For the Indecisive: Tips for Those Who Switch Back and Forth

For the Indecisive: Tips for Those Who Switch Back and Forth

Although many users have made the switch from OS 9 to OS X and never looked (or booted) back, others find themselves switching back and forth between the two somewhat frequently. For some users, it's an issue of important software that doesn't run in OS X and may not run properly in the Classic Environment within OS X (so they're forced to boot into OS 9 to use that software). For others it may just be a matter of evaluating OS X while they do most of their work in the familiarity of OS 9. Whatever the reason, switching back and forth between OS X and OS 9 provides some unique challenges that aren't present for those who primarily use one or the other. In this section I talk about some of these issues, as well as ways to make switching back and forth easier by using multiple OS 9 System Folders and multiple partitions or drives.


Some newer Macs can only boot into OS X and can only run OS 9 within the Classic Environment. If you're using one of these Macs, obviously this section won't apply to you, as you'll be using OS X exclusively. (A list of these models, updated regularly, can be found at Likewise, if you boot exclusively into OS X by choice, this section won't apply.

Switching Issues

Below are some of the most common issues that arise for users who frequently use both OS 9 and OS X, along with some solutions—or at least some explanations that should make dealing with these issues easier. In addition, I mentioned issues with Documents folders and file comments earlier in the chapter (under "Transition Technicalities").

Differing Desktop Folders

If you boot into OS 9, items that were on your Desktop in OS X aren't on your Desktop. Conversely, items on your OS 9 Desktop aren't visible on your OS X Desktop. If you're reading this appendix after reading Chapter 1, you may have deduced (correctly) that this has to do with each user having their own Desktop in OS X (at ~/Desktop). However, it is like-wise due to the fact that under OS 9, there is only one Desktop per volume; that Desktop is actually a folder at the root level of each volume called Desktop Folder.

What this means is that when you're booted into OS X, to access items on your OS 9 Desktop you need to open the folder called Desktop Folder at the root level of the hard drive you use for booting into OS 9. Conversely, if you're booted into OS 9, to get to files on your OS X Desktop you need to browse to /OSXvolume/Users/username/Desktop, where OSXvolume is the volume that contains your OS X system, and username is your OS X username.

Many users get around this inconvenience by creating an alias on each Desktop that points to the other. In fact, under OS X 10.2 and later, if there are items on the OS 9 Desktop, OS X automatically creates an alias to that Desktop for you at startup (and places it on each user's OS X Desktop). If there are no items on the OS 9 Desktop the next time you start up, the alias is removed from all OS X Desktops.


If you're using OS X 10.1.x, you'll need to create an alias to the OS 9 Desktop manually. The easiest way is to open Terminal and type ln -s '/Desktop Folder' ~/Desktop/ 'Desktop (Mac OS 9)' <RETURN>. If your OS 9 startup volume is different from your OS X startup volume, then instead type ln -s '/Volumes/volumename/Desktop Folder' ~/Desktop/'Desktop (Mac OS 9)' <RETURN>. An alias to the OS 9 Desktop Folder will be created on your Desktop in OS X.

The easiest way to do the opposite—create an alias to your OS X Desktop on your OS 9 Desktop—is to do it from within OS 9, since your user folder will be visible in the OS 9 Finder.

Using a Single Desktop for Both OS 9 and OS X

Although you can use the appropriate Desktop for the OS under which you're using your Mac, and access the other using an alias, there are a couple drawbacks. First, when you place documents on your OS 9 Desktop, you lose all of OS X's user security—anyone in OS 9 or OS X can access them easily. But more importantly, using two different Desktops is just plain confusing. If you're the only user of OS 9 on your Mac, you can actually force OS 9 to use your OS X Desktop as its own.

  1. When booted into OS 9, move everything on your OS 9 Desktop into your OS X Desktop folder (/Users/username/Desktop).


    If you don't move items off of your OS 9 Desktop before continuing, they will be deleted by the next step!

