codedbyhermez/redpandaos

RedPandaOS is a hobby operating system built entirely by its creator without using any existing operating system code, standard libraries, or pre-built frameworks. It runs on a simulated computer via QEMU and targets the older 32-bit x86 architecture. The project started from the very first instruction the computer executes at boot and grew from there. The system includes a custom bootloader written in assembly language that fits in a single 512-byte sector, which the computer's firmware loads automatically. That bootloader reads the kernel from disk and hands over control. The kernel then sets up memory management, handles hardware interrupts, drives a PS/2 keyboard and mouse, and talks to the display via a framebuffer that lets it draw individual pixels. On top of that kernel sits a full graphical desktop: a taskbar with a start menu and a live clock, draggable windows with rounded corners and drop shadows, desktop icons, and a trash bin. Files written to a custom filesystem called RPFS persist on disk between reboots. The filesystem uses an ATA disk driver the author also wrote from scratch and stores data in a block-chain format similar in concept to older systems like FAT. The most recent version (v11) adds a working text editor that supports typing, cursor movement, scrolling, saving with Ctrl+S, and undo/redo with Ctrl+Z and Ctrl+Y. Every utility function used by the kernel, including memory copy, formatted text output, and the font renderer, was also written by hand rather than borrowed from a library. This project is primarily educational and creative: a single-person effort to understand how an operating system really works by building every piece independently. The build process requires NASM (an assembler), LLVM/Clang (to cross-compile C code for bare-metal i686), and QEMU to run the disk image. A single PowerShell script handles the full build. Future milestones on the roadmap include userspace programs running in a separate privilege mode and loading applications from disk. It is released under the MIT license.