CSE 2312 - Assignments - Assignment 5

The assignment will be graded out of 100 points. Submit a file called answers.xxx (where you replace xxx with whatever extension is appropriate, depending on the file format you use), that contains answers for all tasks. Acceptable file formats are plain text, Word document, OpenOffice document, and PDF. Put your name and UTA ID on the first line of the document.

Submit your answers.xxx file to Blackboard before the deadline. You will be able to revise your answers until the deadline with no penalty.

IMPORTANT: By submitting your answers, you are certifying that you have followed the UTA standards of academic integrity, and that these answers have been exclusively your own work. All students enrolled in this course are expected to adhere to the UT Arlington Honor Code:

I pledge, on my honor, to uphold UT Arlington's tradition of academic integrity, a tradition that values hard work and honest effort in the pursuit of academic excellence. I promise that I will submit only work that I personally create or contribute to group collaborations, and I will appropriately reference any work from other sources. I will follow the highest standards of integrity and uphold the spirit of the Honor Code.

Task 1 (20 pts.)

You have come up with a parity bit scheme, to be able to do error detection on your company's data. Your parity bit scheme uses one parity bit for every 4 bits of original data.

Your colleague suggests that it is a better idea to use 1 parity bit for every 1000 bits of original data. Your colleague's argument:

in both cases (1 parity bit per 4 bits or per 1000 bits) you can detect one error, not more, so the error detection power of both schemes is the same.
The second case is much more efficient storage-wise.

Is your colleague's argument correct? Justify your answer.

Task 2 (20 pts.)

We know that an error detection method that uses a single parity bit allows us to detect one error per codeword, but does not allow us to correct this error.
We also know that a RAID-5 with 10 disks stores each nine bits of original data as a 10-bit codeword, by simply adding a parity bit to the original nine bits of data. However, when a disks breaks down, a RAID-5 can not only detect that something is wrong, but can also recover the original data.

Do these two statements contradict each other? If a single parity bit can only do error detection and not correction, how can this RAID-5 array figure out the contents of a lost drive using a single parity bit per 9 bits of original data? Justify your answer.

Task 3 (10 pts.)

(This is Problem 28 from Chapter 2 of the textbook).

A monitor has a resolution of 1920 x 1080 pixels, and uses three bytes for each pixel (corresponding to the red, green, and blue components of the color of that pixel). The display is redrawn 75 times a second. The information on what to display is sent from the main memory to the monitor using a 1-bit channel. How long is the pulse corresponding to one pixel? In other words, how much time does it take for the monitor to receive enough information to specify the color of the pixel in the next redrawing?

Task 4 (10 pts.)

(This is Problem 32 from Chapter 2 of the textbook).

A digital camera has a resolution of 3000 x 2000 pixels, with 3 bytes/pixel for RGB color. The manufacturer of the camera wants to be able to write a JPEG image at a 5x compression factor to the flash memory in 2 sec. What data rate is required?

Task 5 (10 pts.)

(This is Problem 33 from Chapter 2 of the textbook).

A high-end digital camera has a sensor with 24 million pixels, each with 6 bytes/pixel. How many pictures can be stored on an 8-GB flash memory card if the compression factor is 5x? Assume that 1 GB means 2³⁰ bytes.

Task 6 (20 pts.)

(This is Problem 34 from Chapter 2 of the textbook).

Estimate how many characters, including spaces, a typical computer-science textbook contains. How many bits are needed to encode a book in 8-bit ASCII (7 bits for the ASCII code and 1 bit for parity)? How many CD-ROMs are needed to store a computer-science library of 10,000 books? How many single-sided, dual-layer DVDs are needed for the same library? Justify your answer.

Task 7 (10 pts.)

(This is Problem 1 from Chapter 5 of the textbook).

A word on a little-endian computer with 32-bit words has the numerical value of 3. If it is transmitted to a big-endian computer byte by byte and stored there, with byte 0 in byte 0, byte 1 in byte 1, and so forth, what is its numerical value on the big endian machine if read as a 32-bit integer?

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