BIOS and booting

[talentlos]

Hi!

So I was looking deeper into how an OS works. I was primarly looking into linux. While reading about the bootup process on Wikipedia I learned that there are several ways for a computer to boot. One of them is BIOS firmware. However, I am having trouble understanding everything. So this will be my own thread for asking some questions.

First question. Where is the best place to read and best understand the workings of BIOS for booting up the machine?

Second q. Under "Startup on systems using BIOS firmware"  on the GRUB 2 wiki page it says that boot.img is first loaded into first sector(sector 0) of MBR. Where is boot.img stored before this? Is it in ROM(cmos) from the motherboard?

-talentlos