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# 2020-09-21

- Checked out Stellarium which is awesome but is harder to use than Starry Sky
- Looking at gravity and orbits

- Chapter 3 reading
- Addressing on networks

- Lecture outcomes
- Distinguish analog vs digital
- Explain compression and calculate compression ratios
- Do text compression
- Explain the nature of sound
- Explain how RGB define color
- Distinguish between raster/vector graphics Todo
- Explain temporal/spatial video compression

- Data
- Values or facts
- Can be unstructured
- Lack context
- All data is stored as binary digits (bits)

- Information
- Data organized and/or processed in a way that is useful in solving some kind of problem

- Analog vs digital
- Analog --> infinite
- Continuous representation
- Analogous to actual information it represents

- Digital --> finite
- Computers are limited by memory
- Represent
*enough*of the world to satisfy computational needs and our senses - Discrete representation
- We can only represent data with
`0`

s and`1`

s

- We can only represent data with
- Breaks up information in separate elements

- Analog --> infinite
- Electronic signals
- Audio information
- Digitized by:
- Sampling --> periodically measure the voltage
- 40,000 times per second

- Quantization --> represent voltage as a number using finite number of bits

- Sampling --> periodically measure the voltage

- Digitized by:
- Color depth
- HiColor
- 16 bits

- TrueColor
- 24 bits

- HiColor