The document explores fundamental concepts in electronics, including binary and decimal number systems, logic gates, and circuits for computation, sensing, and communication. It discusses the principles behind data storage using various technologies such as magnetic and optical storage, as well as the operation of sensors and basic concepts of analog and digital communication. The content highlights the relationship between basic electronic principles and their practical applications in memory devices and information theory.

1. Flavors of Electronics
An exploration of a few simple ideas
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P Joy Prabhakaran
https://www.linkedin.com/profile/view?id=22548506&trk=hp-identity-name

2. Electronics: What does it do for us?
• Compute
• Store
• Communicate
• Sense
• Control
• Interact with humans
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3. Binary numbers
Decimal numbers
– Base 10
– 10 symbols: 0 to 9
– 576 = 5 x 102 + 7 x 101 + 6 x 100
Binary numbers
– Base 2
– 2 symbols: 0 & 1
– 101 = 1 x 22 + 0 x 21 + 1 x 20 = ? In decimal
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4. Compute: How?
• Logic
NOT, OR, AND, XOR
• Numeric Comparison
=, >, <
• Arithmetic
ADD, SUB, MULT, DIV
Can all these be built using the switches shown here?
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Many of the ideas here are probably derived from Shannon’s work referred to at:
http://en.wikipedia.org/wiki/A_Symbolic_Analysis_of_Relay_and_Switching_Circuits

5. The NOT gate
A few notations:
5V, 1, ON, TRUE are all used in a near synonymous manner.
The switch is “pressed” when the Input is 1.
If the connection to 5V is not present, the output is at 0.
Also referred to as OFF or FALSE at times.
With that out of the way let us explore what the NOT
logic is and if we can implement it using these
switches.
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I/P O/P
1 0
0 1

6. AND
What should an “AND” implementation do?
How can this be built using our switches?
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A B O/P
0 0 0
0 1 0
1 0 0
1 1 1

7. OR
What should an “OR” implementation do?
How can this be built using our switches?
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A B O/P
0 0 0
0 1 1
1 0 1
1 1 1

8. XOR
What should an “XOR” implementation do?
How can this be built using our switches?
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A B O/P
0 0 0
0 1 1
1 0 1
1 1 0

9. NAND
How about a NAND (following truth table)?
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A B O/P
0 0 1
0 1 1
1 0 1
1 1 0

10. Gates and the symbols to denote them
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11. Checking for equality
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What does the following do?
O/P = 𝐴. 𝐵 + 𝐴. 𝐵
A B O/P
0 0 1
0 1 0
1 0 0
1 1 1
Build a circuit to check equality of two 2-bit numbers A1A0 and B1B0
O/P = (𝐴1. 𝐵1 + 𝐴1. 𝐵1) . (𝐴0. 𝐵0 + 𝐴0. 𝐵0)
What if we use an XNOR?

12. Comparing two numbers
A = B (𝐴1. 𝐵1 + 𝐴1. 𝐵1) . (𝐴0. 𝐵0 + 𝐴0. 𝐵0)
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(𝐴1. 𝐵1) + (𝐴1. 𝐵1 + 𝐴1. 𝐵1) . (𝐴0. 𝐵0)A > B
Let us work out the truth table for A > B.
How would you implement A < B.
Logic to compare two 2 bit numbers

13. Addition: One bit half adder
A one bit half adder:
What is the truth table for S and Cout?
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Two inputs (A, B) and two outputs (S, Cout)
Addition operation
A B S Cout
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1
What is the logic for S and Cout?
𝑆 = 𝐴 ⊕ 𝐵
𝐶𝑜𝑢𝑡 = 𝐴 . 𝐵

14. One bit full adder
A one bit full adder:
What is the truth table for S and Cout?
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Three inputs (A, B, C) and two outputs (S, Cout)
Addition operation
A B C S Cout
0 0 0 0 0
0 1 0 1 0
1 0 0 1 0
1 1 0 0 1
0 0 1 1 0
0 1 1 0 1
1 0 1 0 1
1 1 1 1 1
… and the logic S and Cout?
𝑆 = 𝐴. 𝐵. 𝐶 + 𝐴. 𝐵. 𝐶 + 𝐴. 𝐵. 𝐶 + 𝐴. 𝐵. 𝐶
𝐶𝑜𝑢𝑡 = 𝐴 . 𝐵 + 𝐴. 𝐶 + 𝐵. 𝐶
• S is true if only one input is true
or if all three are true.
• Cout is true if any two inputs are
true.

