This started as curiosity about how computers actually boot, and somehow escalated into writing a kernel, building a GUI, and setting up CI that produces a bootable OS image on every commit.
BananaOS is a small experimental operating system built mainly for learning and exploration of low-level systems programming. It currently targets i386 BIOS systems and is designed to run on extremely constrained hardware. Fun fact: Wallpaper logic, one of the most important OS functionalities, is directly implemented in the kernel. That cracked my son up!
Some highlights:
Multiboot-compliant kernel loaded via GRUB
VESA framebuffer graphics with double buffering
Custom window manager with movable and resizable windows
Dock-style application launcher
PS/2 keyboard and mouse input handling
PCI enumeration and AHCI SATA support
Basic applications (terminal, notepad, calculator, file explorer, settings)
Memory detection and allocation based on available RAM
Boots in QEMU with about 11.2 MB RAM
Includes an ISR workaround to emulate CMOV so it can boot on Intel 486 CPUs
One thing I found particularly fun: he also added GitHub Actions workflows that automatically build the OS image for every commit, so the repo continuously produces fresh bootable artifacts.
The project is very much experimental and should only be run inside an Virtual Machine.
Repo (with build instructions and screenshots):
https://github.com/Banaxi-Tech/BananaOS
Quick start (only on Linux, check dependencies, and see README):
git clone https://github.com/Banaxi-Tech/BananaOS cd BananaOS make qemu-system-i386 -cdrom bananaos.img -m 128M
Retro mode:
qemu-system-i386 -cpu 486 -cdrom bananaos.img -m 11.2M
He’s mainly building this to understand kernels, memory management, drivers, and how operating systems actually work below user space.
Feedback from people who have built hobby operating systems or worked close to hardware would be especially appreciated.