Am I correct in thinking that there are only three actual software based operting systems (Kernels): Unix, Dos and Windows.
There is of course several different versions and variations and modifications of these. Is this true and if not please post any others.

IBM's OS/2 used to be quite popular too (OS/2 Warp was a big one, even used to have it installed)

But one could argue that OS/2 is just another variation on MS Windows or MS DOS (it had IBM Dos and then the GUI like you have MSDOS and the Win3.x/9.x/etc GUI)

There are several other OSs which are genuinely different.

Probably the most popular of these by number of boxes is MacOS (I'm guessing here)

I'm not sure about previous versions of Mac, but the latest version is Unix-Based, again a variation. A huge variation at that.

palm has its thing
Mac OS original deserves a lot more credit than it gets fool proof and easier to use than windows

OSX is based on BSD, using tcsh by default, and isn't compatible with older versions of MacOS, which seems really strange.

Consequently every time i have a Computer Graphics lecture we have to wait while the lecturer loads "Macintosh classic environment" ontop of OSX to get OS 9 to run powerpoint.

You could say those are the most popular ones, but there are numerous (or at least a few) pet project OS's that programmers like to hack on for fun without intending to release anything.

I don't know if you could really consider Windows an OS along with DOS. Up until XP (built on NT) Windows still needed DOS to run. But I think major variations would be considered OS's as determined by the Merriam-Webster Collegiate Dictionary:

Main Entry: operating system
Function: noun
Date: 1961
: software that controls the operation of a computer and directs the processing of programs (as by assigning storage space in memory and controlling input and output functions)

Specifically mentioning "software" being the director of I/O function, a different enough variation could be seperate. but that's just me.

what about BeOS, is that based upon Unix.. i am unsure but it does run on powerpc's and intel based... hmmmmm...

BeOS was a microkernel written from the ground up. QNX is another example of the same. OSX (I think) is based on the Mach kernel. In short, there are many more then 3 kernels.

--jeremy

There are many different operating systems kernels, but I think you are just trying to make a generalization.

BSD, Linux, Mac OSX and several others are all 'nix based.

Now BeOS and QNX that were mentioned are based on thier own designed kernels, although they both have command shells that also work on a 'nix.

Windows is based on DOS, and the NT variants are the same except they integrated the GUI with the kernel, so you dont really see a command prompt. They are different architectures than normal DOS, but same kinda thing.

OS/2 was based on the a DOS version before IBM and M$ had their falling out. While it is different than MS DOS, it isnt by much.

Jeremy is always direct and to the point. The dichotomy that is getting lost is that a kernel, or whatever it is that DOS really uses, spaghetti? isn't the whole operating system, just the core of it. All those hundreds of commands we all use are programs that could be compiled for half a dozen different er... kernels... Here's a good list as I know it: micro-kernels- NT, 2000, WinXP(all run on a hacksawed NT kernel), OSX runs on Mach, a mis-begotten stepchild of IBM and Apple from the early nineties I think that got a full facelift for OSX. FreeBSD, OpenBSD, and NetBSD are all different enough to be considered unique, and then BeOS, QNX, Solaris, heck, originally all of those Gnu tools GCC, Glibc, etc, were all theoretically one day going to help put out a free Unix-like operating system based on theHurd micro-kernel, Linux kind of happened in there by mistake. Hence RMS's campaign to call it GNU/Linux... er, yeah, whatever Rich.

Linux is an odditity in that its a monolithic kernel. For how that differs from a micro-kernel, either someone is going to follow-up with the basic principle, or if you get really interested, you might want to check out Open Sources or The Cathedral and the Bazaar.

Cheers,

Finegan

there are many more operating systems than dos/windows and unix...

all an operating system does is provide the filesystem and other hardware and memory(services) to programs and stuff.

since there are hundreds of commercial operating systems, i think it would be better to classify them as either monolithic kernels(a big kernel containing all of the services that the kernel uses) or micro kernels(kernels who use services that exist as seperate programs.)

in my oppinion, monolithic kernels are the best because they are fast, and linux has introduced the idea of loadable kernel modules(so that kernel isnt that big) ive also heard of exokernels but i dont understand how they work.

Fatpig wrote:
This is where I must say that I do not think you are correct with this statement. I have always heard that micro-kernel architeture is more desirable, because the kernel is much smaller, therfor faster and more stable, and everything else is loadable, therfor making the system more expandable.

While Linux may be modular, you still have do kernel compiles for some things. With a micro-kernel, you dont have to.

Your rarely have to re-compile Linux these days with all but the entree modularly loadable. I've had to recompile a micro-kernel before, BSD. Albeit I didn't have to, I just didn't know what I was doing. Anyway...

The micro-kernel is still the grand end-all-be-all of Operating system theory, where the different aspects of the system are handled by different, independent chunks of the kernel, and the micro-kernel in the center actually acts as nothing more than a message passer for these different bits to communicate. The downshot to this is that in application the micro-kernel at the center, although it has but the one job, is so kludged up with passing between user space, memory management, etc, that it runs slower than a monolithic kernel by far. With a monolithic kernel such as Linux, everything, the whole dog and pony show is live, albeit a monster.

This is why I didn't try to define either a few entries ago, I knew I would over-simplify due to my lack of knowledge on the topic. For a better explination, google for: "Linus Tanenbaum flame war". Andy Tanenbaum is the creator of Minix, a micro-kernel based i286 OS which Linus used as his platform to build Linux. Actually, I think the whole thing started because Linus wanted a better terminal emulator. Go figure.

Cheers,

Finegan