Ask HN: Weirdest Computer Architecture?

My limited understanding of “the stack” is:

  Physical substrate: Electronics
  Computation theory: Turing machines
  Smallest logical/physical parts: Transistors, Logic gates
  Largest logical/physical parts: Chips
  Lowest level programming: ARM/x64 instructions 
  First abstractions of programming: Assembly, C compiler
  Software architecture: Unix kernel , Binary interfaces
  User interface: Screen, Mouse, Keyboard, GNU

Or at the least uses electronics but substitutes something else for Turing machines and above.