15110 SUMMER SESSION TWO - 2014

Problem Set 1 - due Wednesday, July 2 at 9:00AM in class

Reading Assignment

Read chapter 1 of the book Blown To Bits.

Instructions

• Type or neatly write the answers to the following problems.
• Please STAPLE your homework before you hand it in.
• On the first page of your homework, include your name, andrew ID, lab section (E or U), and the assignment number.
• You must hand in your homework at the start of class on the given due date.

Exercises (10 points total)

1. (1 pt) A picture of a Russian abacus is shown below. Why are there dark beads at the left end of the first row and fourth row of beads? Why is there a row with only four beads? (HINT: Research this on the Internet but answer in your own words... don't just cut and paste text from the web.)

   

2. (1 pt) Babbage's Difference Engine utilized the method of finite differences to compute the values of a polynomial function. Babbage computes the values of the function and all of its difference functions for x=0, and these values are given below. What does the machine compute for f(1), f(2), f(3) and f(4) when the machine is cranked?

   f(0) = 6
   Δf(0) = 3
   Δ²f(0) = 4
   Δ³f(0) = 7
   

3. (1 pt) Charles Babbage wants to compute all of the function values for the polynomial f(x) = 3x² + 6x + 7 for x = 1 to 1000. Using the method of finite differences, what initial values does he set his machine to if he wants it to start at x = 0? (HINT: You'll need to compute the difference (delta) functions first.)

4. (1 pt) Why was each of the following computational machines desperately needed at its time of invention? Be specific.
   1. Herman Hollerith's tabulating machine

   2. ENIAC

5. (1 pt) Punched cards have been used to encode data for tabulating and computing machines for nearly a century. First, determine the question encoded on the following standard IBM 80-column punched card and write this down. Then find the answer to the question.

   

   HINT: Look at the slides for Unit 1 and see how IBM encoded letters on its punched cards.

6. (2 pts) Show your work for each of the following problems.
   1. Moore's Law states that the processing power of a computer doubles approximately every 2 years. Based on this observation, how many years will it take to have a computer that is approximately a million times more powerful than today's computer?

   2. An electronic device has 512GB of memory. It is connected to a communication port that receives data at a rate of 8Mbps. How long will it take to fill up the memory of this device if it starts off as empty?

7. (3 pts) Based on your reading of Chapter 1 of Blown To Bits, answer the following questions.
   1. A common theme in computing is dealing with advances in technology that change exponentially. Exponential changes are often hard to see at first but become very obvious once it's too late to adapt. Give an example from this chapter of a company that didn't see exponential changes in its core business, resulting in massive layoffs and a major loss in revenue.

   2. Eliot Spitzer, former governor of New York, was forced to resign due to a prostitution scandal. How was his involvement detected digitally?

   3. Years ago, people copied songs on to cassette tapes and shared them with their friends, yet the recording industry didn't pursue these people for copyright infringement. Today, however, sending a friend a copyrighted mp3 file can get you into trouble. Why is the response different now?