On x86, BeOS users see a row of icons on the splash screen, lighting up sequentially as the boot sequence commences (though for most users it all happens too quickly to see what’s going on). Ever wonder what those icons mean?

Here’s a quick guide:
Atom: Indicates the handoff of the bootloader to the BeOS kernel.
I/O Card: PCI initialization has been completed.
Lightning Bolt: This icon appears just before the system enables non-boot CPUs (where non-boot CPUs are defined as the additional processors in a multi-proc system).
Oscilloscope: All CPUs have now been enabled.
Disks: All boot drivers and modules have been initialized.
Magnifying Glass: The boot volume has been mounted.
BeBox: The system BootScript is being read into memory and its contents executed.
For a more complete description of this process, see this BMessage article: BeOS Splash Screen Icons