Semester
Subject
Year
Tribhuwan University
Institute of Science and Technology
2077
Bachelor Level / First Year / First Semester / Science
B.Sc in Computer Science and Information Technology (CSC116)
(Digital Logic)
Full Marks: 60
Pass Marks: 24
Time: 3 Hours
Candidates are required to give their answers in their own words as for as practicable.
The figures in the margin indicate full marks.
Section A
Long Answers Questions
Attempt any TWO questions.
[2*10=20]
1.
Design a combinatorial circuit that generates 9's complement of a BCD number.[10]
2.
Implement the following functions using PLA
$w(A, B, C, D) = \sum(7,12,13)$
$x(A, B, C, D) = \sum(7,8,9,10,11,12,13,14,15)$
$y(A, B, C, D) = \sum(0,2,3,4,5,6,7,8,10,11,15)$
$z(A, B, C, D) = \sum(1,2,8,12,13)$[10]
$w(A, B, C, D) = \sum(7,12,13)$
$x(A, B, C, D) = \sum(7,8,9,10,11,12,13,14,15)$
$y(A, B, C, D) = \sum(0,2,3,4,5,6,7,8,10,11,15)$
$z(A, B, C, D) = \sum(1,2,8,12,13)$
3.
Design sequential circuit specified by the following state diagram using T flip-flops.
[10]
Section B
Short Answers Questions
Attempt any Eight questions.
[8*5=40]
4.
List two major characteristics of digital computer. Represent -6 (negative six) using 8 bits in signed magnitude, signed-1's-complement and signed-2's-complement respectively. Represent decimal number 4673 in a) octal, and b) BCD. [5]
5.
Where is CMOS suitable to use? Define Power dissipation. Show that the positive logic NAND gate is a negative logic NOR gate and vice versa. [5]
6.
Design a full subtractor circuit with three inputs $x, y, B_{in}$ and two outputs Diff and $B_{out}$. The circuit subtracts $x - y - B_{in}$, where $B_{in}$ is the input borrow, $B_{out}$ is the output borrow, and Diff is the difference [5]
7.
Design 4-bit even parity generator. [5]
8.
What is the difference between a serial and parallel transfer? Explain how to convert serial data to parallel and parallel data to serial. What type of register is needed? [5]
9.
Explain negative-edge triggered D flip flop with necessary logic diagram and truth table. [5]
10.
Illustrate the use of Binary ripple counter and BCD ripple counter. [5]
11.
Write short notes on (Any two):
$RTL$
$State Reduction$
$RTL$
$State Reduction$
$POS$
[5]12.
Simplify the following function and implement them with two level NOR gate circuit, $F(w, x, y, z) = wx' + y'z' + w'yz'.$ [5]