x86 Operating Systems, Virtual Machines, Emulators and Clustering Software

I record x86 operating systems (OSes) and related software on this page as I become aware of them, but I won't necessarily have the time to keep it up to date - I already have a long list of uncategorised OSes to add.  Latest release dates were last confirmed mid-November 2005 [this page is now - 20 May 2006 - quite out of date and it seems that I won't have time to maintain this page in the way that I'd like to].  It's far from comprehensive although it covers most of the widely-used x86 OSes.  Some of the software also runs on CPUs other than the x86 family.

The OSes are differentiated based on their kernel rather than their overall end-user environment, systems interface or application programmer interface (API), so for example the many Linux distributions are not listed separately.  The notes column non-comprehensively lists distributions.

Links based on the software's name are to the primary vendor or developer site unless otherwise noted.

All archival links are marked with a double-asterisk: **

"But there's already Wikipedia and dozens of sites listing OSes..."  True; this is in part an extension of my bookmarks file.  It also serves to collect - and categorise according to - the details I'm most interested in.

Desktop OS Differentiation

Operating systems suitable for modern desktop use and under active development are styled like this.

Operating systems not-yet ready for modern desktop use but that look promising and that are under active development are styled like this.

Operating systems suitable for modern desktop use, but which are no longer developed or are proprietary and for which support has ended or will be ending soon are styled like this.

...And those looking for other types of operating system most likely don't need (or want!) that kind of styling assistance.

Accuracy

You can let me know if any information on this page is inaccurate.  I've marked unconfirmed information with a parenthesised question mark.  The HTML source has further information.  In particular I haven't confirmed the extent to which the OSS BSDs are POSIX-conformant.

Operating Systems

The Unix Family

This section lists OSes that are either genetic Unix operating systems or obvious clones thereof and does not require them to be POSIX compliant or certified as trademark UNIX.

They are all general-purpose and support a rich CLI including a scriptable shell.  Most (all?) support a rich developer environment including C compiler, linker, debugger and make utility.  Some also support a GUI - typically The X Window System.  Most can be used as servers renowned for stability and reliabity.  Some are extremely scalable, with support for multiple CPUs and/or huge addressable memory and/or large-capacity, robust journalled/soft-update filesystems.

All have a monolithic kernel except for MINIX, a microkernel-based clone.  The OSS OSes are sometimes categorised "research", but are mostly equally suitable for production use.

Abbreviations and other terms in the table below are described in the glossary.

