MikeOS
A very limited and simple operating system written in assembler for 286 computers (and newer compatible architechtures, obviously). Pretty much what I would imagine as a successful outcome if I would write one to see that I can do it. It works, there's a text editor, a game, you can list, edit and execute files. Not much more though at first glance. I didn't look into writing additional software for it myself, yet. There are many forks of MikeOS. Most of them named after the forker and not under active development. It's a project I'd look into if I'd want to learn x86 assembler. Simple, not looking like any other OS I've seen.
MikeOS is neither UNIX-like in any way nor is it similar to CP/M or DOS. It is closer to being a BASIC interpreter with a program menu. But there is a bit more to it. Everything is in the same text mode in VGA resolution. After booting, you get a box with list of menu items in pointing to submenus or executable programs. Among those programs are a BASIC interpreter, some simple games, a text editor and a file browser. That's about the gist of what you get. It's all very simple and fast. Enough to write your own applications or scripts. And it all fits on a single 3.5" HD floppy. There are third-party applications to be found on the internet. But almost all that I stumbled upon were part of MikeOS forks.
Next to the menu there is also a command line with a very small list of commands. To be honest, from a user point of view, I don't know what to do with it.
There are quite a few forks. It seems to be a great hobby project. And because it's all relatively simple it's a project you can actually finish after a while, not like writing your own UNIX clone with system tools, glibc port and modern GUI. MikeOS forks usually come with some additional apps and scripts and some changes in UI. Some add to the few system calls, add their own menu. Some even started to add network support. One MikeOS fork I have to mention is MichalOS because it overhauled the UI to make it more pleasing and added quite a few simple apps and games that all seem to be very stable. It has an image viewer and a music program. TomOS is a fork that adds support for directories. ShoockOS seems to be about simplifying things even more.
On the MikeOS web site there are handbooks, resources for development and links to software projects for MiikeOS. MikeOS is a great help if you want to learn x86 assembly in a practical way without starting from zero. But it is also useful as an OS for embedded applications or simple hobby projects (interacting with Arduino, other serial communication tasks, …). And it could also be considered useful for everyday tasks if you found a home computer from the mid 80s useful.
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