A downloadable game for Windows, macOS, and Linux

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A minimalistic digital logic simulator. You start with an AND and a NOT gate, and from there you can build whatever you want.

I created this as a visualisation tool for my video series on the basics of how computers work, but have released it since a number of people were interested in trying it. May be buggy, and definitely lacking in many features! For something far more complete, take a look at alternatives like logisim.

Source code available here: https://github.com/SebLague/Digital-Logic-Sim

Latest build: v0.25 (6 December 2020)


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Click download now to get access to the following files:

Digital Logic Sim 20 MB
Digital Logic Sim 20 MB
Digital Logic Sim 22 MB

Development log


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Make a link like this:


You should also make it so the chip making area is a drag around thing so there's unlimited space and we can zoom out. that would allow us to make MUCH bigger and better thing


did he die?

i am worried

I sure hope not.


What is the discord server invite? make one so it lasts forever


Could you make it so multiple wires can connect into one spot

is it possible to delete projects? i just dont like a ton clogging up the menu

This is amazing, I've been looking for something like this to help me learn. Also love the videos. 

Thank you!

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https://discord.gg/f7ekYPxT discord digital logic server

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hey, can i join the discord server?

i am Frostie#8802 on discord

Can i join too Kureshik#5677

how do I use other gates then and/not?

if you know then thank you so much :) - Me

I mean the store gates and stuff

That's what that means.

U give it a clock a stor signal an done


bad grammar = 7 yro kid

bruh English is my second language

How do I make the displays

U can create ur own. He posted the source code on github.

I looked through the seemingly relevant .cs files but I couldn't find how to actually make them. How would I go about this?

Do u like my dumb 32 bit register made from 2 parts? =)

yes :)


Hey I know Im a bit late to the party, but can you please add me to this discord server? Wojtex#2648



but i need part 3 please

but have a problem if man need to make 1kb is = 1024 bytes

are bytes = 8 bit how to make?

How to slow down the signal speed in simulation, as in his video?


for anyone interested in deleting logic gates I made a tutorial.

I don't get it.

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What does 'signed' mean when you group inputs and outputs together?

Deleted 14 days ago

do %AppData% in your search bar then go to Appdata at the top then go to LocalLow and then Sebastian Lague

how do i make ram?

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He will make that in the next video I think. There is also a crash course series that shows you how on youtube.

if you what I can tell you the basics of it


on your video, the way you made the ALU made it so if you were to subtract 0 from 0 it would say that the answer is 0 but it would also make the carry output true. here's my fixed ALU, which does not have this problem:

To the peeps who made a discord server dedicated to this simulator, can u pls send a server invite that doesnt expire, and btw my discord is 29#1731, hit me up.

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There needs to be a way to edit chips easily. The only way I've found is to create a chip with the exact same name and close and reopen the project

Could you make something like that about networking/data transformation/data representation or something similar?

btw awesome content!

why is it using so much gpu?  im on a laptop core i5-8250u , UHD 620 . its like 90% gpu usage.

im core i7

i tried making a Carry look ahead adder and somehow i made it slower than a ripple carry adder

time to go back to the drawing board

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I made a button!!!

The adder is part of the video he put on this itch page

who here want me to show or teach or find someone to teach about the basic CPUs

here a basic tutorial on CPUs

no big memory in this Just the Absolute basics


"The invitation has expired"


Gus please click the invite I can’t send one out ever single day

just make it so it never expires

this simulator gotten a little annoying  i tried 5 times to make a main memory BUT IT STILL DOSENT WORK no matter what i do or how careful i plan they don't work can you please make things work without connecting all the dots up Thank you

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i will set up a tutorial on igmur.com (image tutorial) on how basic CPUs work but can you please tell us when or what is going to be in the next update when its small if its a big one you can keep it a surprise if you want but please tell us something.

can you please tell me how to make ram?

do you know the game battleship it’s like that but first you need to know about how to do encoders and decoders. first is decoders what that do is take a 2bit and up binary input (without 2s compliment) and put out a single output per section. 0000 input turns on the 0 output 0001 turns on the  1 output and 0010 turns on the 2 output and etc. with a 4 bit input you’ll get 16 outputs total each 16 outputs represent a number through 0-15.

