Digital logic design

1. By Dr. Javaid Khurshid
DCIS, PIEAS
CIS-111: Digital Logic Design
DCIS, PIEASJavaid Khurshid

2. Who is Who in CIS-111
DCIS, PIEASJavaid Khurshid
● Instructor
– Dr. Javaid Khurshid
● Office: C-211
● Phone: 3234
● E-mail: javaidk@pieas.edu.pk
● Lab Instructor
– Mr. Naeem Ahmed
● Office: C-210
● Phone: 3233
● E-mail: naeem.ahmed@pieas.edu.pk

3. Who is who in CIS-111
DCIS, PIEASJavaid Khurshid
● Lab Technicians:
– Mr. Ali Shah
– Mr. Mazahir Husnain
● Location
– Applied Electronics Lab (C- Block) adjacent to
PIEAS Conference Room
● Contact
– Phone: 3236

4. Lecture and Lab Schedule
DCIS, PIEASJavaid Khurshid
● Lectures:
– Wednesday (3rd Lecture) (10:35 – 11:30)
– Thursday (1st Lecture) (8:25 – 9:20)
● Location:
– Room : B-102
● Laboratory Session:
– Thursday (11:40 – 12:35) (Lab Instructions+)
– Thursday (13:30 – 15:30)
● Lecture Slides:
– 172.30.10.2FacultyShareJavaid Khurshid
DrCourses 2018DLD Session 2017-21
● Discussion (in my office)
– Friday (11:00-11:30)
– Tuesday (14:00-14:30)

5. Grading !
DCIS, PIEASJavaid Khurshid
● Overall grade composed of [Theory part - 100]
– Sessionals – 15 x 2 = 30
– Assignments – 3 x 5 = 15 (Best 5)
– Quizzes – 1 x 5 = 05 (Best 5)
– Final Exam – = 50
● Overall grade composed of [Lab part -100]
– Practicals – 2 x 15 = 30
– Class Project – 30 x 1 = 30
– Quizzes/test – 10 x 4 = 40

6. Some Rules to be observed
DCIS, PIEASJavaid Khurshid
● Please be courteous in class
● Punctuality
● Cell phones/Tabs/ Laptops are not allowed to
be used
● Ask questions related to the course …
● Drinking or eating in the class or laboratory is
strictly prohibited
● There are things that you cannot learn from
reading notes
● …

7. Text / Reference Books
DCIS, PIEASJavaid Khurshid
● Thomas L. Floyd, “Digital Fundamentals”
11th edition
● M. Morris Mano and Michael D. Ciletti,
“Digital Design”, Prentice Hall.
● Course will follow Sequence of my
Lectures
– all topics covered in class
● You are expected to
read any book
related to this course

8. Syllabus
● Introductory Digital
Concepts.
● Number Systems,
Operations, and
Codes.
● Logic Gates.
● Boolean Algebra and
Logic Simplification.
● Combinational Logic.
● Functions of
Combinational Logic
 Flip-Flops and
Related Devices.
 Counters.
 Shift Registers.
 Sequential Logic
 Memory and Storage.
 Interfacing.
 Introduction to
Microprocessors and
Computers.
DCIS, PIEASJavaid Khurshid

9. Your Understanding
 How much have you studied of the subject?
 What is this subject for?
 Why do we need laboratory sessions?
 How is it good for your computer science
studies?

10. Chapter 1 (Floyd)
Introductory Concept
DCIS, PIEASJavaid Khurshid

11. Introduction
DCIS, PIEASJavaid Khurshid
● Digital Systems
● Digital and Analog Quantities
● Advantages of Digital Quantities
● Binary Digits
● Logic Levels
● Digital Waveforms

12. A System
DCIS, PIEASJavaid Khurshid
● Discrete System - a system with a finite
number of sizes or measures
– Shoes, Dresses, Pants, Bolts, Pencils
● Digital System - a system with only two values
of system variables: 1 and 0
– True/False; Yes/No; Male/Female; On/Off
● Analog System - a system with continuous
values information has an infinite amount of
possible states
– Temperature change in a day

13. Digital vs Analog
DCIS, PIEASJavaid Khurshid
● Digital signals are binary; analog signals are
real-valued numbers
● Digital is less susceptible to noise

14. Approximation of Analog Signal with
Digital Signal
DCIS, PIEASJavaid Khurshid

15. Advantages of Digital System
DCIS, PIEASJavaid Khurshid
● Less Noisy
● More Accurate
● Easier to Process (with discrete ICs)
● More Storage on small space
● More safe to store
● Low power consumption

16. Digital Systems Examples
DCIS, PIEASJavaid Khurshid
● Cell phone
● Digital camera
● MP3 / MP4 Player (IPod)
● Industrial process controller, etc.

17. Digital to Analog Systems
DCIS, PIEASJavaid Khurshid
● Many systems use a mix of analog and digital
electronics to take advantage of each
technology.
– A typical CD player accepts digital data from the
CD drive and converts it to an analog signal for
amplification
Digital data
CD drive
10110011101
Analog
reproduction
of musicaudio
signal
Speaker
Sound
waves
Digital-to-analog
converter
Linear amplifier

18. Analog to Digital Systems
DCIS, PIEASJavaid Khurshid
Ref: https://www.allaboutcircuits.com/uploads/articles/An-Introduction-to-Digital-Signal-Processing-(3).png

19. HIGH
LOW
VH(max)
VH(min)
VL(max)
VL(min)
Invalid
Binary Digits and Logic Levels
 Digital electronics uses circuits that
have two states, which are
represented by two different
voltage levels called HIGH and
LOW. The voltages represent
numbers in the binary system.
 In binary, a single number is called
a bit (for binary digit). A bit can
have the value of either a 0 or a 1,
depending on if the voltage is
HIGH or LOW.

