🐍 SnakeOS

SnakeOS is an x86-64 learning operating system with the mission of running a 2D Snake game. ARM and RISC-V architectures are not supported. Compiler support is GCC and clang only.

The project explores low-level OS development, including bootloader design, memory management, graphics, and hardware interfacing, to build a minimalist but fully functional 64-bit OS.

How to run

Prerequisites

Make sure the following tools are installed on your system:

• nasm (x86 assembly)
• gcc (with x86-64 support)
• ld
• make
• qemu-system-x86_64

Arch Linux

sudo pacman -S nasm gcc make qemu-system-x86

Ubuntu / Debian

sudo pacman -S nasm gcc make qemu-system-x86

MacOS (Homebrew)

brew install nasm qemu

Note:
On macOS, the system gcc is typically an alias for clang.
This project uses freestanding C and a custom linker script, so a cross-compiler is recommended if you run into build issues.

Build

From the project root, run:

make

This will:

• Assemble the bootloader (NASM)
• Compile the kernel (C99)
• Link everything into a bootable image
• Produce a FAT12-formatted floppy disk image

The output image is typically located at: build/main.img

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📜 Project Goals

• Build a custom 64-bit operating system from scratch
• Gain hands-on experience with:
  • Bootloaders
  • Memory management & paging
  • Keyboard & input handling
  • Low-level graphics rendering
  • File system basics

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✨ Features

Operating System

• Custom Bootloader — boots from BIOS, switches to 64-bit long mode
• Protected → Long Mode Transition — complete GDT setup and paging
• FAT12 Support — load files directly from a floppy image
• Keyboard Driver — low-level input handling
• Basic Graphics Mode — VGA or custom framebuffer drawing
• Memory Management — paging tables, identity mapping

Snake Game

• 2D grid-based gameplay
• Real-time input
• Score tracking
• Game-over & restart logic
• Runs natively on SnakeOS without external dependencies

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🛠️ Tech Stack

• Language: x86 Assembly (NASM) + C99
• Target Architecture: x86-64
• Build Tools: nasm, gcc, ld, make
• Emulator: QEMU (primary), Bochs (optional)
• Disk Format: FAT12 (floppy image)

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📂 Repository Structure

SnakeOS/
| arch/
| | x86/
| | | gdt.c
| | | i8259.c
| | | idt.c
| | | gdt.asm
| | | idt.asm
| boot/
| | x86/
| | | stage0/
| | | stage1/
| | | kernel_entry.asm
| | | shared_utils.asm
| drivers/
| | cdev.c
| | console.c
| | i8042.c
| | i8253.c
| | init_ram.c
| | keyboard.c
| | timer.c
| | tty.c
| | vga.c
| include/
| init/
| | kmain.c
| kernel/
| | exception.c
| | irq.c
| | kprint.c
| lib/
| Makefile