DIGITAL ELECTRONICS MCQS PART 05

DIGITAL ELECTRONICS MCQS PART 05

1.How many select lines will a 16 to 1 multiplexer will have
(A) 4    
(B) 3
(C) 5    
(D) 1
Ans: A Explanation: In 16 to 1 MUX  four select lines will be required to select 16 ( 24 ) inputs.

2. How many address bits are required to represent 4K memory
(A) 5 bits.     
(B) 12 bits.        
(C) 8 bits.    
(D) 10 bits.
Ans: B Explanation: For representing 4K memory, 12 address bits are required as
    4K = 22  x 210  = 212     (1K = 1024 = 210)

3. For JK flipflop J = 0, K=1, the output after clock pulse will be
(A) 1.    
(B) no change.   
(C) 0.    
(D) high impedance.
Ans: C
Explanation: J=0, K=1, these inputs will reset the flip-flop after the clock pulse. So whatever be the previous output, the next state will be 0.

4. Which of following are known as universal gates
(A)NAND & NOR.    
(B)  AND & OR.   
(C)  XOR & OR.    
(D) None.
Ans: A
Explanation: NAND & NOR are known as universal gates, because any digital circuit can be realized completely by using either of these two gates.

5. Which of the following memories stores the most number of bits
(A)64K × 8 memory.    
(B) 1M × 8 memory.
(C) 32M × 8 memory.    
(D) 64 × 6 memory.
 Ans: C
Explanation: 32M x 8 stores most number of bits
25 x 220   = 225     (1M = 220 = 1K x 1K = 210 x 210)

6. How many flip flops are required to construct a decade counter
(A) 10    
(B) 3
(C) 4    
(D) 2
Ans: C Explanation: Decade counter counts 10 states from 0 to 9 ( i.e. from 0000 to 1001 ) Thus four FlipFlop's are required.

7. Which TTL logic gate is used for wired ANDing
(A)Open collector output    
(B)  Totem Pole
(C)  Tri state output    
(D)  ECL gates
Ans: A
Explanation: Open collector output.

8. CMOS circuits consume power    
(A) Equal to TTL    
(B) Less than TTL
(C) Twice of TTL    
(D) Thrice of TTL
Ans: B
Explanation: As in CMOS one device is ON & one is Always OFF so power consumption is low.

9. In a RAM, information can be stored
(A) By the user, number of times.
(B) By the user, only once.
(C) By the manufacturer, a number of times.
(D) By the manufacturer only once.
Ans: A
Explanation: RAM is used by the user, number of times.

10. The chief reason why digital computers use complemented subtraction is that it
(A)Simplifies the circuitry.
(B) Is a very simple process.
(C) Can handle negative numbers easily.
(D)Avoids direct subtraction.
Ans: C