20. Falling or
leading edge
(b) Negative–going pulse
HIGH
Rising or
trailing edge
LOW
(a) Positive–going pulse
HIGH
Rising or
leading edge
Falling or
trailing edge
LOW
t0
t1
t0
t1
Digital Waveform
 Digital waveforms change between the LOW and
HIGH levels.
 A positive going pulse is one that goes from a
normally LOW logic level to a HIGH level and then
back again.
 Digital waveforms are made up of a series of pulses.

21. 90%
50%
10%
Baseline
Pulsewidth
Risetime Fall time
Amplitude tW
tr tf
Undershoot
Ringing
Overshoot
Ringing
Droop
Pulse Definition
 Actual pulses are not ideal but are described
by the rise time, fall time, amplitude, and other
characteristics.

22. Volts
Time
Amplitude
(A)
Pulse
width
(tW)
Period, T
Pulse Definition
 In addition to frequency and period, repetitive
pulse waveforms are described by the
amplitude (A), pulse width (tW) and duty cycle.
 Duty cycle is the ratio of tW to T.

23. T
f
1

f
T
1


GHz2.3
11
f
T 313 ps
Periodic Pulse Waveforms
 Periodic pulse waveforms are composed of pulses that
repeats in a fixed interval called the period. The
frequency is the rate it repeats and is measured in
hertz.
 The clock is a basic timing signal that is an example of
a periodic wave.
 Example: What is the period of a repetitive wave if f =
3.2 GHz?

24. A timing diagram is used to show the relationship between two
or more digital waveforms,
Clock
A
B
C
A diagram like this can be observed
directly on a logic analyzer.
Timing Diagrams

25. Data can be transmitted by either serial transfer or parallel
transfer.
Computer Modem
1 0 1 1 0 0 1 0
t0 t1 t2 t3 t4 t5 t6 t7
Computer Printer
0
t0 t1
1
0
0
1
1
0
1
Serial and Parallel Data

26. True only if all input conditions
are true.
True only if one or more input
conditions are true.
Indicates the opposite condition.
Basic Logic Functions

27. And, or, and not elements can be combined to form
various logic functions. A few examples are:
The comparison function
Basic arithmetic functions
Adder
Two
binary
numbers Carry out
A
B
Cout
CinCarry in
SumΣ
Two
binary
numbers
Outputs
A
B
A< B
A= B
A> B
Comparator
Basic System Functions

28. The encoding function
The decoding function
Decoder
Binary input
7-segment display
Encoder9
8 9
4 5 6
1 2 3
0 . +/–
7
Calculator keypad
8
7
6
5
4
3
2
1
0
HIGH
Binary code
for 9 used for
storage and/or
computation
Basic System Functions

29. The data selection function
Multiplexer
A
Switching
sequence
control input
B
C
∆t2
∆t3
∆t1
∆t2
∆t3
∆t1
Demultiplexer
D
E
F
Data from
Ato D
Data from
Bto E
Data from
Cto F
Data from
Ato D
∆t1 ∆t2 ∆t3 ∆t1
Switching
sequence
control input
Basic System Functions

30. The counting function
…and other functions such as code conversion and
storage.
Input
pulses
1
Counter Parallel
output
lines
Binary
code
for 1
Binary
code
for 2
Binary
code
for 3
Binary
code
for 4
Binary
code
for 5
Sequence of binary codes
that represent the number
of input pulses counted.
2 3 4 5
Basic System Functions

31. One type of storage function is the shift register, that
moves and stores data each time it is clocked.
0 0 0 00101
Initially,theregister contains onlyinvalid
data or all zeros as shown here.
1 0 0 0010
First bit (1) is shifted serially into the
register.
0 1 0 001
Second bit (0) is shifted serially into
register and first bit is shifted right.
1 0 1 00
Third bit (1) is shifted into register and
thefirst and second bits are shifted right.
0 1 0 1
Fourth bit (0) is shifted into register and
thefirst,second,and third bits are shifted
right.Theregister now stores all four bits
and is full.
Serial bits
on input line
Basic System Functions

32. A Process Control System (Example)

33. Some Key Terms
Analog: Being continuous or having continuous values.
Digital: Related to digits or discrete quantities; having a
set of discrete values.
Binary: Having two values or states; describes a number
system that has a base of two and utilizes 1 and
0 as its digits.
Bit: A binary digit, which can be a 1 or a 0.
Pulse: A sudden change from one level to another,
followed after a time, called the pulse width, by
a sudden change back to the original level.

34. Some Key Terms
Clock: A basic timing signal in a digital system; a
periodic waveform used to synchronize actions.
Gate: A logic circuit that performs a basic logic
operations such as AND or OR
NOT: A basic logic function that performs inversion.
AND: A basic logic operation in which a true (HIGH)
output occurs only when all input conditions are
true (HIGH).
OR: A basic logic operation in which a true (HIGH)
output occurs when when one or more of the
input conditions are true (HIGH).