- Amoeba
- A distributed operating system that is freely available via the Internet for educational and research users - BlueOS
- Ports the BeOS to Linux. - FreeOS.com
- Provides articles, documentation, download sites, news, links and more relating to free operating systems. - K42
- High performance, general-purpose operating system kernel for cache-coherent multiprocessors. - Kerneltrap.com
- News, information, and discussion hub for software engineers and hobbyists interested in low-level systems programming and kernel development. - Living Without Microsoft
- News, FAQs, and essays devoted to Open Source and proprietary alternatives to Microsoft products. - Lockergnome
- Offers a variety of daily newsletters regarding technology and computing. - Menuet OS
- Downloadable OS written in assembly. - Multi-booting Revolution, The
- Short analysis of the options available to those looking to run multiple operating systems from a single hard disk. - Multiuser DOS
- Information, software, patches, and support for the IMS Multiuser DOS real time operating system. - Nemesis
- Design is geared to the support of time-sensitive applications requiring a consistent Quality of Service (QoS), such as those which use multimedia. - Operating System Comparison
 - Operating System Sucks-Rules-O-Meter
- Searches the Web for positive of negative references to various operating systems and compiles them into a graph for easy comparisons. - OS Files, The
- Brief overview of the various operating systems available today. - OS News
- Covering alternative computing environments and technology. - OS/C
- Microkernel operating system designed to perform network activities without excessively engaging system resources. - PetrOS
- 32 bit operating system for PCs, from Trumpet Software. - Plex86.org
- Goal is to create an extensible open source PC virtualization software programme which will allow PC and workstation users to run multiple operating systems concurrently on the same machine. - Posix Programmer's Guide
- Guide to writing programmes for POSIX conforming environments including UNIX, openVMS, MVS, and Windows NT - Review of Operating Systems
 - sysprog.net
- A site for MVS and Linux systems programmers with industry news, tools, quotations, and job banks. - System Toolbox
- Dedicated to covering various server operating systems for administrators. - YouOS
- An operating system that works entirely from your web browser so you can access it anywhere there's an Internet connection.
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