I have no idea either. My strategy was to just mash on the function keys, space bar, DEL key, anything else I can think of. Keep pressing them all through the boot process, and maybe a boot menu will show up.
The F5 hotkey was introduced in Windows 95, where the boot sequence hotkeys were as follows:
- ESC - Boot in text mode.
- F5 - Boot in Safe Mode.
- Shift+F5 - Boot to Safe Mode MS-DOS.
- Ctrl+F5 - Boot to Safe Mode MS-DOS with drive compression disabled.
- Alt+F5 - Boot with LOADTOP=0 for Japanese systems.
- F6 - Boot in Safe Mode with networking.
- F4 - Boot to previous version of MS-DOS.
- Ctrl+F4 - Boot to previous version of MS-DOS with drive compression disabled.
- F8 - Boot to menu.
- Shift+F8 - Boot with step-by-step confirmation.
- Ctrl+F8 - Boot with step-by-step confirmation with drive compression disabled.
Man, that's an insane number of boot options all buried behind obscure function keys. Boy am I glad we got rid of them. This frees up room in my brain for things like Beanie Baby trivia.
Bonus chatter: The next generation of computers boots so fast that there's no time to hit any of these hotkeys!