A rather confusing BIOS
error message in personal computers
when they were still called AT compatible
or industry standard
It would show up when you would try to boot with no floppy disk in the drive and the hard disk did not have any partition flagged as active.
The original IBM PC still had a ROM basic, as well as a port for a cassette drive.
Yes, I admit that it cost me about an hour to find out what had happened when this error first hit me.