Questions tagged [digital-circuits]
Digital circuits use logic gates as the basic building block. A logic gate performs a logical operation on binary inputs and produces a single binary output. The Primary Logical operations are AND (conjunction), OR (disjunction) and NOT (negation).
102
questions
0
votes
1
answer
2k
views
Two dimensional 3 bit parity check
Can someone explain how do we find these parity bit errors?
0
votes
0
answers
34
views
Carry Look Ahead Adder for stabilize the sum
An four-bit carry-look-ahead adder for computing the sum of 2 numbers
, where A and B are integers represented in 2's complement form. If the decimal value of A is 3, the decimal value of B that leads ...
-1
votes
1
answer
875
views
What is Control ROM and Decision ROM?
I have done some research but I cannot answer this question. Please Help.
0
votes
2
answers
270
views
Logic Gates in circuits
We can make all the gates using nand or nor gates. My teacher told us that nand gates are cheap too, then why do we need other gates at all?
1
vote
0
answers
101
views
How to find states in logic circuits?
For hobbyist reasons I wrote a program which takes the equations of the logic gates of a digital circuit as input, does some analysis, outputs the analysis results and generates program code for doing ...
1
vote
1
answer
318
views
Caesar Cipher - logic circuit [closed]
my teacher asked the class to do a digial circuit that encrypted a message using cesar's cipher, and a circuit to decrypt, but my only idea is to solve it using a circuit that does P + K mod N, where ...
78
votes
9
answers
23k
views
Why is addition as fast as bit-wise operations in modern processors?
I know that bit-wise operations are so fast on modern processors, because they can operate on 32 or 64 bits on parallel, so bit-wise operations take only one clock cycle. However addition is a complex ...
0
votes
0
answers
118
views
circuit for finding the index of first zero entry in a binary string
finding the index of first zero entry in a binary string:
Input: binary string ($0$'s and $1$'s)
Output: index of first zero entry
Can you give a circuit for finding the index of first zero entry ...
0
votes
1
answer
996
views
Converting Boolean Expression for NAND Gate Implementation - DeMorgan's Law
If I have the sum-of-products expression B~CD + ACD how would I convert this so it could be implemented using 3-input NAND gates through DeMorgan's Law? Would this ...
5
votes
1
answer
357
views
Size of constant depth circuit for digital comparator?
Is a lower bound of $\Omega(n^2)$ known for the size of any constant depth circuit expressing a digital comparator for two $n$-bit numbers?
Two $n$-bit binary numbers can be compared using a digital ...
2
votes
1
answer
1k
views
Extracting Boolean Function using Machine Learning
How can machine learning help extract a Boolean relationship in a given binary input-output data set?
Let us assume that the given data set is exhaustive - ie. it cover all possible input ...
3
votes
1
answer
187
views
Using analog values with Algebraic Normal Form?
Algebraic normal form (ANF) is a way of describing digital circuits made up of AND and XOR gates.
The below is an example of an ANF expression which evaluates to true if two or more of it's three ...
3
votes
1
answer
82
views
Can bar codes theoretically be considered a type of digital memory?
Bar codes act just like any other device that contains data that you can read from. Can bar codes thus be considered a type of computer memory?
I believe the principle is quite similar to the optical ...
4
votes
3
answers
105
views
Is it possible to determine if C=A+B faster than adding A+B in logical circuits
With an adder circuit where A+B=C, I am trying to have a method to determine when C will be valid based on a change in A or B. I know that it is possible to just determine the longest the circuit ...
3
votes
1
answer
2k
views
General Approach To Calculate Minimum Number Of Flip-Flops Required
In the previous two years of the GATE exams, a question has been asked for finding number of flip flop's for counting sequence $0−1−0−2−0−3$ in 2016 and $0−0−1−1−2−2−3−3−0−0$ in 2015. But still, the ...
0
votes
0
answers
745
views
Binary Division using logic gates
I am building a 64 bit CPU in Minecraft and I'm stuck on adding division into the ALU. I was told I should ask this here. Does anyone know how to divide in binary using only logic circuits? I can't ...
3
votes
1
answer
925
views
Physical significance of Don't cares in Digital Logic design
In many Digital functions we come across don't care conditions where we use don't cares to minimize functions.
