hey all, notes in order of the exam spec (the syllabus), nothing extra, concise and handy, covers key definitions of ALL topics, including some helpful formulas. Good Luck :))

Topic 1: Fundamentals of Algorithms

What is an algorithm? :: set of instructions used to solve a problem or complete a task

What is decomposition? :: breaking larger problems into smaller, sub-problems so that each accomplish an identifiable task, which might itself be further subdivided

What is abstraction? :: Abstraction is the process of removing unnecessary detail from a problem

Topic 2: Fundamentals of Data Representation

Data structure :: way of storing and organizing a set of data, that can easily be edited/changed Subroutine :: named block of code which can be run by calling its name in a program

Function :: a procedure which has a return value Parameter – input variable for a subroutine Assembler :: converts assembly language (low level) into machine code

Interpreter :: converts high level programming into machine code (line by line)

Compiler :: converts high level programming into machine code (whole program at once)

Scope :: which part of a program can see variables/constants/data structures

here’s a neat little comparison table between assembler, interpreter and compiler:

Bit :: one unit of data

Character set :: defined list of characters recognized by computer’s hardware and software

Pixel :: single dot of colour in an image

Bitmap :: graphical image made up of pixels

Pixel resolution :: number of pixels in an image

Colour depth :: bits used per pixel

Sample :: measure of amplitude at a point in time

Sampling rate :: number of samples taken per second

Sample resolution :: number of bits used per sample

here are the important formulas for this topic:

File size of image (in bits) = width (pixels) x height (pixels) x colour depth (bits)

think of this one as a formula triangle, with file size at the top, and the three others below

File size of sound (bits) = sample rate (Hz) x time (sec) x sample resolution (bits)

again, file size is the top of the triangle, with the three others below

Topic 4: Computer Systems

Computer system :: combination of hardware and software used to perform tasks

Hardware :: physical part of a computer

Software :: programs that are downloaded/installed onto a computer

System software :: programs which help run and maintain a computer system

Application software :: programs which help the user perform day to day tasks

Operating system :: platform for hardware to use the software

Volatile memory :: temporary storage that is lost when power turns OFF (RAM)

Non-volatile memory :: permanent storage that is kept when the power turns OFF (ROM, HDD)

Cloud storage :: secondary storage, at a remote location which is accessible via the internet

Embedded System :: computer system with a specific purpose, built into another system/machine

RAM :: stores running applications while the computer is ON

ROM :: stores the BIOS (instructions needed to turn on the computer and cannot be edited) Cache :: stores the most frequently accessed instructions from the RAM (Level 1, Level 2, L3)

here is the memory pyramid

Level 1 cache is used around 50% of the time, Level 2 90%, so its no doubt that cache makes a big difference in the computer’s performance speed, as it is fast access memory location that is quicker to access than RAM and slower than registers.

Topic 5: Computer Networks

Computer Network :: a group of computers connected together to share resources

Network Protocol :: a set of rules which allow devices to communicate

Network Security :: methods which protect networks from unauthorised access and harm

Authentication :: verifying the user’s identity when accessing data/network, to prevent unauthorised access

Firewall :: protects network from unauthorised access by controlling incoming/outgoing network connections

Encryption :: scrambling data to change how it looks to prevent unauthorised access (only people with decryption key can access original)

Topic 6: Cyber Security

Cyber security :: methods which prevent data/programs from Attack, Damage and Unauthorised access

Penetration Testing :: testing the security of a system/network to find any vulnerabilities.

Black-box testing :: stimulates external hacking or cyber warfare attack

White-box testing :: stimulates malicious insider (spy) who knows something about the target system

Social engineering :: art of manipulating people to give up personal information/details Malware :: malicious software/code