LeveretOS_
A small educational operating system built completely from scratch, with each new addition split into a separate lesson. Every change is commented for beginners, so this repository doubles as a step-by-step guide to how an OS actually works, starting from the very first instruction that runs at boot.
The idea
Each lesson has its own numbered folder and adds one new feature on top of the last. Code that is reused from earlier lessons will be left without educative comments, while keeping other comments. New or changed code will contain comments to guide you through each part.
Why "LeveretOS"?
A leveret is a baby hare , small, quick, and one of the fastest-growing young animals around. It felt like the right mascot for an OS that started as almost nothing and grows a little better with every lesson.
Photo by Tony Stoddard on Unsplash.
Lessons so far
| # | Lesson | What it adds |
|---|---|---|
| 01 | Hello World | Booting via GRUB and writing text to VGA memory |
| 02 | Text Output | A moving cursor for typing, putchar/print, newlines and wrapping |
| 03 | Text Input | Reading the keyboard: scancodes, getchar, read_line |
| 04 | Print Numbers | Turning integers into on-screen digits |
| 05 | String helpers | Create helpers for strings and memory |
Building and running a lesson
Each lesson folder is self-contained and includes a build.sh that assembles
the bootloader, compiles the kernel, makes a bootable ISO, and launches it in QEMU. You
will need nasm, a 32-bit-capable g++, grub-mkrescue,
xorriso, and qemu-system-i386 (on Windows, a Linux environment
such as WSL works well).
A good guide for setting up the necessary software to be able to boot: OSDev Bare Bones.
The goal
The current goal is to create an educational OS that can connect to the web.