The following are operating system environments that are relatively traditional in design. Some involve novel uses of network capabilities, but otherwise are readily recognizable as extensions of the designs of existing operating systems.
This was the next OS to come out of Bell Labs, originators of Unix. Major features include the separation of a network of computers into "terminals," "CPU servers" and "File servers," and binding all system services to file systems. There are unfortunately too many components that have cutesy puns of names. If you throw in "database servers," this is a scheme that leads in a natural way to look like "3 tier Client/Server" computer systems.
Bell Labs have released Plan 9 in "Open Source" form.
This page links to collections of Plan 9 software, here and elsewhere. Some of the software was developed specifically for Plan 9. Other packages were developed for other systems and ported to Plan 9.
A problem Plan 9, as currently constituted, faces is that it takes considerable effort to maintain code for device drivers, particularly in view that hardware vendors are continually releasing new models. This is true, notably, for disk interfaces, graphics cards, and I/O interfaces such as USB.
The Glendix project seeks to take some crucial bits of Plan 9, and embed them atop the Linux kernel, so that Plan 9 code may be run "natively" atop Linux. This leverages the device drivers on Linux.
After Unix and Plan 9, comes Inferno along with a host of Dantean jokes and puns. (3) Inferno is intended to provide an architecture-neutral application environment that allows users to run applications over networks. (Sounds a lot like Java, doesn't it?)
All resources are named and accessed as hierarchical file systems (as in Plan 9), which is a clear reflection of The Unix Philosophy.
At one level, Styx consists of messages of 13 types for
Starting communication (attaching to a file system);
Navigating the file system (that is, specifying and gaining a handle for a named file);
Reading and writing a file; and
Performing file status inquiries and changes
It may thus provide a nice general interface for distributed file access.
Hercules is a System/370 and ESA/390 emulator which can IPL and execute S/370 and ESA/390 instructions. It can also emulate CKD and FBA DASD, printer, card reader, tape, channel-to-channel adapter, and local non-SNA 3270 devices. Runs atop Linux, thus far on Intel and Alpha architectures.
Amoeba is an experimental OS that represents a test bed for research on distributed operating systems.
Andrew Tanembaum, noted author of various operating system and distributed system texts, was the creator of Minix , which was the progenitor for Linux. (One of the "base" file system types still supported for Linux is the minix file system.)
At one point, there was a bit of a "flame war" between Andrew Tannembaum and Linus Torvalds; the particular disagreement was that Tanembaum felt that it was foolish to develop a monolithic kernel, whilst our erstwhile hero chose to go ahead and do it despite the comments of the eminent professor.
Linux made some movement towards microkernels, starting with the development of the Apple/powerPC MkLinux (where Mk stands for Microkernel). And having Linux run atop MACH (the microkernel in question) has allowed "easy" ports of Linux to both IA-32 atop Mach (not commonly used, as IA-32 was the original Linux platform, and is by far best-supported) and to HP's PA-RISC architecture atop Mach.
Amoeba Sources are now available at no cost, mainly as research work on the project has ceased, and Amoeba is no longer being very actively maintained.
Apparent successor project to Amoeba
Successor to previous Minix and, it would seem, Amoeba, this is a Posix implementation implemented as a microkernel multiserver.
What is particularly interesting is that Minix 3 at last implements substantial quantities of restartable components. For instance, Ethernet network drivers are implemented as microkernel tasks that may be restarted on demand. One of their performance tests was to kill and restart this process once a second while performing file transfers. They found that this caused only relatively minor slowdowns.
Another interesting aspect is the area of interprocess communications. This has typically been an area where microkernel systems have performed particularly badly. The Minix 3 approach is that system calls are all kept to fixed size records, presumably small enough that they can be fairly certain that they can reside in registers. For larger objects, like filenames, the address of a buffer is passed.
After learning from mistakes in earlier microkernel systems, this system looks like it may be one of the steps forwards towards usefulness...
Intrinsic SMP support (built-in multiprocessing)
A small microkernel (as in QNX)
Services with filesystem-like interfaces (as in Plan 9)
Regrettably, it is no longer under active development.
This is a successor project to VSTa...
Microkernelled OS inspired by VSTa, that uses "Ports" as the low level abstraction for IPC.
