TAJ Operating System
- TAJ is an object oriented operating system written in C++. It is a multitasking, multithreading and a multiuser operating system.
- http://www.viralpatel.net/taj/home.php

Ace Operating System Project
- An open source operating system for X86 architecture. It also contains documents, specifications explaining various hardware.
- http://www.samueldotj.com/Ace/

Yet Another Object Oriented Operating System
- A project of developing new object oriented operating system.
- http://alzt.tau.ac.il/~michaelg/yaooos/

Tuomo Kortesmaa
- Notes and example code for basic operating systems concepts, threads, sockets, and device drivers.
- http://users.evtek.fi/~tk/

Porting UNIX to the 386
- Historic article series appearing in 1991 that started the open source operating system movement.
- http://porting-unix-to-the-386.jolix.com

OSDev
- OS Development RSS News, forums, and the OSDev Wiki including the largest listing of ameatur operating system projects on the internet.
- http://www.osdev.org

Pierre's Library
- A resource center for PC operating system developpers. The aim is to provide reliable documents about software and hardware standards under the aspect of official specifications as well as more friendly documents.
- http://perso.orange.fr/pierrelib/

Virtual Memory Tutorial
- Extensive discussion of virtual memory.
- http://cs.gmu.edu/cne/modules/vm/

Inter-Process Communication Tutorial
- Interactive tutorial about message passing, semaphores, and monitors.
- http://cs.gmu.edu/cne/modules/ipc/

Operating System design & implementation Tutorial
- A educational tutorial on the development of a real mode, single tasking operating system developed in assembler.
- http://www.mohanraj.info/josh.jsp

Mainframe Programming
- The mainframe continues to grow and transform itself while maintaining its reliability, security and speed.
- http://www.muraleedharan.com/mainframe_programming.html

unixsite.net
- A repository of UNIX-related material, consisiting of: tutorials, programs, source code and miscellaneous information.
- http://unixsite.net/

visopsys OS Development
- A collection of source code, information, and links related to general Operating Systems Development on the Web.
- http://www.visopsys.org/osdev/index.html

Intel Pentium 4 Manuals
- The full documentation of system management from Intel for the IA-32 architecture.
- http://www.intel.com/design/Pentium4/documentation.htm#manuals

How to Program a Bootstrap Loader
- A bootstrap tutorial that includes assembly language code to demonstrate loading and executing a binary image from a FAT filesystem.
- http://www.omninerd.com/2005/11/05/articles/40

Agnix
- An open source project, which has been founded to provide an educational, network operating system kernel.
- http://agnix.sourceforge.net/

The Basic Kernel Source Code Secrets
- By William Jolitz and Lynne Jolitz (authors of 386BSD OS). Good book to learn the kernel internals of 386 architecture operating systems.
- http://jolitz.telemuse.net/content/books/scs_vol1/item

Cottontail OS Development Library
- Old non-updated mirror online library covering a plethora of OS development topics. Datasheets, tutorials, reference manuals and hardware programming information.
- http://www.osdever.net/cottontail/

OSDEV Community
- A web portal dedicated to operating system development, attracting programmers into an advanced development environment.
- http://www.osdcom.info/

Bona Fide OS Development
- OS development information and tutorials. Links.
- http://www.osdever.net/

Operating System Lecture Notes
- Notes on operating system theory, source code of describing actual construction of operating system in C programming language. Also OS construction related links to books, notes, tutorials, and news groups.
- http://www.personal.kent.edu/~rmuhamma/OpSystems/os.html

Protected Mode and Operating Systems
- Information on writing operating systems, protected mode, and small independent OS projects with freely-available source code.
- http://my.execpc.com/CE/AC/geezer/os/

Groovyweb: Operating system programming
- An open source os written in Turbo C (for DOS/ windows) and nasm (Windows/Dos/Linux) as well as two exclusive tutorials on how to write an operating system.
- http://www.groovyweb.uklinux.net/index.php?page_name=Operating%20system%20programming

CS 3210 Design of Operating Systems
- A course in operating systems with a focus on the design and construction of a modern OS kernel.
- http://www.cc.gatech.edu/classes/AY2000/cs3210_spring/

The Operating Systems Resource Center
- Extensive information about booting, file systems, memory, architecture, and interfacing with other devices.
- http://www.nondot.org/sabre/os/articles

ACM Special Interest Group for Operating Systems
- Tutorial for writing an operating system and links to group members' projects.
- http://www.acm.uiuc.edu/sigops/

The OSKit Project
- An open source set of libraries that can be used as building blocks for an operating system for x86. Includes documentation and publications.
- http://www.cs.utah.edu/flux/oskit/

DBLP Bibliography: Operating Systems
- Links to many operating systems journals on the web.
- http://www.informatik.uni-trier.de/~ley/db/os.html

KernelCode
- News and reviews of kernels.
- http://www.kernelcode.com/

KernelNewbies.org
- Resources for programmers new to kernel hacking. Example code, FAQs, utilities for debugging modules.
- http://kernelnewbies.org/