CSC103 How Computers Work
Assignment 2

Due Thursday 24 Sep 09 (by midnight)

Please read Assignment and Quiz Rules first!

1. Here is a circuit made of AND and OR gates:
   
   
   It has three inputs, which I've labeled A, B, C.
   • What is its output when the three inputs are set as follows: A → 0,B → 1,C → 0.
   • What is its output when the three inputs are set as follows: A → 1,B → 0,C → 1.
   • What is its output when the three inputs are set as follows: A → 1,B → 1,C → 1.
   • Can you describe in words, succinctly, what it "computes"?
   Feel free to use the simulator here (but I can only get it to fully work under Windows). Although it is perhaps easier to just work it out from the properties of the AND and OR gates (detailed in Notes4).


2. I said in class that an OR gate can be built from AND and NOT gates. Show me a circuit composed of AND and NOT gates which behave like an OR gate (in its input/output behavior). You can either use the simulator linked above to test it out, or just draw your circuit on paper, or in some drawing program of your choice. Use the AND and NOT gate symbols above.


3. The Library of Congress is usually credited as the largest library in the world. If all of its cataloged books were digitized into text, about how many TB would that occupy? Try to find a reasonable answer to this question. Currently one can purchase 2TB disk drives. An array of how many such disks would be needed to hold the Library of Congress's information?


4. What is the largest capacity USB flash drive one can purchase today? Leave me a citation or a web address for your source.


5. How does the display of the Amazon Kindle (Kindle 1 or 2) work? Describe its functioning as clearly and succinctly as possible so that any intelligent person would have a good understanding from your explanation.