Transcript Lecture_1 - bridges to computing

Bridges To Computing
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Electricity & Binary
Basic Concepts of Computing
M. Meyer
Bridges To Computing
2010
Content
1. Computer (basic definition)
2. Non-Electrical Computers
3. Electricity
1. What is it?
2. How do we make it?
3. Why do we want it?
4. Basic Computer Concepts
1.
2.
3.
4.
5.
Relays & Boolean Logic
Transistors
Capacitors
Binary Numbers and Binary Storage
Marble Adder
(1) So what is a computer?
•
•
Complex machines have been
around for a long time, but
usually only did 1 or 2 fixed
jobs. (Calculator)
A computer is a "universal
machine" (Turing). A machine
that can be "programmed" to
do many different jobs.
(2) Non-Electrical Computers
• Babbage Engine: A mechanical
computer proposed 1849 and
finally built in 2002.
• Used gears and mechanical
power. -->
(2) Non-Electrical Computers
• Water Computer (MIT) Uses
the flow of water, rather than
electrons, to power its
circuitry.
• The military and spaceflight
industries need computing
systems able to resist extreme
radiation environments.
(3.1) Electricity (What is it?)
Protons and Neutrons: Want to stick together (getting
them apart can be dangerous).
Electrons: Can skip from atom to atom.
Electricity: Flow of electrons from one atom (location) to
another.
(3.1) Electricity Terms
• Voltage (Volts): The
potential for electron
flow (water behind the
dam).
• Amperage (Amps):
Actual flow.
• Resistance (ohms):
How easily does a
material take-on
and/or give-up
electrons.
(3.2) Making Electricity - Magnets
• We can use magnets. Moving a
conductor (copper wire)
through a magnetic field will
generate an electrical current.
• Electricity and Magnetism are
bound together. If you have
one you can make the other.
(3.2) Making Electricity - Chemicals
• We can use chemicals.
• In the picture to the right, as
the zinc plate dissolves in the
acid it gains extra electrons.
• The copper plate as it dissolves
loses electrons.
• The extra electrons flow from
the zinc plate, to the copper
plate through the wires.
(3.2) Making Electricity - Imbalance
• We can create an imbalance.
• It might help to think of it like
this: Electrons HATE each
other, and want to get as far
away from each other as
possible.
• If I can get a whole bunch of
electrons in one place, and give
them a path to somewhere less
crowded, they will take it.
(3.3) Why Electricity – Heat and Light
• Resistance to electric flow
creates heat.
• Heat is a side-effect of electric
flow. This can be good or bad.
• Enough resistance and enough
heat will eventually produce
light.
(3.3) Why Electricity – Motors
• Electricity can power a
(magnetic) motor.
• Remember electricity and
magnetism are bound together.
• Moving magnets can make
electricity flow, and electric
flow can move a magnet.
(3.3) Why Electricity – Switches
•
•
•
•
It can flip a switch.
This is the most interesting
and important ability for
computer scientists.
To the left is a simple
electro-magnetic relay.
Closing the Green Switch,
will close the blue switch as
well.
Battery A
Battery B
(4.1) Basic Computer Concepts –
Boolean Logic (AND)
Battery A
ON
Battery B
ON
Light-Bulb
ON
Yes
Yes
Yes
Yes
No
No
No
Yes
No
No
No
No
(4.2) Basic Computer Concepts Transistors
• Transistors are tiny devices
(billions can fit on a CPU).
• They use special properties of
some materials (called semiconductors) like impure
silicon, to implement the same
functionality as an
electromagnetic relay (boolean
logic).
(4.3) Basic Computer Concepts Capacitors
• A capacitor is a special type of
battery.
• The difference between a
capacitor and a regular
(chemical) battery is that a
capacitor can dump its entire
charge instantly, where a
normal battery takes much
longer to completely discharge.
• It's very easy to make a type of
capacitor called a Leydan Jar.
(4.4) Binary numbers
• In the decimal number system,
each position in a number can
hold 1 of 10 different symbols
(0-9).
• In binary each position can
only hold 0 or 1. But we can
still represent any number.
• Binary numbers are sometimes
referred to as "Base 2".
(4.4) Storing Binary numbers
• A capacitor can either have a or
not have a charge (0/1).
• We can arrange capacitors in a
row, and use them to store
binary numbers.
• What number is represented
here?
(5) Binary Adder (accumulator)
• If I can flip a switch remotely, I
have a Boolean AND logic.
• If I have Boolean AND logic, I
can ADD.
• The device to the right, uses
wooden gears (instead of
capacitors and transistors) and
marbles (instead of electrons),
but the essential logic is the
same.
• CLICK HERE for the video.
If you can add and store numbers...
• You can do anything related to mathematics:
▫ Subtraction is addition where one number is negative
(see "Two's Complement" )
▫ Multiplication is repeated addition.
▫ Division is repeated subtraction (with a remainder).
▫ Algebra is basic math with the addition of variables.
▫ Trigonometry and Calculus are composed of algebra
along with numerous additional predefined equations.
• If you have Calculus, you can represent any physical
object that exists in the real world, as well as the
forces that act upon that object.
• At the core, computers are powerful,
reprogrammable calculators.
The End