# Combinational analysis

All circuits fall into one of two well-known categories: In a **combinational circuit**, all circuit outputs are a strict *combination* of the current circuit inputs, whereas in a **sequential circuit**, some outputs may depend on past inputs (the *sequence* of inputs over time).

The category of combinational circuits is the simpler of the two. Practitioners use three major techniques for summarizing the behavior of such circuits.

- logic circuits
- Boolean expressions, which allow an algebraic representation of how the circuit works
- truth tables, which list all possible input combinations and the corresponding outputs

The **Combinational Analysis** module of Logisim allows you to convert between these three representations in all directions. It is a particularly handy way of creating and understanding circuits with a handful of one-bit inputs and outputs.

Opening Combinational Analysis

Editing the truth table

Creating expressions

Generating a circuit