Online Digital Electronics Test - Digital Electronics Test - Random

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Total number of questions: 20.
Time allotted: 30 minutes.
Each question carries 1 mark; there are no negative marks.
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In a negative logic system, the area represented by #3 in the given figure would be the ________ level.

HIGH

LOW

off

uncertain

[#]

The binary number 101110101111010 can be written in octal as ________.

51562₈

56577₈

65627₈

56572₈

[#]

15₁₀ = 1111₂ = F₁₆ = 00010101 BCD

True

False

[#]

If a 3-input OR gate has eight input possibilities, how many of those possibilities will result in a HIGH output?

[#]

How many AND gates are required to implement the Boolean expression,

[#]

One characteristic of a ring counter is that the modulus is equal to the number of flip-flops in the register and, consequently, there are never any unused or invalid states.

True

False

[#]

A(n) ________ one-shot starts a pulse in response to a trigger and will restart the internal pulse timer every time a subsequent trigger edge occurs before the pulse is complete.

non-retriggerable

retriggerable

high-level triggered

edge-triggered

[#]

To keep output data accurate, 4-bit series-in, parallel-out shift registers employ a ________.

divide-by-4 clock pulse

sequence generator

strobe line

multiplexer

[#]

What is the significance of the inverted triangles on the outputs of the device in the given figure?

They represent inverters and mean that the outputs are active-LOW.

They represent buffers and mean that the outputs can drive 40 TTL loads, instead of the normal 10.

It means that the outputs will be active only if a change has occurred at that memory location since the last read/write cycle.

The outputs are tristated.

[#]

10.

GAL is an acronym for ________.

Generic Array Logic

General Array Logic

Giant Array Logic

Generic Analysis Logic

[#]

11.

The complex programmable logic device (CPLD) contains several PAL-type simple programmable logic devices (SPLDs) called:

macrocells

microcells

AND/OR arrays

fuse-link arrays

[#]

12.

In a binary-weighted-input digital-to-analog converter, the values of the input resistors are chosen to be proportional to the binary weights of the corresponding input bits.

True

False

[#]

13.

Power dissipation is a measure of a circuit's noise immunity.

True

False

[#]

14.

For a three-input NOR gate, with the input waveforms as shown below, which output waveform is correct?

[#]

15.

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

[#]

16.

An octal-to-binary encoder has eight data inputs and encodes an output of ________ bits.

two

three

four

five

[#]

17.

What does the ring counter in the HDL keypad application do when a key is pressed?

Count to find the row

Freeze

Count to find the column

Start the D flip-flop

[#]

18.

Why is an exclusive-NOR gate also called an equality gate?

The output is false if the inputs are equal.

The output is true if the inputs are opposite.

The output is true if the inputs are equal.

[#]

19.

For the following conditions on a 7485 magnitude comparator, what will be the state of each of the three outputs?

A₀ = 0	B₀ = 1	I_A < B = 0
A₁ = 1	B₁ = 0	I_A = B = 1
A₂ = 1	B₂ = 0	I_A > B = 0
A₃ = 0	B₃ = 0

A = B = 0, A < B = 0, A > B = 1

A = B = 0, A < B = 1, A > B = 0

A = B = 1, A < B = 0, A > B = 0

A = B = 0, A < B = 0, A > B = 0

[#]

20.

The rise time (t_r) is the time it takes for a pulse to rise from its ________ point up to its ________ point. The fall time (t_f) is the length of time it takes to fall from the ________ to the ________ point.

10%, 90%, 90%, 10%

90%, 10%, 10%, 90%

20%, 80%, 80%, 20%

10%, 70.7%, 70.7%, 10%

[#]

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Online Digital Electronics Test - Digital Electronics Test - Random

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