Skip to content
Visual revision

Infographics

Every syllabus topic, drawn the way examiners expect you to draw it — grouped by course and topic, 68 unique diagrams. Download as PNG for your notes, print them, stick them on the wall.

93 diagrams · 68 unique

O Level

2210

Paper 1 · 1. Data Representation open topic →

Number system conversionsDenary ↔ binary ↔ hexadecimal — the routes the exam expects.Denarybase 10 · 0–9Binarybase 2 · 0,1Hexbase 16 · 0–9, A–F÷2, read remainders upadd place values 128…1group 4 bits → digiteach digit → 4 bitsdenary ↔ hex: go via binary (or ÷16 / ×16)128643216842110110110= 128+32+16+4+2= 182 = B6₁₆Two's complement: invert all bits, add 1. Left shift ×2, right shift ÷2.Hex is used for MAC addresses, colour codes, memory dumps and error codes.cswithzak.com

Number system conversions

O Level 1. Data Representation · AS Level 1. Information Representation

O LevelAS
File size calculationsWork in bits first, then ÷ 8 for bytes, then ÷ 1024 for each step up. Show every line of working.IMAGE (bitmap)size = width × height × colour depth1024 × 768 × 24 bits= 18 874 368 bits ÷ 8= 2 359 296 bytes ÷ 1024= 2304 KiB = 2.25 MiBcolour depth 24 bits = 16.7 million colours (2²⁴)SOUNDsize = sample rate × resolution × seconds44 100 Hz × 16 bits × 30 s= 21 168 000 bits ÷ 8= 2 646 000 bytes ÷ 1024≈ 2584 KiB ≈ 2.52 MiB (×2 if stereo)higher sample rate / resolution = better quality, bigger filebitnibble×4byte×2KiB×1024MiB×1024GiB×1024TiB×1024PiB×1024EiB×10241 nibble = 4 bits · 1 byte = 8 bits · 1 KiB (kibibyte) = 1024 bytes · 1 MiB = 1024 KiB · 1 GiB = 1024 MiB · 1 TiB = 1024 GiBBinary prefixes (kibi, mebi, gibi…) are powers of 2. Decimal prefixes (kilo, mega, giga…) are powers of 10: 1 kB = 1000 bytes.Resolution = number of pixels (w × h). Colour depth = bits per pixel.Sample rate = samples per second (Hz). Sample resolution = bits per sample.Compression: lossy (MP3, JPEG) discards data permanently; lossless (RLE, PNG, ZIP) restores the original exactly.cswithzak.com

File size calculations

O Level 1. Data Representation · AS Level 1. Information Representation

O LevelAS
Two's complement, overflow & shifts8-bit two's complement: the MSB is worth −128. Range −128 … +127. Same bits, different meaning — saywhich you are using.Negating +37 → −37+370010010132 + 4 + 1invert11011010flip every bit (one’s complement)+111011011= −128 + 64 + 16 + 8 + 2 + 1 = −37 ✓Shortcut: from the right, copy up to and including the first 1, then flip the rest.Overflow0111111112700000001+ 110000000= −128 ✗ does not fit in 8 bitsOverflow = the answer needs more bits than the register has.Sign flips: two positives give a negative (or vice-versa).ShiftsShift0001 0110 (22) →logical left 10010 1100 (44)logical right 10000 1011 (11)arithmetic right 1keeps the sign bit1111 0100 (−12) →1111 1010 (−6)Left ×2, right ÷2. Bits shifted out are lost — that isanother cause of overflow. Logical fills with 0s.BCD: each denary digit as its own 4-bit nibble — 47 = 0100 0111. Used where exact decimals matter (currency).cswithzak.com

Two's complement, overflow & shifts

O Level 1. Data Representation · AS Level 1. Information Representation · AS Level 4. Processor Fundamentals

