Contents > Introduction

Nodes

A pair of vertically-adjacent playfield cells stores a Boolean value via the following scheme.

• 0 (false) — lower-cell solid, upper-cell empty
• 1 (true) — upper-cell solid, lower-cell empty or solid
• ? (unassigned) — both cells empty

The input, intermediate, and output nodes of combinational logic structures are composed of one or more pairs, all in the same state. Typically, a node is a contiguous, horizontal line of pairs, but not necessarily. The pairs of a node can be separated in space, even vertically separated. For instance, the image below shows one possible encoding of 01010, where a noncontiguous node stores the rightmost bit.