There is the ISA, an abstraction built on top of the physics of the materials out of which electronic calculators are built.
From the standpoint of the application developer, the ISA, this incredibly powerful abstraction, is a meaningless mechanism. Its concepts, its meaning and its purpose are the fruits of further abstraction.
So, in a computer at least, abstraction is a relative concept. One could fend off accusations of abstract thinking in more general matters by pointing out this fact.