15-110 FALL 2009 (CORTINA)

HOMEWORK 10 - due Monday, November 30, 2009 in class

Please remember that homework must be handed in on time. No late homework will be accepted.

Read the following short articles and answer the following questions in your own words (don't just quote the article).

How Moore's Law Works
How Operating Systems Works
How Internet Infrastructure Works
How Can A Totally Logical Machine Like A Computer Generate A Random Number?
How CAPTCHA Works

1. (2 pts)
   1. What is Moore's Law? How has it changed the size and power of computers?

   2. Will Moore's Law last indefinitely? If so, why? If not, why not?

2. (2 pts)
   1. What are the two main functions of an operating system?

   2. The operating system runs from your RAM (Random Access Memory) which is erased when the computer's power is turned off. How does the computer load the operating system into RAM and then run the operating system when your computer is turned on?

3. (2 pts)
   1. What is the role of a router on the Internet?

   2. Describe the format of an IP (Internet Protocol) address. What is it used for?

4. (2 pts)
   1. What properties are desirable for a good pseudo-random number generator?

   2. How do programs get a starting value (seed) for their random number generator to generate a different set of random numbers each time the program is run?

5. (2 pts)
   1. A CAPTCHA is based on the notion of a Turing Test. What is the Turing Test? Describe this in your own words.

   2. Why is a CAPTCHA hard to solve by automated computer programs?

      CAPTCHA and the new Re-CAPTCHA projects come from Carnegie Mellon University!
      Learn more about how researchers at Carnegie Mellon use Games With A Purpose to help computers get smarter! (DO YOUR HOMEWORK FIRST.)