There is a Phrack article with a full kernel. These things are dime a dozen. I cut my teeth on Doug Comer's Xinu, still one of the more accessible ones, if a b

There is a Phrack article with a full kernel. These things are dime a dozen. I cut my teeth on Doug Comer's Xinu, still one of the more accessible ones, if a bit over-commented. Outside the x86 and ISA architectures, OSes are just algorithms. All the magic goes into probing devices and chanting legacy BIOS incantations :-| The first seconds, from moment you press ON until you see the OS splash screen, the machine runs through 30 years of PC history.