⚙️ nox_os — Educational Command-Line Operating System

nox_os is a minimal, educational operating system built entirely from scratch to demonstrate the core principles of OS design — from bootloading and memory management to multitasking and file systems — all through a clean command-line interface.

Unlike Linux-based kernels, nox_os is an independent OS written in C, x86 Assembly, designed to run directly on hardware via QEMU or Bochs. It aims to be readable, hackable, and deeply instructive, making it ideal for anyone learning how operating systems actually work.

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Features

• Custom Bootloader (no GRUB dependency)

• ⚙️ Protected Mode Kernel written in C/C++

• 🧠 Paging and Heap Memory Management

• 🔄 Round-Robin Task Scheduler

• 💾 Simple FAT12-like Filesystem

• ⌨️ Keyboard and VGA Text Drivers

• 🔌 System Call Interface

• 💻 Command-Line Shell with built-in commands:

  help, ls, cat, echo, meminfo, ps, reboot
  

• 💽 Bootable QEMU Image included for easy testing

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🎯 Project Goals

• Understand the low-level boot process and transition from real to protected mode.
• Learn how a kernel manages memory, interrupts, processes, and drivers.
• Provide a minimal, modular OS that’s easy to explore and modify.
• Serve as a hands-on educational tool for OS developers and enthusiasts.

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🛠️ Building nox_os

Prerequisites

You’ll need:

• i686-elf-gcc or x86_64-elf-gcc cross-compiler
• nasm for assembling bootloader code
• qemu-system-x86_64 for running the OS
• make for automated builds

💡 Tip: If you don’t have a cross-compiler, the OSDev Wiki has setup instructions.

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Build Commands

# 1. Build the OS
make all

# 2. Run it in QEMU
make run

# 3. Clean build files
make clean

Once built, the kernel image will appear in:

build/nox_os.bin

Run it directly:

qemu-system-x86_64 -drive format=raw,file=build/nox_os.bin

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💻 CLI Commands

Command	Description
help	Show available commands
ls	List files in the current directory
cat	Display file contents
echo	Print text to screen
meminfo	Show memory usage info
ps	Display running processes
reboot	Restart the system

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🧩 System Overview

Component	Description
Bootloader	Written in x86 assembly; sets up protected mode and loads the kernel
Kernel Core	Initializes system structures and manages memory, tasks, and I/O
Memory Manager	Frame allocator + virtual memory paging
Scheduler	Simple round-robin process scheduler
Filesystem	Minimal FAT12 or custom layout with basic file I/O
CLI Shell	Interactive command-line interface for system interaction
System Calls	Interface layer between user commands and kernel routines