What is the significance of these don't cares in real world scenario where we actually ...
-2
votes
1
answer
183
views
two laws of De Morgans law and its used as NAND gates and NOR gates [closed]
how the all gates can be made by only these two . Yes i know the circuit diagram of basic gates by universal gates which i have learnt. but if there is complex circuit like XOR gate or any other ...
0
votes
0
answers
50
views
How storage affect if we use tertiary language? [duplicate]
as we uses binary language in all the computer systems around us which consist of 0s and 1s (Off and On) bits. Let assume that someone is developing a computer system based on tertiary system -1, 0, 1 ...
0
votes
1
answer
172
views
Difference between cordic algorithm and table based methods for elementary functions computation
In this book both Table Based methods and Cordic iterations are explained. computationally speaking i suppose the Table based is usually faster, even though it probably requires more resource, while ...
0
votes
1
answer
61
views
At what point do electrical signals become actually logic and programmable language?
I get that one transistor can store a value of 1 or 0. That's not the problem. What I don't get is how the fact that a transistor represents a 0 can translate into logic? How do these transistors turn ...
-3
votes
2
answers
636
views
D - Latch or D Flip Flop?
I have a diagram (https://i.stack.imgur.com/UK16E.jpg) where it is either a D Latch or D Flip Flop. I am trying to figure out which one it is and why. If it is a D Flip Flip, I also need to know which ...
0
votes
0
answers
171
views
Is there a complexity metric for digital circuits?
Let's say that I have a digital circuit made up of XOR and AND gates.
Is there any way to describe the complexity of that circuit?
I could just use the total number of gates, but gates being in ...
3
votes
1
answer
672
views
Algorithm for simplifying ANF or polynomials?
I have some digital logic circuits in Algebraic Normal Form, and am limited to using XOR and AND logic gates.
For instance:
$B_{out} = B_1 B_2 \oplus B_1 B_3$
I was wondering, are there any ...
2
votes
2
answers
450
views
Is there a canonical form that uses AND and XOR?
Is there something like the sum of products form of a circuit which uses AND and XOR instead of AND and OR?
I know that you can create an OR gate from AND and XOR (but i can't remember or find the ...
2
votes
1
answer
274
views
How does a register remember value?
So I am studying this great book, and Chapter $3.1$ is about registers.
Quoting from this book / chapter:
A register is a storage device that can "store" or "remember" a value
over time, ...
1
vote
1
answer
451
views
Simplifying Boolean Expression
I am designing a 4-bit comparator with a look ahead unit using a bit slice approach. I have to break the propagation of the Logical expressions for (A<B)i and <...
0
votes
0
answers
90
views
Homomorphic computation?
Cryptography has the concept of homomorphic encryption.
Homomorphic encryption lets you transform binary values into an encoded form, put them through a circuit and then decode the bits, getting the ...
1
vote
0
answers
266
views
Understanding Computer organisation and architecture [closed]
What are some of the books for "computer organisation and architechture" which are best for self study. Such a text that one can grasps the big picture, and understandhow various things are fitting ...
1
vote
1
answer
279
views
Why is c) a combinational circuit, but d) not?
I am doing practice after just learning what combinational circuits are, yet I am unsure of why (c) is combinational, but (d) is not. Can someone please explain to me why this is? The Solution ...
3
votes
1
answer
658
views
Ripple Carry Adder
I'm new to computer science and came across an issue while learning about ripple carry adders. I'm trying to add binary 1+1+1 below (excuse the poor photoshopping). I know the answer should be ...
3
votes
1
answer
6k
views
Full Adder vs. Half Adder
I'm having some trouble figuring out where the "Carry in" value comes from in respects to a one bit full adder diagram. I understand the below half adder,
but my question is: is the the output of ...
19
votes
4
answers
8k
views
Connection between NAND gates and Turing completeness
I know that NAND gates can be used to create circuits that implement every truth table, and modern computers are built up of NAND gates. What is the theoretical link between NAND gates and Turing ...
5
votes
1
answer
294
views
Algorithms for logical synthesis of multiple output bits?
Karnaugh maps and the Quine–McCluskey algorithm can be good choices for coming up with fairly minimal logical expressions that match the requirements of a truth table.
What if I have a situation ...
