Truth Table

Generating a truth table

A truth table lists every possible combination of inputs alongside the outputs the circuit produces. It is the most direct way to answer the question "does this circuit do what I think it does" — no reasoning about gate order, no tracing wires by hand, just the complete behaviour laid out row by row.

Boolflow builds the table by brute force. It finds every INPUT element on the active layer, enumerates all 2^N combinations, simulates the circuit once per combination, and records what each OUTPUT settles to. Because it is exhaustive rather than sampled, a correct table is a proof: there is no untested input the circuit could still get wrong.

• Inputs and outputs are labelled with the names you gave them in the editor, so the table reads like documentation.
• A cell showing “?” means the output never settled — usually an unconnected input or a combinational loop.
• Export to CSV to diff two revisions of a design, or to paste into a report.

The table is capped at 10 inputs. That is not an arbitrary limit: 10 inputs already means 1024 rows, and each additional input doubles it. Above that, targeted test cases are more useful than an exhaustive table.