boot drive missing from screen?
 

Greetings,
Just made a backup of the laptop (Powerbook) so it could go for repairs; took the b/u drive to the desktop (a G4), plugged it in, turned on the computer while pressing Option, and only Mac HD showed up on the screen. Went ahead and started from the Mac HD and set the b/u drive as the startup disc, and restarted.

Everything works fine; but any ideas why the b/u drive didn't show up as an option to boot from that drive?

Thanks in advance!

If it does start up from it, it's quite possible that it didn't respond quickly enough for the BIOS/Firmware to list it...