Drawing and simulating digital circuits

Drawing digital circuits can become a mess very fast which makes testing those even more difficult. Doing it offline is a painful job with all those wires. So, what GUI software is recommended for building digital circuits and testing them?

Logisim is not in the repos, but being a single java jar, should be fairly easy to get going. It is purely digital, without the discrete and analogue components. It is however quite sophisticated - I've been putting together a simulation of a single instruction CPU with it.

Instructions for getting and running it:

1. Download the .jar file from http://sourceforge.net/projects/circuit/

2. If you saved the file to ~/apps/logisim-generic-2.7.1.jar, you can run it from a terminal with:

   java -jar ~/apps/logisim-generic-2.7.1.jar
   

3. To save yourself from typing that the whole time, create the executable ~/bin/logisim containing

   #!/bin/sh
   java -jar ~/apps/logisim-generic-2.7.1.jar
   

4. Make it executable:

   chmod +x ~/bin/logisim
   

5. If ~/bin existed before, it's already in your $PATH. Otherwise, re-login to update your $PATH. From now on, you can start it by running:

   logisim
   

If you update logisim later, it's as easy as putting the new file in ~/apps/ and change the filename in ~/bin/logisim

Well, now it's there in the ubuntu 14.04 repositories as well, just type :-

   sudo apt-get install logisim 

to install it.

I used a promising program called KTechLab in the past, the program is KDE 3 based and has not yet been ported to KDE 4 I used it to teach some youngsters electronics both analogue and digital concepts, it is a fine piece of software, even has PIC microcontroller simulation, sadly development seem to be very very slow and after they made an update to it I started having stability problems, I would still encourage you to try it though.

It is in the repositories but I do not know if the stability problems are still there as I have stopped using it.

The links below may be of some use:

http://sourceforge.net/projects/ktechlab/

http://www.linuxjournal.com/content/computer-logic-design-ktechlab

http://en.wikipedia.org/wiki/KTechLab