where Mac OS 9 is single layered.

Carbon - The current set of programming interfaces, evolving from the previous Mac OS (Classic) toolbox API, migrated over to run on Mac OS X. A distinction is now made between Carbon event handling (Mac OS X) and Classic event handling (Mac OS 9). This architecture implements a preemptive multitasking environment with protected memory.

CFM - The Code Fragment Manager is the loader for executable code and data fragments under Mac OS 9 (CarbonLibStub9) and Mac OS X. It was built using CodeWarrior.

Classic - Refers to the user interface, Platinum Appearance, introduced in Mac OS 8. Under this architecture's design, applications share the processor and memory.

Cocoa - Object-oriented tool kits for user interface development. Cocoa is comprised of two object-oriented frameworks, Objective-C from NextStep, and Java from Sun MicroSystems.

Core Graphics Rendering - Provides the rendering services for Quartz. Its libraries include QuickDraw, OpenGL, and QuickTime. Core Graphics Rendering is also designed to be a black box for input and output conversion of Portable Document Format files.

Core Graphics Services - The primary duties include the window server, which handles the composition of windows. The windowing system is a layered composite engine.

Darwin OS - The underlying kernel environment for Mac OS X. Darwin is a complete operating system without the application layers and graphics interfaces. Darwin is open source technology based on FreeBSD, 4.2BSDLite, and Mach 3.0.

Frameworks - Shared libraries (frameworks) that are bound to a particular application.

FreeBSD - FreeBSD is an open source, freely distributed Unix-like operating system, much like Linux, its counterpart on the Internet. Mac OS X contains a BSD component.

Mach 3.0 - A Mach microkernel performs only a small set of functions. It can handle interprocess communications; low-level processes such as hardware and memory management; and high-level processes such as file systems and network stacks. Higher level functions are run by servers.

Mach-O - Mach-O Carbon applications are built using Apple's Project Builder, and the object code is designed for the Mach kernel.

Objective-C - An object-oriented C language (NextStep) that is based on ANSI C. It is one of the frameworks that comprise Cocoa.

OpenGL - Industry standard for 3D graphics development and display. Apple has optimized an OpenGL environment for Mac OS X.

Quartz - The core portion of the Mac OS X graphics and windowing environment, Quartz is comprised of two core services, Core Graphics Services and Core Graphics Rendering.

QuickDraw - The primary Mac OS X graphics library for manipulating 2D graphics and text.

QuickTime - Apple's powerful tool for multimedia streaming and playback. The Pro version includes an extensive authoring toolbox. QuickTime is equally adept on both Mac and Windows platforms.

Sheets - Aqua's new methodology for handling modal and modeless dialogs. Sheets are used in conjunction with the window to which they are attached. Sheets are translucent in appearance and appear to slide out from underneath the window title.

Michael J. Norton is a software engineer at Cisco Systems.

Derrick Story is the author of The Photoshop CS4 Companion for Photographers, The Digital Photography Companion, and Digital Photography Hacks, and coauthor of iPhoto: The Missing Manual, with David Pogue. You can follow him on Twitter or visit

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