WELCOME TO IP UNIVERSITY QUESTION PAPERS WEBSITE
Homepage : http://ippapers.tripod.com/ 
Back to V semester papers
(Please write your Roll No. immediately) 
Roll No. .................................. 
Fifth Semester [B.Tech]  September 2005
Paper Code : ETEC – 301 Subject : Digital Circuit and Systems I 
Time : 1^{1}/_{2} Hours 
Maximum Marks : 30 
Note : Attempt any 3 questions in all. Q1 is compulsory. Each question carries 10 marks. 
Q1 
( a ) 
How are hazards avoided using SR latches. 
2 

( b ) 
Distinguish between Mealy model and Moore model.  1  
( c ) 
A sequential circuit has two JK flip flops A and B, on input y, and
one output y. The J and K inputs are defined as: Ja = B, Kz = B',
Jb = Kb = (xA' + x'A)' Derive the state table. 
3  
( d )  What are cycles in asynchronous circuits. Give examples.  2  
( e ) 
Assign output values to the dont care conditions in the following
flow tale:

2 
Q2 
( a ) 
A sequential network has one input (X) and one output (Z). The network examines groups of four consecutive inputs and produces an output Z=1 if the input sequence 0101 or 1001 occurs. The network resets after every four inputs. Determine the mealy state graph and state table. 
6 
( b ) 
Draw an ASM chart that specifies a conditional operator to increment register R during state T1 and transfer to state T2 if control inputs z and y are equal to 1 and 0 respectively. 
4 
Q3 
( a ) 
Determine the state table corresponding to the following state diagram: 
3 

( b ) 
Design an asynchronous sequential circuit with two inputs x1 and x2
and one output z. initially both inputs and outputs are equal to 0.
When x1 or x2 becomes 1, z becomes 1. When the second input also
becomes 1, the output becomes 0. The output stays at 0 until the
circuit foes back to the initial state.

Q4 
( a ) 
USE IMPLICATION TABLE TO REDUCE THE FOLLOWING TABLE TO A MINIMUM
NUMBER OF STATES:

3 

( b ) 
The state diagram of a control unit is as shown below. It has four
states and two inputs x and y.

7 