Logisim is a circuit simulator, originally available here.

Carl Burch, the original author of Logisim, abandoned development in 2011 and moved on to a similar successor project, Toves in 2013, because Logisim's code base is in need of a major overhaul. Rather than start from scratch (something you should never do), this fork of Logisim picks up where Dr. Burch left off to improve Logisim incrementally.

Logisim's code itself has numerous smells. Here's an incomplete list of these:

• No test suite!
• Undocumented packages, classes, methods
• Duplicated and dead code
• No coherent organization (it should be MVC)
• High coupling, low cohesion (it would benefit from IoC).
• Unnecessarily reimplements functionality found in standard or third party libraries (e.g., it has it's own Toolbar classes)
• Code to draw components is too low-level

Logisim's user interface has numerous gotchas that need to be addressed. Here's some of the more important issues:

• The file format is not merge-friendly, making it impossible for students to collaborate on circuits.
• Unreasonable defaults
• Limited interaction styles
• Single (graphical) view of circuit

It is arguably the best free tool for teaching circuit design, which is why its development must continue.

Logisim developers: Logisim uses the Gradle build system, so set that up first before attempting to develop Logisim. Ensure that the gradle executable is in the system path. To build the executable for Windows, you must install launch4j and ensure it is on the system path.

The build script recognizes the following commands:

gradle build     # Build application jar
gradle eclipse   # Build Eclipse configuration
gradle createExe # Build logisim executable
gradle run       # Run logisim from gradle