Reading some of the comments its a reasonably close analogy WRT the UI where its not allowed to go to sleep while it's still got something to say or think about. So the buttons and lights of a pinball machine keep flashing while there is at least one ball in play.
The difference between a haphazard device driver, a bootloader by a ragtag group of hackers and a space capsule is national pride and lives at stake. ;-)
We should encourage software to be written as if it will one day fly in space.
This is well commented code, for assembly.