Maybe this is a dumb question but is something I need to know. All laptops, computers, etc that i've used until today runs DOS as bios firmware... So I was wondering if there is motherboards running firmware that it is not DOS...?
You are a bit confused, I will try and keep this simple:
BIOS is an operating system (arguably) of very limited nature, that is typically stored as firmware on a motherboard. It is far less functional and complex, it just to "get things going" with relation to the hardware inside a computer, before starting up a boot loader.
Agree with @javano and @SvenW but fast .... backward a few years and the question may not be so irrelevant. In the days of MS-DOS 3.x and before the BIOS was so custom made (with hooks) for MS-DOS that using it with another OS was virtually impossible. But then there was no other OS in those days other than MS-DOS not on that platform anyway (i86-i386). Just a bit of history...
I'm a bit saddened by the fact you seem to associate a character based interface with DOS. (most server operating systems have nothing else).
But it is true most PC systems still start up in 8-bit mode before switching to full 32/64-bit. All this is mainly for compatibility reasons.
The Coreboot FAQ is quite an interesting read. This project allows you to replace your manufacturer BIOS with Linux for faster boot times and other more powerful features.