FINALTERM EXAMINATION
Fall 2009
CS302- Digital
Logic Design (Session - 1)
Question No: 1 ( Marks: 1 ) - Please choose one
The output of an AND gate is one when _______
►
All of the inputs are one
► Any of the input is one
► Any of the input is zero
► All the inputs are zero
Question No: 2 ( Marks: 1 ) -
Please choose one
The OR Gate performs a Boolean _______ function
►
Addition
► Subtraction
► Multiplication
► Division
Question No: 3 ( Marks: 1 ) - Please choose one
A Karnaugh map is similar to a truth table because it
presents all the possible values of input variables and the resulting output of
each value.
► True
► False
Question No: 4 ( Marks: 1 ) - Please choose one
The binary numbers A = 1100 and B = 1001 are applied to the
inputs of a comparator. What are the output levels?
► A > B = 1, 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 = 1, A = B = 1
Question No: 5 ( Marks: 1 ) - Please choose one
The diagram above shows the
general implementation of _____ form
► boolean
► arbitrary
►
POS
►
SOP
Question No: 6 ( Marks: 1 ) - Please choose one
The device shown here is most likely a 
► Comparator
►
Multiplexer
► Demultiplexer
► Parity generator
Question No: 7 ( Marks: 1 ) - Please choose one
Demultiplexer converts _______ data to __________ data
► Parallel data, serial data
► Serial data,
parallel data
► Encoded data, decoded data
► All of the
given options.
Question No: 8 ( Marks: 1 ) - Please choose one
Flip flops are also called _____________
► Bi-stable dualvibrators
► Bi-stable transformer
►
Bi-stable
multivibrators
► Bi-stable singlevibrators
Question No: 9 ( Marks: 1 ) - Please choose one
If
S=1 and R=0, then Q(t+1) = _________ for
positive edge triggered flip-flop
► 0
► 1
► Invalid
► Input is invalid
Question No: 10 ( Marks: 1 ) - Please choose one
If
S=1 and R=1, then Q(t+1) = _________ for
negative edge triggered flip-flop
► 0
► 1
►
Invalid
► Input is invalid
Question No: 11 ( Marks: 1 ) - Please choose one
The operation of J-K flip-flop is similar to that of the SR
flip-flop except that the J-K flip-flop ___________
► Doesn’t have an
invalid state
► Sets to clear when both J = 0 and K = 0
► It does not show transition on change in pulse
► It does not accept asynchronous inputs
Question No: 12 ( Marks: 1 ) - Please choose one
The minimum time for which the input signal has to be
maintained at the input of flip-flop is called ______ of the flip-flop.
► Set-up
time
►
Hold time
► Pulse Interval time
► Pulse Stability time (PST)
Question No: 13 ( Marks: 1 ) - Please choose one
We have a digital circuit. Different parts of circuit operate
at different clock frequencies (4MHZ, 2MHZ and 1MHZ), but we have a single
clock source having a fix clock frequency (4MHZ), we can get help by
___________
► Using S-R Flop-Flop
►
D-flipflop
► J-K flip-flop
► T-Flip-Flop
Question No: 14 ( Marks: 1 ) - Please choose one
In asynchronous digital systems all the circuits change their
state with respect to a common clock
► True
► False
Question No: 15 ( Marks: 1 ) - Please choose one
A positive edge-triggered flip-flop changes its state
when ________________
► Low-to-high transition of clock
► High-to-low transition of clock
► Enable input (EN) is set
► Preset input (PRE) is set
Question No: 16 ( Marks: 1 ) - Please choose one
A negative edge-triggered flip-flop changes its state when
________________
► Enable input (EN) is set
► Preset input (PRE) is set
► Low-to-high transition of clock
►
High-to-low transition of clock
Question No: 17 ( Marks: 1 ) - Please choose one
A flip-flop is connected to +5 volts and it draws 5 mA of
current during its operation, the power dissipation of the flip-flop is
► 10 mW
► 25 mW
► 64 mW
► 1024
Question No: 18 ( Marks: 1 ) - Please choose one
__________occurs when the same clock signal arrives at
different times at different clock inputs due to propagation delay.
