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This set of Digital Electronics Multiple Choice Questions & Answers (MCQs) focuses on Digital Electronics Set 7

Q1 | Full subtractor is used to perform subtraction of                        
  • 2 bits
  • 3 bits
  • 4 bits
  • 8 bits
Q2 | The output of a full subtractor is same as
  • half adder
  • full adder
  • half subtractor
  • decoder
Q3 | 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
Q4 | Why XOR gate is called an inverter?
  • because of the same input
  • because of the same output
  • it behaves like a not gate
  • it behaves like a and gate
Q5 | Controlled buffers can be useful
  • to control the circuit’s output into the bus
  • in comparison of component’s output with its input
  • in increasing the output from its low input
  • all of the mentioned
Q6 | A logic circuit that provides a HIGH output for both inputs HIGH or both inputs LOW is
  • ex-nor gate
  • or gate
  • ex-or gate
  • nand gate
Q7 | What is the first thing you will need if you are going to use a macro-function?
  • a complicated design project
  • an experienced design engineer
  • good documentation
  • experience in hdl
Q8 | What is the major difference between half- adders and full-adders?
  • full-adders are made up of two half-adders
  • full adders can handle double-digit numbers
  • full adders have a carry input capability
  • half adders can handle only single-digit numbers
Q9 | The binary subtraction of 0 – 0 = ?
  • difference = 0, borrow = 0
  • difference = 1, borrow = 0
  • difference = 1, borrow = 1
  • difference = 0, borrow = 1
Q10 | How many basic binary subtraction operations are possible?
  • 1
  • 4
  • 3
  • 2
Q11 | When performing subtraction by addition in the 2’s-complement system                          
  • the minuend and the subtrahend are both changed to the 2’s-complement
  • the minuend is changed to 2’s- complement and the subtrahend is left in its original form
  • the minuend is left in its original form and the subtrahend is changed to its 2’s- complement
  • the minuend and subtrahend are both left in their original form
Q12 | What are the two types of basic adder circuits?
  • sum and carry
  • half-adder and full-adder
  • asynchronous and synchronous
  • one and two’s-complement
Q13 | Which of the following is correct for full adders?
  • full adders have the capability of directly adding decimal numbers
  • full adders are used to make half adders
  • full adders are limited to two inputs since there are only two binary digits
  • in a parallel full adder, the first stage may be a half adder
Q14 | The selector inputs to an arithmetic/logic unit (ALU) determine the                          
  • selection of the ic
  • arithmetic or logic function
  • data word selection
  • clock frequency to be used
Q15 | The inverter can be produced with how many NAND gates?
  • 2
  • 1
  • 3
  • 4
Q16 | What are carry generate combinations?
  • if all the input are same then a carry is generated
  • if all of the output are independent of the inputs
  • if all of the input are dependent on the output
  • if all of the output are dependent on the input
Q17 | How many shift registers are used in a 4 bit serial adder?
  • 4
  • 3
  • 2
  • 5
Q18 | A D flip-flop is used in a 4-bit serial adder, why?
  • it is used to invert the input of the full adder
  • it is used to store the output of the full adder
  • it is used to store the carry output of the full adder
  • it is used to store the sum output of the full adder
Q19 | What is ripple carry adder?
  • the carry output of the lower order stage is connected to the carry input of the next higher order stage
  • the carry input of the lower order stage is connected to the carry output of the next higher order stage
  • the carry output of the higher order stage is connected to the carry input of the next lower order stage
  • the carry input of the higher order stage is connected to the carry output of the lower order stage
Q20 | If minuend = 0, subtrahend = 1 and borrow input = 1 in a full subtractor then the borrow output will be                      
  • 0
  • 1
  • floating
  • high impedance
Q21 | The decimal number system represents the decimal number in the form of                          
  • hexadecimal
  • binary coded
  • octal
  • decimal
Q22 | 29 input circuit will have total of
  • 32 entries
  • 128 entries
  • 256 entries
  • 512 entries
Q23 | BCD adder can be constructed with 3 IC packages each of                          
  • 2 bits
  • 3 bits
  • 4 bits
  • 5 bits
Q24 | The output sum of two decimal digits can be represented in                          
  • gray code
  • excess-3
  • bcd
  • hexadecimal
Q25 | The addition of two decimal digits in BCD can be done through                          
  • bcd adder
  • full adder
  • ripple carry adder
  • carry look ahead