1. Bridges To Computing General Information: This document was created for use in the "Bridges to Computing" project of Brooklyn College. You are invited and encouraged to use this presentation to promote computer science education in the U.S. and around the world. For more information about the Bridges Program, please visit our website at: http://bridges.brooklyn.cuny.edu/ http://bridges.brooklyn.cuny.edu/ Disclaimers: All images in this presentation were created by our Bridges to Computing staff or were found online through open access media sites and are used under the Creative Commons Attribution-Share Alike 3.0 License. If you believe an image in this presentation is in fact copyrighted material, never intended for creative commons use, please contact us at http://bridges.brooklyn.cuny.edu/ so that we can remove it from this presentation.http://bridges.brooklyn.cuny.edu/ This document may include links to sites and documents outside of the "Bridges to Computing" domain. The Bridges Program cannot be held responsible for the content of 3 rd party sources and sites.

2. Electricity & Binary Basic Concepts of Computing M. Meyer Bridges To Computing 2010

3. 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.Relays & Boolean Logic 2.Transistors 3.Capacitors 4.Binary Numbers and Binary Storage 5.Marble Adder

4. (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.

5. (2) Non-Electrical Computers Babbage Engine: A mechanical computer proposed 1849 and finally built in 2002. Used gears and mechanical power. -->

6. (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.

7. (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.

8. (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.

9. (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.

10. (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.

11. (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.

12. (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.

13. (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.

14. (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

15. (4.1) Basic Computer Concepts – Boolean Logic (AND) Battery A ON Battery B ON Light-Bulb ON Yes No YesNo

16. (4.2) Basic Computer Concepts - Transistors Transistors are tiny devices (billions can fit on a CPU). They use special properties of some materials (called semi- conductors) like impure silicon, to implement the same functionality as an electromagnetic relay (boolean logic).

17. (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.Leydan Jar

18. (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".

19. (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?

20. (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.CLICK HERE

21. 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" )"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.

22. The End