It didn’t take long for the masses of Mac fans to grow impatient with fiddling around with System Preferences just to go back and forth between 9 and X. Here are three ways to reduce the number of steps.
If you have both Mac OS 9 and Mac OS X on the same hard drive, use this sensational shortcut: Just hold down the letter X key while the Mac is starting up. (Hold it down until the Mac stops chiming.) You go straight to Mac OS X.
The only downside to the X key trick is that it’s one-way. You can’t, for example, hold down the 9 key to start up in Mac OS 9 again—at least not if 9 and X are on the same drive.
If you’ve installed 9 and X on two different drives or partitions, though, you can enjoy the D key trick. It works as long as you’ve installed Mac OS 9 on the first partition.
Leave your System Preferences set so that Mac OS X is the startup disk, as described earlier. But on those occasions when you want to duck back into Mac OS 9, hold down the D key just after the startup chime (when turning on or restarting the machine). The Mac starts up in Mac OS 9.
To return to Mac OS X, just don’t do anything. Restart the machine without holding down any keys at all.
As it turns out, the D key tells the Mac to start up from the first internal disk or partition that contains a working System Folder of any type. If it’s a Mac OS 9 partition, that’s what you get.
This trick may be the easiest ...