O LevelAS
Bitmap vs vector graphics & digital soundBitmap = grid of pixels. Vector = list of drawing commands. Sound = analogue wave measured (sampled) atregular intervals.BITMAP8 × 6 pixels · 1 bit eachVECTORellipse(56,42,44,30) line(…)BitmapVectorStored ascolour of every pixelobjects + propertiesResizepixelates / blursscales perfectlyFile sizeresolution × colour depthdepends on object countBest forphotos, scanslogos, fonts, CAD, mapsFormatsBMP, JPEG, PNG, GIFSVG, EPS, AIImage resolution = pixels per inch / total pixels. Colour depth = bits per pixel: 1 bit → 2 colours, 8 bits → 256, 24 bits → 16.7 M.File header stores width, height, colour depth. 2210/9618 both want: file size = W × H × depth (+ header).Sampling sound111100000Sampling rate = samples per second (Hz). CD quality = 44.1 kHz.Sampling resolution = bits per sample (8 levels shown = 3 bits).Higher rate → closer to the analogue wave; higher resolution →finer amplitude steps. Both increase the file size.size = rate × resolution × seconds (× 2 for stereo).Vector = drawing list, bitmap = colour of every pixel — so a vector logo scales cleanly and a bitmap photo does not.cswithzak.com

Bitmap, vector & sound

AS Level 1. Information Representation · O Level 1. Data Representation

ASO Level

Lossless vs lossy compression

AS Level 1. Information Representation · O Level 1. Data Representation

ASO Level

Paper 1 · 2. Data Transmission open topic →

Data packets & transmission modes

O Level 2. Data Transmission

O Level

Error detection methods

O Level 2. Data Transmission · AS Level 6. Security, Privacy and Data Integrity

O LevelAS

Circuit vs packet switching

A2 Level 14. Communication and Internet Technologies · O Level 2. Data Transmission

A2O Level

Paper 1 · 3. Hardware open topic →

Von Neumann architecture

O Level 3. Hardware · AS Level 4. Processor Fundamentals

O LevelAS

Fetch–Decode–Execute cycle

O Level 3. Hardware · AS Level 4. Processor Fundamentals

O LevelAS

Primary, secondary & virtual storage

O Level 3. Hardware

O Level

Paper 1 · 4. Software open topic →

How an interrupt is handled

O Level 4. Software · AS Level 4. Processor Fundamentals

O LevelAS

Compiler, interpreter & assembler

O Level 4. Software · AS Level 5. System Software

O LevelAS

What the operating system does

O Level 4. Software · AS Level 5. System Software

O LevelAS

Paper 1 · 5. The Internet and Its Uses open topic →

URL anatomy & fetching a web page

O Level 5. The Internet and Its Uses

O Level

Cyber threats vs defences

O Level 5. The Internet and Its Uses · AS Level 6. Security, Privacy and Data Integrity

O LevelAS

Paper 1 · 6. Automated and Emerging Technologies open topic →

Automated systems: sensor → actuator

O Level 6. Automated and Emerging Technologies

O Level

Expert systems & machine learning

O Level 6. Automated and Emerging Technologies

O Level

Paper 2 · 7. Algorithm Design and Problem-Solving open topic →

Flowchart symbols & the PDLC

O Level 7. Algorithm Design and Problem-Solving · AS Level 9. Algorithm Design and Problem-Solving

O LevelAS

Bubble sort & linear search

O Level 7. Algorithm Design and Problem-Solving · AS Level 10. Data Types and Structures

O LevelAS

Choosing test data

O Level 7. Algorithm Design and Problem-Solving · AS Level 12. Software Development

O LevelAS

Dry run with a trace table (animated)

O Level 7. Algorithm Design and Problem-Solving

O Level

Decomposing a system into sub-systems (animated)

O Level 7. Algorithm Design and Problem-Solving

O Level

Linear search vs binary search (animated)

