IB Final Papers Revision

Just a last reminder to help you prepare for your IB final papers.

• https://youtu.be/hP5TNI_2VRs how to keep focused (general advice)
• This former IB DP CS student summarises the general recommendations we have shared in class: https://youtu.be/RtWxiryDrek
• http://www.teachcomputing.net/ib/computer-science.html
• http://ibcomp.fis.edu
• I've updated my blog with links to topics you requested in class: http://technomess.blogspot.com/search/label/ib

Best luck in your revision and finals!

FDE Cycle

Fetch-Decode-Execute Cycle

Links with information about the FDE cycle, from simple & concise to deeper and more detailed:

• GCSE Bytesize (Instructions)
• The Fetch–Execute cycle and the role of registers within it (A level Computing WikiBook)
• Also known as the Instruction cycle (Wikipedia article)

An excellent flow chart depicting the FDE cycle (original source https://en.wikipedia.org/wiki/Instruction_cycle):

Plus a nice animation demonstrating how the fetch-decode-execute cycle works, made using Scratch:

• https://scratch.mit.edu/projects/2145440/

I have also made my own, simplified version for study and revision purposes:

Algorithms and Abstract Data Types HL

Resources about various algorithms - Higher Level:

1. http://www.algolist.net/Algorithms/ - various algorithms (sort, binary search) and programming concepts (recursion) explained
2. From this link, be sure to revise the sequential and binary searches, plus the chapters on sorting algorithms and recursion (code examples are on Python, which means it's close to pseudocode, but you can run it if you have the Python 3 interpreter)
3. http://introcs.cs.princeton.edu/java/40algorithms/ - an excellent chapter on Algorithms and Data Structures; there was a performance question in a recent past paper, so it may be a good idea to read 4.1 (performance) as well. Don't obsess over Tilde notation and skip memory usage as well. Our focus is to be aware of how some algorithms are more efficient than others (as you can see by their classification into their order of growth: constant, logarithmic, linear, quadratic, cubic, exponential, etc.)
Stacks and Queues
Binary Search Trees

Resources about Abstract Data Types:

• http://www.webopedia.com/TERM/A/abstract-data-type.html
• http://www.csanimated.com/animation.php?t=Abstract_data_type
• http://www.csanimated.com/animation.php?t=Stack
• http://www.csanimated.com/animation.php?t=Queue
• http://www.csanimated.com/animation.php?t=Linked_list
• http://visualgo.net/en/list.html - animated ADTs (linked list implementations)
• Chapter on Linked Lists, from the same site as #2 in the previous list of links ;-)
• http://www.algolist.net/Data_structures/ - well explained and clear diagrams
• HackerRank's algorithms YoutTube playlist
• HackerRank's data structures YoutTube playlist
• mycodeschool's YouTube playlist on data structures. Examples are in C/C++, but their explanations and diagrams are great!
  

2D Arrays and IB Pseudocode

This brief post shows how to create a bi-dimentional array and describe it using IB pseudocode. It isn't stated in the IB Pseudocode in Examinations or Approved notation for developing pseudocode documents, so it's my answer to it, not an official one. Don't sue me if your examiner disagrees with me! O_o

declare A as integer array of size [ROWS][COLUMNS] or
declare A as integer array of size (ROWS, COLUMNS)
declare A as integer array of size [5][6]
declare A as integer array of size (5, 6)

Obviously, integer should be replaced by the appropriate data type.
IB papers may have defined it for you, or they may not ask you at all to define the size. You could define it (unknown size) as

declare A as integer array of size [ ][ ]

...then you'd use it like

loop ROW from 0 to 5
    loop COL from 0 to 6
        output A[ROW][COL]     or    output A(ROW, COL) 
    end loop
end loop

I'd recommend going for the [ ][ ] style as it'd be more consistent with the single dimensional arrays described in the IB pseudocode documents mentioned above.

Network and security

A very comprehensive glossary of network terms, obviously not all required for our examinations and syllabus, but they are extremely valuable.
Also, links to how stuff work's networking and security.

• Here is a great Networking Tutorial for beginners with pretty much all computer networking essentials covered.

Although you don't need to memorise the OSI reference model, awareness of the layered nature of networks is very important.

