A while back, a funny thing happened whilst working on some hints. I was testing something relatively destructive, and whenever I do such things, I try to protect my main production machine (my Dual G5) as much as possible. Instead, I was using my PowerBook G4, booted off a small FireWire drive. I worked on the testing for a while, wrote up whatever it was I was going to write up, and then closed the lid on the PowerBook.
So far so good, nothing unusual going on here. A day or two later, I noticed that the power light was still on on the FireWire drive. “Hmm, I should probably power that thing down,” I thought. At this point, the synapses in my brain badly misfired. I seemed to recall using the FireWire drive, but only as an external storage unit. I also definitely, absolutely, positively remembered dismounting the drive in the Finder before I put the machine to sleep. I’m not sure which alien species implanted that recollection, but it was vivid. So based on my memories, I did the only logical thing: I yanked the FireWire drive’s cable out of the PowerBook, and put the drive back in its usual storage spot.
Fast forward again another day or two to the next time I needed to use the PowerBook. I opened the lid, saw my familiar desktop appear, and…nothing seemed to work. Well, one thing worked: I could move the mouse around. But I couldn’t type in TextEdit or Terminal, clicking bookmarks in Camino did nothing, double-clicking applications in the Finder didn’t seem to work, and both the Dock and Command-Tab were completely useless. I will admit to some serious confusion at this point—everything looked right, but nothing was working.
I was about to reset the machine and write the whole experience off to the mysterious gods of crashing, when my eagle eye spotted a rather huge “FW 104 Boot Drive” icon on the Desktop. (How did I miss that before?) Then the brain clicked back into gear. Doh! I had just awoken a sleeping Mac, one that had been booted from a FireWire drive, without said FireWire drive attached! At this stage, panic set in. What to do, what to do…
Figuring all was lost at this point, I decided to try something outlandish. I dug the FireWire drive out of its storage spot, and plugged it back in (without trying to sleep the Mac again). After a few seconds delay, the most amazing thing happened—my stored mouse clicks were all sent to the operating system! The Dock appeared, then the Command-Tab switcher, and the applications I had launched opened up! Wow!
After using the machine for a while, I was convinced that no ill had come from this strange excursion into “no boot drive available” land. Everything was fine. I then shut down normally, disconnected the drive, and booted again from the internal hard drive.
There’s no real moral to this story—I do not recommend trying this yourself at home (though I have repeated the experiment with no ill effects). I was probably most amazed by the fact that the machine even woke up to a semi-usable state without a boot disk present. I’m not sure who to thank for this behavior, but I’m very glad it worked as well as it did!