Full Definitions and Terms

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Chapters

A1.1 Computer Hardware and Operation (67) A1.2 Data Representation and Computer Logic (45) A1.3 Operating Systems and Control Systems (44) A2.1 Network Fundamentals (38) A2.2 Network Architecture (31) A2.3 Data Transmission (32) A2.4 Network Security (26) A3.1 Database Fundamentals (25) A3.2 Database Design (22) A3.3 Database Programming (29) A4.1 Machine Learning Fundamentals (32) A4.4 Ethical Considerations (21) B1 Computational Thinking (21) B2.1 Programming Fundamentals (30) B2.2 Data Structures (17) B2.3 Programming Constructs (15) B2.4 Programming Algorithms (13) B2.5 File Processing (7) B3.1 Fundamentals of OOP (17)

A1.1 Computer Hardware and Operation

67 terms, 106 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
CPU (Central Processing Unit)	[2]	The main processing component of a computer that fetches, decodes and executes program instructions. [1] Contains the ALU, the CU and registers. [1]	processing, fetches, decodes and executes, ALU, CU, registers
ALU (Arithmetic Logic Unit)	[2]	Part of the CPU that carries out arithmetic operations (add, subtract). [1] And logical operations / comparisons (AND, OR, NOT, greater than). [1]	arithmetic, logical, comparisons
CU (Control Unit)	[2]	Part of the CPU that directs and coordinates the other components. [1] Decodes instructions and sends control signals to the ALU, memory and I/O. [1]	directs and coordinates, Decodes, control signals
Register	[2]	A very small, very fast storage location inside the CPU. [1] Holds the data, instruction or address the CPU is currently working on. [1]	fast storage location inside the CPU, currently working on
Program Counter (PC)	[1]	Register that holds the memory address of the next instruction to be fetched. [1]	memory address, next instruction
Instruction Register (IR)	[1]	Register that holds the current instruction being decoded and executed. [1]	current instruction
Memory Address Register (MAR)	[1]	Register that holds the address in memory that is about to be read from or written to. [1]	address, read from or written to
Memory Data Register (MDR)	[1]	Register that holds the data or instruction that has just been read from memory or is about to be written to memory. [1]	data or instruction, read from memory, written to memory
Accumulator (AC)	[1]	Register that stores the intermediate results of calculations done by the ALU. [1]	intermediate results, ALU
Bus	[2]	A set of parallel wires / communication pathway that carries signals. [1] Between the CPU, memory and I/O devices. [1]	parallel wires / communication pathway, CPU, memory and I/O
Address bus	[2]	Carries memory addresses from the CPU to memory. [1] Is unidirectional (one way). [1]	memory addresses, unidirectional
Data bus	[2]	Carries the actual data and instructions between CPU and memory. [1] Is bidirectional (both ways). [1]	data and instructions, bidirectional
Control bus	[1]	Carries control signals (read, write, clock, interrupt) between the CU and other components. [1]	control signals
GPU (Graphics Processing Unit)	[2]	A processor with thousands of simple cores designed for parallel processing. [1] Used for graphics rendering and other tasks that repeat the same operation on lots of data (e.g. machine learning). [1]	thousands of simple cores, parallel processing, graphics rendering, machine learning
Integrated GPU	[2]	A GPU built into the same chip as the CPU. [1] Shares system RAM, so it is cheaper and uses less power but is less powerful. [1]	built into the same chip as the CPU, Shares system RAM
Discrete GPU	[2]	A separate graphics card with its own processor. [1] Has its own dedicated VRAM, so it is more powerful but costs more and uses more power. [1]	separate graphics card, VRAM
VRAM	[1]	Dedicated video memory on a GPU that stores textures and frame data for fast access. [1]	Dedicated video memory
Parallel processing	[2]	Many calculations carried out at the same time. [1] By splitting a task across multiple cores / processors. [1]	Many calculations carried out at the same time, multiple cores / processors
Volatile memory	[1]	Memory that loses its contents when the power is switched off (e.g. RAM). [1]	loses its contents, power is switched off
Non-volatile memory	[1]	Memory that keeps its contents when the power is switched off (e.g. ROM, SSD). [1]	keeps its contents, power is switched off
RAM (Random Access Memory)	[2]	Volatile primary memory. [1] Holds the programs and data currently in use so the CPU can access them quickly. [1]	Volatile, programs and data currently in use
ROM (Read Only Memory)	[2]	Non-volatile primary memory that is read only. [1] Stores the boot instructions / firmware (BIOS) needed to start the computer. [1]	Non-volatile, read only, boot instructions / firmware
Cache memory	[2]	Small, very fast memory between the CPU and RAM (levels L1, L2, L3). [1] Stores frequently used data and instructions so the CPU does not wait for slower RAM. [1]	very fast memory, L1, L2, L3, frequently used
L1 / L2 / L3 cache	[2]	L1 is the smallest and fastest, inside each core. [1] L2 is larger and slower, L3 is the largest and slowest and is shared between cores. [1]	L1, inside each core, L2, L3, shared between cores
Memory hierarchy	[2]	Arrangement of memory types by speed, size and cost. [1] Registers → cache → RAM → secondary storage: faster is smaller and more expensive. [1]	speed, size and cost, faster is smaller and more expensive
Latency	[1]	The delay / time taken before data starts to be transferred after a request. [1]	delay / time taken
Throughput	[1]	The amount of data transferred or processed per unit of time. [1]	amount of data, per unit of time
Cache hit	[1]	When the data the CPU needs is found in the cache, so it is accessed quickly. [1]	is found in the cache
Cache miss	[2]	When the data the CPU needs is not in the cache. [1] So it has to be fetched from slower RAM, causing a delay. [1]	is not in the cache, slower RAM
Prefetching	[2]	Loading data into the cache before it is requested. [1] Based on a prediction of what the CPU will need next. [1]	Loading data into the cache before it is requested, prediction
LRU (Least Recently Used)	[1]	Cache replacement policy that removes the item that has not been used for the longest time. [1]	removes the item that has not been used for the longest time
FIFO (First In First Out)	[1]	Cache replacement policy that removes the item that was loaded first (the oldest). [1]	removes the item that was loaded first
Virtual memory	[2]	Using part of secondary storage as if it were RAM. [1] When RAM is full, so more programs can run than physical RAM allows. [1]	secondary storage as if it were RAM, RAM is full
MMU (Memory Management Unit)	[1]	Hardware that translates virtual addresses into physical addresses. [1]	translates virtual addresses into physical addresses
Paging	[2]	Dividing memory into fixed-size blocks called pages. [1] Pages are swapped between RAM and secondary storage as needed. [1]	fixed-size blocks called pages, swapped between RAM and secondary storage
Page table	[1]	A table that maps each virtual page to its physical location (frame) in RAM. [1]	maps each virtual page to its physical location
Swap file	[1]	The file on secondary storage that holds pages moved out of RAM. [1]	secondary storage, moved out of RAM
Process isolation	[2]	Each process gets its own virtual address space. [1] So one process cannot read or change another process's memory. [1]	own virtual address space, cannot read or change another process's memory
Fetch-decode-execute cycle	[2]	The continuous cycle the CPU repeats to run a program. [1] Fetch the instruction from memory, decode it in the CU, execute it. [1]	continuous cycle, Fetch, decode, execute
Fetch (stage)	[2]	The PC address is copied to the MAR, the instruction is copied from memory into the MDR then the IR. [1] The PC is incremented to point to the next instruction. [1]	PC address is copied to the MAR, MDR, IR, PC is incremented
Decode (stage)	[2]	The CU interprets the instruction in the IR. [1] Splitting it into the opcode and the operand. [1]	CU interprets, opcode, operand
Execute (stage)	[1]	The instruction is carried out (e.g. ALU calculation, LOAD, STORE, JUMP). [1]	carried out
Clock speed	[2]	The number of cycles per second the CPU performs. [1] Measured in hertz (GHz). Higher clock speed means more instructions per second. [1]	number of cycles per second, hertz (GHz)
Opcode	[1]	The part of a machine instruction that says which operation to perform (e.g. ADD, LOAD). [1]	which operation
Operand	[1]	The part of an instruction that gives the data or the address of the data to be used. [1]	data or the address of the data
Secondary storage	[2]	Non-volatile storage used to keep data and programs permanently. [1] Not directly accessed by the CPU, it is slower but larger than primary memory. [1]	Non-volatile, permanently, slower but larger
HDD (Hard Disk Drive)	[2]	Magnetic storage using spinning platters and a moving read/write head. [1] Large capacity and cheap per GB, but slower and has moving parts. [1]	Magnetic, spinning platters, slower, moving parts
SSD (Solid State Drive)	[2]	Storage using flash memory with no moving parts. [1] Faster, more durable and quieter than an HDD, but more expensive per GB. [1]	flash memory, no moving parts, Faster
eMMC	[1]	Embedded flash storage soldered onto the motherboard, used in phones, tablets and cheap laptops. [1]	Embedded flash storage soldered onto the motherboard
Optical storage	[1]	Storage (CD, DVD, Blu-ray) read and written by a laser reflecting off the disc surface. [1]	laser
NAS (Network Attached Storage)	[2]	A storage device connected to a network. [1] So multiple users and devices can store and access files centrally. [1]	connected to a network, multiple users and devices
Compression	[2]	Reducing the size of a file (number of bits). [1] To save storage space and reduce transmission time / bandwidth. [1]	Reducing the size of a file, save storage, reduce transmission time / bandwidth
Lossless compression	[2]	Compression where no data is lost. [1] The original file can be perfectly reconstructed (e.g. ZIP, PNG, text). [1]	no data is lost, original file can be perfectly reconstructed
Lossy compression	[2]	Compression that permanently removes data, usually detail people will not notice. [1] Gives smaller files but the original cannot be restored (e.g. JPEG, MP3). [1]	permanently removes data, smaller files, cannot be restored
Run-Length Encoding (RLE)	[2]	Lossless method that replaces runs of repeated values. [1] With one copy of the value and a count (e.g. AAAAA → 5A). [1]	runs of repeated values, one copy of the value and a count
Transform coding	[2]	Lossy method that converts data into another form (e.g. frequencies). [1] Then discards the parts that matter least to human perception. [1]	converts data into another form, discards the parts that matter least
Cloud computing	[2]	Delivering computing resources (storage, processing, software) over the internet. [1] From remote servers, usually on demand / pay as you go. [1]	storage, processing, software, over the internet, remote servers, on demand / pay as you go
SaaS (Software as a Service)	[1]	The provider hosts complete applications that users access through a browser (e.g. Google Docs). [1]	complete applications, through a browser
PaaS (Platform as a Service)	[1]	The provider supplies a platform / environment (OS, tools, runtime) for developers to build and deploy their own apps. [1]	platform / environment, developers to build and deploy
IaaS (Infrastructure as a Service)	[2]	The provider rents out virtual hardware (servers, storage, networking). [1] The user manages the OS and software on top. [1]	virtual hardware, user manages the OS and software
Clock cycle	[1]	One tick of the CPU clock: the basic unit of time in which the CPU does one step of work. [1]	One tick of the CPU clock
Addressing mode	[2]	The way an instruction tells the CPU how to find its operand [1] (e.g. the value itself, or the memory address where the value is). [1]	how to find its operand, memory address
LOAD / STORE / JUMP	[2]	LOAD copies data from memory into a register; STORE copies data from a register into memory. [1] JUMP (JMP) changes the PC so execution continues at a different instruction. [1]	LOAD, from memory into a register, STORE, from a register into memory, JUMP, PC, different instruction
Virtual vs physical address	[2]	A virtual address is the address a program uses. [1] The MMU translates it into the physical address: the real location in RAM. [1]	virtual address, program uses, MMU translates, physical address
Cache replacement policy	[1]	The rule that decides which item to remove from a full cache to make room for new data (e.g. LRU, FIFO). [1]	which item to remove from a full cache, LRU, FIFO
Flash drive (USB)	[1]	Portable secondary storage using flash memory with no moving parts, connected by USB. [1]	Portable, flash memory, USB
Memory card	[1]	Small, removable flash memory storage used in cameras and phones (e.g. SD, microSD). [1]	flash memory, SD, microSD

