How to Build a Bootloader from Scratch — Just Assembly, No OS

This is not GRUB. It’s a hand-written Stage-1 bootloader written in raw x86 assembly, booting directly from BIOS with no operating system and no standard library underneath it.

Part of the NanoBoot project — building up from BIOS POST to a working protected-mode jump, one register at a time.

Related

• Blog post: Bootloader from scratch — what BIOS actually hands you
• GitHub: NanoBoot
• Next: From Real Mode to Protected Mode — Building Custom GDT & IDT