The Classic environment is typically launched once during a Mac OS X login session--either manually or automatically. After it is running, Classic remains active until you log out or manually force it to shut down.
Classic does not gain all the stability features of Mac OS X, such as protected memory. If an application crashes in Classic, it can bring down all applications running in Classic. The Mac OS X system will be unaffected, but you might need to manually restart the Classic environment.
There are two ways to launch the Classic environment: by double-clicking a Classic application and through the Classic panel within System Preferences.
Classic applications appear to the Mac OS X Finder just like any other application. To verify that a piece of software is indeed a Classic application, you can select the icon and select Get Info (Command+I) from the Finder's File menu. Or Control-click on the icon and choose Get Info from the contextual menu. Figure 4.1 shows the General Information panel for the Graphing Calculator, a Classic application.Figure 4.1 The General Information panel will identify Classic applications.
Classic applications, because they still use the Mac OS 9.x Memory Manager, require a preferred and minimum memory size to be set. Because you have no direct access to the 9.2 Finder under OS X, Classic applications have an additional Get Info panel called Memory. This is shown in Figure 4.2.Figure 4.2 Classic applications allow memory limits to be set.
Two limits can be set:
Minimum Size--The minimum amount of memory that an application must have in order to run. The Mac OS 9.x environment will prohibit the application from launching unless the minimum memory size can be met.
Preferred Size--The amount of memory that you want the application to have. This is the upper limit of the memory partition that will be requested from Mac OS 9.x.
To take advantage of the new Mac OS X memory architecture, set these values higher than you would in older versions of the Mac OS. If you do, be aware that your settings here will carry over if you boot directly into Mac OS 9.x, where you might not have as much real or virtual memory available.
Forcing Carbon Apps into Classic
Carbon applications are a special case of Mac OS X application. They are capable of running natively on Mac OS X, and on Mac OS 9.x through the use of CarbonLib. If you'd like to use the Classic environment to launch a Carbon application, there is a setting within the General Information panel that can force a Carbon-compliant package to launch through Classic. Figure 4.3 shows the General Information panel for a Carbon application.Figure 4.3 Carbon applications can be forced to launch in the Classic environment.
To launch a Carbon application in Classic, check the Open in the Classic Environment check box, and then close the info panel. Double-clicking the application will launch it in Classic rather than in Mac OS X until the box is manually unchecked.
Manually Starting and Configuring Classic
If you have multiple Mac OS 9.x installations, or want to manually start or stop the Classic environment, you can do so from the Classic System Preferences panel. First, open System Preferences (path: /Applications/System Preferences), and then click the Classic icon.
The basic Classic controls are shown in Figure 4.4.
The Classic Preferences panel can control how and when Classic boots. The following options are found in the Start/Stop tab of the Classic panel:
Select a Startup Volume for Classic--Mac OS X can start the Classic environment by booting any available Mac OS 9.x system. It is recommended that you use a separate drive or partition for Mac OS 9.x, as you will be able to boot to the Mac OS 9 partition, bypassing Mac OS X in case of an emergency.
Start Classic When You Log In--If you'd like Classic to start up immediately after you log in to your computer (or immediately at startup, if you're using Mac OS X as a single-user system), click this button. Be warned; the Classic environment takes a few minutes to start and your system performance will be degraded during this time.
Warn Before Starting Classic--Use this option to force Mac OS X to prompt you each time it is able to launch the Classic environment. If you find yourself accidentally starting Classic by double-clicking legacy files, and so on, this can be quite helpful.
Start/Stop--Click the Start button to launch Classic manually or Stop to shut it down.
Restart--The Restart button is equivalent to choosing Restart from the Mac OS 9.x Finder. Open applications will prompt you to save open documents, and then exit. The Classic environment will reboot.
Force Quit--If Classic becomes unresponsive (that is, it crashes), the only option is to force it to quit. Open documents are lost, exactly as if Mac OS 9.x crashed (as it tends to do from time to time). You can also use the Control+Option+Escape keystroke to force it to quit.
The Classic System Preferences panel also shows the status of the Classic environment--whether it is running or not. Because Classic does not appear as an active task in the Dock, this is one way to check its current state.
To view Classic's status in the menu bar, download the Classic Spy menu extra from http://www.apple.com/downloads/macosx/system_disk_utilities/classicspy.html.