??
A device without input devices, output devices or a display is now a "full-fledged computer".
Boggles the mind.
My espresso-maker runs Linux - but I'd never consider it to be a "full-fledged computer".
My Tivo runs PowerPC Linux - but I'd never consider it to be a "full-fledged computer".
My network hub runs Linux - but I'd never consider it to be a "full-fledged computer".
My RAID controller card has a quad core processor and 512 MiB of RAM - but I'd never consider it to be a "full-fledged computer".
You are making the fatal mistake of confusing a computer (HARDWARE that does ONE thing: calculations called computations thus computer) and an Operating System which does MANY things (SOFTWARE that receives output and input from a USER to communicate to and from a computer)
Hence a full-fledged computer requires a CPU, a power source, and RAM. NOTHING ELSE.
All the rest is arbitrary based on the needs of the USER. A computer will compute regardless of whether it has a GPU, monitor, or anything else.
So to correct your statement:
Your espresso-maker IS NOT a computer because it requires one to function and its purpose is not to make computations, but to make beverages.
Your Tivo IS A FULL-FLEDGED COMPUTER because it is a stand-alone machine that makes computations.
Your network hub IS NOT a computer because it requires one to function (no processor unless standalone in which case, it would be a computer).
Your RAID controller card IS NOT a computer because it requires one to function (no processor unless standalone in which case, it would be a computer).
Of course, full-fledged is a subjective term and can be argued upon but from a completely literal standpoint, I interpret full-fledged as meaning the most strict definition of computer.
So if a machine CONTAINS a computer, the machine itself is not a computer. If a machine REQUIRES a computer, the machine itself is not a computer.
If a machine's PURPOSE is beyond the scope of making computations it is not a computer.
If a machine's SOLE PURPOSE it to make computations, it is a computer.
So again, the adapter IS a computer because it COMPUTES. This is its purpose. Any other cable (ex: HDMI) is NOT a computer as the COMPUTATIONS are done in the PC or TV which sends SIGNALS through the cable.