It can instead boot from one of several recovery options. On older PowerPC and Intel -based Macs, this required knowing one of a handful of keyboard commands when starting the Mac.

In class the professor boots from the floppy, but while I can use the dd command to write out the disk to a USB floppy drive (I couldn't figure out how to do this under Mac OS X), I have no idea ...

Lack of start-up commands due to faulty cable? There are several reasons why OS X may not accept start-up arguments, though sometimes the reasons can be bizarre and unexpected.

Apple Silicon Macs will introduce a new system for accessing macOS recovery and security options at startup, Apple explained at a WWDC session on Wednesday.