They're in-game inspired diagrams. The key is in the paragraph above the start of the 'Unclocked Logic' section.

     A
  →o * o→M O
   o * o
     B

The mechanical power goes in the first →, and the [M O] part is the output. A and B are the AND inputs. Gearboxes actually look like *, but o is also being used for gearboxes, albeit gearboxes that are just there to drain power.

The colored gif image at the top of the page is an in game implementation. The black and white characters are diagrams, but are quite accurate to what the game would show.