A1.2 Data Representation and Computer Logic

45 terms, 57 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Binary	[1]	A base 2 number system that uses only the digits 0 and 1. [1]	base 2, 0 and 1
Bit	[1]	A single binary digit, 0 or 1. The smallest unit of data. [1]	single binary digit, smallest unit
Nibble	[1]	A group of 4 bits, equal to one hexadecimal digit. [1]	4 bits, one hexadecimal digit
Byte	[1]	A group of 8 bits. [1]	8 bits
Kilobyte / Megabyte / Gigabyte	[1]	1 KB = 1024 bytes, 1 MB = 1024 KB, 1 GB = 1024 MB (each unit is 1024 times the one before). [1]	1 KB = 1024 bytes, 1024 times
Hexadecimal	[2]	A base 16 number system using 0 to 9 and A to F. [1] Used because it is shorter and easier for humans to read than binary (1 hex digit = 4 bits). [1]	base 16, 0 to 9 and A to F, shorter and easier for humans to read
Place value	[1]	The value of a digit depends on its position. In binary each place is a power of 2 (1, 2, 4, 8...). [1]	value of a digit depends on its position, power of 2
Unsigned integer	[2]	Uses all bits for the magnitude, so it can only store zero and positive numbers. [1] Range with n bits: 0 to 2ⁿ − 1. [1]	all bits for the magnitude, zero and positive, 0 to 2ⁿ − 1
Two's complement	[2]	A way of storing signed (negative and positive) integers in binary. [1] The MSB has a negative place value; to negate, flip all bits and add 1. [1]	signed (negative and positive) integers, MSB has a negative place value, flip all bits and add 1
Most Significant Bit (MSB)	[1]	The leftmost bit, with the highest place value. In two's complement it is the sign bit. [1]	leftmost bit, highest place value, sign bit
ASCII	[2]	A character set that uses 7 bits to represent 128 characters. [1] Covers English letters, digits and punctuation only. [1]	7 bits, 128 characters
Unicode	[2]	A character set covering the characters of all languages and symbols (including emoji). [1] Encoded with UTF-8, which uses 1 to 4 bytes per character and is backward compatible with ASCII. [1]	all languages, UTF-8, 1 to 4 bytes, backward compatible with ASCII
Pixel	[1]	The smallest element of a digital image, a single point of colour. [1]	smallest element of a digital image
RGB colour model	[2]	Colour is made by mixing red, green and blue channels. [1] In 24-bit colour each channel is 1 byte (0 to 255), so each pixel uses 3 bytes. [1]	red, green and blue, 24-bit colour, 1 byte (0 to 255)
Colour depth	[1]	The number of bits used to store the colour of one pixel. More bits means more possible colours. [1]	number of bits used to store the colour of one pixel, more possible colours
Sampling	[1]	Measuring the amplitude of an analogue sound wave at regular intervals to convert it to digital. [1]	amplitude, at regular intervals
Sample rate	[2]	The number of samples taken per second, measured in Hz. [1] Higher sample rate gives better quality but a larger file. [1]	number of samples taken per second, Hz, better quality, larger file
Bit depth (audio)	[2]	The number of bits used to store each sample. [1] Higher bit depth gives more possible amplitude values and more accurate sound. [1]	number of bits used to store each sample, more possible amplitude values
Quantization	[1]	Rounding each sampled amplitude to the nearest available value allowed by the bit depth. [1]	Rounding each sampled amplitude to the nearest available value
Frame (video)	[1]	A single still image in a video. Frames shown quickly one after another create motion. [1]	single still image, motion
Multiplexing (video)	[1]	Interleaving audio and video data in one stream so they stay synchronised. [1]	Interleaving audio and video data, synchronised
Logic gate	[2]	An electronic circuit (made of transistors) that takes one or more binary inputs. [1] And produces one binary output according to a Boolean function. [1]	transistors, binary inputs, one binary output, Boolean function
AND gate	[1]	Outputs 1 only when all inputs are 1. [1]	only when all inputs are 1
OR gate	[1]	Outputs 1 when at least one input is 1. [1]	at least one input is 1
NOT gate	[1]	Has one input and inverts it (0 → 1, 1 → 0). [1]	one input, inverts
NAND gate	[1]	NOT AND. Outputs 0 only when all inputs are 1. [1]	NOT AND, only when all inputs are 1
NOR gate	[1]	NOT OR. Outputs 1 only when all inputs are 0. [1]	NOT OR, only when all inputs are 0
XOR gate	[1]	Exclusive OR. Outputs 1 when the inputs are different. [1]	inputs are different
XNOR gate	[1]	Outputs 1 when the inputs are the same. The inverse of XOR. [1]	inputs are the same
Truth table	[2]	A table showing every possible combination of inputs. [1] And the resulting output for a logic circuit or Boolean expression (n inputs give 2ⁿ rows). [1]	every possible combination of inputs, resulting output, 2ⁿ rows
Boolean expression	[1]	An algebraic expression made of Boolean variables and logical operators (AND, OR, NOT) that evaluates to true or false. [1]	Boolean variables, logical operators, true or false
Logic diagram	[1]	A diagram of connected logic gates showing how inputs are processed to give an output (Q), read left to right. [1]	connected logic gates, inputs are processed to give an output (Q)
Flip-flop	[1]	A circuit of logic gates that stores one bit by holding a stable state. The building block of memory. [1]	stores one bit, stable state
Karnaugh map (K-map)	[2]	A grid method for simplifying Boolean expressions. [1] By grouping adjacent 1s in blocks of 1, 2, 4 or 8. [1]	grid method, simplifying Boolean expressions, grouping adjacent 1s
Gray code	[1]	Ordering of K-map labels (00, 01, 11, 10) so that adjacent cells differ by only one bit. [1]	00, 01, 11, 10, adjacent cells differ by only one bit
Fixed-width binary	[1]	Every value is stored using the same number of bits, whatever its size (padded with leading zeros). [1]	same number of bits, leading zeros
Leading zeros	[1]	Zeros added to the left of a binary number to fill a fixed width (e.g. 101 → 00000101). [1]	Zeros added to the left, fixed width
Variable-width encoding	[1]	Characters use a different number of bytes depending on the character (e.g. UTF-8 uses 1 to 4). [1]	different number of bytes, UTF-8
Colour channel	[1]	One of the red, green or blue components of a pixel, usually stored in 1 byte (0 to 255). [1]	red, green or blue, 1 byte (0 to 255)
Stereo audio	[1]	Sound recorded on two channels (left and right), which doubles the file size compared with mono. [1]	two channels (left and right), doubles the file size
Video codec	[1]	Software that compresses and decompresses video data for storage and transmission (e.g. H.264, H.265). [1]	compresses and decompresses, H.264, H.265
Transistor	[1]	A tiny electronic switch inside the CPU. Logic gates are built from transistors. [1]	electronic switch, Logic gates are built from transistors
Intermediate column	[1]	An extra column in a truth table showing the output of one part of the expression, used to build up to Q. [1]	one part of the expression
K-map group	[2]	A rectangle of adjacent 1s on a K-map, sized 1, 2, 4 or 8, which can wrap around the edges. [1] Variables that stay the same within the group are kept; those that change are dropped. [1]	adjacent 1s, 1, 2, 4 or 8, wrap around, stay the same, kept, dropped
Minterm	[1]	One row of the truth table where the output is 1, matching one cell of the K-map. [1]	output is 1, one cell