  2. Boot into OS X, log in, and launch Terminal.

  3. If your OS X boot volume and OS 9 boot volume are the same, type rm -rf '/Desktop Folder' <RETURN>. If they're different, type rm -rf '/Volumes/volumename/Desktop Folder' <RETURN>, where volumename is the name of your OS 9 boot volume. This step deletes your original OS 9 Desktop.

  4. If your OS X boot volume and OS 9 boot volume are the same, type ln -s ~/Desktop '/Desktop Folder' <RETURN>. If they're different, type ln -s ~/Desktop '/Volumes/ volumename/Desktop Folder' <RETURN>, where volumename is your OS 9 boot volume. This step replaces the original OS 9 Desktop with an alias to your personal OS X Desktop.

Your OS 9 Desktop will now be the same as your OS X Desktop.


The only caveat to this setup is that if anyone else boots into OS 9, they'll have access to everything on your Desktop. Of course, they would anyways, since permissions aren't enforced in OS 9, so they could just as easily navigate to your personal Desktop folder in the Finder.

Some users have accomplished similar functionality to the above procedure by simply changing the name of the "Desktop (Mac OS 9)" alias created by OS X (or by the user in 10.1.x) to "Desktop" and then replacing their personal Desktop folder with this alias. However, although the above procedure lets anyone view the contents of your Desktop by booting into OS 9, this latter procedure lets anyone view the contents of your Desktop in both OS 9 and OS X.

Clipping Compatibility

Like OS 9, OS X supports clipping files (I actually talked about using clippings in OS X in Chapter 7). You can create new clipping files, and you can open and use clipping files created in OS 9. However, for some reason (another mystery to me), in OS X Apple changed the creator code for clipping files from drag to MACS. Although OS X understands both of these codes, OS 9 doesn't—with the end result being that clipping files created in OS X cannot be opened in OS 9.

If you frequently boot into OS 9 and want to be able to open clipping files created in OS X, you'll need to manually change their creator codes to drag. I talked about creator codes and utilities for changing them in Chapter 5; any of these utilities will work just fine. However, the utility File Buddy ( lets you create "Droplets"—small utilities that can perform any function available in File Buddy by simply dropping files onto its icon. I've created a Droplet that changes the creator code of any file I drop onto it to drag.

Filename Formats

In Mac OS 9 and earlier, the length of file and folder names is limited to 31 characters. However, in OS X you can actually use a name of up to 256 characters. When you boot into OS 9, any file or folder name over 31 characters will be truncated; unfortunately, this truncation isn't pretty. OS 9 not only cuts characters off of the file's name; it also adds funky characters. These characters help preserve the file's name when you switch back to OS X, but they further reduce the number of "usable" characters that you see.

This means that if you switch between OS X and OS 9, you may want to be careful to keep filenames to 31 characters or less (including the file extension).

Multiple User Usernames

Although OS X is a multiple-user operating system from the ground up, OS 9 also had the (more limited) ability to accommodate more than one user via the Multiple Users control panel. In fact, from a file and folder point of view, it worked similarly to OS X—user folders were located in a folder called Users. For the most part, OS X's user directories can coexist with OS 9's. However, if you use OS 9's Multiple Users, do not create a new user in OS 9 that has the same username as a user in OS X; you run the risk of wiping out the OS X user. Likewise, if you somehow manage to have a user with the same name in both OS 9 and OS X, deleting that user from OS 9 will also delete them from OS X.


This is just a warning box to remind you that the section you just read tells you how to avoid data loss.

Why You Should Consider Multiple OS 9 System Folders

In Chapter 8, I discussed the advantages of customizing the OS 9 System Folder used for OS X's Classic Environment—slimming it down to the bare essentials. However, when you boot into OS 9, this optimized System Folder may not have all of your favorite OS 9-specific support files and system add-ons (all of the things you want when booted into OS 9 but that slow down, or are incompatible with, the Classic Environment). Likewise, some users report that the files installed into the Classic System (the one used by the Classic Environment) can actually cause problems if you use that System Folder to boot into OS 9.

