www.logiccircuit.org

When developping large projects (like an 8-bit computer) I have encountered the following problems:
-When creating a large module like a combinational multiplicator, the module gets really messy, I think there should be an option to only allow 90 degrees angles in wires, that would increase readability.
-I think there should be a button to temporarily disable logic gates connection to wires, because sometimes when I want to reorganize the whole module, and I want to move the gates, they connect with wires I don't want them to connect.
-Also, I would suggest adding a little circle when two wires are connected together, sometimes I have a lot of wires, and without a junction point, I don't know if the wires are connected or not.
-It is very uncomfortable to copy and paste gates, because they appear where you have copied them, maybe adding a hotkey to paste where the mouse cursor is could save a lot of time?
-When I want to calculate aproximately the highest possible clock speed, I have to go module by module to see what's the largest number of gates to calculate the largest propagation delay. I think this could be added to the project report.
-It is very hard to test large projects, though truth table is very useful, I would suggest adding a mini script language to be able to test circuits.
-When working with people on a source control, it gets very difficult to know who made changes. Maybe you could add a visual diff?
-Maybe a good UI upgrade would be adding a context menu when right-clicking the circuits in the left pane?
-Logisim also has a feature to all the gates in the circuit to nand and 2 input gates, that can be really useful.
-If I want to build a pcb with it in Autodesk Eagle, for example, I have to recreate the entire project, which can be really annoying. I think you could add a export button to a standard format that other software can read?

Thank you very much for making this great and free simulator.

Hi,
Thank you for suggestions. Some of your concerns are already addressed. You can have a look at the documentation at http://www.logiccircuit.org/help.html for more details.
When you moving selection if you press shift key before you release mouse button it will move selection without unselected connected wires. This trick you can use also after paste; just move them where you want and hold shift when release mouse.
There is a connection dot when three and more wires are connected. If you only connect two wires that are angled to each other, you will never need to have a dot on them. If you have some other case in mind please let me know.
I do not understand you question about clock time. Are you talking about real circuits? What propagation time do you want to calculate?
Script language and visual diff are good ideas; I will think what I can do about them.
I did not understand what feature of logisim you have mentioned.
I am not aware of any standard format. Please let me know if you have something specific in mind.
Best regards,
Eugene

Hi,
Thanks for replying.
I didn't found the option of having 90 degrees angle in the help documentation.
What I meant for moving was that when moving the ic and the wires and releasing mouse button, if there are wires near the ic pins, they will connect to them, and I think it would be great to have a hotkey to not automatically connect those wires to the pins when releasing mouse button.
And for pasting I meant having a hotkey to paste where the mouse is.
What I meants for the dots in the wires is shown in the wires.png file attached. For example, it would be very useful to have a dot in the second case, to mark there that the two wires are connected, not like in the first case, that the wire goes through.
With clock time I meant to say to calculate the maximum amount of logic gates in series, not in parallel, and show them in the project report. In real circuits, we use that information to calculate propagation delay and therefore clock speed.
Logisim has an option to convert all the logic gates from the ic to 2 input nands, which can save a lot of time.
I didn't have anything specific in mind with the standard format.
Best regards,
Pedro

Hi,
There is no option for making wire horizontal or vertical. You can always draw them that way.
There is no notion of connected wires. If a wire is touching with its end another wire or connection pin then it is connected. So when you are moving selection it is usually also dragging all connected wires. In order to avoid this you can press and hold Shift key on your keyboard when dropping the selection at the new location. When you paste the pasted elements are selected. So you can move them without dragging all other wires with the same Shift key gesture.
On your image there is no connection between wires. You might have more than one wire on the same place. In general it is better to avoid overlapping wires. On the other hand when you connect more than two wires in one point it will be a dot indicating that. You can have a look at samples or screen shots to see the dots on wire connection.
There is no option to convert to nand, but you can use project report to see if you have anything that you need to convert.
Hope this help,
Eugene

Hi,
the new version supports Python as a scripting language. I hope this will solve your testing needs.
Eugene