I'm aware of the differences between a common microcontroller and a full blown motherboard from a computer server. But consider what happens when the PC memory testing tool memtest86 is run:-
Here the tool can be seen running on a largish core i7, accessing 16GB of RAM. Clearly it also has access to the hard disk from which it booted, loaded and ran. Access to the network, usb and serial interfaces is probably possible then too. And it's running with no operating system, just itself.
So instead of running memory tests, could some application be written that would do what I wanted it to do and control things via the available interfaces? Or are there on board devices and components that need a full blown OS?
I'm not asking if this is particularly useful, but whether it's possible?