Logisim free tool to design and simulate digital logic circuits. Its interface is very intuitive and simple to use, which lets the user learn concepts related to digital circuits without problems. This makes it a very interesting tool for students, who can create complex circuits from other more basic ones.
Proof of this is its widespread use in universities around the world, where it is used as an introduction to IT engineering and also for courses on PC architecture. Logisim lets you create CPUs and processors.
As it is developed completely in Java, for its correct working you need to install Java Runtime Environment 1.4.