How can FreeBSD work with keyboard on a dead southbridge where other systems fail?

[Dmitry Bachilo]

So, here is the story: I have a laptop Acer Aspire 5100, which has a 
dead southbridge. In any operating system it predictibly results in 
non-working audio, usb, keyboard and touchpad. I tried Windows XP, 
Windows 7, Linux and FreeDOS. They all work ok on it except this minor 
stuff. I also obvioulsy can't access BIOS since keyboard is dead. And if 
I install FreeBSD on it ofcouse I cant skip that autoboot delay with the 
boot menu. But if system boots - the keyboards suddenly works like a 
charm, and that makes my laptop totally usable and fine (for example to 
set up ethrenet switches using cardbus serial adapter). That's a 
miracle! Or is it?

So the question is: what makes FreeBSD so different? How does it work 
with the keyboard and why no other OS uses this method then?

P.S. I even made the video about this situation and it has an image of 
this laptop's motherboard if needed. Here it is: 
https://youtu.be/JBt_fbvpGww