+11 votes
1.2k views

Choose the correct alternatives (more than one may be correct) and write the corresponding letters only:

All digital circuits can be realized using only

1. Ex-OR gates
2. Multiplexers
3. Half adders
4. OR gates
asked
edited | 1.2k views
0

Half-Adder, and MUX both need help of constant 1, and can realize all logic circuits, hence B,C are the correct options.

## 3 Answers

+12 votes
Best answer
Answer: B, C

NOR gate, NAND gate, Multiplexers and Half adders can also be used to realise all digital circuits.
answered by Boss (34k points)
selected
0
OR  gate?
+1
Corrected. NOR gate, NAND gate, Multiplexers and Half adders can also be used to realise all digital circuits.
+1
Now? Or am I still missing something?
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How possible with Half adder? We have an EXOR and AND gate. Can we make a NAND gate with this?
+12
Yes, we can perform any operation using Half adder:

AND operation C = AB
NOT operation = S (with A and 1) = A⊕1 = A'.1+A.1' = A'
OR operation = ((A⊕1).(B⊕1))⊕1= (A'.B')' = A+B

AND followed by NOT will give NAND operation.
+1
+3

@Arjun Sir,

Half Adder is partially functionally complete not fully functionally complete.

+1
I don't think they have used any Partially functional Complete term in Gate, So it is either complete or not complete.
+6 votes

## So, most appropiate answer should be MULTIPLEXERS i.e. (b)

### Thanks :)

answered by (451 points)
0
given the logic 0 and 1 as input , we can use half adders to compute any function
+4
Even MUX requires, 0 and 1 inputs to be functionally complete.
+1
@sushmita, Even multiplexer requires logic 0 & 1 to become functionally complete. Same is the case with half-adder. So why only multiplexer is answer?

@arjun sir, I feel answer by Rajarshi Sarkar should be the selected answer.
+1 vote
Only Mux is functionally complete.

Desired option Is only B..
answered by Boss (28.5k points)
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