MCQs on Digital Electronics


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01․ Which of these circuits will give yield carry with more delay 1. Carry look ahead adder 2. Ripple carry adder
1.
2.
both are same
none

Carry look ahead adder has the concept of propagating and generating carries.

02․ Which GATE IS CALLED INEQUALITY COMPARATOR?
1. NOR
2. AND
3. XOR
4. NOT

XOR i.e. Exclusive OR gate is called inequality comparator.

03․ Fastest memory element is
RAM
ROM
Cache
Hard Drive


04․ Slowest memory element is
RAM
ROM
Cache
Hard Drive

According to computer memory hierarchy hard drive is the slowest and large size capacity memory.

05․ Which of these sets of logic gates are designated as universal gates?
NOR, NAND.
XOR, NOR, NAND.
OR, NOT, AND.
NOR, NAND, XNOR.

Using any one of these 2 gates - NAND, NOR we can design all logic gates.

06․ In the toggle mode a JK flip-flop has
J = 0, K = 0.
J = 1, K = 1.
J = 0, K = 1.
J = 1, K = 0.

J = 0, K = 0 → no change condition between pre-state and next state. J = 0, K = 1 → it is always reset condition means next state is always 0. J = 1, K = 0 → it is always set condition means next state is always 1. J = 1, K = 1 → it is toggle condition means when pre-state is 1 then next state is 0 or when pre-state is 0 then next state is 1.

07․ The resolution of a 12 bit analog to digital converter in percent in
0.01220.
0.02441.
0.04882.
0.09760.

The resolution of a 12 bit analog to digital converter ADC is 2.44mV or in percent it is 0.02441.

08․ What will be Excess - 3 code for decimal ( 584 )?
(0111 0100 1000).
(1000 1011 0111).
(1011 0111 1000).
(1000 0111 1110).

5 8 4 + 3 3 3 = 8 11 7. Then 8 is a decimal no. So it is converted to binary when result is 1000, 11 convert to binary 1011, 7 convert to binary-0111. So result is (1000 1011 0111).

09․ The number of comparators in a parallel conversion type 8-bit analog to digital converter is
8.
16.
255.
256.

Number of comparators = ( 2N - 1 ) = ( 212 - 1 ) = 255 ( N = no. of bits ).

10․ Excess 3 code is known as
weighted code.
redundancy code.
self complementing code.
algebraic code.

Complement of Excess 3 code is 9s complement of that digit in excess 3. So excess 3 code is also called self complementing code.

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