# Education In Pakistan

## VU CS302 – DIGITAL LOGIC DESIGN (Session – 2 ) FINALTERM EXAMINATION FALL 2006

.

FINALTERM EXAMINATION

FALL 2006

CS302 – DIGITAL LOGIC DESIGN (Session – 2 )

Marks: 60

Time: 120min

Student Name: ______________________________

Center Name/Code: ______________________________

Exam Date: Tuesday, February 13, 2007

of the questions:

1. Attempt all questions.

2. Calculators are NOT allowed.

3. Do not ask any questions about the contents of this examination

from anyone.

a. If you think that there is something wrong with any of the

questions, attempt it to the best of your understanding.

b. If you believe that some essential piece of information is

missing, make an appropriate assumption and use it to solve the

problem.

4. Circuit Diagrams, Equations and Truth Tables should be clear.

For Teacher’s use only

Question

Marks

1 2 3 4 5 6 7 8 9 10 Total

.

The OR gate performs Boolean ___________.

► multiplication

► subtraction

► division

.

Question No: 2

( Marks: 2 )

How many states does a modulus-4 counter have?

► 1

► 2

► 4

► 16

Question No: 3

( Marks: 2 )

How will a serial in/serial out shift register accept data serially?

► one bit at a time

► 8 bits at a time

► only after a load pulse

► only after being cleared

Question No: 4

( Marks: 2 )

If an S-R latch has a 1 on the S input and a 0 on the R input and then the S input goes to

0, the latch will be

► set

► reset

► invalid

► clear

Question No: 5

( Marks: 2 )

The storage cell in SRAM is

► a flip –flop

► a capacitor

► a fuse

► a magnetic domain

.

Question No: 6

( Marks: 5 )

Convert the following POS expression to minimum SOP expression using K-Map

( A B) ( A B C ) ( B C D) ( A B C D)

Question No: 7

( Marks: 5 )

Draw the circuit diagram of the 4×1 Multiplexer.

Question No: 8

( Marks: 20 )

Design a 2-bit count-down counter. This is a sequential circuit with two flip flops and

one input x. when x=0 the state of flip flop doesn’t change. When x=1 the state

sequence is 11, 10, 01, 00,11 and repeat.

Question No: 9

( Marks: 10 )

Show a complete timing diagram showing the parallel outputs for the shift register in figure.

Use the waveforms in figure below with the register initially clear.

Data input

D

C

D

C

D

C

D

C

CLK

Q0

Q1

Q2

Q3

CLK

Serial

data in

Q 0

Q 1

Q 2

Q 3

Question No: 10

( Marks: 10 )

Draw block diagram of 4-bit Johnson Counter?