Because of this, if you tend to boot into OS 9 frequently and use the Classic Environment, you may want to consider having two OS 9 System Folders: one optimized for the Classic Environment and one chock full of all your favorite OS 9 stuff. You can do this by installing two copies of OS 9 on your OS X boot volume (you can even name the one for Classic "Classic System Folder"), or by installing one or more copies of OS 9 on an alternate volume (a partition, second hard drive, etc.).


As an alternative to having two OS 9 System Folders, you can also use Extensions Manager or Conflict Catcher to create sets of startup files, as described in Chapter 8. You can use the slim/optimized set when using OS 9 in the Classic Environment, and the full monte when actually booting into OS 9.

In addition to being able to have "slim" and "full" versions of the Classic Mac OS, having multiple System Folders also allows you to use different versions of the Classic Mac OS. For example, the Classic Environment requires OS 9.2.1 or later. If you prefer to use a version of the Mac OS prior to 9.2.1 when you boot into OS 9—or need to use an older version, even OS 8, in order to run older software—you need multiple System Folders.

Finally, if you frequently switch between booting into OS 9 and OS X, you should consider partitioning your hard drive or installing a second drive. I talk about this option next.

Why You Should Consider Having OS 9 on a Different Partition or Drives than OS X

If having multiple OS 9 System Folders sounds like something you might want to do—or even if you don't have multiple OS 9 System Folders, but tend to switch between booting into OS 9 and OS X—you should also think about partitioning your hard drive.

I discuss partitioning in detail in Appendix B, but it's basically a way of splitting a hard drive into two or more partitions, each of which behaves as if it's a separate hard drive or volume. In fact, if you have a single hard drive divided into three partitions, you can boot off of any of them, provided they each have a valid OS 9 System Folder or OS X installation. In the context of this discussion, you can install OS X and your Classic System Folder on one partition, and a second OS 9 System Folder—to be used when booting into OS 9—on another.

In fact, to reduce disk "clutter," some users actually place their "full" version of OS 9—the one they use when booting into OS 9—on a second drive or partition, and place their "slim" OS 9—the one used by the Classic Environment—on a disk image on their OS X volume. You can create a 250–300MB disk image using Disk Copy, and install OS 9 onto it. Select that System Folder in Classic preferences, and whenever you want to launch the Classic Environment, just mount the image first. The rest of the time the Classic System Folder is stored in a single file.

You may be wondering why you'd need partitions to do this, since you can simply install multiple OS 9 System Folders on your OS X volume, and then choose between them in both Classic preferences (for use in the Classic Environment) and Startup Disk preferences (for use when booting into OS 9). There are a couple additional benefits that partitions provide. The first—as I explained in Chapter 3—is that Startup Manager, accessed by holding the option key down at startup, only recognizes different bootable volumes. In other words, if you have your OS X and OS 9 system software installed on the same volume, you can't use the Startup Manager to choose which to boot into; you need to open the Startup Disk preferences, choose the OS to use for booting, and then restart. This means that if your computer isn't running, you need to boot up, switch OSs, and then reboot. However, with multiple partitions, you can choose which OS to boot into at startup, since OS X and OS 9 will be installed on different volumes.

The second advantage of having multiple volumes—and this is true regardless of the versions of the Mac OS you install on them—is that it provides you with an "emergency" boot volume. If one volume or OS installation gives you problems, you can boot from the other volume and run any disk utilities or perform any maintenance tasks you may need.


Most of the benefits of multiple partitions can also be attained by buying and installing a second hard drive. In fact, if you're using an older desktop Mac and buy a new hard drive, you can transfer OS X to the new drive, which will surely be much larger than your original drive, and then use the original drive for booting into OS 9.

If after reading this discussion you decide that multiple partitions is for you, be sure to read the next appendix for more information, including instructions on how to partition a drive, as well as special considerations and challenges that come with using partitions and multiple volumes.


For more information on choosing a startup OS and/or volume, see Chapter 3. For easy one-key switching between OS X and OS 9, see the ResExcellence tutorial at