Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [adder]

Digital circuits that adds values

An adder or summer is the designation of a digital circuit that adds values.

For more details refer to this article.

278 questions
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How to determine overflow from an adder/subtractor?

I suppose in binary addition (no negative numbers), overflow happens when theres a carry out? Then for subtractor (2s complement), how do I determine it? From my understanding of my lecture notes, overflow happens when theres a change in sign or…
Jiew Meng
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What is the purpose of a "carry in"?

I'm currently trying to learn how binary adders work, but I don't understand what a "carry in" is for. What is the purpose of a "carry in"?
Ethan Bierlein
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What is wrong with my 2-bit adder?

I attempted to build an 8-bit adder in Logisim by carefully chaining together a half-adder and 7 full adders, all made from basic logic gates. Unfortunately, it produced erroneous results; for example, 00000011 + 00000011 = 000000100 ! I found that…
norman
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Binary Adder and Parallel Adder

Are binary adder and parallel adder same thing? I couldn't find any information about parellel adder in my book. Does anybody have an idea?
berkc
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Can anyone explain to me how a carry select adder works?

Doesn't get more complex then the question above. I've been looking through textbooks and using google and I feel like the explanations are not suffice or unclear. Can anyone explain this to me well?
munchschair
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Inversion property of full adder

The given inverting property states that the FA stays the same if I invert all the inputs and outputs. Using this idea we modify the ripple carry adder into the below form, but why can it be translated as below? Clearly there are many inversions…
kissinger david
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Carry Skip (Bypass) Adder wcs vs Crit. Path

I'm studying adder types and, as the title says, I'm having a problem with the carry-skip. From what I know the critical path of an equal blocks carry-skip adder is supposed to go from the LSB of the sum through the whole first block ripple, then…
DDCCoder
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What is a Carry Propagate Adder?

It's in my syllabus but there's no mention of it in my book. Can someone explain to me what is a Carry Propagate Adder?
Lakshay Kharayat
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2's Complement 4 Bit adder. (Multisim)

I am hoping I am doing something dumb here. I know there are other posts about this but everything I have found leads me to believe my circuit should be working. Yes this is for homework. No, I am not looking for "here's the file so you can cheat. I…
Vincent Ledbetter
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3 bit full adder designing

I am new to the concepts of using adders to add numbers but I tried using the definitions which I understood as given two binary digits A, B the full adder takes three inputs A, B, C where C acts as a control bit or a carry bit, gives the SUM= (A…
Upstart
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Question about 4-bit binary adder on 7 segment display and subtraction

In my lab, we successfully built a 4-bit binary parallel adder and were able to display the results of some tests on the 7 segment display. But our TA asked us to try something: subtract 1-9, and we got 7. Why is that?
gbm0102
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Truth Table Accuracy

I made a truth table for this sequential circuit, and I wanted to make sure that it is correct. Is this right? The top left is a full adder, and the top right is a D flip-flop.
David
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2-bit adder implementation

How can I implement this 2-bit adder circuit: (source) Onto http://www.neuroproductions.be/logic-lab/ or logic.ly? After several attempts (and in spite of the half adder and full adder working) I cannot seem to get this adder working. Here is the…
Tomas
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Find x cubed with half adder

My excercise is the following: Make a circuit which outputs X^3 of two bit input of X. Use the lowest number of HALF ADDERS as you can. I don't really understand how to compute x cubed with half adders. Any hints or help is appriciated.
Alan
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What is wrong with my 16 bit adder? How can I fix it?

I did this 16 bit adder in a simulator. Something is wrong. The automatic check returned FAIL. What did I do wrong? How can I fix it?
Sonya Lyu
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