15. Build an 8 bit adder
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16. Latches & Flip Flops
• Latches & Flip flops are built using basic gates and
can store data.
• They can be level triggered or edge triggered.
• They are an intrinsic part of storage, counters etc.
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S R CLK D Q 𝐐
0 1 X X 1 0
1 0 X X 0 1
0 0 X X Unstable
1 1 ↑ 1 1 0
1 1 ↑ 0 0 1
1 1 ↓ X No change
1 1 ― X No change
The D flip flop

17. What would this circuit do
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• R is made zero and then kept high throughout. After this, a clock is applied.
• What will the output be each time the clock goes high from low.
R Clk 𝑸 𝟑 𝑸 𝟐 𝑸 𝟏 𝑸 𝟎
0 X 0 0 0 0
1 ↑ 0 0 0 1
1 ↑ 0 0 1 1
1 ↑ 0 1 1 1
1 ↑ 1 1 1 1

18. … and what about this?
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R Clk 𝑸 𝟑 𝑸 𝟐 𝑸 𝟏 𝑸 𝟎
0 X 0 0 0 0
1 ↑ 0 0 0 1
1 ↑ 0 0 1 1
1 ↑ 0 1 1 1
1 ↑ 1 1 1 1
1 ↑ 1 1 1 0
1 ↑ 1 1 0 0
1 ↑ 1 0 0 0
1 ↑ 0 0 0 0

19. Store: A few examples of data storage
• Mechanical
• Electrical
• Magnetic
• Optical
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20. Store: A few examples of data storage
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21. Magnetic storage
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Source: http://en.wikipedia.org/wiki/Hard_disk_drive

22. Optical storage
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http://www.britannica.com/EBchecked/media/106454/On-optical-discs-such-as-compact-
discs-and-digital-videodiscs?topicId=430490

23. A conceptual exploration of addressable and
programmable storage with no moving parts
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What is O/P in relation with A1?
Assuming only one of A1 and A2 can be
1 at any time, what is the relationship
between A1 and A2 in the two
schematics on the right
Any ideas on how all this could lead to a memory device?

24. ...conceptual exploration of memory
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Discuss how the schematic can become the basic idea behind
devices like RAMs, EPROMs, EEPROMs etc with Ai becoming
the addressing mechanism

25. Communicate: How?
Send a signal from the source to the destination.
• Challenges
– How does one “send a signal”?
• Transmitter
• Conceptually, what should a transmitter look like?
– How does one receive a signal?
• Receiver
• Conceptually, what should a receiver look like?
– How does the signal go from the sender to the
receiver?
• Transmission channel and medium.
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26. Sense: How?
• Sensors are used to sense. A sensor is a
transducer.
• A sensor (transducer) converts a physical
parameter into some other physical parameter
that can be used to sense the former. Example: A
thermometer
• In electronics and automated systems, the
physical parameter is typically converted to a
voltage or current for this can be easily
measured.
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27. Physics behind a few common sensors
• Resistive sensors.
– Uses the fact that resistance of certain materials vary with
physical parameters. Eg: Resistive temperature detectors, Strain
gauges.
• Photoelectric sensors
– Uses the fact that a measurable current is generated in a
photo diode when exposed to light. Eg: Used in light sensors
• Thermocouples
– Uses the fact that Any junction of dissimilar metals will
produce an electric potential related to temperature. Eg:
Temp sensors used in Steel industry, water heaters etc.
• Piezo electric sensors
– Uses the fact that electric charge accumulates in certain
solid materials (such as crystals, certain biological matter
such as bone, DNA and some proteins) in response to
applied mechanical stress. Eg: Early use as a submarine sonar
by responding to the sonar echo. 28

28. A few basic concepts from analog
communication
• Wavelength
• Frequency
• Period
• Amplitude
• Low pass, high
pass, band
pass signals
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29. Switching to the digital domain
• Sampling
• Quantization
• Quantization error
• Types of quantization
• Nyquist
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30. Sampling
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31. Quantization
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32. Loss due to quantization.
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33. Impact of quantization loss
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34. Time domain – Frequency domain
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35. Ideas in Information Theory and
compression
• Is all information created equal? Did you tell
me anything if you told me that the Sun rose
in the east today?
• What is ASCII code? Compare with a Variable
Length Code (VLC)?
• What if monochrome image is to be coded
with each pixel being a 0 or a 1 (like in Fax)?
Does any possibility to compress come to
mind?
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36. …ideas in compression contd.
• Eliminating “unnecessary” and less important
information.
• Using the probability distribution of symbols
to arrive at a more efficient code.
• Regenerating parts of the data from other
parts of the data and a difference component.
• Dictionary coding.
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37. The END
(only because I don’t know if anyone cares for this stuff)
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