Digital Electronics Set 7 MCQs

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