Name and Latest Release Development Status and Licence Features of Latest Release Non-x86 Support Links and Notes
Linux 2.6.14.2 [1] (2005-11-10) PROD/Q; >=386 + 64-bit; GPL (OSS); ongoing led by Linus Torvalds GUI, CLI, M/T, M/U, SRVR, PSX, SMP, DRV++ [4], N/W, F/S++, MIN, K/MON, K/MOD; exts. for SEC, R/T, DIST, PAR Widely ported Developed independently of the original Unix codebase; [wp]; distributions: DistroWatch (Gentoo and Debian are popular)
MINIX 3.1.1 (2005-10-24) PROD/Q/IM; >=386 - 64-bit; MINIX 3 licence (OSS); ongoing led by Andrew S. Tanenbaum CLI, M/T, M/U, PSX, N/W, MIN, K/µ Being ported to ARM7 and PowerPC Developed independently of the original Unix codebase for teaching purposes; GUI (X port) in progress; [wp]; comp.os.minix
386BSD 1.0 aka JOLIX PROD/Q; 386 only; BSD licence [wp] (OSS); ceased - was led by William Jolitz and Lynne Jolitz GUI(?), CLI, M/T, M/U, N/W, K/MON The first BSD to run on x86; [wp]
NetBSD 2.1 (2005-11-02) PROD/Q; >=386 + 64-bit; BSD licence (OSS); ongoing led by a core group, backed by a foundation GUI, CLI, M/T, M/U, SRVR, PSX(?), N/W, SMP, K/MON Widely ported Forked off 386BSD (second to run on x86); renowned for portability and portedness; [wp]
OpenBSD 3.8 (2005-11-01) PROD/Q; >=386 + 64-bit; BSD licence (OSS); ongoing led by Theo de Raadt GUI, CLI, M/T, M/U, SRVR, PSX(?), N/W, SMP, SEC [5], K/MON Widely ported Forked off NetBSD; renowned for security; [wp]
FreeBSD 6.0 (2005-11-04) PROD/Q; >=386 + 64-bit; FreeBSD licence (OSS); ongoing led by a core team GUI, CLI, M/T, M/U, SRVR, PSX(?), N/W, SMP, K/MON, exts. for SEC Moderately ported with more in progress (total about 9) Forked off 386BSD and later accreted some 4.4BSD-Lite; [wp]
DragonFlyBSD 1.2.6 (2005-10-09) Near-PROD/Q; >=386 - 64-bit; DragonFlyBSD licence (OSS); ongoing led by Matthew Dillon GUI, CLI, M/T, M/U, SRVR, PSX(?), N/W, SMP, K/MON None; possible future SPARC port Fork of the FreeBSD 4.x series to try a different approach to SMP/threading and other innovations; [wp]
BSD/OS 5.0 ISE** (with final upgrade to 5.1 ISE for existing customers in 2003) aka BSDi aka BSD/386 PROD/Q; >=386 -(?) 64-bit; commercial licence with viewable source; sales ended 2003-12-31; support ended 2004-12-31; final licensor Wind River Systems GUI, CLI, M/T, M/U, SRVR, N/W, PSX, SMP, K/MON SPARC, PowerPC Originally developed commercially by Berkeley Software Design Inc**, who subsequent to the 4.2** release** on 2000-11-29, sold the OS to Wind River, who rolled out version 4.3 on 2002-03-14; [wp]
Solaris 10 (2004-11-15) PROD/Q; >=386 + 64-bit; financially cost-free license (non-OSS); ongoing led by Sun GUI, CLI, M/T, M/U, SRVR, PSX/CRT, N/W, SMP, K/MON SPARC Descended from the original AT&T Unix source code; renowned for reliability; [wp]; free availability announced 2005-02-01
OpenSolaris Build 27 (2005-11-16 ) PROD/Q; >=386 + 64-bit; CDDL (OSS licence) with parts under OpenSolaris Binary Licence; ongoing led by a Community Advisory Board (majority appointed by Sun) GUI, CLI, M/T, M/U, SRVR, PSX, N/W, SMP, K/MON SPARC An OSS release of Solaris announced 2005-06-14; CDDL announced 2005-01-25; [wp]; distributions: Nexenta (GNU-based), SchilliX
NextStep 3.3 (1994-12-07**) PROD/Q; >=486 - 64-bit; commercial licence (non-OSS); for sale through Black Hole, Inc; development ceased; final licensor Apple GUI, CLI, M/T, M/U, SRVR(?), PSX(?), N/W, SMP(?), K/MON Motorola 68000, SPARC, HP Developed by Next** and purchased by Apple (announced 1996-12-20); driver support site (Apple); renowned for its revolutionary GUI; [wp]
Darwin 8.3 (2005-10-31) PROD/Q; "certain" x86 chips; various licences, primarily the APSL (OSS); ongoing led by Apple GUI, CLI, M/T, M/U, SRVR, PSX(?), N/W, SMP(?), K/MON PowerPC The evolution of NextStep, based on FreeBSD over a Mach microkernel; the core of Apple's commercial OSX (previously "Rhapsody"; x86 release soon); [wp]; distributions: GNU-Darwin
Xenix 2.3.4 (1989) [source: Wikipedia] PROD/Q; 16-bit and 386; commercial licence (non-OSS); no longer sold or supported; final licensor SCO CLI, M/T, M/U, N/W, K/MON Moderately ported e.g. Zilog, Altos, PDP-11, Tandy's and Apple Lisa's 68000-based machines Microsoft's version of Unix, descended from the original AT&T source code and later sold to SCO; [wp]
SCO OpenServer 6 (2005-06-22) aka SCO UNIX aka SCO ODT PROD/Q; >=Pentium - 64-bit; commercial licence (non-OSS); ongoing led by SCO GUI, CLI, M/T, M/U, SRVR, PSX, RAM to 64 Gb, N/W, SMP to 32 CPUs, K/MON None Descended from Xenix; [wp]
SCO UnixWare 7.1.4 (2004-06-15) with later maintenance packs PROD/Q; >=386 + 64-bit in 32-bit mode; commercial licence (non-OSS); ongoing led by SCO GUI, CLI, M/T, M/U, SRVR, PSX, SMP, K/MON None Originally developed by Univel, a joint-venture between Novell and AT&T's UNIX Systems Laboratory; [wp]
Coherent 4.x(?) (1995?) PROD/Q for 286, 386 and 486; commercial licence (non-OSS); sales and support ended 1995(?); development ceased; licensor Robert Swartz(?) GUI, CLI, M/T, M/U, PSX(?), some N/W [2], mem lims [3], K/MON PDP-11, z8000, Atari ST Developed by now-defunct Mark Williams Company, independently of existing code, from UNIX Version 7 specs; [wp]
Interactive UNIX System V/386 Release 3.2 Version 4.1.1 (1997?) PROD/Q; >=386 - 64-bit; commercial licence (non-OSS); sales ended (date?); support ends 2006-06-23; final licensor Sun GUI, CLI, M/T, M/U, PSX, N/W, RAM to 256Mb, K/MON None(?) Product description of version 4.1**

... and the yet-to-be-tabulated:

