1 Foundations – AS‑Level Content (Syllabus 1‑12)
1.1 Information Representation
- Number systems – binary, octal, decimal, hexadecimal.
- Binary arithmetic: addition, subtraction, multiplication, division.
- Two’s‑complement for signed integers; overflow detection.
- Floating‑point representation (IEEE‑754 single precision).
- BCD and packed‑BCD for decimal data.
- Prefixes – kibi (Ki), mebi (Mi), gibi (Gi) etc.
Example
Convert the decimal number -23 to an 8‑bit two’s‑complement binary value:
23 = 00010111
Invert bits → 11101000
Add 1 → 11101001 (‑23)
1.2 Data Structures & Algorithms
| Structure | Key Operations | Typical Use |
|---|
| Array (static) | Indexing O(1), insert/delete O(n) | Lookup tables, image pixels |
| Linked list (singly/doubly) | Insert/delete O(1) at head/tail | Dynamic memory, queues |
| Stack | Push/Pop O(1) | Expression evaluation, recursion |
| Queue / Circular queue | Enqueue/Dequeue O(1) | Scheduling, buffering |
| Binary tree | Traversal (in‑order, pre‑order, post‑order) | Hierarchical data, expression trees |
| Binary Search Tree (BST) | Search/Insert/Delete O(log n) average | Ordered data, dictionary |
| Heap (binary) | Insert/Extract‑max O(log n) | Priority queue, scheduling |
1.3 Algorithm Design & Problem Solving
- Algorithm notation – pseudocode, flowcharts, N‑step notation.
- Complexity analysis – time (Big‑O) and space.
- Common patterns: search (linear, binary), sort (bubble, selection, insertion, merge, quick).
- Recursion – base case, recursive step, stack‑frame illustration.
Example: Binary Search (pseudocode)
function binarySearch(A, target):
low ← 0; high ← length(A)‑1
while low ≤ high:
mid ← (low+high) // 2
if A[mid] = target return mid
else if A[mid] < target low ← mid+1
else high ← mid‑1
return NOT_FOUND
1.4 Computer Architecture & Processor Fundamentals
- CPU components – ALU, control unit, registers, cache.
- Fetch‑decode‑execute cycle; instruction formats (R‑type, I‑type, J‑type).
- Machine language vs. assembly language; basic MIPS/ARM examples.
- Interrupts, pipelining basics, hazards.
1.5 System Software
- Operating system functions – process management, memory management, file system, I/O control.
- System calls and API examples (open, read, write, close).
- Virtual memory – paging, page tables, page‑fault handling.
1.6 Translators
- Assembler, compiler, interpreter – purpose and workflow.
- Phases of compilation – lexical analysis, parsing, semantic analysis, optimisation, code generation.
- Intermediate code (three‑address code) and its advantages.
1.7 Communication & Networks
- Network topologies – star, bus, ring, mesh, hybrid.
- OSI model – 7 layers, key functions of each layer.
- Common protocols – HTTP, FTP, SMTP, TCP, UDP, IP.
- Data transmission concepts – bandwidth, latency, throughput, error detection (parity, checksum, CRC).
1.8 Security & Ethics
- Confidentiality, integrity, availability (CIA triad).
- Symmetric encryption (DES, AES) and asymmetric encryption (RSA, ECC).
- Hash functions (MD5, SHA‑1/2) and digital signatures.
- Ethical issues – privacy, bias, intellectual property, professional conduct.
1.9 Databases
- Relational model – tables, primary keys, foreign keys.
- SQL – DDL (CREATE, ALTER, DROP) and DML (SELECT, INSERT, UPDATE, DELETE).
- Normalization – 1NF, 2NF, 3NF with example tables.
- Indexing – B‑tree index basics, impact on query performance.
1.10 Programming Fundamentals (Python/Java‑like pseudocode)
- Variables, data types, operators, control structures (if, switch, loops).
- Procedures / functions – parameters, return values, scope.
- Arrays, strings, simple file I/O.
- Basic debugging techniques – print‑statement, step‑through, breakpoints.
1.11 Software Development Life‑Cycle (SDLC)
- Stages – requirements, design, implementation, testing, deployment, maintenance.
- Modelling tools – UML class diagram, sequence diagram, use‑case diagram.
