A small or intelligent device is so called because it contains within it a

A small or intelligent device is called so because it contains a sensor that lets it perceive its surroundings.

Calling the part simply a computer is too broad to explain what makes the device intelligent.

A microcomputer names a size of machine rather than the sensing element.

A programmable unit describes control ability, not the sensing that makes a device smart.

Sensors turn physical signals like light, heat or motion into data.

Smart devices pair sensors with a processor to react to their environment.