The Classic compatibility environment contains several directories used to support Classic applications. The directories of the Classic environment are the directories of a Mac OS 9 installation. Mac OS X requires an installation of Mac OS 9.1 (or later) for the Classic environment. If a system has an earlier version of Mac OS 9 installed, the user must install a newer version to support Mac OS X.
A system may have multiple versions of Mac OS 9 installed on different partitions. If this is the case, the user can choose the preferred version of Mac OS 9 to use for the Classic environment from the Classic pane of System Preferences. The user can also switch Classic environments at any time or change the startup disk to boot directly into Mac OS 9 (on computers that support it).
When you install Mac OS 9.1 (or later) on a volume, the installer creates several directories to store the system files. Table 1 lists the directories created by the installer along with a description of the contents. If a user already has a version of Mac OS X or Mac OS 9.1 (or later) installed, the Mac OS 9 installer may not create all of these directories.
The first time the user launches Classic, the system adds some required files to the System Folder of the selected Mac OS 9 volume. When a user installs Mac OS X on a system with Mac OS 9 already installed, the installer performs some additional tasks to support the Classic environment. In particular, the Mac OS X installer creates an alias to the Mac OS 9 desktop folder and puts it on the desktop of the admin user who ran the installer. This alias contains links to any files that were on the Mac OS 9 desktop prior to the Mac OS X installation.
Last updated: 2009-08-14