A1.3 Operating Systems and Control Systems

44 terms, 68 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Operating system (OS)	[2]	System software that manages the hardware and software resources of a computer. [1] And acts as the interface between the user, applications and hardware. [1]	manages the hardware and software resources, interface between the user, applications and hardware
Abstraction (OS)	[2]	The OS hides the complex details of the hardware. [1] Behind a simpler interface, so applications call the OS instead of controlling hardware directly. [1]	hides the complex details of the hardware, simpler interface
Memory management	[2]	The OS allocates and deallocates RAM to processes. [1] And keeps processes apart (isolation), using virtual memory / paging when needed. [1]	allocates and deallocates RAM, keeps processes apart, virtual memory / paging
File system management	[2]	The OS organises how files are stored, named, retrieved and organised in folders. [1] And controls access permissions. [1]	stored, named, retrieved and organised, access permissions
Device management	[2]	The OS controls peripheral devices using device drivers. [1] And handles their interrupts. [1]	peripheral devices, device drivers, interrupts
Device driver	[1]	Software that translates OS commands into signals a specific hardware device understands. [1]	translates OS commands into signals a specific hardware device understands
Scheduling	[2]	The OS deciding which process gets the CPU. [1] For how long and in what order. [1]	which process gets the CPU, For how long, in what order
Accounting (OS)	[2]	Recording each process's use of resources (CPU time, memory, disk, bandwidth). [1] For monitoring performance or billing. [1]	use of resources, monitoring performance, billing
Virtualisation	[2]	Running several virtual machines on one physical machine. [1] Each VM is isolated and behaves like a separate computer. [1]	several virtual machines on one physical machine, isolated
Process	[1]	A program that is currently running / being executed, with its own memory and resources. [1]	program that is currently running / being executed
Thread	[2]	The smallest unit of execution within a process. [1] Threads of one process share the same memory. [1]	smallest unit of execution within a process, share the same memory
Sandboxing	[2]	Isolating a process so it can only access the resources it strictly needs. [1] Limiting the damage from bugs or malicious code. [1]	Isolating a process, resources it strictly needs, damage
User mode vs kernel mode	[2]	Applications run in user mode with no direct hardware access. [1] The OS kernel runs in kernel mode with full hardware access, protecting the OS from faulty programs. [1]	user mode, no direct hardware access, kernel mode, full hardware access
Time slice (quantum)	[1]	A fixed amount of CPU time given to a process each turn before it is switched out. [1]	fixed amount of CPU time, each turn
Pre-emption	[1]	The OS interrupting a running process to give the CPU to another process. [1]	interrupting a running process, another process
Non-pre-emptive scheduling	[1]	A process keeps the CPU until it finishes (or blocks). It cannot be interrupted. [1]	keeps the CPU until it finishes
Starvation	[2]	A process waits indefinitely for the CPU. [1] Because higher priority processes keep being chosen first. [1]	waits indefinitely, higher priority processes
Ageing	[2]	Gradually increasing the priority of processes that have been waiting a long time. [1] To prevent starvation. [1]	Gradually increasing the priority, prevent starvation
First Come First Served (FCFS)	[2]	Processes run in the order they arrive. [1] Each runs to completion (non-pre-emptive). [1]	in the order they arrive, to completion
Convoy effect	[1]	Short processes stuck waiting behind a long process (in FCFS), increasing waiting time. [1]	Short processes stuck waiting behind a long process
Round Robin	[2]	Each process gets an equal time slice in turn. [1] Unfinished processes go to the back of the queue (pre-emptive). [1]	equal time slice, back of the queue
Priority scheduling	[2]	The CPU is given to the process with the highest priority. [1] Can be pre-emptive or non-pre-emptive. [1]	highest priority, pre-emptive or non-pre-emptive
Multilevel queue scheduling	[2]	The ready queue is split into several queues by process type. [1] Each queue has its own scheduling algorithm. [1]	split into several queues, Each queue has its own scheduling algorithm
Polling	[2]	The CPU repeatedly checks each device at regular intervals. [1] To see whether it needs attention. [1]	repeatedly checks, at regular intervals, needs attention
Interrupt	[2]	A signal from hardware or software to the CPU that an event needs attention. [1] The CPU saves its current state, runs the ISR, then resumes the task. [1]	signal, event needs attention, saves its current state, ISR, resumes
Interrupt Service Routine (ISR)	[1]	The specific code that runs to handle a particular interrupt. [1]	specific code that runs to handle a particular interrupt
Multitasking	[2]	The OS running several processes apparently at the same time. [1] By rapidly switching between them (or truly in parallel on multiple cores). [1]	several processes apparently at the same time, rapidly switching
Multithreading	[1]	Several threads of one process running concurrently, sharing the same memory. [1]	Several threads of one process running concurrently
Context switch	[2]	Saving the state (registers, PC) of the current process. [1] And loading the saved state of the next process. [1]	Saving the state, loading the saved state
Context switching overhead	[1]	The CPU time wasted saving and loading states instead of doing useful work. Grows if time slices are too short. [1]	CPU time wasted saving and loading states
Resource allocation	[1]	The OS sharing limited resources (CPU, memory, storage, I/O) between competing processes, balancing fairness and efficiency. [1]	sharing limited resources, between competing processes
Deadlock	[2]	Two or more processes are each waiting for a resource held by the other. [1] So none of them can continue. [1]	each waiting for a resource held by the other, none of them can continue
System integrity	[2]	The system performs its intended functions correctly and reliably. [1] Without unauthorised or accidental changes to hardware, software or data. [1]	performs its intended functions correctly and reliably, Without unauthorised or accidental changes
I/O management	[1]	The OS controls data flow to and from input and output devices, using drivers and interrupts. [1]	controls data flow, drivers, interrupts
Power management	[1]	The OS controls the power used by hardware, e.g. sleep modes, to save energy and battery. [1]	controls the power used, sleep modes
Network management (OS)	[1]	The OS handles the network stack: protocols, connections and bandwidth, sending packets through the NIC. [1]	network stack, protocols, connections and bandwidth, NIC
User interface (GUI / CLI)	[1]	How the user interacts with the OS: a GUI uses windows, icons and a mouse; a CLI uses typed commands. [1]	interacts with the OS, GUI, CLI
Fairness (scheduling)	[1]	Every process gets a reasonable share of CPU time and none is starved. [1]	reasonable share of CPU time
Turnaround time	[1]	The total time from a process arriving to finishing. [1]	total time, arriving to finishing
Waiting time	[1]	The time a process spends in the ready queue waiting for the CPU. [1]	in the ready queue waiting
Interrupt overhead	[1]	The extra CPU work to save and restore the current state each time an interrupt is handled. [1]	save and restore the current state
Real-time system	[1]	A system that must respond to events within a strict time limit (e.g. airbag, pacemaker). Uses interrupts. [1]	respond to events within a strict time limit, interrupts
Deadlock prevention / recovery	[2]	Prevention: refuse resource requests that would create a circular wait. [1] Recovery: detect the deadlock, then terminate a process or take back a resource. [1]	Prevention:, circular wait, Recovery:, terminate a process or take back a resource
Resilience	[1]	The system keeps working correctly under stress or after a failure. [1]	keeps working correctly, after a failure

A2.1 Network Fundamentals

38 terms, 57 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Network	[1]	Two or more devices connected together to share data and resources. [1]	devices connected together, share data and resources
LAN (Local Area Network)	[2]	A network covering a small geographical area (one building or site). [1] Usually owned and managed by one organisation, with fast speeds. [1]	small geographical area, owned and managed by one organisation
WAN (Wide Area Network)	[2]	A network covering a large geographical area (cities, countries). [1] Connects LANs together, often using third party infrastructure (e.g. leased lines). [1]	large geographical area, Connects LANs together, third party infrastructure
PAN (Personal Area Network)	[1]	A very small network (about 10 m) around one person, connecting their personal devices (e.g. Bluetooth). [1]	10 m, around one person
Leased line	[2]	A dedicated, fixed capacity connection between two sites. [1] Rented from a telecoms provider for exclusive use. [1]	dedicated, fixed capacity connection, Rented from a telecoms provider
VPN (Virtual Private Network)	[2]	An encrypted connection (tunnel) over a public network such as the internet. [1] Lets a user access a private network securely as if directly connected to it. [1]	encrypted connection, over a public network, private network securely
Digital infrastructure	[1]	The physical and virtual components (cables, servers, data centres, software) that let digital data flow and support digital services. [1]	physical and virtual components, digital data flow
The Internet	[2]	A global network of interconnected networks. [1] That exchange data using standard protocols (TCP/IP). [1]	global network of interconnected networks, standard protocols
World Wide Web (WWW)	[1]	A service that runs on the internet: a collection of web pages linked by hyperlinks, accessed using HTTP/HTTPS. [1]	service that runs on the internet, web pages linked by hyperlinks, HTTP/HTTPS
Distributed system	[2]	A group of independent computers (nodes) that appear to the user as one system. [1] And coordinate by passing messages. [1]	independent computers (nodes), appear to the user as one system, coordinate by passing messages
Edge computing	[2]	Processing data at or near where it is generated instead of a central server. [1] To reduce latency and bandwidth use. [1]	Processing data at or near where it is generated, reduce latency
Mobile network	[1]	A wireless telecommunications network of cell towers giving devices connectivity over large distances (4G, 5G). [1]	wireless telecommunications network, connectivity over large distances
Gateway	[2]	A device that connects two networks that use different protocols. [1] By translating between them. [1]	connects two networks that use different protocols, translating
Modem	[2]	Converts digital signals into analogue (modulate) and back (demodulate). [1] To send data over telephone / broadband lines. [1]	digital signals into analogue, telephone / broadband lines
NIC (Network Interface Card)	[2]	Hardware that connects a device to a network. [1] Has a unique MAC address. [1]	connects a device to a network, MAC address
Router	[2]	Forwards packets between different networks. [1] Using IP addresses and a routing table to choose the best path. [1]	packets between different networks, IP addresses, routing table
Switch	[2]	Connects devices within a LAN. [1] Forwards frames only to the intended device using MAC addresses. [1]	within a LAN, frames only to the intended device, MAC addresses
WAP (Wireless Access Point)	[1]	Lets wireless devices connect to a wired network by converting between Ethernet and radio signals. [1]	wireless devices connect to a wired network, radio signals
Protocol	[2]	A set of rules that governs how data is formatted, transmitted and received. [1] So that different devices can communicate. [1]	set of rules, formatted, transmitted and received, different devices can communicate
Stateless protocol	[1]	Each request is treated independently, the server keeps no memory of previous requests (e.g. HTTP). [1]	treated independently, keeps no memory
Stateful protocol	[1]	The server keeps track of the session across several requests and responses. [1]	keeps track of the session
TCP (Transmission Control Protocol)	[2]	A connection-oriented protocol (sets up a connection with a three-way handshake). [1] Reliable: packets are acknowledged, error checked, resent if lost and put back in order. [1]	connection-oriented, three-way handshake, Reliable, acknowledged, error checked, resent if lost, put back in order
UDP (User Datagram Protocol)	[2]	A connectionless protocol with no guarantee of delivery or order. [1] Faster, so used for streaming, gaming, VoIP. [1]	connectionless, no guarantee of delivery, Faster, streaming, gaming, VoIP
Three-way handshake	[1]	TCP connection setup: SYN, SYN-ACK, ACK, completed before data is sent. [1]	SYN, SYN-ACK, ACK, before data is sent
HTTP	[2]	Protocol for transferring web pages between a web server and a browser. [1] Uses a request / response model and is stateless. [1]	transferring web pages, server and a browser, request / response, stateless
HTTPS	[2]	HTTP secured with TLS encryption. [1] Protects data from eavesdropping and tampering and authenticates the server with a certificate. [1]	secured with TLS encryption, eavesdropping and tampering, authenticates the server
TLS (Transport Layer Security)	[1]	Protocol that encrypts data sent between client and server (used by HTTPS). [1]	encrypts data sent between client and server
Cookie	[2]	A small file stored on the client by a website. [1] Sent back with each request to remember state (e.g. staying logged in). [1]	small file stored on the client, remember state
DHCP (Dynamic Host Configuration Protocol)	[2]	Protocol that automatically assigns IP addresses to devices when they join a network. [1] Along with other settings (subnet mask, default gateway, DNS). [1]	automatically assigns IP addresses, subnet mask, default gateway, DNS
DHCP scope	[1]	The range of IP addresses a DHCP server is allowed to give out. [1]	range of IP addresses
DHCP lease	[1]	The limited time a device may use a dynamically assigned IP before it expires and can be reused. [1]	limited time, before it expires
Tunnel (VPN)	[1]	The encrypted logical connection that wraps VPN data so anyone intercepting it cannot read it. [1]	encrypted logical connection, cannot read it
Satellite link	[1]	A WAN connection through a satellite, used in remote areas without cables. High latency. [1]	satellite, remote areas, High latency
Hardware firewall	[1]	A standalone physical device between the network and the outside world that filters all traffic centrally. [1]	standalone physical device, filters all traffic centrally
Software firewall	[1]	A firewall application installed on one device that controls only that device's traffic. [1]	application installed on one device, that device's traffic
Flow control	[1]	TCP regulates the rate data is sent so the receiver and network are not overwhelmed. [1]	regulates the rate, not overwhelmed
Acknowledgement (ACK)	[1]	A message from the receiver confirming a packet arrived. Packets not acknowledged are resent. [1]	confirming a packet arrived, not acknowledged are resent
Site-to-site VPN	[1]	A VPN that permanently links two or more offices over the internet, replacing leased lines. [1]	permanently links two or more offices, leased lines