O Level 7. Algorithm Design and Problem-Solving

O Level

Paper 2 · 8. Programming open topic →

Three kinds of loop

O Level 8. Programming · AS Level 11. Programming

O LevelAS

Procedure vs function

O Level 8. Programming · AS Level 11. Programming

O LevelAS

Arrays, records & text files

AS Level 10. Data Types and Structures · O Level 8. Programming

ASO Level

Paper 2 · 9. Databases open topic →

Single-table database & SQL

O Level 9. Databases · AS Level 8. Databases

O LevelAS

Paper 2 · 10. Boolean Logic open topic →

Logic gate symbols

O Level 10. Boolean Logic · AS Level 3. Hardware

O LevelAS

From logic circuit to truth table

O Level 10. Boolean Logic · AS Level 3. Hardware · A2 Level 15. Hardware and Virtual Machines

O LevelASA2

AS Level

9618

Paper 1 · 1. Information Representation open topic →

Number system conversions

O Level 1. Data Representation · AS Level 1. Information Representation

O LevelAS

File size calculations

O Level 1. Data Representation · AS Level 1. Information Representation

O LevelAS

Two's complement, overflow & shifts

O Level 1. Data Representation · AS Level 1. Information Representation · AS Level 4. Processor Fundamentals

O LevelAS

Bitmap, vector & sound

AS Level 1. Information Representation · O Level 1. Data Representation

ASO Level

Lossless vs lossy compression

AS Level 1. Information Representation · O Level 1. Data Representation

ASO Level

Paper 1 · 2. Communication open topic →

Network topologies

AS Level 2. Communication

AS

IP addressing, subnets & DNS

AS Level 2. Communication

AS

Paper 1 · 3. Hardware open topic →

Logic gate symbols

O Level 10. Boolean Logic · AS Level 3. Hardware

O LevelAS

From logic circuit to truth table

O Level 10. Boolean Logic · AS Level 3. Hardware · A2 Level 15. Hardware and Virtual Machines

O LevelASA2

Paper 1 · 4. Processor Fundamentals open topic →

Two's complement, overflow & shifts

O Level 1. Data Representation · AS Level 1. Information Representation · AS Level 4. Processor Fundamentals

O LevelAS

Von Neumann architecture

O Level 3. Hardware · AS Level 4. Processor Fundamentals

O LevelAS

Fetch–Decode–Execute cycle

O Level 3. Hardware · AS Level 4. Processor Fundamentals

O LevelAS

How an interrupt is handled

O Level 4. Software · AS Level 4. Processor Fundamentals

O LevelAS

Assembly language & addressing modes

AS Level 4. Processor Fundamentals

AS

Paper 1 · 5. System Software open topic →

Compiler, interpreter & assembler

O Level 4. Software · AS Level 5. System Software

O LevelAS

What the operating system does

O Level 4. Software · AS Level 5. System Software

O LevelAS

Paper 1 · 6. Security, Privacy and Data Integrity open topic →

Error detection methods

O Level 2. Data Transmission · AS Level 6. Security, Privacy and Data Integrity

O LevelAS

Cyber threats vs defences

O Level 5. The Internet and Its Uses · AS Level 6. Security, Privacy and Data Integrity

O LevelAS

Security, privacy & integrity

AS Level 6. Security, Privacy and Data Integrity

AS

Paper 1 · 7. Ethics and Ownership open topic →

Ethics, codes of conduct & licensing

AS Level 7. Ethics and Ownership

AS

Artificial intelligence: applications & impact

AS Level 7. Ethics and Ownership

AS

Paper 1 · 8. Databases open topic →

Single-table database & SQL

O Level 9. Databases · AS Level 8. Databases

O LevelAS

Entity-relationship diagrams & keys

AS Level 8. Databases

AS

Normalisation 1NF → 3NF

AS Level 8. Databases

AS

SQL: DDL vs DML

AS Level 8. Databases

AS

Paper 2 · 9. Algorithm Design and Problem-Solving open topic →

Flowchart symbols & the PDLC

O Level 7. Algorithm Design and Problem-Solving · AS Level 9. Algorithm Design and Problem-Solving

