Google's Android is a smartphone operating system – most users are well aware of that. Fewer, however, are aware that it's built around the Linux kernel – the "core" of the system, which establishes the communication between the hardware and software of the device. Since the kernel is open-source, developers are free to modify it for whatever they wish the operating system to run on.
As if to make this as evident as possible, a developer has ported Android 1.6 Donut on a calculator, as can be seen in the video below. The demo shows a fully functional system, which can even run a game.
The device used in the clip is a Texas Instruments nSpire CX – a smart calculator reminiscent of a feature phone. It does run its own OS, which can already be used for document viewing and editing, image insertion, graph creation, and other complex actions.
The developer has shared all the source files needed to run Android on your own TI nSpire CX on GitHub – you can find the link below. The question is – would you want to do it?