When is a new operating system not a new operating system?

Reading Steve Ballmer's comments about Google Chrome OS, I'm struck by how odd some of his ideas are. Like what constitutes a brand new operating system, for instance. He also appears to think One Size Fits All is a good way to develop software.

Let me set you straight on a few things, Steve. First, Chrome OS is anything but a new operating system. Google is planning to use the Linux kernel, which has been around for quite a while now. The Chrome browser may well be very new, but it hasn't been written just for Chrome OS. Since Google is planning to release the whole project as open source anyway, they're going to reuse as many bits of existing software as possible. It will also share a huge amount of code with Android. You'll probably be able to count the lines of brand new code in Chrome OS in an 8-bit buffer.

So if you're confused as to why Google would want to have two client operating systems, Steve, it's because you can't see that they won't. They're just different packaging of very simliar codebases. Just exactly what are Windows Vista and Windows Mobile if not two client OSs, anyway?

Which brings me to my next point: that the idea of a single operating system to suit any type of client device is ridiculous. It may seem like I'm contradicting myself here somewhat, but that depends on what you define as an "operating system". If it's the totality of software that is installed on a device by its manufacturer — which is close to Microsoft's idea of what an OS is — then each Linux distribution or version of Vista constitutes a different operating system, despite having the majority of their respective codebases in common. If it's binary compatibility, the same codebase on different processor architectures becomes separate OSs. Higher level API compatibility? That's a whole other can of worms. Whichever way you look at it, there doesn't seem to be any definition of an operating system that means you can have the "same" one on different classes of device.

What matters most is having the right mix of software, all the way up the stack from kernel to applications, that suits your device's intended use. Whether that means you have one, two or three hundred "operating systems" is besides the point.