# Computer and Number Systems Assignment Questions 2015

August 30, 2017

Question
Computer and Number Systems

1. (10 pt) You have been hired to develop a website-based sales system for a large international retail firm. List and describe at least four features that are specific to the Web design of your system and customer service important to consider if your system is to be successful at attracting and keeping customers living outside of the US. Include not only characteristics of the user interface, but those issues that must be uniquely addressed to successfully service your non-US customers.

2. (2.5 pt each) In order to receive credit for these problems, you must show all of the steps you took to arrive at your answers.

(c) Convert the following decimal number to binary:
51948

(d) Convert the following binary number to decimal:
11010100111011.10111

(c) Convert the following hexadecimal number to decimal:
CA97B

(d) Convert the following binary number to hexadecimal:
1110011111011010101

CPU and Memory

3. (10 pt) ASCII, Unicode, and EBCDIC are, of course, not the only numeric / character codes. The Sophomites from the planet Collegium use the rather strange code shown in the Figure below. There are only thirteen characters in the Sophomite alphabet, and each character uses a 5-bit code. In addition, there are four numeric digits, since the Sophomites use base 4 for their arithmetic. Given the following Sophomite sequence, what is the corresponding binary message being sent by the Sophomites?

(HINT: Decode the sequence reading from left to right then write the corresponding binary sequence, leaving a space between each binary sequence.)

4. (10 pt) Define memory cache write-through and write-back techniques and describe the advantages and disadvantages of each.

Input / Output

a. (5 pt) When an interrupt occurs, what happens to the program that is currently executing at that time?

b. (5 pt) Describe how these steps differ in the case when a system receives multiple interrupts

Computer Systems

a. (5 pt) Describe how you might use a cluster to provide fault-tolerant computing

b. (5 pt) Describe how you might use a cluster architecture to provide rapid scalability for a web-based company experiencing rapid growth.

Networks

a. (5 pt) Using the operations of UDP (User Datagram Protocol) and TCP (Transmission Control Protocol) as a basis, carefully explain the difference between connectionless and connection-oriented communication.

b. (5 pt) If you were ordering a number of items from an online seller, such as amazon.com, which Protocol (TCP or UDP) would you recommend and explain why.

8. In the context of network security,

a. (3 pt) explain the purpose of non-repudiation.

b. (3 pt) How does non-repudiation differ from authentication?

c. (4 pt) Create a business scenario that illustrates the importance of each.

Data Communications

9. (2 pt each) Circle or highlight the correct answer to the following questions / statements about data communications:

(a) What characteristic of an analog signal is measured in Hertz, or cycles per second?

a. Amplitude c. Phase

b. Frequency d. Skew

(b) What measurement unit describes the speed and capacity of a communication channel?

a. Throughput c. Response Time

b. Access Time d. Data Transfer Rate

(c) ____ can be produced by a variety of sources, including electric motors, radio equipment, and nearby power transmission or communication lines.

a. EMI c. Distortion

b. Attenuation d. Signal/noise (S/N) ratio

(d) A(n) ____ can extend the range of an electrical signal by boosting signal power to overcome attenuation.

a. repeater c. amplifier

b. return wire d. signal wire

(e) Which of the following does not allow multiple messages to be carried on a single channel?

a. time division multiplexing c. packet switching

b. frequency division multiplexing d. half-duplex

Operating Systems

(a) (5 pt) List and explain at least two of the definite advantages to the use of a command line interface (CLI) over other types of interfaces.

(b) (5 pt) There are some capabilities that are easy to achieve with a GUI (graphical user interface), but much more difficult with a CLI. Describe at least two of these capabilities.

File Management

a. (5 pt) Use the following four processes that have arrived in the ready queue in the sequence shown below and answer the following about process scheduling:

Process 1 has a total run time of 25 seconds and a priority of 2, but it will require 15 seconds of I/O after 10 seconds of execution
Process 2 has a total run time of 30 seconds, a priority of 1, but it will require 10 seconds of I/O after 20 seconds of execution
Process 3 has a total run time of 15 seconds and a priority of 3
Process 4 has a total run time of 20 seconds, a priority of 2, but it will require 15 seconds of I/O after 5 seconds of execution
(i) Both shortest job first and non-preemptive priority queue scheduling algorithms will complete all four processes at the same time, but not in the same order. In which algorithm will Process 1 finish first? Provide the time Process 1 finishes and explain your answer.

(ii) If the round robin scheduling algorithm is used, which process will finish first? At what time will it complete?

b. (5 pt) Using a variable-partitioned multiprogramming memory, which of the four holes shown below will be used to satisfy a 40 KB program requirement under the conditions of:

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0-15 KB

15-40 KB

40-125 KB

125-155 KB

155-275 KB

275-330 KB

330-420 KB

420-470 KB

470-505 KB

occupied

Hole A

occupied

Hole B

occupied

Hole C

occupied

Hole D

occupied

___ Best-fit

___ Worst-fit

Internet

12. (10 pt) Show the bit pattern in an asynchronous transmission with even parity if the data to be sent is the character string “FINAL”. Use 7-bit ASCII code found in Englander’s Figure 4.3 (page 102) and be sure to include start and stop bits.

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