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(comp355)[2009](s)midterm-sol~PPSpider^_10209.pdf
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COMP 355 Embedded Systems Software
Spring Semester 2009
Midterm Examination
Date: 19 Mar. 2009 Time: 9:00 pm - 10:20 am
Name:___SOLUTION________ Student ID: ________________Email:____________________
Instructions
1. Please write your name, student ID and email address on this page.

2. Please answer all the questions within the space provided on the examination paper. You may use the back of the pages for your rough work.

3. This paper consists of 8 questions and 6 pages.

4. Please read each question very carefully and answer the questions carefully and clearly to the point. Make sure your answers are neatly written, legible and readable.

5. Show all the steps used in deriving your answer, wherever appropriate.




Question
Points
Score

1
10


2
10


3
10


4
10


5
10


6
10


7
20


8
20


Total
100






1. (10 points) Among the characteristics of embedded systems that are listed on p. 34-36 of the Introduction chapter, which do you think apply to an embedded system controlling an airplane? Briefly justify your choices.




Reliability: The system should never develop faults even if running for a long time
Performance: tasks must meet their deadlines. Its not necessary to be fast, but deadline misses are unacceptable.
Power, cost and memory size will not pose any significant limitations on the system.
(2 pts each for the characteristics, 2 pts each for reasoning, 2 points for the last sentence)





2. (10 points) The following questions are about embedded hardware

a) A software-defined radio is a software oriented approach built around a processor to handle the processing of radio signals completely in software. This will enable the design of mobile phones to act as a universal wireless device capable of handling wireless signals ranging from WiFi, GSM or CDMA. This requires the constant processing of incoming radio signals very quickly. Do you have a recommendation of a suitable CPU architecture for this purpose? Justify your choice in a couple of sentences.



Harvard architecture or Super-Harvard Architecture (1. pts).
We need to process a steady stream of data (signal processing) by performing the same set of operations which is typically handled by digital signal processing approach. Hence the Harvard architecture is better suited for this purpose. (1. pts).
b) Since NVRAM is very fast and can retain the data for a long time, why do embedded devices still prefer to use Flash memory? Briefly explain.



NVRAM still continues to draw power from the power source to maintain its contents. So it might drain out the battery after a long period of no activity.




3. (10 points) Buffalo Inc. has developed a new SD card slot compatible Wi-Fi Ethernet card for use on a Pocket PC. They are planning on writing a device driver for the card. What kind of