# Software for simulating logic gates? **URL:** \ **Category:** Factual Questions\ **Created:** [November 22, 2010, 4:38pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545 "2010-11-22T16:38:53Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 22, 2010, 4:38pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/1 "2010-11-22T16:38:53Z")
I have to give a presentation on digital logic and I want to show some pretty animations and stuff. What software would you recommend (MacOS or Linux) that I can use to make some simulations of simple logic gates; maybe a 4-bit adder? This is not a very sophisticated audience, so I want to make something where it would be clear to the layman what’s going on. Also it will help me review the subject. 😃 Free software is nice but I’m willing to shell out a few bucks. Not a lot of bucks, though. ---
**Author:** ![gonzoron](https://avatars.discourse-cdn.com/v4/letter/g/a6a055/32.png) [@gonzoron](https://boards.straightdope.com/u/gonzoron)\ **Post date:** [November 22, 2010, 5:24pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/2 "2010-11-22T17:24:27Z")
Google for a free verilog or VHDL simulator. I don’t know if there are any, but I’d be surprised if there weren’t. The one I use at work runs \>$10k per license, but for this you don’t need anything that fancy. (In fact, I don’t see why you need much more than powerpoint for what you’re doing. You can figure out the logic states for a 4-bit adder on paper, no?) ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [November 22, 2010, 5:32pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/3 "2010-11-22T17:32:26Z")
Would this be handy? [http://logic.ly/](http://logic.ly/) ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 22, 2010, 6:56pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/4 "2010-11-22T18:56:50Z")
> [@gonzoron](#): > > Google for a free verilog or VHDL simulator. I don’t know if there are any, but I’d be surprised if there weren’t. The one I use at work runs \>$10k per license, but for this you don’t need anything that fancy. (In fact, I don’t see why you need much more than powerpoint for what you’re doing. You can figure out the logic states for a 4-bit adder on paper, no?) Yeah, I could just make an animation, but I would prefer something that actually “works” so I can demonstrate how it can be extended by adding new bits, or playing around with components in response to audience questions. (These are high schoolers.) ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 22, 2010, 6:57pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/5 "2010-11-22T18:57:51Z")
> [@control-z](#): > > Would this be handy? [http://logic.ly/](http://logic.ly/) That looks really cool! ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 22, 2010, 7:46pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/6 "2010-11-22T19:46:27Z")
> [@friedo](#): > > That looks really cool! OK, this is officially awesome! Using the free demo I was able to make a one bit [full adder](http://www.friedo.com/adder.jpg) in just a few minutes, and it actually works! (Not the most efficient design but it’s the easiest one I could remember.) This will be $30 well spent. Thanks. ---
**Author:** ![gonzoron](https://avatars.discourse-cdn.com/v4/letter/g/a6a055/32.png) [@gonzoron](https://boards.straightdope.com/u/gonzoron)\ **Post date:** [November 22, 2010, 8:53pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/7 "2010-11-22T20:53:14Z")
nice! ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 22, 2010, 9:28pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/8 "2010-11-22T21:28:26Z")
[opencores.org](http://opencores.org) is a good place to go, and [here](http://opencores.org/newsletter,2010,10,#n2) is something about a free Verilog simulator. However I think logic.ly sounds better as a teaching tool. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [November 23, 2010, 12:03am UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/9 "2010-11-23T00:03:50Z")
[I like tkGate, myself.](http://www.tkgate.org/) It’s fully graphical. [There’s even microprocessors implemented in it!](http://xidus.xidus.net/mips) ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 23, 2010, 1:30am UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/10 "2010-11-23T01:30:10Z")
> [@Derleth](#): > > [I like tkGate, myself.](http://www.tkgate.org/) It’s fully graphical. > > [There’s even microprocessors implemented in it!](http://xidus.xidus.net/mips) That looks pretty good too, thanks. ---
**Author:** ![PuddingCat](https://avatars.discourse-cdn.com/v4/letter/p/b4bc9f/32.png) [@PuddingCat](https://boards.straightdope.com/u/PuddingCat)\ **Post date:** [November 23, 2010, 3:46pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/11 "2010-11-23T15:46:30Z")
Now that it seems the OP has been asked and answered, I’d like to make a very minor hijack if I could. I’m in the process of getting ready to teach arcade game repair theory to a bunch of hobbyists and I could really use a logic simulation package which includes standard 74 series logic. I realise I could probably re-purpose one of the above tools and build my own 74LS parts, but I’d prefer to get on with writing the tutorials and building the simulations instead of chaining flip-flops and other gates together to make an LS139 🙂 I used something like this many years ago at university, but my google-fu has let me down. thanks t. ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [November 23, 2010, 3:51pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/12 "2010-11-23T15:51:24Z")
trmatthe, will this do what you need?: [http://www.gamedev.net/community/forums/topic.asp?topic\_id=488374](http://www.gamedev.net/community/forums/topic.asp?topic_id=488374) My Google search was: _“74 series” logic simulator_ ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [November 24, 2010, 1:56am UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/13 "2010-11-24T01:56:49Z")
My “WTF” is that you are teaching them, and are using software to simulate the things. Why not give them _actual_ 7400 TTLs, and a breadboard. That’s how I learned, and I spent no more on those parts than the software to simulate them costs. Plus, you need a several hundred dollar computer to run the software. This just isn’t adding up, to me… ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 24, 2010, 2:13am UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/14 "2010-11-24T02:13:10Z")
> [@Cheshire\_Human](#): > > My “WTF” is that you are teaching them, and are using software to simulate the things. Why not give them _actual_ 7400 TTLs, and a breadboard. That’s how I learned, and I spent no more on those parts than the software to simulate them costs. Plus, you need a several hundred dollar computer to run the software. This just isn’t adding up, to me… I have 45 minutes. And I already have a laptop and they have a projector. 45 minutes not enough time to teach everyone how to set up and use a breadboard and wire a bunch of chips. The purpose of the presentation is to introduce the concepts of digital logic and show an example of what can be done. ---
**Author:** ![HardlySanguine](https://avatars.discourse-cdn.com/v4/letter/h/96bed5/32.png) [@HardlySanguine](https://boards.straightdope.com/u/HardlySanguine)\ **Post date:** [November 24, 2010, 5:52am UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/15 "2010-11-24T05:52:36Z")
I was going to suggest [this circuit simulator](http://www.falstad.com/circuit/) which is better for analog circuits but it has some digital stuff, too. Menu: Circuits-\>Combinational Logic for examples of what you were looking for. You click on the 1s and 0s to change their states. Right-click to select and place additional components. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [November 26, 2010, 11:36pm UTC](https://boards.straightdope.com/t/software-for-simulating-logic-gates/561545/16 "2010-11-26T23:36:19Z")
I’d like to know if there was a Macintosh one for simulating basic electronic components.