MikeOS - simple x86 assembly language operating system

x86 operating system

MikeOS is an operating system for x86 PCs, written in assembly language. It is a learning tool to show how simple 16-bit, real-mode OSes work, with well-commented code and extensive documentation. Features:

A text-mode dialog and menu-driven interface
Boots from a floppy disk, CD-ROM or USB key
Over 60 system calls for use by third-party programs
File manager, text editor, image viewer, games...
Includes a BASIC interpreter with 46 instructions
PC speaker sound and serial terminal connection

The code is completely open source (under a BSD-like license), and is written by Mike Saunders and other developers.

News

9 April 2022: MikeOS 4.7 released! -- Many updates, as described in the changelog. Thanks to everyone who contributed! Get it here.

9 April 2022: BASIC compiler for MikeOS -- From Wojtek Grzela, this is "written in C and compiles MikeOS's BASIC dialect to executables for the operating system". Download it from GitHub.

17 Mar 2019: MikeOS 4.6.1 released -- Includes an updated macOS build script, documentation updates, and MikeTron from TachyonOS. Get it here!

9 Feb 2019: MikeOS 4.6 released! -- Many updates in this release, including a Forth Handbook, extra CLI commands, updates to the supplied BASIC apps and more; see doc/CHANGES.TXT for the full list.

29 Jul 2018: New spin-off project, MichalOS -- An awesome new MikeOS-based project that runs in 32-bit "unreal" mode, has VESA graphics and built-in mouse functions, custom fonts, a screensaver and more. Check it out!

Downloads

The link below contains the source code (see the source and programs directories), along with disk images for floppies/USB keys and CD-Rs in the disk_images folder.

You can write the images to a floppy disk, USB key or CD-R and boot your PC from them to test -- or use a PC emulator such as QEMU, VirtualBox or VMware. See the User Handbook below for a guide. System requirements: minimum 386 PC with a keyboard and 1MB of RAM.

MikeOS 4.7.0 -- zip file

Here are some contributed add-on programs:

Mouse library -- Add mouse support to MikeOS programs
MikeOS C library (84K) -- Write programs in C (see ReadMe.txt)
MikeOS Xfer (68K) -- Xmodem file uploader (see Xfer.htm)
BFM file manager -- With editor and viewer, by Ondrej Cerman
BIN2POKE -- Convert .bin files to BASIC POKE routines, from Paulo Valongo

And projects that use (or are for) MikeOS:

MikeOS BASIC compiler -- By Wojtek Grzela
Analogue to Digital Converter (244K) -- Project for kids
Test Card Generator (17K) -- Basic engineering tool (see README.TXT)
Monitor alignment tool (14K) -- Written in MikeOS BASIC
Arduino project (216K) -- Arduino Diecimila board access using MikeOS
USB keyboard project (585K) -- USB KB I/O project/guidelines

Images

Click on the thumbnails below to see full-size versions.

Handbooks

These four Handbooks provide the complete documentation for MikeOS:

User Handbook -- Running MikeOS and programs

BASIC App Developer Handbook -- Writing MikeOS software in BASIC
Assembly App Developer Handbook -- Writing MikeOS software in assembly language
Forth Handbook -- For using the supplied Forth interpreter MikeOS
System Developer Handbook -- Modifying and building the OS

Note that the Handbooks are also included with MikeOS, in the doc directory. If you're new to the world of OS development, see our guide: write a simple assembly language operating system from scratch (Serbo-Croat translation).

Discussion

To discuss MikeOS and similar 16-bit real mode operating systems, join us on Google Groups.

Credits

Project admin

Mike Saunders -- main code and Handbooks

Development

E Dehling
Ian Seyler
John Endler
Joshua Beck
Justin Tokarchuk
Matej Horvat
Michael van Tellingen
Mike Gonta
Peter Nemeth
Paulo Valongo
Takayoshi Sasano
Tomasz Gorol
Tslil Clingman
Walt Nagel
Yutaka Saiko
Pete Dietl

Website, docs and artwork

Nitin Reddy Katkam -- logo and site design
Paul Sommers -- Handbook API reference
Helen Ewart -- MikeOS cat mascot

Some website artwork from the Tango icon set.