When your iPhone battery is "almost" dead, it turn off, and then if you want to turn it on again it loads this very informative graphic:
The problem is that when you turn on "power button" this picture show up almost immediately, without starting up operating system or anything.
I just wonder how they done it ? Is this behaviour is hardcoded in hardware ? Is it configurable and could be changed (to flatter design) when iOS 7 will come ?
My understanding is that, they have to make it in hardware, make special circuit that when battery sensor inform about very low battery status, show this picture.
PS: I saw similar behaviour in Nexus 7 (2013)