It is interesting how folks who come from a commercial exposure to OS'es hated UNIX. I admit I was one of them, I was a big TOPS-20 fan, thought RSX-11M had a lot going for it, Unix not so much. Then I went to work for Sun Micro and later joined the kernel group there.

Operating systems are 'easy' in the sense that a small group can create them, and pretty much do all the legwork needed to get them into a product. Building hardware is more complex, it involves coordinating manufacturers, part suppliers, and the software to run it.

What happens then is if you're a hardware manufacturer and an operating system supplier, then you can tell your designers to make the hardware like you want, you can write the libraries you need in the OS, and everyone leverages the work of everyone else. In the Windows world the 'duopoly of Microsoft and Intel' led to an artificial relationship between hardware manufacturer and OS vendor but it was the same.

But if you're not a hardware supplier, you spend an inordinate amount of your operating system resource trying to deal with random bits of hardware you might want to use. Then your OS makes as few assumptions about the hardware as possible and it becomes as simple as it can in order to avoid incurring a huge overhead in getting new hardware into the system. It was this latter feature of UNIX which I really didn't appreciate until I went to work at Sun.

I agree with Thompson that it would be nice to have more general purpose operating systems. They are out there, Spring, Chorus, eCos, VMX, Qnx, Etc. but generally they target a more specialized niche whether its embedded or research or some level of security. I'd love to see more accessible OSes as well.

One of the projects I started a while back has been an OS for ARM systems that is more like DOS or CP/M or AmigaOS than UNIX or Windows. The thought was something simple that was straight forward to program, not your next Cell Phone OS or something that you'll need a couple of Gigabytes of memory to run, just something you could write and deploy code on for fun or educational purposes. It has been fun to look at "apps" like this. Imagine something that had a shell that was sort of like the Arduino processing UI except self contained. But again, its not general purpose. It's just a tool.

I think the next wave in the 'real' OS wave is going to be something very much different than what we think of today, something where it assumes there is a network behind it and that the rest of itself is out there somewhere as APIs. Of course civilization may collapse first :-)