Squeezing, Errors and Limits: teacher key

How Computers Work, grade 12 edition, written for 12th grade and up. How data is squeezed and kept safe, how early machines led to chips, and what a Stanford course says about Moore's law.

Read the book. Print this page for the key.

Questions and answers

1. What does lossless compression keep?
   • All of the original detail (answer)
   • Only a sample
   • Only color
2. How much space does MP3 audio compression save?
   • None
   • About 10 times (answer)
   • About 2 times
3. What does a source file let you do that a compiled file does not?
   • Only run the program
   • Change the program (answer)
   • Wipe the RAM
4. What does a reboot do to the data in RAM?
   • Saves it to the drive
   • Wipes all of it (answer)
   • Squeezes it
5. What does error detection add?
   • Extra information (answer)
   • A smaller file
   • A second drive
6. What does Stanford's course say about Moore's law?
   • It never ends
   • It is a law of nature
   • It will probably not go on forever (answer)

Words

• lossless: keeps all detail
• lossy: discards some detail
• compiled: machine code file
• reboot: wipes all RAM