LBSC 690: Assignment #1 (Fall 2008)

This assignment is due before class on 9/17. To turn in your assignment, send me an email with the subject "LBSC 690 assignment #1". In the message body, either type your answers to attach a document that contains the answer. Show your work, as it will provide an opportunity to receive partial credit.

Consider the specifications of a computer system that you might consider buying:

Processor type: Intel Core 2 Duo
Processor speed: 2.5 GHz
Hard drive: 200 GB, 10 ms access time
RAM: 2 GB, 50 ns access time
Peripherals: DVD-RW

Although we talked about modern processors having multiple "cores", for this assignment assume that all operations are performed by a single core. To simplify calculations, you can assume that 1 megabyte is 1,000,000 (one million) bytes, 1 gigabyte is 1,000,000,000 (one billion) bytes, etc.

Answer the following questions:

1. If you buy some 4.7 GB DVDs, how many would you need to back up a full hard drive to DVDs (assuming no compression)? At 30 cents per DVD, how much would a full backup cost? At 10 minutes per DVD, how long would a full backup take?

2. Now let's see how much stuff that hard drive can hold. Assume you have access to the following information for all 300 million people in the United States:

   Name: 40 characters
   Phone Number: 10 characters
   SSN: 9 characters
   taxes owed: one four-byte number
   

   Assume that each character is stored in one byte.

   Would all of these data fit on the hard drive of the computer described above? If not, how big a hard drive would you need? If so, what fraction of the disk would this fill?

3. Now let's see how long it would take to read that much data off the disk. Assume you have a hard drive large enough to store all the data.

   Suppose you wanted to add up the taxes owed by all 300 million people. Assume that you access the data in a random order, and that you start a new disk access for each person (in the specifications above I have provided the latency of disk access). How long would it take to access all the data? Could this be done in a second? In a minute? In an hour? In a day? In a month? In a year?

4. Assume for the sake of comparison that all of this data could fit in RAM.

   How long would it take to access all the data from RAM? In the specifications above I have provided the latency of RAM access. Could this be done in a second? In a minute? In an hour? In a day? In a month? In a year?

5. Which is faster, RAM or the hard disk?

6. Now let's see how long it would take to move the bits around.

   How long would it take to move the contents of your entire hard drive to your friend's computer in California over a modem? Over DSL? Over a dedicated T1 line? Overnight mail?

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This page, first created: 7 Sep 2008; last updated: