How Many Different Operating Systems Are Running in Your House?

How would I begin to know how many operating systems are running in my house? Most importantly, why would I possibly care? 

They either work or the device they power gets thrown out and we buy a new one. Which gets installed that day. There is no ceremony, no day of mourning, no shrine to its place in our lives. It's become the functional equivalent of a toaster oven that communicates.

And by the way, what's an operating system? JL

Jamie Cundliffe reports in Gizmodo:

How many, exactly?

Between phones, tablets, laptops, media centers, smart home devices and whatever other technology is scattered around your home, there are likely multiple operating systems in your life. But how many, exactly?

Yesterday's XKCD took an amusing look at the past, present and future of Randall Munroe's OS habits. How do they compare to your current set-up and vision of the future? [XKCD]