A simple clock you can turn on and off

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ya well the clock here docent has a 50/50 tempo it has a random speed from slow to high tempo constantly

Another clock which seems to be steadier is this:

ok ill just clock it by hand sense its more reliable till he adds a clock to the simulator 

the ability to zoom out or scroll would be nice

Unfortunately this doesn't seem to be working on the new M1 Macbook Pro. The buttons on the top and the settings under CREATE all disappear when clicked.

Okay, so a few problems. Solid GUI, but come on man why can't you delete anything? Like, you can delete individual instances of a certain gate, but if you put a typo in the name or something there's nothing you can do except restart the whole project or learn to live with it. Speaking of, if you did make a mistake in a project and have to start over, you can't delete the old project. Plus, maybe instead of starting with AND and NOT you could just start with NAND or NOR, since you can make every logic gate out of either of those as a starting point.

all gates (including NAND and NOR gates) can be made with the AND and NOT gates but its much more complicated for no reason if you went the other way meaning starting with the AND gate and the NOT gate makes it both simple and diverse.


If there is a feature missing that you like then make it. He made it open source on Github.  I cant stand when people put out a project for free and everybody acts all entitled without lifting a finger to help.

I downloaded it and accidentally put on the highest graphics. It crashed and now when i open it it instantly crashes. I have reinstalled it five times and restarted my computer. Can someone please help. On mac btw

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Does this work on Windows 32-bit? I am using a 32-bit Windows tablet. When I try to open an application that says "Digital Logic Sim", it says that this is not compatible for my computer. It is in the Digital Logic Sim (windows) folder. I extracted the folder. I have 2.14 GB free.

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I built a small 4-bit CPU that is really hard to program, because it heavily relies on swapping registers. It's basically a river-crossing puzzle. :)

If you want to try it out here's the Github link: https://github.com/gschwaer/Swappy/blob/main/Readme.md

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you don't need that many registers all you need a is main memory and 2 accumulators for the processing, a 2nd larger main memory for Control unit and memory data registers, also known as MDR or multiple like Cache, Cache is THE main memory that is between the CPU and RAM what it dose is that it take HUGE chunks of memory at once (mostly 4 eight bit registers at once) then send it to the CPUs memory and control unit. it also sends data back to ram or to main bus. (about the memory input from ram to cache is much bigger than that IRL)

Thanks for your suggestions.

Why "that many registers"? I only have two. They are in the SWAPR4. (Btw, all the 4s refer to word size.)

I do not use a main memory, but two stacks (+1 for consts) and one code memory (in CMD4) instead.  If you only have 4 bit as the instruction word, you don't want to waste a lot on immediates for offsets, nor with only 16 instructions on two word instructions. I don't understand what you wanted to imply regarding caches, surely in this simulator and on this level of CPU memory access latency plays not a role (compare with CPU in "the early days" like the 6502).

Yes, it's not a "classic" architecture, but I thing in might be Turing complete (assuming the stacks and program RAM would be infinite ;) ). I went for this arch because I wanted to test the individual chips well before putting them together (editing is not possible atm).

Merry Christmas! :)

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I’ll show you the setup because you only need 2 accumaltors and 4 registers nothing special 

How'd you add those displays to it?

It was video editing, they werent actually there.

actually you can press the + key while hovering over the input/output bar to add them. you can also select the word size by pressing it again until you have the desired size.

I have watched your videos are really great.

but now I want to download this software.

But i m having a problem downloading it. once I download the software and extract the zipped files and then open it it shows a pop-up message that this is not compatible with my computer.

could you please tell me how to solve that problem?

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Are you sure you downloaded the correct version for your operation sistem?

If you downloaded the correct version, I dont know whats happening, try to talk with Sebastian.

oh yeah you are right thank you for helping me😊.

thank you very much :)

what pc r u on


has anyone managed to mod this to make the icons smaller or something along those lines?

Triple andTriple And : Following this logic you can do many more and.

how to download this??????????????????????????


Click on the big red "Download now" button. You will get the source files, bc this is itch.io.

You can then unpack the .zip. 

You will find the Executable at:

Folder/Digital Logic Sim (windows)/Digital Logic Sim/Digital Logic Sim.exe
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