A few months ago, a tweet by [Ken Shirriff] asking about simple digital simulators caught my attention. The topic came up again in May when a repair video by [CuriousMarc] featured one such simulator called Logisim-evolution. It made me want to take a fresh look on what’s out there and which features set the different simulators apart.
So today, let’s take a quick survey of a few such simulators that I found. I’m focusing on plain logic simulators, analyzing ones and zeros using Boolean logic. They are not doing SPICE-like analog analysis of transistor logic gates, but they’re still quite handy for proofing out designs.
Logicsim from 1983 is the oldest one on our list, developed by Wun Chin Kau and Douglas Jones in support of computer science lab classes at the University of Iowa Computer Science department. It is a text-based simulator, open source for personal and research use, and written in Pascal. As recent as 2008, one user was able to compile it using FreePascal.
Next is TKGate, developed as a project by undergraduates in 1987 at the Carnegie Mellon University. It is written in C and Tcl, last updated in 2016, and maintained by Jeffery Hansen here on Sourceforge. Of all the simulators I found, this is the only one which contains a hidden pancake recipe.
The next one is Logisim (note the missing ‘c’), developed by Prof Carl Burch in 2000 for his students at the College of St Benedict and St John’s University in Minnesota. Written in Java, it is open source and is available on Sourceforge. He changed focus in 2013 to develop a follow-on program called Toves, also open source on Sourceforge, but written in C#/Mono. It appears both projects have been abandoned, though are still available. Logisim seems to have been quite popular among colleges and universities
There are a number of forks of Logisim which popped up to fill the void when Prof Burch stepped aside. Among these are:
- Logisim fork by Joseph Lawrance of the Wentworth Institute of Technology, Boston.
- Logisim-evolution out of the Institute of Reconfigurable & Embedded Digital Systems (REDS), Yverdon-les-Bains Switzerland. UPDATE: Since writing this article, [CuriousMarc] has posted a tutorial video on how to get started with Logisim-evolution.
- Digital, a simulator Inspired by Logisim, but built from scratch by Prof Helmut Neemann in Baden-Württemberg Cooperative State University, Germany
Logic Circuit and a Few Others
Logic Circuit, developed in 2016, is open source written in Visual Studio for Windows.
Missing in action is a program called logic-sim by Richard Reid of Michigan State University. We found this one explained in great detail in a computer science course syllabus at Emory University. Alas, the program itself is either proprietary or lost to internet digital rot.
Here are a few more from the replies to [Ken]’s tweet:
- Chipmunk Open Circuit Design
- Anitra Development Tools
- Labcenter VSM for Proteus
- SmartSim (on Raspberry Pi)
- Antares Digital Circuit Learning Platform
- EDA Playground
- Open Source Quantum Development
- Multisim Live
- Autodesk Tinkercad
- CEDAR Logic Simulator
- iCircuit 3D
- Logic Friday