MODD / Mr. Hansen
10/15/2010

Name: _______________________

General Instructions: Raise your hand if you have a question. Write answers in the space provided. If you need additional room, write "OVER" and use reverse side.

Part I: Essay.

1.

Explain, in general terms, how undersampling of a digital image can lead to “banding” patterns. What are these bands called?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.

State Nyquist’s Theorem (the “sampling theorem”) in general terms. Exact precision is not required, since it is a fairly difficult theorem. Come as close as you can.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3.

State one advantage that two’s complement representations have over one’s complement.


Part II. Computation. Please show adequate work. After you have computed an answer for all the questions, you may use Mr. Hansen’s computer to check your answers.

 

4.

Convert the following bitstream to (a) big-endian hex and (b) little-endian hex using 16-bit words:

0100101010101111010101010101001101010101010110100101011010100000

 

 

(a)

 

 

 

 

 

(b)

 

 

 

 

 

5.

Perform the following additions in hex:

0BBF
+288
_____



0818
+EEE
_____

 

 

 

 

 

 

 

 

6.

Perform the following hex subtractions using two’s complement arithmetic, showing enough work so that it is clear that you know what you are doing. You may check your answer using borrowing and regrouping, of course. If your answer represents a negative number, be sure to indicate that. Then reinterpret your final answer as a decimal number using conventional human notation.

 

 

 

0415
−6E7
_____

 

 

 

 

 

 

 

 

 

 

 

03CC
−2FB
______


Part III. Bits, Bytes, Hex, Hertz, and Moore’s Law

7.

Suppose that a certain computer capability costs me $1000 to acquire today. Approximately how far in the future will it be before I can acquire the same hardware capability for about $1? Show your work, and write a sentence or two.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8.

In our class, we define a kilobyte to be ________ bytes or ________ bits.

 

 

9.

How many megabytes are in a terabyte? Give both an approximate answer and an exact answer. Exponential notation is acceptable.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10.

Mr. Hansen’s old antique laptops have a clock speed of about 2.5 MHz. Modern computers are generally between 2 and 3 GHz in their clock speed. How much faster is this (to the nearest order of magnitude)? [“Order of magnitude” refers to powers of 10.]

 

 

 

 

 

 

 

 

 

 

 

 

11.

What do we mean when we say that a modern computer runs at, say, 3 GHz? What are we talking about, in plain English?


 

12.

I wish to perform digital audio sampling of a 3-minute song using 2-channel stereo, a bit depth of 16 bits per sample, and a sampling rate of 44.1 KHz. Compute the data requirement (uncompressed). Show work.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

13.

How many different colors can be represented with a bit depth of 8 bpp for digital imaging?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

14.

Unless the palette is carefully optimized in #13 to choose the “best” colors for the image, the image will almost certainly exhibit what artifact? _____________

 

 

15.

Does a higher resolution (megapixel count) help to solve the problem in #14? Why or why not?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

16.

Explain, in general terms, how it is possible for a car wheel in a TV advertisement to appear to be stationary (or even turning backwards!) when the ad is shot at 30 frames per second. Diagrams may be helpful.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

17.

Make a circuit diagram fragment to show the concept of (~A) NAND (~B). Then give a truth table proof to show that (~A) NAND (~B) is equivalent to A OR B.