Love this software... would be the best out there if only oscillations resolved. Other lesser logic simulators do it, but cedar doesn't. Is it possible to add two simulation engines...a basic one for simple stepwise logic as currently used, and another with some risetime metric in the background with a hint of randomness to let oscillations settle.
this alone would make the software useable for me.
You may not think it serious, but I cannot recreate a flip-flop even from published schematics and respected standard cells. Anything with feedback runs the risk of getting into oscillations which refuse to settle down even where the design is from an accepted standard schematic.
Also, there should really be a reset button added to the play/pause/step buttons. Creating an OR with feedback as a write-once memory (for a flag) is fine but with no way to reset it I have to disconnect and reconnect its signal sources before restarting the circuit. Some other designs also get these 'stuck' states wth no way to 'power cycle' without deleting wires or parts.
Lastly the propagation of 'ambiguity' (green) signals. These propagate like nobodies business and are sometimes the cause of wierd oscillations, perhaps the option to use a slightly more advanced engine would allow you to give these signals a slightly better treatment than currently. Having said this, I think the stepwise signals engine you're using at present has advantages for simple circuits and should be retained... but as the SOLE engine it makes your software unuseable for my designs.
There is so much that CEDAR just refuses to deal with, which is a shame as the things it DOES do, it does SO well.
It's also such a shame I cannot find source as I'd so love to contribute. I've written an abstracted signals emulator which is very efficient (using a random initial value for the rise step along with a catastrophy function to settle fast) and this will settle an oscillating circuit such as a flip-flop into any permissible stable states pretty fast as under this scheme getting a stable circuit to oscillate is like balancing a biro on its nib.
Log in to post a comment.