Logisim 2.5.0 connects wires when moving, etc

Logisim, a graphical design and simulation tool for logic circuits, is now at version 2.5.0. This major release includes many new features, bug fixes, and internal improvements.

The headline feature is that Logisim adds new wires when you move circuit elements, so that connections are preserved between the moved elements and those that remain unmoved. In cases where you wish to move elements without wires being changed, you can press the shift key while dragging. (The feature can be turned off entirely through the Project Options dialog's Canvas tab.)

Another big feature in this version is improved keyboard support. In previous versions, you could type the arrow key while a component is selected to change its Facing attribute. Now, for many components, typing the digit keys will also alter the component in some way. For example, for an AND gate, typing 3 will change it to a 3-input AND gate. Also, you can press Alt along with the digit keys to change components' Data Bits attribute.

The libraries received several enhancements. The gates were enhanced to include attributes allowing individual inputs to be negated, and the number of inputs on each gate can now be anywhere from 2 to 16. In addition, the Base library includes three new components: Bit Extender, Pull Resistor, and Tunnel. The Tunnel component may be the most interesting: It allows you to connect two points far across a circuit without drawing wires between them.

At the same time, Ilia Lilov continued his translation work started in 2.4.0 by adding a Russian translation of the documentation, now packaged with Logisim. Another new feature is several new options to the command-line verification system introduced in 2.4.0, including the ability to specify a file from which RAM should be loaded. And this release includes many bug fixes, most of which were discovered by Ilia Lilov, who went well beyond his translation work to perform some outstanding testing of development versions and provide suggestions for improvements.

And finally, but not least, Logisim's internals were changed dramatically. Most notably, the code was migrated to Java 5, and Logisim's internal approach to dealing with changes to a circuit is very different, allowing wires to be maintained properly in a much simpler and more reliable way. These internal changes should pave the way for further dramatic improvements to Logisim in the near future.

Educational institutions around the world use Logisim as an aid to teaching about digital logic and computer architecture. As a Java application, Logisim can run on most major operating systems. Read more about Logisim at http://www.cburch.com/logisim/, and download it from SourceForge.net at http://sourceforge.net/projects/circuit/.