Where Are We Going? CPSC 120 Principles of Computer Science September 23, 2012

Course Themes  Complexity and Structure  Encoding and Decoding  Hardware and Software  Theory and Application  Local and Remote  Humans and Machines

Coming Attractions  Basic Electricity Theory  Switches, lights, and LEDs  Logic of switches: AND, OR, NOT, etc  Computing using logic: Adders  Arithmetic/logic units: ALUs  Central processing units: CPUs  Microprocessors: Real devices  A general view of a computer

When Hardware Meets Software: A Robot Odyssey  Programs are coded instructions  Programming in PBASIC  Meet the Basic Stamp II Microprocessor  BOE: Building a mobile robot  Motors and sensors: hardware control  Robot programming: Meet the real world  Robot Exhibition: line following, obstacles

A Bit Further Down the Road  Looking at the bigger picture of computing  Internet: coding/decoding all the way down  Publish yourself on the web: HTML  Getting stylish, getting more control  Programming once again: Javascript  Video editing: Looks easy? Try it and see.  Video Exhibition: Show off your stuff

Another Approach: Computing seen from very large to very small  How about understanding computing by starting with the big picture? About people!  The largest tangible computing organization spans the entire world  Let’s start there and narrow down in search of the essentials to doing a computation  We will see this approach presents some problems!

Earth at Night

Internet Connections

Computer Motherboard

A Computer Diagram

Microprocessor Central Processing Unit (CPU)

Very Large Scale Integration View of Chip Interior

Individual Transistors

We are almost at the very bottom of the complexity tower! Question : What do we know is fundamental to (all) computers? Answer: Electricity So, to understand computers we should take the plunge and learn something about electricity.

Electricity and Computation (Short Version)  Electricity is the flow of electrons  Positively (+) charged areas attract electrons (-)  Conductors (metal) allow electron flow  Insulators (ceramic, air) prevent electron flow  We can control electricity by switches  Switches create a logic of on/off control  Off/on, false/true, 0/1 encodes numbers also  Arithmetic can be done using true/false logic  We can encode hardware control using 0/1’s

Electricity and Circuits A physical lamp circuit The corresponding schematic Single Pole-Double Throw SwitchAn LED circuit using Power/GND symbols

Circuits All Around You  How do I design a seatbelt safety circuit like the one in my car?  How do I add a door ajar feature as well?  How do I design a staircase lighting circuit like the one in my two story house?  What about my three story house?  What about my twelve story building?

What comes next?  Actually handle some components in lab and make some simple circuits: LEDs, etc  Think about how to make some useful circuits using simple switches  Combine switches to create logic circuits  Discover that logic and computation overlap in just the right way using base 2  Make a circuit that computes something!