A2.2 Network Architecture

31 terms, 43 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Network topology	[2]	The arrangement of nodes and the links between them in a network. [1] Can be physical (actual cables) or logical (how data flows). [1]	arrangement of nodes and the links, physical, logical
Node	[1]	Any device connected to a network (computer, printer, router). [1]	device connected to a network
Star topology	[2]	Every device is connected directly to one central device (switch / hub). [1] If one cable fails only that device is affected, but the central device is a single point of failure. [1]	connected directly to one central device, central device is a single point of failure
Mesh topology	[2]	Devices are connected to many (partial mesh) or all (full mesh) other nodes. [1] Gives multiple routes, so data can be rerouted if a link fails. [1]	many (partial mesh) or all (full mesh) other nodes, multiple routes, rerouted
Hybrid topology	[1]	A network that combines two or more topologies (e.g. several stars joined by a mesh). [1]	combines two or more topologies
Hop	[1]	One step of a packet's journey from one device to the next. [1]	One step of a packet's journey
Single point of failure	[1]	One component whose failure stops the whole network / system from working. [1]	One component whose failure stops the whole network / system
Client-server model	[2]	A central server provides resources / services. [1] Clients request them and the server responds. [1]	central server provides resources / services, Clients request, responds
Server	[1]	A computer that provides resources or services to other computers (clients) over a network. [1]	provides resources or services to other computers (clients)
Client	[1]	A device or program that requests resources or services from a server. [1]	requests resources or services from a server
Peer-to-peer (P2P) model	[2]	A decentralised network with no central server. [1] Every peer is equal and acts as both client and server, sharing resources directly. [1]	decentralised, no central server, peer is equal, both client and server
Blockchain ledger	[1]	A decentralised record of transactions, with a copy stored on every node (e.g. Bitcoin). [1]	decentralised record of transactions, copy stored on every node
Network segmentation	[2]	Dividing a network into smaller separate segments. [1] To improve security (controlled access) and performance (less congestion). [1]	Dividing a network into smaller separate segments, security, performance
Subnetting	[2]	Dividing one IP network into smaller logical networks called subnets. [1] Using the subnet mask to decide how the address is split. [1]	Dividing one IP network into smaller logical networks, subnet mask
Subnet mask	[2]	A 32-bit value that shows which part of an IP address is the network (1s). [1] And which part is the host (0s). [1]	which part of an IP address is the network, which part is the host
Network address	[1]	Found by doing a bitwise AND of the IP address and the subnet mask. [1]	bitwise AND of the IP address and the subnet mask
ACL (Access Control List)	[2]	A list of rules stating which users or processes (subjects). [1] May perform which operations (read, write, execute) on which objects. [1]	list of rules, which users or processes (subjects), which operations, on which objects
VLAN (Virtual LAN)	[2]	A logical network that groups devices regardless of their physical location / switch. [1] Separates traffic and reduces the broadcast domain. [1]	logical network, regardless of their physical location / switch, reduces the broadcast domain
Broadcast domain	[1]	The area of a network that a broadcast message reaches. [1]	broadcast message reaches
CIDR	[2]	Classless Inter-Domain Routing: writing an IP address with a slash and prefix length (e.g. /24). [1] Showing how many bits are the network part; replaces class A, B, C. [1]	Classless Inter-Domain Routing, slash and prefix length, how many bits are the network part
VLSM	[1]	Variable Length Subnet Masking: subnets of different sizes, so IP addresses are not wasted. [1]	Variable Length Subnet Masking, different sizes, not wasted
Full mesh	[1]	Every node is connected to every other node. [1]	Every node is connected to every other node
Partial mesh	[1]	Some nodes are connected to several others, but not all to all. [1]	Some nodes, not all to all
Scalability	[1]	How easily a network or system can grow (more users, devices or data) without losing performance. [1]	grow, without losing performance
Collision	[1]	When two transmissions clash on the same link, so the data must be resent. [1]	two transmissions clash, resent
Peer	[1]	An equal participant in a P2P network that both requests and provides resources. [1]	equal participant, requests and provides
Centralised vs decentralised	[2]	Centralised: control and data in one place (client-server). [1] Decentralised: control spread across all participants (P2P). [1]	Centralised:, one place, Decentralised:, spread across all participants
Subnet	[1]	A smaller logical network created by dividing a larger IP network. [1]	smaller logical network
Network portion / host portion	[1]	The network portion of an IP address identifies the network; the host portion identifies the device on it. [1]	network portion, network, host portion, device
Bitwise AND	[1]	Comparing two binary numbers bit by bit: result is 1 only when both bits are 1. IP AND mask = network address. [1]	bit by bit, only when both bits are 1, network address
Inter-VLAN routing	[1]	Rules on a router or layer 3 switch that decide which VLANs may communicate with each other. [1]	Rules on a router or layer 3 switch, which VLANs may communicate

A2.3 Data Transmission

32 terms, 42 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
IP (Internet Protocol)	[1]	Protocol responsible for addressing and routing packets across networks. [1]	addressing and routing packets
IP address	[1]	A unique numerical address that identifies a device on a network. [1]	unique numerical address, identifies a device on a network
IPv4	[2]	32-bit address written as four decimal numbers (e.g. 192.168.1.1). [1] About 4.3 billion addresses, which have run out. [1]	32-bit, four decimal numbers, 4.3 billion, run out
IPv6	[2]	128-bit address written as eight groups of hexadecimal separated by colons. [1] Gives a vastly larger address space, simpler header, built-in IPsec. [1]	128-bit, eight groups of hexadecimal, vastly larger address space
Public IP address	[1]	A globally unique address that is reachable from the internet, assigned through IANA / ISPs. [1]	globally unique, reachable from the internet, IANA
Private IP address	[2]	An address used only inside a local network, not routable on the internet (e.g. 192.168.x.x). [1] Needs NAT to reach the internet. [1]	only inside a local network, not routable on the internet, NAT
Loopback address	[1]	A reserved address (127.0.0.1 / ::1) that sends traffic back to the same device, used for testing. [1]	127.0.0.1, sends traffic back to the same device, testing
Static IP address	[1]	A fixed IP address that does not change, set manually. Used for servers and printers. [1]	fixed IP address, does not change, servers and printers
Dynamic IP address	[1]	An IP address assigned automatically by DHCP that can change each time the device connects. [1]	assigned automatically by DHCP, can change
NAT (Network Address Translation)	[2]	The router translates private IP addresses into one public IP address. [1] So many devices share one public address, saving IPv4 addresses and hiding internal addresses. [1]	translates private IP addresses into one public IP address, many devices share one public address, hiding internal addresses
Fibre optic cable	[2]	Transmits data as pulses of light through glass / plastic strands. [1] Very high bandwidth, long range, immune to electromagnetic interference, but expensive. [1]	pulses of light, glass / plastic strands, Very high bandwidth, immune to electromagnetic interference
Twisted pair cable	[2]	Copper wires twisted in pairs carrying electrical signals. [1] Twisting reduces interference. Cheap but shorter range (UTP unshielded, STP shielded). [1]	Copper wires twisted in pairs, electrical signals, reduces interference, shorter range
Wireless transmission	[1]	Data sent through the air as electromagnetic waves (radio, microwave, infrared) without cables. [1]	electromagnetic waves, without cables
Bandwidth	[1]	The maximum amount of data that can be transmitted per second (bits per second). [1]	maximum amount of data, per second
Attenuation	[1]	The loss of signal strength as it travels over distance through a medium. [1]	loss of signal strength, over distance
Electromagnetic interference (EMI)	[1]	Disruption of a signal by external electromagnetic fields (e.g. motors, other cables). [1]	Disruption of a signal, external electromagnetic fields
Packet	[2]	A small unit of data sent over a network. [1] Made of a header (addresses, sequence number, error check) and a payload (the data). [1]	small unit of data, header, payload
Payload	[1]	The actual data carried inside a packet. [1]	actual data
Header	[1]	The part of a packet holding control information: source and destination IP, sequence number, error detection code. [1]	control information, source and destination IP, sequence number, error detection code
Packet switching	[2]	Data is split into packets that are sent independently, possibly by different routes. [1] And reassembled in order at the destination using sequence numbers. [1]	split into packets, sent independently, different routes, reassembled in order, sequence numbers
Encapsulation	[1]	Adding headers / protocol information to data at each layer before it is sent. [1]	Adding headers / protocol information, before it is sent
Decapsulation	[1]	Removing the headers at each layer on arrival to get back the original data. [1]	Removing the headers, on arrival
Routing table	[1]	A table in a router listing destinations and the best next hop to forward packets to. [1]	destinations and the best next hop
MAC address	[2]	A unique hardware address permanently assigned to a NIC. [1] Used by switches to deliver frames within a LAN. [1]	unique hardware address, NIC, switches, within a LAN
IANA	[1]	Internet Assigned Numbers Authority: the body that manages and allocates public IP addresses through regional registries. [1]	Internet Assigned Numbers Authority, manages and allocates public IP addresses
NAT table	[1]	The router's record of which private device each outgoing connection belongs to, so replies are forwarded correctly. [1]	which private device, replies are forwarded
UTP / STP	[2]	UTP (unshielded twisted pair) is cheap and common. [1] STP (shielded twisted pair) has extra shielding against interference. [1]	UTP, STP, extra shielding against interference
Repeater	[1]	A device that regenerates / boosts a signal so it can travel further, overcoming attenuation. [1]	regenerates / boosts a signal, attenuation
Sequence number	[1]	A number in each packet's header so the destination can put packets back in the correct order. [1]	put packets back in the correct order
Error detection code (checksum)	[1]	A value in the header used to check whether the packet data was damaged in transit. [1]	check whether the packet data was damaged
Next hop	[1]	The next router a packet is forwarded to on its way to the destination. [1]	next router
Routing	[1]	Choosing the path a packet takes: each router reads the destination IP and uses its routing table to pick the next hop. [1]	path, destination IP, routing table