O LevelAS

Stepwise refinement & identifier tables

AS Level 9. Algorithm Design and Problem-Solving

AS

Paper 2 · 10. Data Types and Structures open topic →

Bubble sort & linear search

O Level 7. Algorithm Design and Problem-Solving · AS Level 10. Data Types and Structures

O LevelAS

Stack, queue & linked list

AS Level 10. Data Types and Structures · A2 Level 19. Computational Thinking and Problem-Solving

ASA2

Arrays, records & text files

AS Level 10. Data Types and Structures · O Level 8. Programming

ASO Level

Paper 2 · 11. Programming open topic →

Three kinds of loop

O Level 8. Programming · AS Level 11. Programming

O LevelAS

Procedure vs function

O Level 8. Programming · AS Level 11. Programming

O LevelAS

BYVAL vs BYREF & scope

AS Level 11. Programming

AS

Paper 2 · 12. Software Development open topic →

Choosing test data

O Level 7. Algorithm Design and Problem-Solving · AS Level 12. Software Development

O LevelAS

Waterfall, iterative & RAD

AS Level 12. Software Development

AS

Testing & maintenance

AS Level 12. Software Development

AS

A2 Level

9618

Paper 3 · 13. Data Representation open topic →

User-defined data types

A2 Level 13. Data Representation

A2

Floating-point representation

A2 Level 13. Data Representation

A2

File organisation & hashing

A2 Level 13. Data Representation

A2

Paper 3 · 14. Communication and Internet Technologies open topic →

Circuit vs packet switching

A2 Level 14. Communication and Internet Technologies · O Level 2. Data Transmission

A2O Level

TCP/IP protocol stack

A2 Level 14. Communication and Internet Technologies

A2

Application protocols & BitTorrent

A2 Level 14. Communication and Internet Technologies

A2

Paper 3 · 15. Hardware and Virtual Machines open topic →

Half adder & full adder

A2 Level 15. Hardware and Virtual Machines

A2

SR & JK flip-flops

A2 Level 15. Hardware and Virtual Machines

A2

Karnaugh maps & Boolean algebra

A2 Level 15. Hardware and Virtual Machines

A2

RISC vs CISC & pipelining

A2 Level 15. Hardware and Virtual Machines

A2

Parallel processing & virtual machines

A2 Level 15. Hardware and Virtual Machines

A2

From logic circuit to truth table

O Level 10. Boolean Logic · AS Level 3. Hardware · A2 Level 15. Hardware and Virtual Machines

O LevelASA2

Paper 3 · 16. System Software open topic →

Compiler pipeline

A2 Level 16. System Software

A2

Process states & scheduling

A2 Level 16. System Software

A2

Paging, segmentation & virtual memory

A2 Level 16. System Software

A2

BNF, syntax diagrams & RPN

A2 Level 16. System Software

A2

Paper 3 · 17. Security open topic →

Asymmetric encryption & digital signatures

A2 Level 17. Security

A2

Digital certificates & the TLS handshake

A2 Level 17. Security

A2

Paper 3 · 18. Artificial Intelligence open topic →

Graphs & Dijkstra's algorithm

A2 Level 18. Artificial Intelligence

A2

Machine learning & neural networks

A2 Level 18. Artificial Intelligence

A2

Paper 4 · 19. Computational Thinking and Problem-Solving open topic →

Stack, queue & linked list

AS Level 10. Data Types and Structures · A2 Level 19. Computational Thinking and Problem-Solving

ASA2

Recursion: winding & unwinding

A2 Level 19. Computational Thinking and Problem-Solving

A2

Big O & algorithm performance

A2 Level 19. Computational Thinking and Problem-Solving

A2

Binary tree & hash table

A2 Level 19. Computational Thinking and Problem-Solving

A2

Paper 4 · 20. Further Programming open topic →

OOP: classes, inheritance & polymorphism

A2 Level 20. Further Programming

A2

Paradigms, files & exception handling

A2 Level 20. Further Programming

A2
Enroll nowOnline classes