Computer Systems
Computer Systems
Examination Format
&
Preparation
Examination Process
The School’s guidance is definitive. These notes are just to help you
• The January exams for all modules will take place
online.
• The exam for Computer Systems is at:
• Wednesday, January 12, 09:30-12:00 UK time
• All exams have the following durations:
• 1 hour 30 minutes for the exam itself
• An extra 1 hour to allow for resolving any internet
connectivity issues and typing up, scanning and
uploading your answers, giving a total of 2 hours 30
minutes to complete the exam and your submission
• Finally, late submissions will be accepted, with penalty,
for a further 1 hour
• Any further queries about the exams (either before
or during the exam) should be emailed to:
.ac.uk
Notes:
• Prepare your answers in a word processor and
generate a .pdf document
• You can include images etc. as necessary
• You must make sure that everything is easily readable
• You can submit multiple times:
• The last version is the one that will be marked
• Practice!
• Your answers must be entirely your own work
• But see school’s detailed guidance
• My advice:
• Use a word processor
• If you want to include pictures/diagrams, then do them
on paper, scan them and include in your document
• Submit an early version and then review. You can
upload revised versions.
Module Content
Numbers
Memory, CPU & Program Execution
Instructions Assembly and Machine Code
High and low level; Compilation and Interpretation
Subroutines and Stacks
Java Virtual Machine (JVM) and Bytecode
Efficiency (Algorithm Complexity)
Introduction to OS and its Elements
Computer Systems Architecture and OS Structures
Process Management
Process Scheduling
Multithreading and its Challenges
Concurrency and Synchronization
Deadlocks
Introduction to Networks
Application Layer
Transport Layer
Network Layer
Network Security
Preparing for examinations
• Understand the course content
• Study
• Revisit exercises & Quizzes
• Look at the example paper
• Make sure that you are in a fit state to take the
exam:
• Concentrate & focus
• Sleep well
• Have a light meal beforehand
• …….
• Read the Questions:
• What is being asked?
• What is the weighting of parts?
• Answer the questions
• Completely!
• Give 3 Reasons …..
• And that they are different
• Using Examples …..
• Compare and contrast/Advantages and Disadvantages
• Be explicit!
• Don’t assume that marking is done globally:
• You might say X in Q1 ii) – but that will not get you credit
in Q2 iii) !
• Make sure your answer is clear, understandable, legible
……
• Think about the question & your answer from the
examiners’ perspective!
Format of examination
• 3 questions
• Answer all questions
• Each question may have subparts
• These subparts may not be related
• There will NOT be any ‘recall’
questions:
• All questions expect you to apply your
understanding
• Every paper is marked out of 60
• Each question carries 20 marks
• The marks for each subpart:
• May vary
• Are shown explicitly
• The overall mark (out of 60) is
scaled to a percentage
• Overall grade:
• 50% Examination
• 50% Continuous Assessment
Computer Systems
Sample Questions
Example Question #1
The diagram below shows roads connecting towns near to Rochdale.
The numbers on each arc represent the time, in minutes, required to
travel along each road. Peter is delivering books from his base at
Rochdale to Stockport. Use Dijkstra’s algorithm to find the minimum time
for Peter’s journey.
Example Question #2
Consider that you live in a small town where only dial-up access is
available, with a maximum possible speed of 300-Kbps (using
V.44 modems). You are interested in uploading a large video file of
2 gigabytes to a server on the Internet.
A bus visits your town everyday from the closest city, which is
located at 210km away, and stops in front of your house for 5
minutes max (but it can leave as soon you indicate you are done).
The bus has a 100- NAME Fi connection and it can collect data
from users in rural areas and transfer them to the Internet through
a 2-Gbps link once it gets back to the city.
Suppose the average speed of the bus is 70 km/h. What is the
fastest way the user can transfer the data to the server?
Example Question #3
You are designing a network for a multinational corporation with
offices in 50 different countries. Each office is required to be on a
different subnet and the corporation has obtained a Class B
network address of 150.32.0.0.
Design subnets for all of the site offices and indicate how many
hosts (usable ones) can be assigned to each site office. Also,
indicate if there is any room for expansion to 10 more countries,
using the same network IP address and subnetting scheme.
You are not required to list all subnets, however, you can mention
the subnet addresses, subnet masks and host address ranges for
the first three and last subnet.
Example Question #4
Consider the block cipher shown in the following figure.
(see the question in the next slide)
Example Question #4 (contd)
Suppose that each block cipher Ti simply reverses the order of the eight
input bits (so that, for example, 11110000 becomes 00001111).
Further suppose that the 64-bit scrambler does not modify any bits (so
that the output value of the mth bit is equal to the input value of the
mth bit).
(a) With n = 3 and the original 64-bit input equal to 10100000 repeated
eight times, what is the value of the output?
(b) Repeat part (a) but now change the last bit of the original 64-bit
input from a 0 to a 1.
(c) Repeat parts (a) and (b) but now suppose that the 64-bit scrambler
inverses the order of the 64 bits.
Questions?
• Post in the chat