Computer System Architecture MCQ - Digital Logic Circuits - Combinational Circuits

26 The digital multiplexer is basically a combination logic circuit to perform the operation

A
AND-AND
B
OR-OR
C
AND-OR
D
OR-AND

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The equation for digital multiplexer includes AND and OR operations . For example AB+CD. So here firstly we have to solve AND operation then OR operation. Option is 'C'.

27 The output of NOR gate is

A
High if all of its inputs are high
B
Low if all of its inputs are low
C
High if all of its inputs are low
D
High if only of its inputs is low

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28 How many lines the truth table for a four-input NOR gate would contain to cover all possible input combinations ?

A
4
B
8
C
12
D
16

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29 A toggle operation cannot be performed using a single

A
NOR gate
B
AND gate
C
NAND gate
D
XOR gate

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For XOR gate complements the single input eg if input 1 is given then you get 1 in output and vice versa This is called toggling. NAND and NOR are universal gates and can be used to design XOR gate so they can also perform toggle operation. Therefore correct answer is AND gate.

30 Which table shows the electrical state of a digital circuit's output for every possible combination of electrical states in the inputs ?

A
Function table
B
Truth table
C
Routing table
D
ASCII table

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