Logisim 2.7.1 fixes bugs, improves file handling

March 21, 2011 [change log]

Logisim, a graphical design and simulation tool for logic circuits, is now at version 2.7.1. This release's primary purpose is to address several issue discovered since 2.7.0 was released two weeks ago.

One of the primary bugs addressed in this release is one where a user could inadvertently change a component's attribute to an invalid value. The circuit would typically continue to work normally, but when the file is later reloaded, the file would refuse to load. This release repairs the cause of the invalid value assignments; and it enhances the file-loading process so that a dialog box appears explaining any problems found, and the portion of the file that could be interpreted is still loaded.

Another issue found in 2.7.0 was in the behavior of the transistors. In particular, a transistor would "convert" a floating (Z) value into an error value when told to transmit its source input; now, floating values are transmitted as floating values.

Besides addressing many other issues besides these, this version also adds a "Select Location" attribute to the multiplexer, demultiplexer, and decoder, allowing the user to configure where these components' select (and enable) inputs are located relative to the component.

Finally, this release marks the introduction of a mailing list where users can subscribe to hear about new developments regarding Logisim. We promise that the traffic on this list will average below one message per month. To subscribe, go to https://lists.sourceforge.net/lists/listinfo/circuit-announce

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/.

Logisim 2.7.0 has simulation tree, Greek, much more

March 7, 2011 [change log]

Logisim, a graphical design and simulation tool for logic circuits, is now at version 2.7.0. The new version includes numerous enhancements and fixes; the most radical are a new Wiring library, a new method for drawing splitters, and enhancements to the main window's left-side explorer and attribute pane.

This version introduces the Wiring library, into which have been moved the circuit components previously found in Base: splitter, pin, probe, clock, tunnel, pull resistor, and bit extender (and also constant, previously located in Gates). Additionally, the Wiring library now includes a transistor, transmission gate, power, and ground.

Another major change was in how splitters are drawn. The new technique conforms more closely to traditional circuit diagrams, and it includes labels showing the bit(s) to which each split end corresponds. The new Appearance attribute allows one to continue using the older technique, and projects created in older versions of Logisim will continue to load using this legacy support. However, projects can easily switch to the new appearance with labels by changing the splitters' Appearance attribute to Centered.

The GUI has also received several updates. The explorer pane in the upper left corner has traditionally shown the current project's circuits and libraries; this is now called its Toolbox view. However, one can switch the explorer pane to instead show the Simulation Tree, which includes a toolbar for controlling the simulation and the hierarchy of subcircuits in the current simulation. This provides a visualization of the full hierarchy as well as an alternative to right-clicking subcircuits (or double-clicking them using the Poke Tool) to descend into viewing their states. Another notable enhancement to the GUI is an addition of a title bar to the attribute table, which indicates whose attributes are currently being displayed.

Additional features include a Greek translation of the GUI elements, labels specific to one instance of a subcircuit, an enable input for multiplexers/demultiplexers/decoders, an Output Value attribute for gates allowing them to emit floating values (permitting wired-and and wired-or logic), and support for product-of-sums expressions in the combinational analysis module. This version also marks the removal of the Legacy library and other code meant for supporting projects built in Logisim 1.0. And the project toolbar — previously disabled by default — is now always enabled.

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/.

Discussing Logisim's future at SIGCSE

January 24, 2011

At a birds of the feather session in the upcoming SIGCSE conference, the developer behind Logisim, Carl Burch, will lead a discussion on future development directions for Logisim. In addition to this discussion, this should be an opportunity to learn from others who use Logisim in their classes. SIGCSE, the primary conference concerning computer science education in the United States, will be March 9-12, 2011, at Dallas, Texas. The Logisim session is scheduled for 6:10pm, Thursday, March 10, 2011, in State Room 2. More information about conference registration is at: http://db.grinnell.edu/sigcse/sigcse2011/ — the early registration deadline is January 31, 2011.

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/.

Previous announcements

2.5.1 to 2.6.2