HW 1. Due: Wed Sep. 27. CS105: Great Insights in Computer Science Michael L. Littman, Fall Rules

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1 HW 1 Due: Wed Sep. 27 CS105: Great Insights in Computer Science Michael L. Littman, Fall 2006 Covering Lectures 1, 2, and 3 Rules You may work together, but you are expected to turn in your own writeup of answers. HW is due at the beginning of class. questions to: - Michael <mlittman@cs.rutgers.edu> - Monica Babes <babes@cs.rutgers.edu> - John Asmuth <jasmuth@gmail.com>

2 1. Python Check Download and install python: (windows), python/2.5/python-2.5-macosx.dmg (mac). Download my barcode program to your desktop and double click: python/upc.py Python Check (contd) Now, type in to the first box and to the second. Press enter to see the barcode. (A) Take the check digit that appears. What is it? (B) Enter all 12 digits in a row (no spaces) into Google. What product does this UPC refer to?

3 2. Barcode Hopping Find two different UPC-A (12-digit) barcodes from products from the same company. (Remember, the company is the 5 digits starting at the second one.) (A) What are the products and the codes? 3. What s Missing? I ve hidden three of the digits from the barcode on the next page. (A) What digit is behind the (first) blue box? Hint: You can use the python program to see which digit makes the bars look right. Or, you can carefully count the bars and lines and use the lecture notes to disclose the digit. (B) What digit is behind the (2nd) red box? (C) What is the check digit (3rd, green box)?

4 What s Missing? (contd) 4. Pictures and Words byte = 8 bits mega = a million giga = a billion pixels = picture element, typically specified by one byte each of R, G, and B intensity MB = megabyte Kbps = kilobits per second kilo = a thousand video rate = frames per second audio rate = 128 Kbps

5 Pictures and Words (contd) (A) A 3MP digital camera has an image size of 2048 x 1536 pixels. How many bits is a picture from this camera? (B) At normal speaking rates, a person takes about 350 seconds to say a thousand words. How many bits is a thousand words recorded at 128 Kbps? 5. Relay Circuit a. Fill in the truth table for this relay circuit. b. Invent a name for this logic gate. A A B C False False False True True False True True B power source C

6 6. Invent a Bit Bits can be represented many ways. Make a new way. It doesn t have to work---it should be creative and sound plausible. Describe: a. How does it encode 1/0? b. How do bits move? c. How do bits spread? d. How do you build a not gate? e. How do you build an or gate? 7. AntoNim9 There s a pile of 9 objects to start. On her turn, a player can take away either one or two objects. Players alternate. The player to take the last object loses.

7 Win AntoNim9 (contd) Go to courses/cs105-06b/python/. Put the following files on your desktop: - nim9.py, lightbulboff.gif, lightbulbon.gif, sw_off_gray.gif, sw_on_gray.gif Double click nim9.py (you might have to tell it to open the file with python). Win AntoNim9 (contd) (A) What sequence of switches should you flip to guarantee a win (light the You Win bulb)?

8 8. What Can They Be? A B C False False False False True True True False False True True True A B C False False False False True False True False True True True False (A) Write a logical expression (C = something that can include As, Bs, nots, ands, and ors) to match the truth table on the left. (B) Write a logical expression (C = something that can include As, Bs, nots, ands, and ors) to match the truth table on the right. (A) 9. True or False? (False or (not True and False)) or (True and False) (B) (not not not ((True and False) or True) or not False) or (False and not False) (C) ((not not True or not not False) or not False) and (not False or ((not not False or False) or False))

9 10. Equal32 To compare two 32-bit patterns to see if they are identical, we can construct an equal32 gate. (A) Using the equal5 gate as a guide, figure out how many and, or, and not gates would be needed to make an equal32 gate.