Lab 0: Introduction to Logisim

Quick Logisim Tutorial

Setting up

1) Download Logisim evolution from https://github.com/logisim-evolution/logisim-evolution/releases. Get the latest .jar version.

2) To run the JAR file, install Java 16 or higher. Recommended: Adoptium OpenJDK 17 from https://adoptium.net/temurin/releases/

• For Windows: Get the .msi installer
• For MacOS: Get the .pkg installer

3) Once Java is installed, double-click the JAR file to run it.

Navigating Logisim

Interface Tools

Finger Pointer Tool

Allows clicking circuit elements to change values

Lets you inspect wire values during simulation

Cursor Pointer Tool

Used to manipulate circuit elements

Create wire connections between different elements

Circuit Elements

Wiring Elements

Splitter

Combines or splits multi-bit wires

Configurable splitting options

Pin

Introduces inputs to logic gates/blocks

Can be clicked to change values (0 or 1)

Probe

Checks wire values anywhere in the circuit

Can display multi-bit wire values

Tunnel

Creates 'portals' to reduce wire clutter

Connections made by matching tunnel names

Logic Gates

• Located in the Gates folder
• Configurable options:
  • Data Bits (input/output width)
  • Number of Inputs
  • Facing direction

Advanced Logic Blocks

Plexers (Multiplexers/Demultiplexers/Decoders)

Configurable select bits

Determine number of inputs

Arithmetic Blocks

Includes adders, subtractors, comparators

Memory Elements

Registers

Multiple-bit inputs/outputs

Require 1-bit clock input

Write Enable (WE) pin controls updating

RAM and ROM

Addressable memory blocks

Configurable address and data bit widths

User-preset contents possible

Memory Configuration

• Right-click RAM/ROM module
• Select "Edit Contents..."
• Enter hexadecimal values
• Can save and load memory contents

Navigation Tips

• Infinite workspace - zoom in/out
• Use CTRL + mouse wheel to zoom
• Switch between cursor and pointer tools
• Hover over pins for information
• Save designs frequently

Debugging Wire Colors

Green

Normal signal state (0 or 1)

Red

Conflicting wire values

Multiple drivers on same wire

Blue

Floating wire (no driver)

Orange

Mismatched wire widths

Incompatible multi-bit connections

Common Problems

• Avoid connecting multiple output ports
• Ensure consistent wire widths
• Have a single driver per wire
• Check for floating wire values

Accessibility

• Color scheme can be customized
• Go to File → Preferences → Simulation Tab