A freely-redistributable program loader and associated utilities that is fairly much compatible with Microsoft's MS-DOS.
Caldera acquired the rights to Novell-DOS, which used to be DR-DOS. They released the sources (to portions of it not encumbered by other organizations, at least) via the GPL.
I've got some other links to various old OSes and computing platforms.
Geoworks sells a GUI system that was originally designed as a GUI for Commodore 64 systems. They then constructed a version to run atop MS-DOS; their system is quite reminiscent of Digital Research's GEM system, only it is a couple of years newer and thus "prettier."
Despite the fact that it runs nicely on pre-386 systems with small amounts of memory, it has never been popular on PCs as Windows 3.1 was available earlier and has a much larger software base.
They have spun-off their "Office" package; it is now sold by New Deal, Inc.
The target platform that has proven quite successful has been PDAs. Various palmtop manufacturers have sold GEOS-based systems. This probably is what validated to Microsoft that "Windows CE" was a useful thing to create and sell.
Their direct competition definitely is Microsoft Windows CE. I think Geoworks has a better product; it's certainly more highly developed.
Unfortunately, Geoworks may be another company that falls prey to the problem that everyone seems to believe that as soon as Microsoft enters a new sector that they will outsell and make obsolete every other product in that sector. This effect actually does seem to occur despite the fact that in many cases Microsoft is trumpeting an inferior product that people agree is inferior. Examples of this include:
Microsoft Windows versus MacOS
Microsoft Windows 95 vs. OS/2
Microsoft Windows NT vs. Unix
Microsoft Word vs. WordPerfect
It should be noted that WP was severely hindered by software bugs; early versions of WP for Windows were extremely crash-prone. It seems likely that this was "assisted" by Microsoft's extensive creation and use of undocumented APIs.
Microsoft Excel vs. Lotus 123
Microsoft Bob versus not having a computer...
At no point in time can it be readily argued that the Microsoft product is substantially superior to its alternative; they tend to be resource hogs; except in the Word/WP situation (where there may have been some implicit "sabotage") the competing software has been less prone to crash or otherwise function incorrectly.
Nonetheless, despite the relative inferiority in each and every application area, Microsoft's marketing and legal strategies have frequently resulted in sales "triumphs."
Runs atop Unix variants; could arguably be thought of as a "microkernelled" single server...
eCOS is an open-source, configurable, portable, and royalty-free embedded RTOS that runs on such architectures as ARM-7, StrongARM, PowerPC, SPARCLite, amongst others...
What with the availability of PDP-10 emulators, and ITS tape images, there is now a process for Building an ITS from scratch on the Supnik PDP-10 simulator.
Seeing as how the discontinuance of PDP-10s by Digital, thus orphaning the ITS platform, was the putative reason for RMS to start the GNU project, a particularly waggish person might now argue that the availability of fast emulation of PDP-10s makes the whole GNU project pointless.
More practically, any of the Unix Haters that were ITS fans can certainly satisfy themselves now in that they probably have hardware that can nicely support an ITS emulation session.
OS providing Quality of Service guarantees; rather exokernel-like...
KADAK's AMX multitasking kernel is the underlying real time kernel for PalmOS
Oberon is both a programming language in the Pascal /Modula tradition as well as a single-user, multi-tasking system that runs on bare hardware or on top of a host operating system such as Windows, Unix , or Linux .
It runs on "Intel-compatible PCs" as well as custom ETH hardware, and the development environment includes support for persistent objects, networking, including WWW, Ethernet, and PPP, and its own GUI environment.
Project aiming to develop an OS using free software, but not based on Unix. Based on OSKit, it will be distributed using CORBA and will include kernel, developer tools, and a GUI, perhaps based on Fresco (was Berlin).
A quick-and-dirty clone of System/360 DOS that emerged from GE around 1970; originally called GECOS (the General Electric Comprehensive Operating System). Later kluged to support primitive timesharing and transaction processing.
A field added, on Unix , to
/etc/passwd to carry GCOS ID information was
called the `GECOS field' and survives today even in Linux as the
field used to store the user's name or other such ID
An operating system for IA-32 PCs. It seems to most resemble BeOS , but having a preference for C rather than C++.