► Race condition
► Clock
Skew
► Ripple Effect
► None of given options
Question No: 19 ( Marks: 1 ) - Please choose one
A counter is implemented using three (3) flip-flops, possibly
it will have ________ maximum output status.
► 3
► 7
►
8
► 15
Question No: 20 ( Marks: 1 ) - Please choose one
A
divide-by-50 counter divides the input ______ signal to a 1 Hz signal.
► 10 Hz
► 50 Hz
► 100 Hz
► 500 Hz
Question No: 21 ( Marks: 1 ) - Please choose one
The design and implementation of synchronous counters start
from _________
► Truth table
► k-map
► state table
►
state
diagram
Question No: 22 ( Marks: 1 ) - Please choose one
A synchronous decade counter will have _______ flip-flops
► 3
► 4
► 7
► 10
Question No: 23 ( Marks: 1 ) - Please choose one
The output of this circuit is always ________.
► 1
► 0
► A
► 
Question No: 24 ( Marks: 1 ) - Please choose one
At T0 the value stored in a
4-bit left shift was “1”. What will be the value of register after three clock
pulses?
► 2
► 4
► 6
► 8
Question No: 25 ( Marks: 1 ) - Please choose one
In _______ the 
output of the last flip-flop of
the shift register is connected to the data input of the first flip-flop.
► Moore machine
► Meally machine
► Johnson counter
► Ring counter
Question No: 26 ( Marks: 1 ) - Please choose one
In ________ Q output of the last flip-flop of
the shift register is connected to the data input of the first flip-flop of the
shift register.
► Moore
machine
► Meally
machine
► Johnson
counter
► Ring counter
Question No: 27 ( Marks: 1 ) - Please choose one
Which
is not characteristic of a shift register?
► Serial in/parallel in
► Serial
in/parallel out
► Parallel
in/serial out
► Parallel
in/parallel out
Question No: 28 ( Marks: 1 ) - Please choose one
Assume
that a 4-bit serial in/serial out shift register is initially clear. We wish to
store the nibble 1100. What will be the 4-bit pattern after the second clock
pulse? (Right-most bit first.)
► 1100
► 0011
► 0000
► 1111
Question No: 29 ( Marks: 1 ) - Please choose one
The _________ of a ROM is the time it takes for the data to
appear at the Data
Output of the ROM chip after an address is applied at
the address input lines
► Write
Time
► Recycle Time
► Refresh
Time
► Access Time
Question No: 30 ( Marks: 1 ) - Please choose one
The sequence of states that are implemented by
a n-bit Johnson counter is
► n+2
(n plus 2)
► 2n (n multiplied by 2)
► 2n (2 raise to power n)
► n2 (n raise to power 2)
Question No: 31 ( Marks: 1 )
In the statement
"X PIN 22 ISTYPE ‘reg.buffer"
What is the meaning of the keyword
“reg.buffer”
Question No: 32 ( Marks: 1 )
What are the two basic operations which are performed on
memory?
Reading of information from the memory and
Writing of data on the memory.
Question No: 33 ( Marks: 2 )
Explain state assignment process.
Question No: 34 ( Marks: 2 )
What is RAM Stack, which register stores the address of the
top of the stack?
Question No: 35 ( Marks: 3 )
How
can we calculate the frequency of an unknown signal?
Question No: 36 ( Marks: 3 )
Explain dynamic RAM in your own words.
Question No: 37 ( Marks: 3 )
Suppose a 2 bit up-down counter having states “A, B, C, D”.
the counter counts upward when X=1 and downward when X=0. Write down
IF-THEN-ELSE statements to show how present states change to next states and
previous states.
Question No: 38 ( Marks: 5 )
Explain memory read operation with the help of an example.
Question No: 39 ( Marks: 5 )
Draw the next-state table of any sequential counter with the
help of J-K flip flop transition
Question No: 40 ( Marks: 10 )
You
are given the diagram of up-down counter; explain how it works as an up and
down counter.
Question No: 41 ( Marks: 10 )
Consider a state sequence a, b, c, f, d, d, c, f, d, c, a, f,
d, c. Starting from initial state a, draw a table for the inputs and outputs
for the state diagram given below (up to first ten transitions).
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