MoleculeOS

MoleculeOS is a minimalist, text-based i386 monolithic operating system, developed in C++ as a hobby project.

The goal of this project is to create a clearly structured, modular learning and experimentation system that makes the fundamental building blocks of an operating system understandable and transparent - hence the name MoleculeOS.

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Features (current / planned)

• Minimal 32‑bit kernel in C++
• VGA text mode output
• Basic hardware initialization
• Interrupt Descriptor Table (IDT)
• Global Descriptor Table (GDT)
• Simple endless-loop scheduling
• simple ATA-PIO-driver
• block-allocator System Heap
• PS/2 Keyboard input
• Shell Interpreter
• Simple Terminal
• grub Boot-Setup
• custom direct RAM flat file-system
• central APIs for all components
• strict separation between architecture-specific and non-architecture-specific code

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Design Philosophy

MoleculeOS is intentionally simple:

• no paging
• no multitasking
• no 64‑bit mode
• no complex drivers

The goal is to understand the essence of OS development without unnecessary complexity.

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Current Boot Output

Below is the current state of MoleculeOS running in QEMU:

Below is the current state of MoleculeOS running in QEMU (deliberately triggered panic with a division by 0):

Demo Preview

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Requirements

To build and run MoleculeOS, the following software is required:

• Grub (for the Boot setup and configurations)
• NASM (Netwide Assembler for assembling the Bootloader and Assembly Files in the Kernel)
• Clang++ (for compiling the 32‑bit kernel and the C++ runtime, requires i386 target support)
• Clang (for compiling the C Runtime and C components in the Kernel, requires i386 target support)
• Make (for Building and running the Project)
• ld.lld (for the linking)
• QEMU (for running the OS in a virtual machine)
• WSL (Windows Subsystem for Linux, if you work under Windows) (for using Grub and run Shell Scripts)

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Build & Run

if you using VS Code and WSL

    CTRL + SHIFT + B

if you using the shell

    chmod +x build.sh
    ./tools/build.sh

This will:

• assemble the bootloader
• compile the kernel
• compile the runtime
• build a .iso File
• launch QEMU