A2.4 Network Security

26 terms, 34 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Firewall	[2]	Hardware or software that monitors and filters incoming and outgoing traffic. [1] Allowing or blocking packets according to rules (IP address, port, protocol). [1]	monitors and filters incoming and outgoing traffic, rules
Next-generation firewall	[1]	A firewall that also inspects packet contents (deep packet inspection, layer 7), not just headers. [1]	inspects packet contents, layer 7
Whitelist	[1]	A list of approved addresses / applications. Only these are allowed, everything else is blocked. [1]	approved, Only these are allowed
Blacklist	[1]	A list of banned addresses / applications. These are blocked, everything else is allowed. [1]	banned, These are blocked
Deep packet inspection (DPI)	[1]	Examining the contents (payload) of packets, not only the headers. Adds latency. [1]	Examining the contents (payload) of packets, Adds latency
IP masquerading	[1]	NAT that lets many internal devices share one public IP, hiding their private addresses. [1]	many internal devices share one public IP, hiding their private addresses
MAC filtering	[2]	Allowing or blocking devices on a network based on their MAC address. [1] Weak on its own because MAC addresses can be spoofed. [1]	based on their MAC address, spoofed
MAC spoofing	[1]	Faking a MAC address to impersonate an allowed device. [1]	Faking a MAC address
Encryption	[2]	Scrambling plaintext into ciphertext using an algorithm and a key. [1] So that only someone with the correct key can read it. [1]	plaintext into ciphertext, algorithm and a key, only someone with the correct key can read it
Plaintext / ciphertext	[1]	Plaintext is readable data before encryption, ciphertext is the unreadable data after encryption. [1]	Plaintext, before encryption, ciphertext, after encryption
Symmetric encryption	[2]	The same secret key is used to encrypt and decrypt. [1] Fast, but the key must be shared securely first. [1]	same secret key, encrypt and decrypt, Fast, shared securely
Asymmetric (public key) encryption	[2]	Uses a pair of mathematically linked keys: a public key and a private key. [1] Data encrypted with the public key can only be decrypted with the matching private key. [1]	pair of mathematically linked keys, public key, private key
Public key	[1]	The key that is shared openly, used to encrypt data or verify a signature. [1]	shared openly, encrypt, verify a signature
Private key	[1]	The key kept secret by its owner, used to decrypt data or create a signature. [1]	kept secret by its owner, decrypt, create a signature
Hash function	[2]	A one-way function that turns any input into a fixed-size output (digest). [1] A tiny change in input gives a completely different hash; it cannot be reversed. [1]	one-way function, fixed-size output (digest), tiny change in input gives a completely different hash
Digital signature	[2]	The hash of a document encrypted with the sender's private key. [1] Proves who sent it (authentication) and that it has not been changed (integrity). [1]	hash of a document encrypted with the sender's private key, who sent it (authentication), has not been changed (integrity)
Digital certificate	[2]	An electronic document that binds a public key to an identity (e.g. a website). [1] Signed by a trusted Certificate Authority. [1]	binds a public key to an identity, Signed by a trusted Certificate Authority
Certificate Authority (CA)	[1]	A trusted organisation that verifies identities and issues digital certificates. [1]	trusted organisation, verifies identities, issues digital certificates
SSH	[1]	Protocol for secure remote login / command line access using public and private keys. [1]	secure remote login / command line access, public and private keys
Key management	[1]	The processes for securely generating, storing, distributing, backing up and replacing encryption keys. [1]	securely generating, storing, distributing, backing up and replacing
Firewall rule	[1]	An instruction to allow or block traffic based on source/destination IP, port and protocol, checked in order until one matches. [1]	allow or block, source/destination IP, port and protocol, in order
Intrusion prevention system (IPS)	[1]	Security that monitors traffic for attacks and automatically blocks them. [1]	monitors traffic for attacks, automatically blocks
APT (advanced persistent threat)	[1]	A long-term, targeted attack that hides in a network, often getting past firewalls using encryption or zero-day exploits. [1]	long-term, targeted attack, getting past firewalls
Digest	[1]	The fixed-size output of a hash function. [1]	fixed-size output
CSR (certificate signing request)	[1]	A request sent to a CA containing a public key and identity details, asking for a digital certificate. [1]	CA, public key and identity details, digital certificate
Code signing	[1]	Developers sign software with their private key so users can check it is genuine and unaltered. [1]	sign software with their private key, genuine and unaltered

A3.1 Database Fundamentals

25 terms, 30 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Database	[1]	An organised, structured collection of data stored so it can be easily accessed, managed and updated. [1]	organised, structured collection of data, easily accessed, managed and updated
Flat file database	[2]	All data stored in one single table. [1] Leads to data redundancy and inconsistency. [1]	one single table, data redundancy, inconsistency
Relational database	[2]	Data stored in multiple tables (entities). [1] Linked by relationships using primary and foreign keys, so each fact is stored once. [1]	multiple tables (entities), Linked by relationships, primary and foreign keys
Data redundancy	[1]	The same data stored more than once (unnecessary duplication). [1]	same data stored more than once
Anomaly	[1]	A problem / error caused by incorrect handling of data (insert, update or delete), usually from redundancy. [1]	problem / error caused by incorrect handling of data, redundancy
Insert anomaly	[1]	Data cannot be added without also adding other unrelated data. [1]	Data cannot be added, adding other unrelated data
Delete anomaly	[1]	Deleting one record also removes other data that is still needed. [1]	Deleting one record, removes other data that is still needed
Update anomaly	[1]	Data is changed in some places but not others, so the database becomes inconsistent. [1]	changed in some places but not others, inconsistent
Entity	[1]	A thing / object about which data is stored, represented as a table (e.g. STUDENT). [1]	thing / object about which data is stored, table
Attribute	[1]	A property / characteristic of an entity, represented as a column / field. [1]	property / characteristic of an entity, column / field
Record (tuple)	[1]	One row of a table holding all the data about one instance of the entity. [1]	One row, one instance
Primary key	[2]	A field (or fields) that uniquely identifies each record in a table. [1] Cannot be null and cannot repeat. [1]	uniquely identifies each record, Cannot be null, cannot repeat
Foreign key	[2]	A field in one table that is the primary key of another table. [1] Used to create a relationship / link between the tables. [1]	primary key of another table, create a relationship / link
Composite key	[1]	A primary key made of two or more whole attributes that together uniquely identify a record. [1]	two or more whole attributes, together uniquely identify
Concatenated key	[1]	A key made by joining parts of attributes into one value (e.g. initials + date of birth). [1]	joining parts of attributes into one value
Relationship	[1]	A link between two entities, made using a foreign key. [1]	link between two entities, foreign key
Cardinality	[1]	How many instances of one entity relate to another: 1:1, 1:N, M:N. [1]	How many, 1:1, 1:N, M:N
Modality	[1]	Whether a relationship is optional (0) or mandatory (1): must a related record exist? [1]	optional (0) or mandatory (1), must
Data integrity	[1]	The accuracy, consistency and reliability of data over its whole life. [1]	accuracy, consistency and reliability
Data consistency	[1]	The same data has the same value everywhere it appears in the database. [1]	same data has the same value everywhere
ACID	[1]	Properties that make transactions reliable: Atomicity, Consistency, Isolation, Durability. [1]	Atomicity, Consistency, Isolation, Durability
Normalization	[2]	Organising data into multiple related tables. [1] To reduce redundancy and remove anomalies. [1]	Organising data into multiple related tables, reduce redundancy, remove anomalies
Concurrency control	[1]	Managing many users accessing the database at the same time so their changes do not conflict. [1]	many users accessing the database at the same time, do not conflict
Object-relational impedance mismatch	[1]	Tables do not map neatly onto OOP objects, so extra work is needed to convert between them. [1]	Tables do not map neatly onto OOP objects
Rigid schema	[1]	The structure must be defined in advance and is hard to change later. [1]	defined in advance, hard to change

A3.2 Database Design

22 terms, 28 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Schema	[2]	The blueprint / structure of a database: entities, attributes, relationships and constraints. [1] Contains no actual data. [1]	blueprint / structure of a database, no actual data
Conceptual schema	[1]	The least detailed level: shows entities and relationships only, for users and stakeholders. [1]	least detailed, entities and relationships only
Logical schema	[1]	Adds attributes, primary keys and foreign keys to the conceptual model, independent of any DBMS. [1]	attributes, primary keys and foreign keys
Physical schema	[1]	The most detailed level: data types, indexes, files and storage, how the database is actually built. [1]	most detailed, data types, indexes, files and storage
ERD (Entity Relationship Diagram)	[1]	A diagram showing the entities, their attributes and the relationships between them (with cardinality). [1]	diagram showing the entities, attributes, relationships
Link (associative) entity	[2]	An entity added between two entities in an M:N relationship. [1] Turning it into two 1:N relationships (holds both primary keys as foreign keys). [1]	between two entities in an M:N relationship, two 1:N relationships
Data type	[1]	Defines the kind of data a field can hold (e.g. VARCHAR, INT, DATE) and so what operations are allowed. [1]	kind of data a field can hold, operations
Referential integrity	[1]	Every foreign key value must match an existing primary key in the related table (no orphan records). [1]	foreign key value must match an existing primary key
Cascade delete	[1]	When a record is deleted, all records linked to it by a foreign key are deleted too. [1]	deleted, linked to it by a foreign key are deleted too
Cascade update	[1]	When a primary key changes, all matching foreign keys update automatically. [1]	primary key changes, matching foreign keys update automatically
Functional dependency	[1]	Attribute B depends on attribute A: if you know A you can find exactly one B (A → B). [1]	depends on, if you know A you can find exactly one B
Partial dependency	[1]	A non-key attribute depends on only part of a composite primary key. [1]	depends on only part of a composite primary key
Transitive dependency	[1]	A non-key attribute depends on another non-key attribute rather than directly on the primary key. [1]	depends on another non-key attribute
Repeating group	[1]	A set of attributes that occurs many times for one key value (several values in one record). [1]	set of attributes that occurs many times
Atomic value	[1]	A value that cannot be divided further: one value per cell. [1]	cannot be divided further, one value per cell
First normal form (1NF)	[2]	All values are atomic and there are no repeating groups. [1] Every table has a primary key. [1]	atomic, no repeating groups, primary key
Second normal form (2NF)	[2]	Is in 1NF. [1] And has no partial dependencies. [1]	1NF, no partial dependencies
Third normal form (3NF)	[2]	Is in 2NF. [1] And has no transitive dependencies (every non-key attribute depends on the key, the whole key and nothing but the key). [1]	2NF, no transitive dependencies, the key, the whole key and nothing but the key
Denormalization	[2]	Deliberately adding redundancy back into a normalized database (merging tables, storing calculated values). [1] To speed up queries / reads at the cost of storage and risk of anomalies. [1]	Deliberately adding redundancy back, speed up queries / reads
Unnormalized form (UNF)	[1]	A table that is not normalized: it still contains repeating groups. [1]	not normalized, repeating groups
Crow's foot notation	[1]	An ERD notation that shows cardinality and modality with symbols on the line ends: crow's foot = many, bar = one, circle = zero. [1]	cardinality and modality, crow's foot = many
fsp	[1]	Fractional seconds precision: stores up to 6 decimal places of a second in a time value. [1]	Fractional seconds precision, 6 decimal places

