Digital Electronics
Dr. Bahawodin Baha, University of Brighton, UK.
March 2007
Digital Systems, Principles and Applications, 10th Edition
R.J Tocci, N. S. Windmer, G. L. Moss, 2007.
Applications:
Computers
Telecommunication
Automation
Medical Science and
Technology
Transportation
Space Exploration
Entertainment
Home Appliances
Others
Course Summary
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Overview of Electronics
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Digital Electronics Number systems,
decimal, binary, hexadecimal
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Combinational logic circuits
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Sequential logic circuits
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Computer Systems
Course Summary (cont.)
Combinational Logic Systems
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Number systems: Binary, decimal and hexadecimal conversions
and calculations
Basic logic gates: AND, OR, NOT and Ex-OR
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Truth tables, Boolean equations.
Combinational logic circuit design: General hierarchical logic design
methodology
Minimisation using Karnaugh maps and Boolean algebra, DeMorgan’s laws.
Simulation of gates and combinational logic designs
Implementation and testing of designs using a suitable version of
TTL series ICs.
Practical aspects of using logic ICs: data sheets, current and
voltage characteristics, timing issues, output types, compatibility,
families etc..
Course Summary (cont.)
Sequential logic design
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Flip-flops: SR, JK, D, T types, truth tables,
excitation tables and device operation.
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Flip-flop applications: Registers and
counters (asynchronous); MSI and LSI
devices
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Synchronous counter and sequence
generator design method
Course Summary (cont.)
Introduction to Microprocessor Systems
 Overview of computer systems architectures, a
simple microprocessor-based system, the stored
programme concept.
 Design of a microprocessor based system
 Differences between microprocessors and
microcontrollers.
 Brief history of microprocessors and
microcontrollers.
Overview of Electronics

Analogue electronics
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Power electronics
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Physical electronics
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Differences between digital and other types
of electronics
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Numerical Presentation
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In 1947, Transistor was invented in Bell labs
in the USA.
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It was as tall as the face of wristwatch.
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In November 2001, another Bell lab team has
built a transistor from a single Molecule small enough to fit about 10 million
transistors on the head of a pin.
Numerical Representation
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There is two ways to represent numerical values.
1- Analogue
In analogue representation one quantity is represented by another
quantity which is directly proportional to the first quantity.
Analogue = Continuous
2- Digital
In digital representation the quantities are not represented by
proportional quantities but symbols called digits. The digital
representation is in discrete steps.
Digital = Discrete
Logic Level in digital representation, 0 – 0.8 logic 0 and 2 – 5 logic 1.
Voltage between 0.8 V and 2 V are unacceptable and are never used.
Number systems

Type of Numbers
 Decimal,
Binary, Octal and Hexadecimal
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Converting decimal to binary and
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Converting decimal to hexadecimal
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Converting binary to hexadecimal
Number Systems
Decimal
Binary
Hexadecimal
Base of 10
Base 0f 2
Base of 16
0
0000
0
1
0001
1
2
0010
2
3
0011
3
4
0100
4
5
0101
5
6
0110
6
7
0111
7
8
1000
8
9
1001
9
10
1010
A
11
1011
B
12
1100
C
13
1101
D
14
1110
E
15
1111
F
g
Converting Decimal to Binary
2
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Convert Therefore, 810
= (1000)2
LSB, Less Significant Bit
MSB, Most significant
Bit
To examine
(0 X 2 0) + (0 X 2 1) + (0 X
2 2) + (1 X 2 3) = 8
decimal into binary
8
2 4
Reminder
0
2
2
0
2
1
0
0
1
LSB
M SB
2nd Example
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Convert 624 decimal into
binary
624 decimal = 1001110000
in binary.
To examine the result
(1 X 2 4) + (1 X 2 5) + (1 X
2 6) + (1 X 2 9) = 624
2
624
2
2
2
312
0
156
0
78
0
2
39
0
2
19
1
2
2
2
2
9
1
4
1
2
0
1
0
2
0
1
Reminder
LSB
MSB
Converting Decimal to Hex
16
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Find the Hex equivalent
of (3875)
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(3875) = (F23)H
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To examine
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(15 X 162) + (2 X 161) + (3
X 160) = 3875
3875
Reminder
16
242
3
16
15
2
16
0
15
LSB
MSB
Converting Hex to Decimal
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Convert (AF16B)16 to decimal.
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(AF16B)16 = [(10 X 164) + (15 X 163) + (1
X 162) + (6 X 161) + (11 X 160)]
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= (655360 + 61440 +256 +96 +11)
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= (717163)10
Converting Binary to Hex
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To convert Binary into Hex, simply group them
in four and write down the Hex equivalent for
each group.
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Example:
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(10110011) 2 = (1011)2 (0011)2 = (11)10 (3)10 =
B316
Main Points
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Digital Electronics use many exciting
applications
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Introduction to digital electronics
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Number systems: Decimal, binary and hex
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Converting from one number system into
another
The End
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Thank you for your
attention.
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Any questions?
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Good luck and have
fun!