2
votes
2
answers
261
views
Converting a digital circuit to two layers of OR and AND gates
The other day someone mentioned to me that you could take an arbitrary digital circuit which mapped N input bits to M output bits, and replace it with a layer of OR gates and a layer of AND gates. I ...
2
votes
1
answer
114
views
Determining whether a digital circuit is optimal
Are there any techniques that can be used to determine whether a digital logic circuit is optimal, or if it has extraneous operations that don't contribute to the output?
I'm especially curious in ...
1
vote
1
answer
528
views
Adder circuit with sign bit (not twos complement)
I've found and implemented a full adder to be able to do unsigned or two's complement addition on wikipedia:
https://en.wikipedia.org/wiki/Adder_(electronics)#Full_adder
However, in my particular ...
0
votes
1
answer
1k
views
Implementing a Boolean function with NOR gates
Implement f(a, b, c, d) = Σ m(3, 4, 5, 6, 7, 11, 15) as a 2-level gate circuit
(a) Using OR gates and NOR gates.
(b) Using NOR gates only.
I have found that F=ab+d using Karnaugh map.
I have also ...
5
votes
1
answer
1k
views
In fast multiplier circuits, what is the difference between a Counter and a Compressor?
When working on fast parallel multiplier circuit designs, like Wallace tree multipliers or Dada tree multipliers I found many papers and books refer to different components used in the tree to reduce ...
3
votes
2
answers
134
views
Classical Computation without NOT
Is it possible to do universal classical computation using bits and 2-bit gates when you cannot perform a NOT operation on a single bit (hence cant do CNOT and so on). If yes, what are the possible ...
-1
votes
1
answer
161
views
Digital Logic Settle Time
I have an exam tonight and I'm reviewing my midterm exam. I got this question completely wrong, with no solution given.
...
4
votes
2
answers
696
views
Why is Computer Architecture in $2^n$ bits?
I have always wondered why is computer architecture in $2^n$ bits. We have 8 / 16 / 32 / 64-bit microprocessors or for that matter other parts of computer are also in power of 2 bits.
The only logic ...
2
votes
3
answers
7k
views
Is Karnaugh Map possible for Maxterms?
I read about Minterms i.e. sums of products, simplification using
Karnaugh Graph. Can this graph be used for Maxterms, i.e. products
of sums, as well? If yes, then how?
If not, then is there some ...
0
votes
1
answer
3k
views
Conversion from Decimal form to BCD
I have seen a way how to convert a decimal number to BCD (packed & unpacked) using 8,4,2,1 weighing forms but how to do it using 4,2,2,1 and 7,4,2,1 ? Any method please.Suggestions
4
votes
2
answers
2k
views
Do Karnaugh maps yield the simplest solution possible?
I'm learning to use a Karnaugh map, but I'm not sure if I obtained the simplest expression possible. Have a look at this example:
Truth table (inputs are A B C; output is F):
...
1
vote
1
answer
86
views
How many possible prime implicants are there in total for a 4-variable Karnough-map? [closed]
The answer for this question is 81. But I count figure out why. Can someone explain to me how does this work. Thank you.
1
vote
1
answer
216
views
How to construct a truth table
Yes this is a homework problem, but I only need help setting it up, there are 7 parts to the question once I set it up:
We want to build a function Y = 2X + 3 where X denotes a 3-bit
unsigned ...
-1
votes
1
answer
119
views
Question on SR latch functionality
Below is the diagram of SR latch
The following is the functional table as per my scrutiny .
Sl.no S | R Q(t) | Q'(t) Q(t+1) | Q'(t+1) Q(t+2) | Q'(t+2) Q(t+3) | Q'(t+3) Remark
===== ...
1
vote
1
answer
6k
views
Difference between end carry and overflow
I am confused with end carry and overflow. When will an end carry be the overflow? How to identify whether the end carry is overflow or not? Are they both same?
Sometimes end carries obtained are ...
3
votes
1
answer
935
views
Karnaugh map with don't care: increasing the number of groups instead of simplifying
AB
00 01 11 10
00 | x | 1 | 0 | 1 |
CD 01 | 0 | 1 | x | 0 |
11 | 1 | x | x | 0 |
10 | x | 0 | 0 | x |
The answer to the ...