• http://www.computerhope.com/jargon/network.htm
• http://computer.howstuffworks.com/computer-networking-channel.htm
• http://computer.howstuffworks.com/security-channel.htm
• http://www.webopedia.com/quick_ref/OSI_Layers.asp
• http://searchnetworking.techtarget.com/definition/OSI 
• http://searchnetworking.techtarget.com/feature/Wireless-encryption-basics-Understanding-WEP-WPA-and-WPA2
• http://www.webopedia.com/DidYouKnow/Computer_Science/WEP_WPA_wireless_security.asp

And finally, a slideshow on error detection and correction:

Computer Networks - Error Detection & Error Correction from Saikrishna Tanguturu

What is usability?

I have been looking for useful definitions of usability within the context of Computer Science.

I'll update this post as I find more and better resources.

• http://www.usabilityfirst.com/glossary/usability/
• https://msdn.microsoft.com/en-us/library/ms997577.aspx

Binary Search Trees

Best Links to Revise: Binary Search Trees (BSTs)

• http://visualgo.net/bst.html - animated binary search trees (BSTs)
• http://www.algolist.net/Data_structures/Binary_search_tree
• http://www.geeksforgeeks.org/618/ - BST traversals
• A great wikibook for A Level Computing including the best way to learn BST traversals
• http://www.cs.swarthmore.edu/~newhall/unixhelp/Java_bst.pdf - slideshow on BSTs
• https://www.cs.rochester.edu/~gildea/csc282/slides/C12-bst.pdf - more slides on BSTs; recommended to read up to and including the topic on deleting a node from a BST
• Trees and tree algorithms from the interactivepython.org

Java programming

Just a couple of great online resources on Java programming:

• http://howtodoinjava.com/2013/06/07/5-class-design-principles-solid-in-java/
• http://www.ntu.edu.sg/home/ehchua/programming/
• http://introcs.cs.princeton.edu/java/home/
• http://nclass.sourceforge.net/downloads.html

Hope this helps!

SLC

Resources to revise Systems/Software Development Life Cycle:

• https://en.wikibooks.org/wiki/IB_Computer_Science/Science_Systems_Life_Cycle_and_Software_Development/Systems_Life_Cycle
• http://www.doc-department.com/what-are-user-documentation-and-technical-documentation/

Algorithms Videos 2015

2015 collection of links to videos of sorting (and searching) algorithms:

Bubble sort:

• https://youtu.be/UnK5ueUgc88
• https://youtu.be/y_Nuui4Qf-k
• https://youtu.be/P00xJgWzz2c

Insertion sort:

• https://youtu.be/Fr0SmtN0IJM
• https://youtu.be/UUswQbT6xQc
• https://youtu.be/c4BRHC7kTaQ

Selection sort:

• https://youtu.be/TW3_7cD9L1A
• https://youtu.be/Aq2E47uU2ao
• https://youtu.be/6nDMgr0-Yyo

Binary and linear search:

• https://youtu.be/wNVCJj642n4

OS process management

Found a really good summary about the different techniques used by processors to manage tasks/processes. For our syllabus, we are concerned about multi-tasking and time sharing, but if you're curious, other important and related concepts are also explained (i.e. multi-processing and multi-threading).

• http://www.8bitavenue.com/2012/10/difference-between-multiprogramming-multitasking-multithreading-and-multiprocessing/

IB Computer Science Exam Revision

Hi there!

I will be using this blog to save and manage my resources for the computer subjects I teach. I may transfer them later to a wiki, which in my opinion is the ideal format for this, but I want to try the blog format first, as I will do my best to post every time we are meant to have a lesson (both standard and higher levels). If you subscribe, you should get notifications as soon as I post an entry, and perhaps this way you can also study "on the go"/wherever you are.

A full list of topics for IB Computer Science can be found here.
A couple of glossaries of Computer Science terms can be downloaded from our school's online class resources.

Hope you will find this useful. Mainly for my awesome IB Computer Science students, but this may also be useful if you're taking (I)GCSE ICT/Computer Science and similar courses.

I will be working on a "Table of contents" blog entry as well, which I will post separately and link to this entry as well, so if you're interested, keep an eye on this blog!

Thanks for reading and best luck!

tM.

VPNs

On the concept, advantages and disadvantages of VPNs:

• http://computer.howstuffworks.com/vpn.htm (excellent explanation, but no need to read beyond page 5)
• https://youtu.be/DhYeqgufYss (a good video explaining VPNs)
• https://youtu.be/IWcgvOPYPgw ("infomercial" about VPNs, nice animations, but more of a commercial than a source of information, beware)

IB Computer Science Topic 3: Networks - Types of networks