# Online Electronics and Communication Engineering Test - Digital Electronics Test 3 Loading Test...

Instruction:

• This is a FREE online test. DO NOT pay money to anyone to attend this test.
• Total number of questions : 20.
• Time alloted : 30 minutes.
• Each question carry 1 mark, no negative marks.
• DO NOT refresh the page.
• All the best :-).

1.

DeMorgan's first theorem shows the equivalence of

A.
 OR gate and Exclusive OR gate B.
 NOR gate and Bubbled AND gate C.
 NOR gate and NAND gate D.
 NAND gate and NOT gate Explanation:

First theorem A + B = A . B.

2.

In the given figure, the flip flop is A.
 negative edge triggered B.
 positive edge triggered C.
 level triggered D.
 either (a) or (c) Explanation:

The small circle indicates negative and small triangle indicates edge triggering.

3.

In a 4 input OR gate, the total number of High outputs for the 16 input states are

A.
 16 B.
 15 C.
 14 D.
 13 Explanation:

OR gate gives high output when one or more inputs are high.

4.

What will be output for decimal input 82?

A.
 0.82 V B.
 8 V C.
 0.1 V D.
 10 mV Explanation:

Output for decimal input 82/(10000010) = 0.01 x 82 = 0.82 V.

5.

The resolution of 4 bit counting ADC is 0.5 volt, for an Analog input of 6.6 volts. The digital output of ADC will be

A.
 1011 B.
 1101 C.
 1100 D.
 1110 Explanation:

Digital output of ADC resolution = .

6.

The circuit in the figure is has two CMOS-NOR gates. This circuit functions as a A.
 flip-flop B.
 schmitt trigger C.
 monostable multivibrator D.
 astable multivibrator Explanation:

It is simple monostable multivibrator.

7.

ALU carries out

A.
 arithmetic operations B.
 logic operations C.
 both arithmetic and logic operations D.
 none of the above 8.

The Boolean function A + BC is a reduced form of

A.
 AB + BC B.
 (A + B) . (A + C) C.
 AB + ABC D.
 (A + C) . B 9.

Which of the following pairs of octal and binary numbers are not equal?

A.
 111 110112 = 7678 B.
 1101101012 = 6658 C.
 110102 = 38 D.
 10101.112 = 25.68 10.

Fastest memory cell

A.
 bubble memory B.
 core memory C.
 semiconductor memory D.
 superconductor memory 11.

A mod-2 counter followed by a mod 5 is same as

A.
 mod-7 counter B.
 A decade counter C.
 mod-3 counter D.
 none 12.

The values of 25 in octal system is

A.
 40 B.
 20 C.
 400 D.
 200 13.

In a four variable K map eight adjacent cells give

A.
 single variable term B.
 two variable term C.
 three variable term D.
 four variable term 14.

A Charge Couple Device (CCD) is a

A.
 RAM B.
 sequential accessed memory C.
 content addressable memory D.
 read only memory 15.

A(A + B) =

A.
 A B.
 A B C.
 AB D.
 AB 16.

The 54/74164 chip is an 8-bit serial-input-parallel-output shift register. The clock is 1 MHz. The time needed to shift a 8-bit binary number into the chip is

A.
 1 μs B.
 2 μs C.
 8 μs D.
 16 μs 17.

Which device uses Pneumatic fluid?

A.
 LED B.
 LCD C.
 VF display D.
 None of these 18.

In a clocked NAND latch, race condition occur when

A.
 R and S are high CLK is low B.
 R and CLK are high and S is low C.
 R, S, CLK are high D.
 R, S, CLK are low 19.

The microprograms provided by a manufacturer to be used on his microprogrammed computer are generally called

A.
 software B.
 network C.
 firmware D.
 hardware 20.

A microcomputer has memory locations from 0000 to FFFF, each storing 1 byte. How many bytes can be the memory store?

A.
 12333 B.
 14666 C.
 16384 D.
 16655 