DIGITAL LOGIC DESIGN (ELE 241)

Ali Mustafa Lecture # 01

Instructor Introduction

Ali Mustafa

BSC Computer Engineering

(Comsats Pakistan)

MS Mobile Communication

(University of Bradford England)

Worked as

GSM Engineer in I-Track

Telecom Engineer in UFONE

WiMAX Engineer in NUST

Get in Touch with Instructor

Class Meeting Times & Locations: Monday 10:00 am – 11:30 am

Wed 11:30 am – 1:00 pm

Instructor Name: Ali Mustafa

Instructor Telephone: 057-9316329-137

Instructor E-Mail Address: ali.mustafa@ciit-attock.edu.pk

Instructor Office Hours:

Tuesday 9:00 am -4:30 pm

Instructor Office Location* : Engineers Room – DLD Lab EE Department

(* Will confirm later)

Subject Information

SUBJECT CODE & NAME: ELE 241, DLD

CREDIT HRS : 03

CONTACT HRS : 03 per week

TEXT BOOK : Digital Design (4th Edition)

M. Morris Mano, Michael D. Ciletti

REFERANCE BOOK : Digital Fundamentals (9th Edition)

Floyd

Objectives

Understand theory of operation for most of digital

electronic devices.

Analyzing how can a digital computer perform the

complex operations based on simply manipulating

bits (zeros and ones).

Design of digital logic systems.

Topics to be covered

Digital Systems and Binary Systems

Boolean Algebra and Logic Gates

Gate-Level Minimization

Combinational Logic

Synchronous Sequential Logic

Registers And Counters

Digital Integrated Circuits

Evaluation Plan

The Course assessment will be made up of the

following four components;

1. Sessionals --- 25%

2. Quizzes --- 15%

3. Assignments --- 10%

4. Final Examination --- 50%

Students are responsible for:

1. Attendance. If a student misses more than 3 class sessions they may be dropped.

2. Arriving to each class on time. Late comers are disruptive to the class.

3. Letting the instructor know if you require any special considerations such as special seating.

4. Turning off all cell phones while in class.

5. Conducting themselves in a professional manner; refraining from talking in class except as part of a classroom discussion or to ask a question.

Students are responsible for:

6. Knowing and adhering to due dates for all

assignments, mid-term and final exam.

7. Taking or acquiring class notes.

8. Knowing COMSATS policies and procedures, This

includes plagiarism and cheating.

9. Letting the instructor know if you are having

difficulty with any part of the course. Special time

can be arranged for individual assistance.

Student Introduction

Welcome to COMSATS

Welcome to this Course

Brief Introduction

About yourself

Last semester experience

Suggestions

NOTE: Medium of communication will be English in the class.

What’s the importance of digital logic

Flash back on Digital logic history

1850: George Boole invents Boolean algebra.

1946: ENIAC: 1s telectronic computer

18,000 vacuum tubes

5,000 operations per second

1,000 square feet

It really cost a lot of power to turn on the switch?

And it went on………

1947: Shockley, Brittain, and Bardeen invent the transistor

replaces vacuum tubes

enable integration of multiple devices into one package

1955: TRADIC: AT&T Bell Laboratories announced the first fully transistorized

1958: 1stIntegrated Circuit

1972: Intel’s 8088 1stmicroprocessor.

Applications of logic design

Conventional computer design

CPUs, busses, peripherals

Networking and communications

Phones, modems, routers

Embedded products

Cars

Toys

Appliances

Entertainment devices, e.g. MP3 players, PS3, and many others

Classification of Signals/Systems

They are classify into two categories

Analog Signal:

They have infinite number of different magnitudes or values.

They varies continuously with time.

Digital Signal:

A signal is known as digitised if it has finite number of

magnitudes.

Analog Signals

An analog or analogue signal is any variable

signal continuous in both time and amplitude.

e.g. Sound

ExampleThey have infinite number of values

They are continuous in nature

Source of signals can be signal generator

Sine wave is an example

Digital Signals

Digital describes any system based on discontinuous

data or events.

Computers are digital machines because at their most

basic level they can distinguish between just two

values, 0 and 1, or off and on.

Number of values can be finite (2,8,16)

Nature of signals are discrete

Source can be computer or A to D converter

Binary signal is an example

Advantages of Analog signals

They are used in

Filter design

Amplifier circuits

Signal Generators

Motor Speed Controller

Drawback of Analog System

Less accurate

Less reliable

Memory/Storage is an issue

Performance changes as temperature varies

Distortion and noise

Advantages of Digital System

It manipulates discrete element of information such

as decimal digits or alphabets.

Signal in digital system represented by a binary

digit called a bit.

Discrete elements of information are represented by

a group of bits called Binary Codes.

They are reliable,flexible,programmable and

updating technology.

Basic Digital Devices

Logic Gates

Combinational circuits

Sequential circuits

ICs

Logic Gates

Digital Logic Gates are the basic unit to build any

digital circuit.

It operates on a number of binary inputs to perform

a logical function.

There are different types of gates available ,e.g

AND,OR,NOT,NAND,EX-OR,NOR

Combinational Circuits

When number of logical gates are connected

together to produce specified output by

combination of input variables.

It has no memory element.

Combinational Logic Circuit N Inputs M Outputs

Sequential Circuits

The circuit in which digital outputs are required to

be generated in accordance with the specified

sequence.

It has the memory interface (Flip Flop)

Combinational

Circuit

Memory Element Input

Output

Integrated IC

For complex circuits which involves number of

gates,IC is used.

Small Scale IC (SSI) 20 gates circuit

Medium Scale IC(MSI) 20-200

Large Scale IC(LSI) 200 – 200,000

Very Large Scale IC(VLSI) 1,000,000

Binary Logic

Logic is defined as a statement which is true ,if

some condition is satisfied or vice versa.

Binary logic has two levels

High (1)

Low (0)

Lamp

OFF , LOW (Logic 0)

Negative

ON , High (Logic 1)

Positive

Negative & Positive Logic

Electrical Signals [ voltages or currents ] that exist throughout a digital system is in either of two recognizable values [ logic 1 or logic 0 ]

Logic 0 and 1 can be represented by another way of logic

Positive Logic Logic 0 (Low) 0V

Logic 1 (High ) +5V

Negative Logic Logic 0 (Low) +5V

Logic 1 (High ) 0V

Introduction to Number System

Number system is basis for counting various items.

Modern computer operated in binary number

system.

Decimal,Octal,Hexa,BCD represents more bits in a

binary numbers in a compressed form.

Base/Radix of the number systems are 2,8,10,16

Base decides the total no of digits available in a

system E.g Binary Base 2 0 or 1

Introduction to Number System

1st digit is always zero and last digit is always base

-1.

Each digit position represent different multiples of

base.

3 4 9 . 2 5

Radix Point

Power 0 Power1 Power 2 Power -1 Power -2

Different Number Systems

Decimal

Binary

Octal

HexaDecimal

Conversion of Number System

Examples