Kind of reminds me of writing single-sector bootloaders¹ for the Apple ][. The idea was that you wouldn’t have DOS on a floppy disk to free up that storage for other stuff, but then if you accidentally turned on your computer with that disk in the drive, you’d want a nice message letting you know you messed up and a prompt so you could put in a DOS disk and boot up properly.

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1. It might have been a whole track on the disk, it’s hard to remember the details of this when it’s 37 years since I last used an Apple ][.