Appendix C. The Classic Environment

The Classic environment is an application environment in Mac OS X that allows you to run Mac OS 9compatible applications. An application environment is a set of libraries, resources, APIs, and API-dependent services. Classic uses foundation components in the operating system: core services (Quartz, OpenGL, QuickTime, and so on) and the core operating system (Darwin kernel). This enables Classic to use printing, device drivers, and networking as though you were booted in Mac OS 9.

Classic supports applications that run in Mac OS 9.2 and later. In mixed Mac OS 9/Mac OS X installations, this allows you to retain your investment in older Macintosh applications. Classic provides a fully-featured Mac OS 9 environment, with virtually all of the functionality that is available when running Mac OS 9 as the primary operating system on your Macintosh.

The Classic environment requires a Mac OS 9.2 or later System Folder, with fonts, extensions, control panels, and system preferences. However, you use Classic preferences in Mac OS X to manage Classic. That is where you can perform maintenance tasks, such as restarting or stopping Classic, rebuilding the Classic desktop, or starting Classic with extensions off.

For ease of use, and due to the legacy nature of Mac OS 9, Classic components are easier to identify than components for other application environments such as Java and X11. In this appendix, you will learn about Classic components, the architecture of the Classic Environment, and troubleshooting issues.