A3.3 Database Programming

29 terms, 39 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
SQL	[1]	Structured Query Language: the language used to create, query and change relational databases. [1]	Structured Query Language, create, query and change
DBMS	[1]	Database management system: the software that creates, manages and controls access to a database. [1]	Database management system, software that creates, manages and controls access
DDL (Data Definition Language)	[2]	SQL commands that define and change the structure of the database (schema). [1] e.g. CREATE, ALTER, DROP, TRUNCATE. [1]	define and change the structure, CREATE, ALTER, DROP, TRUNCATE
DML (Data Manipulation Language)	[2]	SQL commands that read and change the data inside tables. [1] e.g. SELECT, INSERT, UPDATE, DELETE. [1]	read and change the data, SELECT, INSERT, UPDATE, DELETE
DCL (Data Control Language)	[1]	SQL commands that control access / permissions: GRANT and REVOKE. [1]	control access / permissions, GRANT, REVOKE
TCL (Transaction Control Language)	[1]	SQL commands that manage transactions: COMMIT saves, ROLLBACK undoes. [1]	manage transactions, COMMIT, ROLLBACK
Query	[1]	An SQL instruction that extracts information from a database. [1]	SQL instruction that extracts information
Constraint (SQL)	[1]	A rule the DBMS enforces on a column or table (e.g. PRIMARY KEY, NOT NULL, UNIQUE, FOREIGN KEY). [1]	rule the DBMS enforces, PRIMARY KEY, NOT NULL, UNIQUE, FOREIGN KEY
NULL	[1]	A marker meaning no value: not zero and not an empty string. Tested with IS NULL. [1]	no value, IS NULL
Wildcard	[1]	A symbol used with LIKE for pattern matching: % = any number of characters, _ = exactly one. [1]	LIKE, %, _
Alias	[1]	A temporary name for a column or table in the output, created with AS. [1]	temporary name, AS
Join	[2]	Combining rows from two or more tables [1] Where the foreign key matches the primary key (`JOIN ... ON`). [1]	two or more tables, foreign key matches the primary key
Inner join	[1]	Returns only rows that have a match in both tables. [1]	only rows that have a match in both tables
Left / right join	[2]	LEFT JOIN returns all rows from the left table, with NULL where there is no match on the right. [1] RIGHT JOIN returns all rows from the right table, with NULL where there is no match on the left. [1]	LEFT JOIN, all rows from the left table, RIGHT JOIN, all rows from the right table
Cross join	[1]	A join with no join condition: every row is paired with every row of the other table. [1]	no join condition, every row is paired with every row
DELETE vs TRUNCATE vs DROP	[2]	DELETE (DML) removes chosen rows; TRUNCATE (DDL) removes all rows but keeps the table. [1] DROP (DDL) removes the whole table: structure and data. [1]	DELETE, chosen rows, TRUNCATE, all rows, DROP, whole table
Index (database)	[2]	A separate sorted lookup structure on a column with pointers to rows, so searches are faster. [1] But every INSERT, UPDATE and DELETE must also update the index, adding overhead and using storage. [1]	separate sorted lookup structure, searches are faster, INSERT, UPDATE and DELETE must also update the index
Aggregate function	[1]	A function that takes many rows and returns one value: COUNT, SUM, AVG, MIN, MAX. [1]	takes many rows and returns one value, COUNT, SUM, AVG, MIN, MAX
GROUP BY	[1]	Groups rows that share a value so an aggregate function runs once per group. [1]	Groups rows that share a value, once per group
HAVING vs WHERE	[2]	WHERE filters individual rows before grouping. [1] HAVING filters groups after grouping, and is used with aggregate functions. [1]	WHERE, individual rows before, HAVING, groups after, aggregate functions
Calculated field	[1]	A column worked out in the query with arithmetic (e.g. Quantity * Cost AS Total). It is not stored in the table. [1]	worked out in the query, not stored
View	[2]	A virtual table defined by a saved SELECT query. [1] It stores the query, not the data, so it always shows current data. Used for security and simplicity. [1]	virtual table, saved SELECT query, current data, security and simplicity
Materialized view	[1]	A view whose result is physically stored: fast to read but must be refreshed or it becomes out of date. [1]	result is physically stored, fast to read, refreshed
Transaction	[2]	A group of operations treated as one single unit [1] That either completes fully or not at all. [1]	group of operations treated as one single unit, completes fully or not at all
COMMIT / ROLLBACK	[2]	COMMIT makes a transaction's changes permanent. [1] ROLLBACK undoes them, returning to the last committed state. [1]	COMMIT, permanent, ROLLBACK, undoes, last committed state
Atomicity	[1]	ACID: a transaction is all or nothing. [1]	all or nothing
Consistency (ACID)	[1]	ACID: a transaction moves the database from one valid state to another; all constraints still hold. [1]	from one valid state to another
Isolation	[1]	ACID: transactions running at the same time do not see each other's unfinished changes. [1]	at the same time do not see each other's unfinished changes
Durability	[1]	ACID: once committed, changes are permanent even after a crash or power cut. [1]	permanent even after a crash or power cut

A4.1 Machine Learning Fundamentals

32 terms, 39 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Machine learning (ML)	[2]	A branch of AI where computers learn from data using algorithms and statistical models. [1] To improve / make predictions without being explicitly programmed for each case. [1]	AI, learn from data, improve / make predictions without being explicitly programmed
Training	[1]	Feeding data to a model and adjusting its parameters to reduce error. [1]	Feeding data to a model, adjusting its parameters
Labelled data	[1]	Data where each example is tagged with the correct output / answer. [1]	each example is tagged with the correct output / answer
Supervised learning	[2]	The model is trained on labelled data (inputs with known correct outputs). [1] Learns to map inputs to outputs to predict results for new data. [1]	labelled data, map inputs to outputs, predict
Classification	[1]	Supervised task where the output is a category / class (e.g. spam or not spam). [1]	category / class
Regression	[1]	Supervised task where the output is a continuous numerical value (e.g. a house price). [1]	continuous numerical value
Unsupervised learning	[2]	The model is trained on unlabelled data. [1] And finds hidden patterns, structure or groups by itself. [1]	unlabelled data, hidden patterns, structure or groups
Clustering	[1]	Unsupervised method that groups similar data points together (e.g. customer segments). [1]	groups similar data points together
Market basket analysis	[1]	Finding items frequently bought together (association rules: if X then Y), used for recommendations. [1]	items frequently bought together, if X then Y
Reinforcement learning	[2]	An agent learns by trial and error by interacting with an environment. [1] Receiving rewards or penalties and aiming to maximise cumulative reward. [1]	agent, trial and error, interacting with an environment, rewards or penalties, maximise cumulative reward
Exploration vs exploitation	[2]	Exploration: trying new actions to find better rewards. [1] Exploitation: using actions already known to give rewards. [1]	Exploration, new actions, Exploitation, already known to give rewards
Deep learning	[2]	A subset of ML that uses artificial neural networks with many layers. [1] Each layer learns increasingly abstract features from raw data. [1]	artificial neural networks with many layers, increasingly abstract features
Neural network	[1]	A model inspired by the brain made of layers of interconnected nodes (neurons) that learn patterns from data. [1]	brain, layers of interconnected nodes (neurons)
CNN (Convolutional Neural Network)	[1]	Deep learning architecture for image data that detects spatial patterns (edges → shapes → objects). [1]	image data, spatial patterns
RNN (Recurrent Neural Network)	[1]	Deep learning architecture for sequential data (text, audio) that remembers previous inputs. LSTM handles long sequences. [1]	sequential data, remembers previous inputs, LSTM
Transformer	[1]	Architecture that uses self-attention to weigh all parts of the input at once. Basis of GPT and BERT. [1]	self-attention, all parts of the input at once, GPT and BERT
Transfer learning	[2]	Reusing a model pre-trained on one task as the starting point for a related task. [1] Then fine-tuning, so less labelled data and training time is needed. [1]	Reusing a model pre-trained on one task, related task, fine-tuning, less labelled data
Tensor	[1]	A multi-dimensional array of numbers used to represent data in deep learning (0D number, 1D list, 2D table...). [1]	multi-dimensional array
Natural Language Processing (NLP)	[1]	ML that processes and understands human language (translation, chatbots, sentiment analysis). [1]	processes and understands human language
Sentiment analysis	[1]	Deciding whether text expresses positive, negative or neutral opinion. [1]	positive, negative or neutral
Object detection	[1]	Identifying and locating objects in an image, marking each with a bounding box. [1]	Identifying and locating, bounding box
TPU (Tensor Processing Unit)	[1]	Google's custom chip built specifically for tensor / neural network operations (TensorFlow). [1]	Google's custom chip, tensor / neural network operations
ASIC	[1]	Application-Specific Integrated Circuit: a chip designed for one task only, very fast and low power but cannot be reprogrammed. [1]	Application-Specific Integrated Circuit, designed for one task only, low power, cannot be reprogrammed
FPGA	[1]	Field-Programmable Gate Array: a chip that can be reprogrammed after manufacture for different tasks. [1]	Field-Programmable Gate Array, can be reprogrammed after manufacture
Edge device	[1]	Hardware that runs ML models locally, near the data source, giving low latency without the cloud. [1]	runs ML models locally, near the data source, low latency
Agent	[1]	In reinforcement learning, the learner / decision maker that takes actions in an environment to earn rewards. [1]	learner / decision maker, takes actions in an environment
Association rule	[1]	A rule of the form if X then Y found in transaction data (e.g. bread → butter). Used in market basket analysis. [1]	if X then Y, market basket analysis
Self-attention	[1]	The mechanism in transformers that weighs how relevant every part of the input is to every other part, all at once. [1]	weighs how relevant every part of the input is, all at once
LSTM	[1]	Long Short-Term Memory: a type of RNN that can remember information over long sequences. [1]	Long Short-Term Memory, RNN, long sequences
Bounding box	[1]	A rectangle drawn around an object in an image to show where it is. [1]	rectangle drawn around an object, where it is
Inference	[1]	Using a trained model to make predictions on new data (as opposed to training it). [1]	trained model to make predictions
Cloud-based ML platform	[1]	On-demand, scalable virtual hardware (CPUs, GPUs, TPUs) rented over the internet, with no physical infrastructure needed. [1]	On-demand, scalable virtual hardware, no physical infrastructure

