The mac is interesting in a lot of ways. For example, did you know that you can boot the mac from different sources? And did you know that you can choose these sources from the Systems Prefs panel? (On x86 systems it has to be done in the BIOS)
And did you know that fooling around and then exiting that panel is the same as saying “Please, change where I boot from!”? I didn’t know that either. That was a big surprise when the system rebooted and showed me a flashing globe as it sat there unresponsive to the mouse and keyboard…
fortunately, by holding down the command button while powering up forces the mac to search for drives, then you can select the drive and boot normally… But wow, that was quite a shocker/scare.