Digital Principles And System Design Set 5

Computer Science Engineering (CSE)

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This set of Digital Principles and System Design Multiple Choice Questions & Answers (MCQs) focuses on Digital Principles And System Design Set 5

Q1 | The full subtractor can be implemented using
  • two xor and an or gates
  • two half subtractors and an or gate
  • two multiplexers and an and gate
  • two comparators and an and gate
Answer: two half subtractors and an or gate
Explaination:
a full subtractor has 3 input bits and two outputs bits borrow and difference. the full subtractor can be implemented using two half subtractors and an or gate.
Q2 | The output of a subtractor is given by (if A, B and X are the inputs).
  • a and b xor x
  • a xor b xor x
  • a or b nor x
  • a nor b xor x
Answer: a xor b xor x
Explaination:
the difference output of a subtractor is given by (if a, b and x are the inputs) a xor b xor x.
Q3 | The decimal number system represents the decimal number in the form of                          
  • hexadecimal
  • binary coded
  • octal
  • decimal
Answer: binary coded
Explaination:
binary-coded decimal (bcd) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. hexadecimal and octal are number systems having base 16 and 8 respectively.
Q4 | 29 input circuit will have total of                          
  • 32 entries
  • 128 entries
  • 256 entries
  • 512 entries
Answer: 512 entries
Explaination:
29 input circuit would have 512(2*2*2*2*2*2*2*2*2 = 512) entries.
Q5 | BCD adder can be constructed with 3 IC packages each of                          
  • 2 bits
  • 3 bits
  • 4 bits
  • 5 bits
Answer: 4 bits
Explaination:
binary-coded decimal (bcd) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. bcd adder can be constructed with 3 ic packages. each of 4-bit adders is an msi(medium scale integration) function and 3 gates for the correction logic need one ssi (small scale integration) package.
Q6 | The output sum of two decimal digits can be represented in                          
  • gray code
  • excess-3
  • bcd
  • hexadecimal
Answer: bcd
Explaination:
the output sum of two decimal digits can be represented in bcd(binary-coded decimal). binary-coded decimal (bcd) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight.
Q7 | The addition of two decimal digits in BCD can be done through                          
  • bcd adder
  • full adder
  • ripple carry adder
  • carry look ahead
Answer: bcd adder
Explaination:
the addition of two decimal digits in bcd can be done through bcd adder. every input inserted, in addition by the user converted into binary and then proceed for the addition. whereas, full adder, ripple carry adder and carry look adder are for the addition of binary bits.
Q8 | 3 bits full adder contains                          
  • 3 combinational inputs
  • 4 combinational inputs
  • 6 combinational inputs
  • 8 combinational inputs
Answer: 8 combinational inputs
Explaination:
3 bits full adder contains 23 = 8 combinational inputs.
Q9 | The simplified expression of full adder carry is
  • c = xy+xz+yz
  • c = xy+xz
  • c = xy+yz
  • c = x+y+z
Answer: c = xy+xz+yz
Explaination:
a full adder is a combinational circuit having 3 inputs and 2 outputs, namely sum and carry. the simplified expression of full adder carry is c = xy+xz+yz.
Q10 | Decimal digit in BCD can be represented by
  • 1 input line
  • 2 input lines
  • 3 input lines
  • 4 input lines
Answer: 4 input lines
Explaination:
binary-coded decimal (bcd) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. decimal digit in bcd can be represented by 4 input lines. since it is constructed with 4-bits.
Q11 | The number of logic gates and the way of their interconnections can be classified as                          
  • logical network
  • system network
  • circuit network
  • gate network
Answer: logical network
Explaination:
the number of different levels of logic gates is represented in a fashion which is known as a logical network.
Q12 | The addition 1+1 gives 0 as a result.
  • true
  • false
Answer: true
Explaination:
the two result obtained is 0 with a carry of 1. this carry is transferred to the next higher column.
Q13 | The result of 0*1 in binary is                          
  • 0
  • 1
  • invalid
  • 10
Answer: 0
Explaination:
the binary multiplication of any number with 0 will give the result 0 itself. any binary number when multiplied by 0 gives 0 only.
Q14 | The multiplication of 110 * 111 is performed. What is a general term used for 111?
  • dividend
  • quotient
  • multiplicand
  • multiplier
Answer: multiplier
Explaination:
111 is called the multiplier.
Q15 | What do you call the intermediate terms in binary multiplication?
  • multipliers
  • mid terms
  • partial products
  • multiplicands
Answer: partial products
Explaination:
the intermediate terms are called partial terms. the mid terms obtained in the binary multiplications are the partial ones whereas the answer obtained is called the final product.
Q16 | The result that is smaller than the smallest number obtained is referred to as                        
  • nan
  • underflow
  • smallest
  • mantissa
Answer: underflow
Explaination:
it is referred to as underflow. nan stands for not a number. mantissa is the part after the decimal.
Q17 | The number of sign bits in a 32-bit IEEE format is
  • 1
  • 11
  • 9
  • 23
Answer: 1
Explaination:
there is only 1 sign bit in all the standards. in a 32-bit format, there is 1 sign bit, 8 bits for the exponent and 23 bits for the mantissa.
Q18 | Express the decimal format of the signed binary number (101010)2 .
  • 10
  • 12
  • -12
  • -10
Answer: -10
Explaination:
the first bit is the sign bit whereas the
Q19 | All the comparisons made by comparator is done using                          
  • 1 circuit
  • 2 circuits
  • 3 circuits
  • 4 circuits
Answer: 1 circuit
Explaination:
a comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. because, all the input is compared to each other, therefore it is possible only by using 1 circuit.
Q20 | One that is not the outcome of magnitude comparator is                          
  • a > b
  • a – b
  • a < b
  • a = b
Answer: a – b
Explaination:
a comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. in a digital comparator, only 3 outputs are possible (i.e. a = b, a > b, a < b). so, a – b is incorrect option.
Q21 | If two numbers are not equal then binary variable will be                          
  • 0
  • 1
  • a
  • b
Answer: 0
Explaination:
a comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. in a digital comparator, only 3 outputs are possible (i.e. a = b, a >b, a < b). other than this, the output will be 0.
Q22 | How many inputs are required for a digital comparator?
  • 1
  • 2
  • 3
  • 4
Answer: 1
Explaination:
a comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. thus, there are two inputs required for a digital comparator (i.e. a & b).
Q23 | In a comparator, if we get input as A>B then the output will be                          
  • 1
  • 0
  • a
  • b
Answer: 1
Explaination:
a comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. if a > b, it means that it satisfies one of the condition among three. hence the output will be 1.
Q24 | Which one is a basic comparator?
  • xor
  • xnor
  • and
  • nand
Answer: xor
Explaination:
generally, an xnor outputs high for even number of 1s or all 0s and outputs low for otherwise. thus, an xnor gate is a basic comparator, because its output is “1” only if its two input bits are equal.
Q25 | Comparators are used in                          
  • memory
  • cpu
  • motherboard
  • hard drive
Answer: cpu
Explaination:
comparators are used in central processing unit (cpus). because all the arithmetic and logical operations are performed in the alu(arithmetic logic unit) part of the cpu.
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