A4.4 Ethical Considerations

21 terms, 24 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Ethical implication	[2]	A possible positive or negative effect of a decision or technology. [1] On well-being, fairness, justice, rights or freedom. [1]	possible positive or negative effect, well-being, fairness, justice, rights or freedom
Bias (in ML)	[2]	Systematic unfairness in a model's output. [1] Caused by unrepresentative or prejudiced training data, which the model learns and amplifies. [1]	Systematic unfairness, unrepresentative or prejudiced training data, learns and amplifies
Algorithmic fairness	[1]	AI decisions should not discriminate against individuals or groups. [1]	not discriminate
Accountability	[1]	Being clear who is responsible / liable when an AI system causes harm. [1]	who is responsible / liable
Transparency	[1]	AI decisions can be explained and understood by people, building trust. [1]	AI decisions can be explained and understood, trust
Black box model	[1]	A model whose internal decision process cannot be easily explained, reducing trust. [1]	internal decision process cannot be easily explained
Consent	[1]	Personal data should only be used with the informed permission of the person, and anonymised. [1]	informed permission, anonymised
Privacy	[1]	A person's right to control how their personal data is collected, used and shared (e.g. GDPR). [1]	right to control how their personal data is collected, used and shared, GDPR
Misinformation	[1]	False information spread without intent to deceive. [1]	without intent to deceive
Disinformation	[1]	False information spread deliberately to deceive or manipulate. [1]	deliberately to deceive or manipulate
Deepfake	[1]	ML-generated fake media showing people saying or doing things they never did. [1]	ML-generated fake media, saying or doing things they never did
Quantum computing	[2]	Computing that uses qubits and quantum effects (superposition) to solve certain problems far faster. [1] Could break current encryption (RSA, ECC). [1]	qubits, far faster, break current encryption
Augmented Reality (AR)	[1]	Overlays digital information onto the real world through a phone, tablet or glasses. [1]	Overlays digital information onto the real world
Virtual Reality (VR)	[1]	Places the user in a fully immersive, computer-generated environment using a headset. [1]	fully immersive, computer-generated environment
Pervasive AI	[1]	AI built into everyday devices and environments, often working in the background. [1]	AI built into everyday devices and environments, in the background
Anonymity	[1]	Users cannot be identified. Protects free speech but can enable cyberbullying and trolling. [1]	cannot be identified, free speech, cyberbullying and trolling
Environmental impact	[1]	Training and running AI uses large amounts of energy, increasing carbon emissions. [1]	large amounts of energy, carbon emissions
Societal impact	[1]	AI can displace jobs and change society, so its benefits should be shared fairly. [1]	displace jobs, benefits should be shared fairly
Harassment bot	[1]	An automated program that sends abuse at scale. [1]	sends abuse at scale
Proactive regulation	[1]	Creating laws and ethical frameworks before harm happens, not after. [1]	laws and ethical frameworks before harm happens
Qubit	[1]	The basic unit of a quantum computer: it can be in a superposition of 0 and 1 at the same time. [1]	quantum computer, superposition of 0 and 1

B1 Computational Thinking

21 terms, 26 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Computational thinking	[2]	A problem solving approach that expresses a solution as steps a computer could carry out. [1] Using decomposition, abstraction, pattern recognition and algorithmic design. [1]	problem solving approach, steps a computer could carry out, decomposition, abstraction, pattern recognition and algorithmic design
Decomposition	[2]	Breaking a complex problem into smaller, more manageable sub-problems. [1] That can be solved separately. [1]	Breaking a complex problem into smaller, more manageable sub-problems, solved separately
Abstraction	[2]	Removing / ignoring unnecessary detail. [1] To focus on the essential features of a problem. [1]	Removing / ignoring unnecessary detail, focus on the essential features
Pattern recognition	[2]	Identifying similarities / repeated parts within or between problems. [1] So existing solutions can be reused. [1]	Identifying similarities / repeated parts, existing solutions can be reused
Algorithmic design	[1]	Creating a clear, ordered set of step by step instructions to solve a problem. [1]	clear, ordered set of step by step instructions
Algorithm	[1]	A finite sequence of well-defined steps that solves a problem. [1]	finite sequence of well-defined steps, solves a problem
Problem specification	[1]	A document defining a problem through its problem statement, constraints, objectives and goals, inputs, outputs and evaluation criteria. [1]	problem statement, constraints, objectives and goals, inputs, outputs and evaluation criteria
Problem statement	[1]	Describes what the problem is and why it matters. [1]	what the problem is, why it matters
Constraint	[1]	A limit / boundary on the solution (e.g. budget, time, hardware, rules). [1]	limit / boundary on the solution
Objectives and goals	[1]	The objective is the broad aim; the goals are specific, measurable targets that achieve it. [1]	objective, broad aim, goals, specific, measurable targets
Input / output specification	[1]	The format and type of data going in and the format and content of results coming out. [1]	format and type of data going in, format and content of results coming out
Evaluation criteria	[1]	The measures used to judge whether the solution succeeded. [1]	measures used to judge whether the solution succeeded
Flowchart	[1]	A diagram showing the steps of an algorithm using standard shapes (terminator, process, decision, input/output) joined by arrows. [1]	diagram showing the steps of an algorithm, standard shapes, joined by arrows
Trace table	[2]	A table recording the values of variables at each step of an algorithm. [1] Used to test / find logic errors by hand. [1]	values of variables at each step, test / find logic errors
Single responsibility principle (SRP)	[1]	Each part (module, function, class) should do one clear job. [1]	Each part (module, function, class) should do one clear job
Pseudocode	[1]	A structured, language-independent way of writing an algorithm in plain steps, not real code. [1]	structured, language-independent, not real code
Terminal (flowchart)	[1]	A rounded rectangle that marks the start or end of a flowchart. [1]	rounded rectangle, start or end
Process (flowchart)	[1]	A rectangle showing a calculation or assignment that changes data. [1]	rectangle, calculation or assignment
Input / output (flowchart)	[1]	A parallelogram showing data being read in or printed out. [1]	parallelogram, read in or printed out
Decision (flowchart)	[1]	A diamond containing a yes/no question, with exactly two exits. [1]	diamond, yes/no question, exactly two exits
Connector (flowchart)	[1]	A small circle with a label that joins two parts of a flowchart without a long line. [1]	small circle with a label, without a long line

B2.1 Programming Fundamentals

30 terms, 38 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Variable	[1]	A named location in memory that stores a value which can change while the program runs. [1]	named location in memory, stores a value which can change
Constant	[1]	A named value that does not change while the program runs. [1]	does not change
Data type	[2]	Defines the kind of value a variable holds (integer, float, string, Boolean). [1] And so what operations can be done on it and how much memory it uses. [1]	kind of value, what operations, how much memory
Integer	[1]	A whole number with no decimal part. [1]	whole number
Float (real)	[1]	A number with a decimal / fractional part. [1]	with a decimal / fractional part
String	[1]	A sequence of characters. [1]	sequence of characters
Boolean	[1]	A data type with only two values: True or False. [1]	two values: True or False
Casting	[1]	Converting a value from one data type to another (e.g. int("5")). [1]	Converting a value from one data type to another
Global variable	[2]	Declared outside any function / subroutine. [1] Can be accessed anywhere in the program. [1]	outside any function / subroutine, accessed anywhere in the program
Local variable	[2]	Declared inside a function / subroutine. [1] Only exists and can be used within that function while it runs. [1]	inside a function / subroutine, exists and can be used within that function
Scope	[1]	The part of the program where a variable can be accessed. [1]	part of the program where a variable can be accessed
Index	[1]	The position of an item in a string or list, starting at 0. [1]	position of an item, starting at 0
Substring	[1]	A sequence of characters taken from within a larger string. [1]	sequence of characters taken from within a larger string
Immutable	[1]	Cannot be changed after it is created. Python strings are immutable, methods return a new string. [1]	Cannot be changed after it is created, return a new string
Exception	[2]	An unexpected event / error that occurs during program execution. [1] That disrupts normal flow and crashes the program if not handled. [1]	unexpected event / error, during program execution, disrupts normal flow, crashes the program if not handled
Exception handling	[2]	Code that detects and responds to runtime errors. [1] So the program does not crash and can continue or end safely (try, except, finally). [1]	detects and responds to runtime errors, does not crash, continue or end safely
try / except / finally	[2]	try holds the risky code, except runs if an error occurs. [1] finally always runs, error or not (used for cleanup). [1]	try, except, finally, always runs
Validation	[1]	Checking that input is sensible / reasonable before it is used (range check, type check, presence check, format check). [1]	Checking that input is sensible / reasonable
Logic error	[1]	The program runs without crashing but gives the wrong result, because the algorithm is wrong. [1]	runs without crashing, gives the wrong result
Syntax error	[1]	Code that breaks the rules of the language, so it cannot be run / translated. [1]	breaks the rules of the language, cannot be run / translated
Debugging	[1]	The process of finding and fixing errors (bugs) in a program. [1]	finding and fixing errors (bugs)
Breakpoint	[2]	A marker that pauses the program at a chosen line. [1] So the values of variables can be inspected at that point. [1]	pauses the program at a chosen line, values of variables can be inspected
Step into / over / out	[2]	Step into runs inside a called function line by line; step over runs the whole call as one step. [1] Step out finishes the current function and returns to the caller. [1]	Step into, inside, step over, whole call as one step, Step out, finishes the current function
Type hint	[1]	A note in Python showing the intended data type of a variable (e.g. `age: int`). Not enforced. [1]	intended data type, Not enforced
Character (char)	[1]	A single letter, digit or symbol. Python has no char type: it uses a string of length 1. [1]	single letter, digit or symbol, string of length 1
Negative index	[1]	Counts from the end of a string or list: `-1` is the last element. [1]	from the end, last
Slicing	[1]	Taking part of a string or list with `[start:end]`; the end index is not included. [1]	end index is not included
Runtime error	[1]	An error that happens while the program is running (e.g. dividing by zero), which crashes it if not handled. [1]	while the program is running, crashes it
Garbage in, garbage out (GIGO)	[1]	Bad input data produces bad output, however good the program is. [1]	Bad input data produces bad output
Print debugging	[1]	Adding print statements at key points to show variable values and find where the code goes wrong. [1]	print statements, show variable values

