DIGITAL LOGIC AND DESIGN MCQS
1.In which of the following base systems is 123 not a valid number?
(a) Base 10
(b) Base 16
(c)Base8
(d) Base 3
2. Storage of 1 KB means the following number of bytes
(a) 1000
(b)964
(c)1024
(d) 1064.
3. What is the octal equivalent of the binary number: 10111101
(a)675
(b)275
(c) 572
(d) 573.
4. Pick out the CORRECT statement:
(a) In a positional number system, each symbol represents the same value irrespective of its position
(b) The highest symbol in a position number system as a value equal to the number of symbols in the system
(c) It is not always possible to find the exact binary
(d) Each hexadecimal digit can be represented as a sequence of three binary symbols.
5.The binary code of (21.125)10 is
(a) 10101.001
(b) 10100.001
(c) 10101.010
(d) 10100.111.
6.A NAND gate is called a universal logic element because
(a) it is used by everybody
(b) any logic function can be realized by NAND gates alone
(c) all the minization techniques are applicable for optimum NAND gate realization
(d) many digital computers use NAND gates.
7. Digital computers are more widely used as compared to analog computers, because they are
(a) less expensive
(b) always more accurate and faster
(c) useful over wider ranges of problem types
(d) easier to maintain.
8. Most of the digital computers do not have floating point hardware because
(a) floating point hardware is costly
(b) it is slower than software
(c) it is not possible to perform floating point addition by hardware
(d) of no specific reason.
9. The number 1000 would appear just immediately after
(a) FFFF (hex)
(b) 1111 (binary)
(c) 7777 (octal)
(d) All of the above.
10. (1(10101)2 is
(a) (37)10
(b) ( 69)10
(c) (41 )10
(d) - (5)10
11. The number of Boolean functions that can be generated by n variables is equal to
(a) 2n
(b) 22 n
(c) 2n-1
(d) - 2n
12. Consider the representation of six-bit numbers by two's complement, one's complement, or by sign and magnitude: In which representation is there overflow from the addition of the integers 011000 and 011000?
(a) Two's complement only
(b) Sign and magnitude and one's complement only
(c) Two's complement and one's complement only
(d) All three representations.
13. A hexadecimal odometer displays F 52 F. The next reading will be
(a)F52E
(b)G52F
(c)F53F
(d)F53O.
14. Positive logic in a logic circuit is one in which
(a) logic 0 and 1 are represented by 0 and positive voltage respectively
(b) logic 0 and, -1 are represented by negative and positive voltages respectively
(c) logic 0 voltage level is higher than logic 1 voltage level
(d) logic 0 voltage level is lower than logic 1 voltage level.
15. Which of the following gate is a two-level logic gate
(a) OR gate
(b) NAND gate
(c) EXCLUSIVE OR gate
(d) NOT gate.
16. Among the logic families, the family which can be used at very high frequency greater than 100 MHz in a 4 bit
synchronous counter is
(a) TTLAS
(b) CMOS
(c)ECL
(d)TTLLS
17. An AND gate will function as OR if
(a) all the inputs to the gates are "1"
(b) all the inputs are ‘0'
(c) either of the inputs is "1"
(d) all the inputs and outputs are complemented.
18. An OR gate has 6 inputs. The number of input words in its truth table are
(a)6
(b)32
(c) 64
(d) 128
19. A debouncing circuit is
(a) an astable MV
(b) a bistable MV
(c) a latch
(d) a monostable MV.
20. NAND. gates are preferred over others because these
(a) have lower fabrication area
(b) can be used to make any gate
(c) consume least electronic power
(d) provide maximum density in a chip.
21. In case of OR gate, no matter what the number of inputs, a
(a) 1 at any input causes the output to be at logic 1
(b) 1 at any input causes the output to be at logic 0
(c) 0 any input causes the output to be at logic 0
(d) 0 at any input causes the output to be at logic 1.
22. The fan put of a 7400 NAND gate is
(a)2TTL
(b)5TTL
(c)8TTL
(d)10TTL
23. Excess-3 code is known as
(a) Weighted code
(b) Cyclic redundancy code
(c) Self-complementing code
(d) Algebraic code.
24. Assuming 8 bits for data, 1 bit for parity, I start bit and 2 stop bits, the number of characters that 1200 BPS communication line can transmit is
(a)10 CPS
(b)120 CPS
(c) 12CPS
(d) None of the above.
25. Indicate which of the following three binary additions are correct?
I.1011 + 1010 = 10101
II. 1010 + 1101 = 10111
III. 1010 + 1101 = 11111
(a) I and II
(b) II and III
(c) III only
(d) II and I
26.The number of digits in octal system is
a.8
b.7
c.10
d. none
27.The number of digits in Hexadecimal system is
a.15
b.17
c.16
d. 8
28.The number of bits in a nibble is
a.16
b.5
c.4
d.8
29.The digit F in Hexadecimal system is equivalent to -- in decimal system
a.16
b.15
c.17
d. 8
30.Which of the following binary numbers is equivalent to decimal 10
a.1000
b.1100
c.1010
d.1001
31.The number FF in Hexadecimal system is equivalent to -- in decimal system
a.256
b.255
c.240
d.239
32. IC s are
a. analog
b. digital
c. both analog and digital
d. mostly analog
33.The rate of change of digital signals between High and Low Level is
a. very fast
b. fast
c. slow
d. very slow
34. Digital circuits mostly use
a. Diodes
b. Bipolar transistors
c. Diode and Bipolar transistors
d. Bipolar transistors and FETs
35.Logic pulser
a. generates short duration pulses
b. generate long duration pulses
c. generates long and short duration
d. none of above
36.What is the output state of an OR gate if the inputs are 0 and 1?
a.0
b.1
c.3
d.2
37.What is the output state of an AND gate if the inputs are 0 and 1?
a.0
b.1
c.3
d.2
38.A NOT gate has...
a. Two inputs and one output
b. One input and one output
c. One input and two outputs
d. none of above
39. An OR gate has...
a. Two inputs and one output
b. One input and one output
c. One input and two outputs
d. none of above
40.The output of a logic gate can be one of two _____?
a. Inputs
b. Gates
c.States
d. none
41.Logic states can only be ___ or 0.
a. 3
b. 2
c.1
d.0
42.The output of a ____ gate is only 1 when all of its inputs are 1
a. NOR
b. XOR
c. AND
d. NOT
43.A NAND gate is equivalent to an AND gate plus a .... gate put together.
a. NOR
b. NOT
c. XOR
d. none
44.Half adder circuit is ______?
a. Half of an AND gate
b. A circuit to add two bits together
c. Half of a NAND gate
d. none of above
45. Numbers are stored and transmitted inside a computer in
a. binary form
b. ASCII code form
c. decimal form
d. alphanumeric form
46.The decimal number 127 may be represented by
a. 1111 1111B
b. 1000 0000B
c. EEH
d. 0111 1111
47. A byte corresponds to
a. 4 bits
b. 8 bits
c. 16 bits
d. 32 bits
48.A gigabyte represents
a.1 billion bytes
b. 1000 kilobytes
c. 230 bytes
d. 1024 bytes
49. A megabyte represents
a. 1 million bytes
b. 1000 kilobytes
c. 220 bytes
d. 1024 bytes
50. A Kb corresponds to
a. 1024 bits
b. 1000 bytes
c.210 bytes
d. 210 bits.