Operating systems run your computer!
There are lots of innovative OS projects but only a few are really used.
Aside from Linux, Windows, MacOS and derivatives… https://www.ipredia.org/os/
IlluminOS:: An operating system that claims to provide advanced system debugging, a next-generation file system, networking and visualization.
https://ameliorated.info/ :: Windows 10 with the crap removed
DawnOS:: An operating system built on the subleqhigher level language architecture. See the videofor a detailed overview!
Redox:: is a Rust operating system with a microkernel-based design.
Urbit:: A 'universal function'.
MetalOS:: A hobby project written by a single person.
InterimOS:: Written to accompany mntmn's custom hardware.
CirnOS:: An operating system that transforms a Raspberry Pi into an Arduino. effectively.
Demikernel:: interesting approach to architecture
NotOS:: An operating system generator based on NixOS.
CrysaLisp:: A next-generation Lisp machine.
TempleOS (racist)
CollapseOS:: An OS written entirely in the Forth programming language.
Fuscia https://blog.quarkslab.com/playing-around-with-the-fuchsia-operating-system.html
Gentoo :: An operating system that prides itself on building everything from source. Leaving Gentoo https://www.paritybit.ca/blog/my-beginnings-with-gentoo https://timboudreau.com/blog/gentoo/read gentoo seems like a great learning exp https://wiki.gentoo.org/wiki/Raspberry_Pi#Hardware help loading gentoo onto a pi {might be more helpful to put on qemu}
Qubes OS:: An operating system that isolates every application and device on the computer, granting permission to each only when necessary. Many journalists and security professionals rely on this.
WhoNix:: An operating system designed to completely sandbox your activity inside of a virtual machine.
Plan9 :: Defer to Devine's notes on the subject
Spectrum:: An OS modeled after Qubes, but making full use of the Nix reproducible build system, and dedicated to supporting mainstream x86-64 hardware.
SmartOS :: combines opensolaris tech with linux kvm virtualization. has zfs. contributed to illumos project
https://news.ycombinator.com/item?id=23100713
LineageOS :: The most popular alternative Android operating system, built off of CyanogenMod. https://wiki.lineageos.org/devices/starlte/install https://www.reddit.com/r/degoogle/comments/gu2kk9/lineageos_vs_e_vs_alternatives/
e :: An operating system designed to function efficiently on older, refurbished devices. Built on LineageOS.
NixOS Mobile :: A full port of NixOS to a mobile platform. It's built on top of many previous efforts and relies on a tool to convert GTK applications to mobile equivalents.
Wii-Linux ::
https://mirror.dernuntius.de/projects/wii-linux/ http://songseed.org/dinghy/concept.html reenvisioning the os
Operating Systems: Three Easy Pieces Books
hobby operating system written in C
https://www.reddit.com/r/osdev/comments/husrzq/looking_for_a_specific_tutorial_from_10_years_ago/ macos emulation layer for linux toy os
https://blog.twitter.com/engineering/en_us/topics/open-source/2020/hunting-a-linux-kernel-bug.html demikernel/demikernel: Demikernel OS
nickbjohnson4224/rhombus: a hobby operating system written in C jmgrosen/shorai: A super-amazing OS that will bring world peace. Demikernel
How to Protect Your Privacy on Linux well known operating systems course at upitt just in time specialization for opencl kernels http://c9x.me/articles/gthreads/intro.html trigger kernel races reliably
kabbi/wonderland: Inferno clone to conquer the world
http://intermezzos.github.io/ a demo operatin system for learning https://littleosbook.github.io/ the little book of of development
https://en.m.wikipedia.org/wiki/Genode
http://wintermute.org/brendan/ the screenless office and other artistic efforts
https://github.com/mkilgore/protura toy os kernel and utilities https://makelinux.github.io/kernel/map/ map of the linux kernel
https://www.mercuryos.com/ reengineering of the operating system as a ux project, fluid experience driven by human intent
https://github.com/ssrg-vt/hermitux binary compatible unikernel
https://github.com/oasislinux/oasis statically linked linux system https://github.com/dlannan/ljos luajit command line os
https://news.ycombinator.com/item?id=10957020: overview of real alternative operating systems for considering. lots of interesting innovations!