B2.2 Data Structures

17 terms, 23 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Data structure	[1]	A way of organising data in memory so it can be accessed and used efficiently. [1]	organising data in memory, accessed and used efficiently
Static data structure	[1]	Its size is fixed when it is declared (at compile time) and cannot change while the program runs. [1]	size is fixed, compile time, cannot change
Dynamic data structure	[2]	Can grow and shrink while the program runs (at runtime). [1] Memory is allocated as items are added and freed when they are removed. [1]	grow and shrink, runtime, Memory is allocated, freed
Compile time vs runtime	[2]	Compile time: before the program runs, when code is translated into machine code. [1] Runtime: while the program is running in memory. [1]	Compile time:, translated into machine code, Runtime:, running in memory
Element	[1]	One value stored in a list or array. [1]	One value
Traversal	[1]	Visiting every element of a data structure in order. [1]	Visiting every element, in order
2D list	[1]	A list of lists, like a table. An element is reached with [row][column]. [1]	list of lists, [row][column]
Tuple	[1]	A Python sequence that cannot be changed after it is created (immutable, fixed size). [1]	cannot be changed after it is created
Stack	[2]	A data structure where items are added and removed only at the top. [1] LIFO: last in, first out. [1]	added and removed only at the top, LIFO: last in, first out
LIFO	[1]	Last in, first out: the most recently added item is the first removed. [1]	Last in, first out, most recently added, first removed
push / pop / peek	[2]	push adds an item to the top; pop removes and returns the top item. [1] peek returns the top item without removing it. [1]	push, top, pop, removes and returns, peek, returns the top item without removing
Stack overflow	[1]	Trying to push onto a full stack, e.g. when recursion goes too deep and fills the call stack. [1]	push onto a full stack, recursion goes too deep
Stack underflow	[1]	Trying to pop or peek an empty stack. [1]	pop or peek an empty stack
Queue	[2]	A data structure where items join at the back and leave from the front. [1] FIFO: first in, first out. [1]	join at the back, leave from the front, FIFO: first in, first out
FIFO	[1]	First in, first out: the first item added is the first removed. [1]	First in, first out, first item added, first removed
enqueue / dequeue / front	[2]	enqueue adds an item to the back; dequeue removes and returns the front item. [1] front returns the front item without removing it. [1]	enqueue, back, dequeue, removes and returns, front, returns the front item without removing
isEmpty	[1]	Returns True if the stack or queue contains no items. Checked before pop or dequeue. [1]	True if the stack or queue contains no items, before pop or dequeue

B2.3 Programming Constructs

15 terms, 18 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Sequence	[1]	Instructions are executed one after another in the order they are written. [1]	executed one after another in the order they are written
Selection	[1]	A condition is tested and the program takes a different path depending on whether it is True or False (if / elif / else). [1]	condition is tested, takes a different path
Iteration (repetition)	[1]	Repeating a block of code, using a for or while loop. [1]	Repeating a block of code, for, while
Infinite loop	[1]	A loop whose end condition is never met, so it never stops (e.g. the counter is never updated). [1]	end condition is never met, never stops
Comparison operator	[1]	An operator that compares two values and gives True or False: == != < > <= >=. [1]	compares two values, == != < > <= >=
Logical operators (and / or / not)	[2]	and: True only if both conditions are True; or: True if at least one is True. [1] not: reverses a condition. [1]	and:, both, or:, at least one, not:, reverses
Case statement (match / switch)	[1]	Compares one value against several possible options and runs the matching branch. [1]	one value against several possible options
Count-controlled loop (for)	[1]	Repeats a known number of times, or once for each item in a list. [1]	known number of times, each item in a list
Condition-controlled loop (while)	[1]	Repeats while a condition is True; used when the number of repeats is unknown. May run zero times. [1]	while a condition is True, number of repeats is unknown
Nested loop	[1]	A loop inside another loop: the inner loop runs fully for each pass of the outer loop. [1]	loop inside another loop, runs fully for each pass
Function	[1]	A named block of code that performs a task and can be called whenever needed, often returning a value. [1]	named block of code that performs a task, called, returning a value
Modularization	[2]	Splitting a program into separate functions or modules, each doing one task. [1] Makes code easier to read, test, reuse and update. [1]	Splitting a program into separate functions or modules, one task, read, test, reuse and update
Parameter vs argument	[2]	A parameter is the placeholder in the function definition. [1] An argument is the actual value passed in when the function is called. [1]	parameter, placeholder in the function definition, argument, actual value passed in
Return value	[1]	The value a function sends back to the code that called it. [1]	value a function sends back
Library	[1]	A collection of pre-written, pre-tested code that can be imported, saving development time. [1]	pre-written, pre-tested code, imported

B2.4 Programming Algorithms

13 terms, 19 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Big O notation	[2]	Describes how the time (or memory) an algorithm needs grows as the input size n grows. [1] Gives the upper bound / worst case; used to compare scalability. [1]	time (or memory) an algorithm needs grows, input size n, upper bound / worst case, scalability
O(1) constant	[1]	The number of operations stays the same whatever the input size (e.g. access by index). [1]	stays the same whatever the input size
O(log n) logarithmic	[1]	The problem halves each step (e.g. binary search). [1]	halves each step, binary search
O(n) linear	[1]	Operations grow in direct proportion to n (e.g. one loop, linear search). [1]	in direct proportion, one loop
O(n²) quadratic	[1]	Operations grow with n squared, usually from nested loops (e.g. bubble and selection sort). [1]	n squared, nested loops, bubble and selection sort
O(2ⁿ) exponential	[1]	Operations double every time n increases by 1 (e.g. brute forcing every combination). [1]	double every time n increases by 1
Time vs space complexity	[2]	Time complexity: how the number of operations grows with n. [1] Space complexity: how much extra memory is needed as n grows. [1]	Time complexity:, number of operations, Space complexity:, extra memory
Linear search	[2]	Checks each element in turn from the start until the target is found or the list ends. [1] Works on unsorted data. O(n). [1]	each element in turn, found or the list ends, unsorted, O(n)
Binary search	[2]	On sorted data: check the middle element and discard the half that cannot contain the target. [1] Repeat until found or no data is left. O(log n). [1]	sorted, middle, discard the half, O(log n)
Bubble sort	[2]	Repeatedly compares adjacent pairs and swaps them if they are in the wrong order. [1] After each pass the largest value is in place at the end. O(n²), O(1) space. [1]	compares adjacent pairs and swaps, largest value is in place, O(n²)
Selection sort	[2]	Each pass finds the smallest value in the unsorted part [1] And swaps it into the first unsorted position. O(n²), O(1) space, at most n − 1 swaps. [1]	finds the smallest value, swaps it into the first unsorted position, O(n²), n − 1 swaps
Sorting in place	[1]	Sorting by swapping elements within the same list, so no extra memory is needed (O(1) space). [1]	swapping elements within the same list, no extra memory
Pass	[1]	One complete run through the list by the inner loop of a sort. [1]	One complete run through the list

B2.5 File Processing

7 terms, 8 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
File	[1]	Data saved in secondary storage that persists after the program ends. [1]	saved in secondary storage, persists after the program ends
Sequential file	[2]	A file whose records are stored one after another [1] And can only be read in order from the start. [1]	records are stored one after another, read in order from the start
Record	[1]	One complete item of data in a file (e.g. one line). [1]	One complete item
Write mode ("w")	[1]	Opens a file for writing and overwrites everything already in it; creates the file if it does not exist. [1]	overwrites everything, creates the file
Append mode ("a")	[1]	Opens a file and adds new data to the end, keeping the existing data. [1]	adds new data to the end, keeping the existing data
Read mode ("r")	[1]	Opens a file for reading only. Raises FileNotFoundError if the file does not exist. [1]	for reading only, FileNotFoundError
Closing a file	[1]	Releases the file so data is saved and not corrupted. Python's `with open()` closes it automatically. [1]	saved and not corrupted, closes it automatically

B3.1 Fundamentals of OOP

17 terms, 22 marks | Read the article → | ↑ Top

Term	Marks	Model answer (one mark per point)	Key words
Class	[1]	A blueprint / template that defines the attributes (instance variables) and behaviours (methods) of an object. [1]	blueprint / template, attributes (instance variables), behaviours (methods)
Object	[1]	An instance of a class that exists in memory with its own values for the instance variables. [1]	instance of a class, exists in memory
Instantiation	[2]	Creating an object by calling the constructor with starting values [1] So it is allocated memory and given an identifier. [1]	Creating an object, calling the constructor, allocated memory, identifier
Constructor	[1]	A special method that creates an object and sets its starting values (Python: `__init__`). [1]	creates an object, sets its starting values
Instance variable (attribute)	[1]	Data stored about each object; every object has its own copy. [1]	about each object, every object has its own copy
Method (behaviour)	[1]	A function inside a class that defines what an object can do. [1]	function inside a class, what an object can do
Accessor (getter)	[1]	A public method that returns the value of a private attribute. [1]	public method that returns, private
Mutator (setter)	[1]	A public method that changes a private attribute, often validating the new value first. [1]	public method that changes, private, validating
Static variable	[2]	A variable that belongs to the class, not the object [1] One copy shared by all objects, accessed through the class name. [1]	belongs to the class, not the object, One copy shared by all objects, class name
Static method	[1]	A method that belongs to the class, called without an object; can only use static variables directly. [1]	belongs to the class, without an object, static variables
UML class diagram	[2]	A standard diagram of a class in three boxes: name, attributes, methods [1] With - private, + public, # protected, and underline for static. [1]	standard diagram of a class, name, attributes, methods, - private, + public, # protected, underline for static
Encapsulation (OOP)	[2]	Bundling data and methods inside one class [1] With the data hidden (private) and accessed only through public methods. [1]	Bundling data and methods inside one class, hidden (private), only through public methods
Information hiding	[1]	Internal data and details are hidden so other code cannot see or change them directly. [1]	Internal data and details are hidden, cannot see or change them directly
Access modifiers	[2]	Private: only inside the class; protected: class, subclasses and package. [1] Public: accessible from anywhere. [1]	Private:, protected:, Public:, anywhere
Dot notation	[1]	Using a dot to call a method or reach data on a specific object: `object.method()`. [1]	on a specific object
Inheritance	[1]	A subclass takes the attributes and methods of a superclass and adds its own, so common code is written once. [1]	subclass takes the attributes and methods of a superclass, adds its own
Polymorphism	[1]	"Many forms": the same method name behaves differently depending on the object or parameters. [1]	"Many forms", same method name behaves differently

Ninja Notes:

Define means give the precise meaning. Usually [1] or [2]. Do not explain or give examples unless asked.
Outline or describe means more points. Count the marks and write one clear point per mark.
For a [2] definition, write what it is plus what it does or why.
Never define a word using the same word. "Encryption is encrypting data" scores zero.
Learn pairs together: lossy and lossless, TCP and UDP, symmetric and asymmetric, static and dynamic IP, polling and interrupts, misinformation and disinformation.

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