Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [logisim]

Logisim is software for designing simple and advanced logic circuits such as RAMs, Registers, CPUs, etc.

Logisim site

109 questions
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Very simple CPU design in LogiSim

I'm currently a junior in highschool, and I've been interested in computer/electrical engineering, specifically microprocessor design. I've read Code by Charles Petzold, , and have begun reading the Microprocessor Design Wikibook (which seems to be…
Will Hodges
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What is wrong with my D flip-flop toggle switch?

Until a few weeks ago, I had never drawn a circuit diagram in my life, so bear with me. I am currently trying to design (in Logisim) a circuit that acts like a toggle switch, using only basic logic gates and no clock. Basically, I want the LED…
norman
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How do I implement a rotate left 1 bit operation in a 16-bit ALU in logisim

I'm creating a 16-bit ALU that has to perform logical AND, logical OR, addition, subtraction and rotate left one bit. I have everything working perfectly except the rotate left one bit. I think I need to implement this at the 16-bit level instead of…
Matt L.
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Are there any "Both Rising Edge and Falling Edge Triggered" Shift Register?

I was designing this circuit in Logisim-evolution. In the book, it is mentioned that an n-bit multiplier would require n-clock cycles to work. I think this will be possible only when we have the shift register load during its rising edge, and make…
Vedanta Mohapatra
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Logisim Help - Using Custom D Flip Flop

I am trying to create a D Flip Flop to use in a bidirectional 4-bit shift register, using Logisim. However, when using my D flip flop the shift register acts just as a normal register setting the bit for all 4 D flip-flops outputs instead of one by…
lilnut
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Digital Circuit with Toggle Switch using Logisim

I'm supposed to design a small digital circuit (with Logisim) using basic logic gates, so that when this circuit is used with the chosen switch (which has to be a button), it will make the circuit function as a toggle switch. So when I press the…
Yash Chitneni
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Why is this NAND gate not turning on with both inputs off?

Problem I am trying to simulate a circuit that acts like a memory bit in Logisim Evolution but for some reason the NAND gates don't turn on with both outputs set to 0. I suspect that the problem might be that the gates are not connected to any…
Sujal Singh
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Glitch in circuit consisting of 2 flip flops

So I have been trying to figure this out. I made the circuit in Logism: Though I am having trouble figuring out whats causing it. From what I understand, it could be because 1 of the inputs of the last OR gate (G3) is delayed, and so the output we…
Crab00189
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Is A XNOR B logically equivalent to A XOR (NOT B)?

I am just wondering if its fair to say that A XNOR B is logically equivalent to A XOR ~B? If yes, how do I justify that without a truth table?
alwaysconfused
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Blue wire in logisim

I created this circuit and at first all the wires were green but when I copied it out of the main folder into another one, the wires turned blue. I've tried messing around with it and looking up what the problem is but I cannot find a solution. The…
Tyler Bloom
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How do I expand the divider?

I'm trying to make a 128-bit divider in Logisim using Logisim's built-in arithmetic library. How do I connect the dividers so that I can work with divisions of more than 32 bits? What I have considered: Create the divider from logic gates (takes…
TChapman500
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How does logisim differ from redstone and real life circuitry?

I recently developed an interest building circuitry systems. It started in Minecraft and then grew when I picked up a micro controller from Radio shack to build an RC car with. Obviously I'm most familiar with Minecraft mechanics. So in an effort to…
Musixauce3000
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Logisim: "Oscillation apparent"

I am trying to simulate an RS master slave flip-flop in Logisim, and I have encountered the "Oscillation apparent" error. What does this error mean and how is it resolved? I am required to use two nor gates for the basic RS latch implementation and…
Patrick Taylor
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There's something wrong with my 2-bit adder

I made a 2-bit adder in Logisim Evolution and for some reason it gives the wrong output. I searched a ton of forum posts and all of them use the exact same design and they say it works. Here's a truth table:
wetturtle45
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How to pipeline CPU instructions in sequence?

I am designing a 16 bit CPU in Logisim Evolution. I have already designed single clock cycle instructions. I have 19 bits to control. I tried using the register and clock divider circuit to send data in a pipeline. It works, but it outputs a…
dulatello08
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