# Education In Pakistan

## VU CS302- Digital Logic Design MIDTERM EXAMINATION Spring 2010

.

MIDTERM EXAMINATION

Spring 2010

CS302- Digital Logic Design

Time: 60 min

Marks: 38

Question No: 1 ( Marks: 1 ) – Please choose one

A SOP expression is equal to 1 ______________

► All the variables in domain of expression are present

► At least one variable in domain of expression is present.

► When one or more product terms in the expression are equal to 0.

► When one or more product terms in the expression are equal to 1.

Question No: 2 ( Marks: 1 ) – Please choose one

The output A < B is set to 1 when the input combinations is __________

► A=10, B=01

► A=11, B=01

► A=01, B=01

► A=01, B=10

Question No: 3 ( Marks: 1 ) – Please choose one

Two 2-bit comparator circuits can be connected to form single 4-bit comparator

► True

► False

Question No: 4 ( Marks: 1 ) – Please choose one

High level Noise Margins (VNH) of CMOS 5 volt series circuits is _____________

► 0.3 V

► 0.5 V

► 0.9 V

► 3.3 V

Question No: 5 ( Marks: 1 ) – Please choose one

If we multiply “723” and “34” by representing them in floating point notation i.e. by

first, converting them in floating point representation and then multiplying them, the

value of mantissa of result will be ________

.

► 24.582

► 2.4582

► 24582

► 0.24582

Question No: 6 ( Marks: 1 ) – Please choose one

The output of the expression F=A+B+C will be Logic ________ when A=0, B=1, C=1.

the symbol’+’ here represents OR Gate.

► Undefined

► One

► Zero

► 10 (binary)

Question No: 7 ( Marks: 1 ) – Please choose one

If an active-HIGH S-R latch has a 0 on the S input and a 1 on the R input and then the R input

goes to 0, the latch will be ________.

► SET

► RESET

► Clear

► Invalid

Question No: 8 ( Marks: 1 ) – Please choose one

3.3 v CMOS series is characterized by __________ and _________as compared to the 5 v CMOS

series.

► Low switching speeds, high power dissipation

► Fast switching speeds, high power dissipation

► Fast switching speeds, very low power dissipation

► Low switching speeds, very low power dissipation

Question No: 9 ( Marks: 1 ) – Please choose one

The binary value “1010110” is equivalent to decimal __________

► 86

► 87

► 88

► 89

Question No: 10 ( Marks: 1 ) – Please choose one

The _______ Encoder is used as a keypad encoder.

.

► 2-to-8 encoder

► 4-to-16 encoder

► BCD-to-Decimal

► Decimal-to-BCD Priority

Question No: 11 ( Marks: 1 ) – Please choose one

How many data select lines are required for selecting eight inputs?

► 1

► 2

► 3

► 4

Question No: 12 ( Marks: 1 ) – Please choose one

the diagram above shows the general implementation of ________ form

► boolean

► arbitrary

► POS

► SOP

Question No: 13 ( Marks: 1 ) – Please choose one

The Quad Multiplexer has _____ outputs

► 4

► 8

► 12

► 16

Question No: 14 ( Marks: 1 ) – Please choose one

Demultiplexer has

► Single input and single outputs.

► Multiple inputs and multiple outputs.

► Single input and multiple outputs.

► Multiple inputs and single output.

Question No: 15 ( Marks: 1 ) – Please choose one

The expression _________ is an example of Commutative Law for Multiplication.

.

► AB+C = A+BC

► A(B+C) = B(A+C)

► AB=BA

► A+B=B+A

Question No: 16 ( Marks: 1 ) – Please choose one

“Sum-of-Weights” method is used __________

► to convert from one number system to other

► to encode data

► to decode data

► to convert from serial to parralel data

Question No: 17 ( Marks: 2 )

Why a 2-bit comparator is called parallel comparator?

Question No: 18 ( Marks: 2 )

Explain at least two advantages of the circuit having low power consumption

Question No: 19 ( Marks: 2 )

Name the four OLMC configurations

Question No: 20 ( Marks: 3 )

Explain “Test Vector” in context of ABEL

Question No: 21 ( Marks: 3 )

For a two bit comparator circuit specify the inputs for which the output A < B is set to 1

Question No: 22 ( Marks: 5 )

Explain Tri-State Buffers with the help of block diagram

Question No: 23 ( Marks: 5 )

Explain the Operation of Odd-Parity Generator Circuit with the help of timing diagram