Building Your First Circuit in Logisim Evolution

Experiment: Two-Input AND Gate

Objectives

• Become familiar with basic Logisim Evolution operations.
• Learn how to use input pins, logic gates, and output pins.

Principles

A two-input AND gate is one of the most basic combinational logic devices. Its behavior is:

• The output is 1 if and only if all inputs are 1.

Let inputs be A and B, and output be Y. The logic expression is:

• $Y = A \cdot B$

Task: Build and verify a two-input AND gate

1. Prepare input and output pins
   1. In the Wiring category, place two Pin components. In the properties panel (or using the text tool), name them A and B.
   2. Place one more Pin, name it Y, and set its Type to Output in the properties panel.
2. Place the AND gate
   1. In the Gates category, place one AND gate.
3. Wire the circuit
   1. Connect inputs A and B to the two inputs of the AND gate.
   2. Connect the AND gate output to Y.
4. Verify functionality
   1. Click pins A and B to cycle through input combinations: (A,B) = 00, 01, 10, 11.
   2. Observe how output Y changes.

Results

• A full screenshot of your completed AND-gate circuit.
• Complete the experiment record table below.

A	B	Y
0	0
0	1
1	0
1	1

Table 1.1: Two-input AND gate truth table (fill in Y during the experiment).

Questions

1. If you replace the AND gate with an OR gate, how does the output logic change?
2. Does this circuit have “memory” (i.e., can it keep a previous output state after the inputs change)? Why?