Week 4

This unit's written assignment will have your second Impacts of Computing prompt.

Upon finishing this learning module, you should be able to:

  • Identify and evaluate the basic Boolean logic rules.
  • Predict the output of a simple logic circuit
  • Describe how asymmetric (public-key) cryptography can be used to either authenticate a message or send a secret message
  • Describe how certificate authorities provide a basis for trust on the Internet
  • Design a simple program via decomposition
  • Define a Python function that returns the result of a calculation

Boolean Logic and Circuits

Boolean Logic

Read about Boolean logic rules in sections 5.1–5.4 of Welcome To CS.

Explore the short Boolean Practice worksheet.

Logic Circuits

Read about logic gates and circuits in sections 5.5–5.8 of Welcome To CS. Don't worry about memorizing the details in 5.7 and 5.8. They are examples of how circuits do “real” work in a computer that you should check out, but you are not responsible for knowing them.

Explore the Circuit Practice worksheet. You can use the Circuit Playground to build and test the circuits on the worksheet. This video shows how to use it.

Optionally, watch this video, which does a good job of tying together bits, binary, logic and circuits. If you are still feeling a little fuzzy on how bits and gates and circuits all tie together, I highly recommend checking it out. Don't stress the details from minutes 7–10, just focus on the big picture of how circuits manipulate on/off values to do math in a computer.

Algorithm of the Week: Public-Key Encryption

Read the Authentication and Public-Key Encryption supplement. Make sure to read all the way through until the page titled “RSA”. This material is a replacement for chapter 9 in Nine Algorithms.

Optionally, read chapter 9 of the Nine Algorithms book. It covers similar ground to the reading above. However, the Nine Algorithms chapter has a slightly different focus—feel free to read it as a second perspective on this unit's algorithm.

Optional Extras: Domino Computer and Blockchain

You can build a computer's logic gates with almost anything, even dominoes!

Bitcoin is a digital currency that uses cryptography to record transactions so that they can be verified by everyone who uses Bitcoins. This video explains how it works.