TL;DR: This entire operating system (over 115,000 lines of C code) was built entirely through iterative AI prompting over the course of about 6 weeks (spending roughly 1 hour per day). I, the author, had only basic programming experience, but zero experience in OS development or complex systems programming.
Before you dive into the code, I want to be 100% transparent: I am not claiming this code is secure, well-architected, or even "good".
While I understand the fundamentals of C, I am by no means an experienced developer or OS engineer. I cannot accurately judge the architectural quality or security of the code the AI produced. There are likely severe security vulnerabilities, memory leaks, race conditions, and architectural nightmares hidden in here. This project is meant to be an experiment on the limits of Large Language Models, not a production-ready system. If you are an experienced systems programmer, you will probably find things that make you want to pull your hair out—and that's exactly what makes this project so interesting!
PromptOS is an experiment exploring what current LLMs can do. The guiding question was: Is an AI capable of building the most complex software architecture in computer science from scratch, without a human developer writing a single line of code manually?
The result is PromptOS: a runnable x86_64 OS with its own custom kernel, virtual file system, complete networking stack, and a graphical user interface (GUI) with a window manager. Everything was orchestrated through a massive Plan.md, using an AI Code Auditor to verify implementation, and building custom web-based tooling to allow the AI to debug and iterate autonomously.
Despite being built entirely by AI, PromptOS includes the following features:
- 🧠 Custom x86_64 Kernel: Multitasking scheduler, SMP (Symmetric Multiprocessing), Physical/Virtual Memory Management (PMM/VMM).
- 📁 BetterFS & VFS: A completely custom file system designed by AI (
BetterFS), along with support for FAT32, DevFS, ProcFS, and RamFS. - 🌐 Networking Stack: Custom TCP/IP stack, UDP, DHCP, DNS, and basic routing.
- 🖥️ Desktop Environment: A window compositor, taskbar, and a custom widget library (Buttons, TextBoxes, TreeViews).
- 🔒 Security & Crypto: Custom crypto stack (AES, SHA256, Ed25519, TLS 1.3 basics) and code-signing mechanisms.
- 🛠️ Userland & Apps: A C standard library (
libc), shell, package manager (npkg), editor, paint, calculator, and file manager.
PromptOS reaching Phase 10 (Desktop Environment) in the Web Debugger
Kernel initialization phases shown in the Web Debugger console
Because this project grew without deep human C expertise, the AI made some interesting (and sometimes questionable) architectural decisions to solve problems:
- Autonomous Debugging & Tooling: Instead of manually feeding error logs, we built a custom website and specialized tooling that allowed the AI to read QEMU logs, trace page faults, and debug memory leaks completely on its own until it successfully patched the pointer errors.
- Extensive Test Strategy: To ensure its own code worked, we developed a highly professional Testing Strategy and the AI generated dozens of unit tests running directly on the host (
tests/host/unit/) as well as in-kernel tests and fuzzers (tests/fuzzer/,tests/bench/). We actually run a suite of host tests instantly without QEMU to guarantee libc and logic stability!
The system is configured to run in modern emulators and hypervisors.
- GCC Cross-Compiler for x86_64-elf (or WSL)
make- QEMU or Hyper-V
The repository includes handy scripts to get you started immediately:
# Build the complete system (Kernel, Bootloader, Userland, Apps)
make all
# Create a bootable ISO / Disk Image
./scripts/make-iso.sh
# or
./scripts/make-image.sh
# Start PromptOS in the emulator
./scripts/run-qemu.sh(Windows/Hyper-V users can use the provided .ps1 scripts in the scripts/ directory).
| Document | Description |
|---|---|
| INSTALL.md | Development environment setup (cross-compiler, QEMU, etc.) |
| docs/dev-guide.md | Developer guide: architecture, build, extending PromptOS |
| docs/SYSCALL.md | Syscall ABI v1 specification (100 syscalls) |
| docs/BOOT_PROTOCOL.md | Custom UEFI boot protocol specification |
| docs/STYLE.md | Coding style guide |
| docs/TESTING_STRATEGY.md | Testing strategy and test infrastructure |
| docs/GUI_PROTOCOL.md | GUI display protocol |
| docs/IPC_PROTOCOL.md | IPC mechanisms |
| CHANGELOG.md | Version history |
If you are an OSDev enthusiast, AI researcher, or C hacker and want to check out the code: Welcome! Feel free to explore the architectural anomalies, open issues, or discuss the capabilities of modern LLMs in the context of systems programming.
- Read CONTRIBUTING.md for contribution guidelines
- Check SECURITY.md for the security policy
- See INSTALL.md to set up your build environment
Built with 🤖 (primarily Claude Opus 4.5, via Cursor) & ☕