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Which device converts, a decimal input number to binary
An encoder converts information from one format or code to another. An encoder can be used to encode the decimal number to binary number.
Combinational Logic circuits are circuits for which the present output depends only on the present input, i.e. there is no memory element to store the past output.
A combinational circuit can have ‘n’ number of inputs and ‘m’ number of outputs as shown:
Combinational circuits are:
Multiplexers:
32 decoder circuit can be implemented with ______.
Concept:
Decoder expansion
n1 × m1 → n2 × m2
The number of D2 decoder required is given as:
∑ K = K_{1} + K_{2} + K_{3} + 
Calculation:
One 2:4 decoder and four 3:8 decoders can represent 5:32 decoder in the following way:
Hence option (A) is the correct answer.
Which of the following circuit has its output dependent only upon the present input?
Combinational Logic circuits are circuits for which the present output depends only on the present input, i.e. there is no memory element to store the past output.
A combinational circuit can have ‘n’ number of inputs and ‘m’ number of outputs as shown:
Combinational circuits are:
In a sequential circuit, the output depends on both the present and the past values. The circuit diagram is as shown:
Examples of sequential circuits:
Construct a 16 × 1 multiplexer using 2 × 1 multiplexer. How many 2 × 1 multiplexer are required to construct?
To implement 2^{n} × 1 MUX using 2 × 1 MUX, the total number of 2 × 1 MUX required is (2^{n}  1).
∴ The number of 2 × 1 multiplexer required to implement 16 × 1 MUX will be:
n = 16  1 = 15
Or we can follow the below steps to calculate the same:
1^{st }stage = 16/2 = 8
2^{nd } stage = 8/2 = 4
3^{rd} stage = 4/2 = 2
4^{th} stage = 2/2 = 1
The sum will give the total number of MUX required to implement 16 × 1 multiplexer using 2 × 1, i.e.
n = 8 + 4 + 2 + 1 = 15
A combinational circuit is the one in which output depends on the
Combinational Logic circuits:
The Combinational Logic circuits are circuits for which the present output depends only on the present input.
There is no memory element to store the past output.
It performs an operation that can be specified logically by a set of Boolean functions.
A combinational circuit can have ‘n’ number of inputs and 'm' number of outputs as shown:
Hence, All the above statements are correct.
Sequential Circuits: The block diagram shown below explains this:
The memory elements used are flip flops or latches.
A half adder circuit is basically made up of and a AND gate with an XOR gate as shown below.
Sum (S) = A⊕B, Carry = A.B
In a half adder, the carry output is high if the inputs are:
The truth table for half adder is given below:
Therefore, the carry is given by AB.
Hence the carry output is high if the both inputs are high i.e. 1,1
In half adder, the total number of inputs and outputs are:
Concept:
A half adder circuit is basically made up of and a AND gate with XOR gate as shown below.
For the multiplexer shown below, the number of selection lines is equal to ________?
Concept:
Multiplexer:
In the given multiplexer circuit, we have 8 input lines.
∴ 2^{n} = 8
2^{n }= 2^{3}
By comparing exponents on both sides we get;
n = 3
In conclusion, the total number of select lines is (n) = 3
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