Almost Unix

General-purpose Desktop-based

General-purpose Console-based

Distributed / Parallel

Distributed / Parallel but not an OS

Special-purpose

Incomplete Hobby/Abandoned OSes

Emulators / Virtual Machines

General OS-Related Links

The Meaning of Terms, Abbreviations And Phrases As Used Within This Page

command-line interface (CLI)
An interface based on a sequence of text-only commands and responses.
console
A CLI that may in addition allow graphics (e.g. 3D games or image viewers) outside of a GUI.
desktop
Used synonymously with GUI except when qualified with modern.
DIST
A distributed OS.
DRV++
Extensive range of drivers available.
F/S++
Extensive range of filesystem types supported.
GUI
Graphical user interface - a graphical windowing system.  Text-based windowing systems, where for example the borders and buttons of the windows are represented by characters like | and ¬, don't qualify.
K/MOD
The OS's kernel is modular and supports loading and unloading of kernel modules at runtime.
K/MON
The OS's kernel is monolithic.
K/µ
The OS's kernel is a microkernel.
MIN
Minimalist hardware supported - can be configured for very small memory, disk and CPU requirements.
M/T
Multitasking - can simultaneously run multiple programs/processes, either virtually through preemption on a single CPU or actually on multiple CPUs.
M/U
Multiuser - supports multiple users who can be logged in and running programs simultaneously.
N/W
Networking supported - this includes TCP/IP (for internet connectivity), dial-up modem and network card support unless otherwise indicated.  It does not imply USB ADSL or cable-modem drivers, but these may be supported anyway.  Also not supported may be some software-based internal modems.
OSS
Open source software - software whose licence requires its source code to be viewable, modifiable and freely redistributable.  A term promoted by the Open Source Initiative (OSI) as more palatable to business minds than the term Free Software as promoted by the Free Software Foundation (FSF).  The two terms have substantially the same meaning despite the copyleft provision of the GPL, since neither term requires this provision.  The GPL is, however, compatible with both terms.
PAR
Supports parallel computing.
PROD/Q
Production quality - sufficiently performant and free of serious bugs to be used for regular or important purposes.
PROD/Q/IM
Production quality but still immature and lacking in features.
PSX
POSIX compliant - completely or very nearly completely implements one of the revisions of the POSIX/SUS standards - not necessarily the latest one.  See also UNIX, POSIX and SUS.
PSX/CRT
Certified UNIX - completely implements one of the revisions of the POSIX/SUS standards and certified as an official trademark UNIX.
R/T
A realtime OS.
SEC
Security-focused or security-enhanced.
SRVR
Capable of hosting a modern server.  Implies that the OS -
  • supports fast modern hardware
  • supports at least one large-capacity and/or robust filesystem type such as a journalled or soft update filesystem
  • has scalable performance - doesn't badly degrade as the number of processes or threads increase or the amount of available/used memory is increased
  • strongly separates processes - so that a failure/security breach in one process is not likely to affect others
SMP
Symmetric multiprocessing supported [wp]
suitable for modern desktop end-use
The following criteria may be considered to be satisfied when appropriate components provided (possibly under a different licence) by distributors/vendors other than the kernel developers exist, as well as when those components are provided by a default distribution -
  • a GUI
  • availability of a minimum number of applications - in particular internet browser, email client and word processing facilities
  • networking support including TCP/IP for internet access
  • sound support - at a minimum playback of one audio file format
  • modern hardware support -
    • Pentium and higher CPUs
    • drivers for network, graphics and sound hardware. Latest and greatest hardware support not required but at least one of the more popular hardware solutions must be supported, preferably several.  Up-to-date hardware drivers may not be available for OSes that have EOLed.
UNIX, POSIX and SUS
Unix (or UNIX - this page mostly but not consistently reserves use of the all-characters-capitalised version to indicate the trademark term) is both a genetic operating system codebase descended from the original AT&T Bell Labs source code, as well as a trademark owned by The Open Group.  Permission to use the trademark in reference to a particular OS is granted dependent on its certified conformance to the POSIX/SUS standards (searchable index) maintained by The Open Group's Austin Working Group.  The standards have several revisions going back to (at least) 1993 and the earlier versions were known as POSIX prior to the existence of the term SUS, so this page prefers to use the term POSIX.
[wp]
A link to the relevant Wikipedia article.
x86
A family of processors widely used in desktop PCs and servers, originally developed by Intel and cloned/extended by AMD and others.  The earliest models in the family are the 16-bit 8086 and the partly 16-bit 8088 - the basis of the first IBM PC.  The other main CPUs in this family are the 286, 386, 486 and Pentium.  More recently chips in this family with 64-bit extensions have become available, largely lead by AMD.  [wp]
**
Indicates that a link is a Wayback Machine archive.

Footnotes

[1] This is the latest version of the kernel. The kernel is only a small part of a typical Linux distribution. The distributions themselves have different versioning to the kernel. Most of the other listed OSes are distributed by the same developer team that maintains the kernel so for those the kernel and OS distribution version numbers aren't typically distinguishable.

[2] No network cards(?) nor TCP/IP support. Only dial-up modems supported, for such purposes as uucp (unix-to-unix copy).

[3] Program memory limited to 64k for code and 64k for data

[4] Outside of MS Windows, Linux probably has the most extensive range of x86 drivers available.

[5] OpenBSD developers focus on proactive security including regular code reviews, integrated cryptography and special-purpose tools.  OpenBSD has a strong record of very few security holes found in the default installation.