Well, I figured that I should take an opportunity to introduce a few opensource OSs that really haven't been in the lime light much. We all know about Linux and many of us also know about Darwin and BSD. Still some know about OpenSolaris. Which ever ones you know or don't here's a chance to get the scoop.
No. I am not talking about a wildebeest. On September 27th of 1983, Richard Stallman began the GNU operating system project. By 1990, he still lacked a decent working kernel for that operating system. In 1991, a guy in Helsinki named Linus Torvalds had that kernel available in the form of Linux. What Torvalds needed Stallman had. By 2000, Linux was available in over 300 distributions with varying components of the GNU project, and was the darling of the OpenSource movement, and the second most popular UNIX variant around.
When Steve Jobs left Apple in the 80s, many wondered what he would do. The 80s have come and gone, and we now know the he started NeXT... which wasn't all that successful. When NeXT did do, was create a BSD variant that has been very successful. Apple was trying to reinvent its OS, and was failing miserably. Steve brought OPENSTEP to Apple, and it was reinvented as Darwin. On top of Darwin, Apple has laid two closed source technologies that make up the GUI (Finder and Cocoa). These three components combine to make OSX, which as of this writing is the most popular UNIX system on Earth. Apple is also the largest distributor of both OpenSource software and of UNIX due to its current popularity in the market of personal computers, cellphones, and iPods.
For most of us, thinking of the University of California Berkley doesn't bring about images of nerdy software engineers, but instead makes us think more of LSD, hippies, the children's revolt, and Vietnam... Despite all of that, they are a prominent uni, and they did create Berkley Unix. While BSDs are usually source compatible with AIX, HPUX, and Linux there are also two API layers available, Linux and WINE. Currently, there are four main flavors: OpenBSD, NetBSD, FreeBSD, Darwin. OpenBSD is focused on security, FreeBSD is focused on being general purpose, and NetBSD is focused on running everywhere (really... everywhere like toasters, palmtop computers, servers, mainframes... you name it, NetBSD runs on it). The Berkley Software Distribution has long been considered one of the most stable, secure, and efficient platforms available.
While Sun Microsystems has been eaten alive by Oracle, Solaris lives on. It was started by Sun in 1992 to be a successor to Sun OS. There are currently several distributions out there (Nexenta, Blastwave, OpenSolaris, and so on). While highly stable and efficient, Solaris lacks a lot of the maturity and diversity available on both BSD and Linux platforms. You'll also find that the community is far smaller, although most UNIX source code will compile just fine.
Haiku is an OpenSource BeOS implementation with many enhancements. Notably, Haiku has added quite a bit of hardware support, enhanced BFS, and ported many applications to the platform (including KDE). While the system is not ready for production environments, it does have a small and active community. Hardware support is limited, and the project aims only at x86 right now.
Syllable is a pre-emptive multitasking, multiuser, modular, and SMP-capable operating system that sports a fresh GUI. It's based upon AtheOS, which was initially inspired by Amiga OS. It uses AthFS, which is a child of OpenBFS. While AtheOS was initially a one man hobby OS, it is now actively developed by many people and is rapidly growing and evolving. It's aims are clear enough, and it's stable operating system. The community and hardware support are comparable to Haiku's (also x86 only).
ReactOS is an opensource NT clone, written from scratch, and using some code from the WINE project. After several years of development, ReactOS is still in an alpha stage. It also doesn't support too much Windows software, and for what it does support it is still only 32bit. No 64bit Windows applications will run. Hardware support is also limited, and the system targets only x86. Despite all of these limitations, ReactOS is certainly a project whose development I will follow with some excitement.
MINIX was initially an educational operating system developed by Andrew Tannenbaum, and is mingled with the origins of Linux. Many years later, MINIX is still alive, and is now a UNIX-like, microkernel operating system that is rather robust, efficient, and small. Its community is small like the last few mentions, but it is in active development and it's quite promising. The latest version (as of this writing) is 3.1.6 (released 8 days passed). One of the attractions to MINIX is that should a driver fail, it will not crash the system, and the kernel will attempt to automatically reload the driver. Currently MINIX is x86 only, but ports to other platforms are being worked on.
FreeDOS is by far one of the most interesting projects listed here. FreeDOS is a DOS-compatible operating system for x86 machines. Yet, it has USB drivers, audio drivers, network drivers, and even has access to 4GB of RAM. Interesting? I sure think so. It has limitations. While alot of drivers exist (considering that it is a DOS), hardware support is limited, and by default it is still 16bit. It does have quite a bit of software available to it, thanks to the opensource community as a whole.
These two operating systems are interesting for several reasons. First, they are coded in Assembly language. Second, each can fit on a single floppy diskette with some room left over. Third, they support almost as much hardware as some of the others on this list. Menuet also has a 64bit version, but that version is not opensource. These two operating systems may be useful for those who are struggling to find something to do with that old Pentium2 in the corner. Both have USB support, and vesa display support.