- Testing levels – unit, integration, system, acceptance; test‑case design (black‑box, white‑box).
1.12 Evaluation of Solutions
- Correctness, efficiency, maintainability, usability, reliability.
- Use of metrics – time/space complexity, cyclomatic complexity, code coverage.
2 Advanced – A‑Level Extensions (Syllabus 13‑20)
2.1 User‑Defined Data Types & Abstract Data Types (ADTs)
- Structures / records – grouping heterogeneous fields.
- Classes (OOP) – encapsulation, inheritance, polymorphism.
- Interface definition – abstract methods, contracts.
2.2 File Organisation & Advanced File Processing
- Sequential, random, indexed, and hashed file organisations.
- File access methods – sequential read/write, random access via seek.
- Binary file formats – fixed‑length vs. variable‑length records.
- Example: Reading a binary record of a student (ID int, GPA float) in C‑like pseudocode.
2.3 Floating‑Point Arithmetic (Extended)
- Normalised scientific notation, exponent bias, rounding modes.
- Common errors – catastrophic cancellation, overflow/underflow.
2.4 Network Protocols & Data Link Layer
- TCP vs. UDP – connection‑oriented vs. connection‑less, flow control, congestion control.
- Ethernet framing, MAC addressing, ARP, VLAN tagging.
- Protocol stacks – client‑server model, socket programming basics.
2.5 Virtual Machines & Runtime Environments
- Purpose – platform independence, sandboxing, JIT compilation.
- Examples – Java Virtual Machine (JVM), .NET CLR, Python interpreter.
- Bytecode vs. native code – trade‑offs.
2.6 Advanced Security Topics
- Public‑key infrastructure (PKI), certificate authorities.
- Secure protocols – TLS/SSL handshake, SSH.
- Authentication methods – passwords, biometrics, multi‑factor.
- Common attacks – Man‑in‑the‑Middle, SQL injection, buffer overflow.
2.7 Artificial Intelligence (AI) – Complete Overview
2.7.1 Graph‑Based AI
- Search graphs – state‑space representation, uninformed (BFS, DFS, Dijkstra) and informed (A*) search.
- Knowledge graphs – triples (subject‑predicate‑object), RDF, SPARQL queries.
- Decision trees – also a basic ML classifier; entropy, information gain.
2.7.2 Machine Learning (ML)
| Learning type | Description | Typical tasks |
|---|
| Supervised | Learn from labelled pairs (x, y) | Image classification, spam detection |
| Unsupervised | Find structure in unlabelled data | Clustering, dimensionality reduction |
| Semi‑supervised | Combine small labelled set with large unlabelled set | Web‑page categorisation |
Key algorithms (A‑Level depth)
| Algorithm | Core idea | Use case |
|---|
| Decision tree | Recursive splitting on attribute tests | Rule extraction, simple classification |
| k‑Nearest Neighbour (k‑NN) | Majority vote of k closest points (distance metric) | Handwritten digit recognition |
| Linear / Logistic regression | Fit line (linear) or sigmoid (logistic) to data | House‑price prediction, binary diagnosis |
| Support Vector Machine (SVM) | Maximum‑margin hyper‑plane (kernel tricks for non‑linear) | Text categorisation, small‑data image tasks |
2.7.3 Deep Learning (DL)
- Artificial Neural Networks (ANNs) – layers of neurons, weights, biases, activation functions (sigmoid, ReLU, tanh).
- Training – loss function L, gradient descent, back‑propagation:
w ← w – η · ∂L/∂w
- Architectures
- Convolutional Neural Networks (CNNs) – convolution + pooling for images.
- Recurrent Neural Networks (RNN) / LSTM – memory cells for sequences.
- Transformers – self‑attention, dominant in NLP and multimodal tasks.
2.7.4 Reinforcement Learning (RL)
- Modelled as a Markov Decision Process (MDP): set of states S, actions A, transition probability P(s'|s,a), reward R(s,a).
- Policy π(s) → a; objective is to maximise expected return
Gₜ = Σγⁿ Rₜ₊ₙ.
Core RL algorithms
| Algorithm | Idea | Typical domain |
|---|
| Q‑learning | Learn action‑value Q(s,a) via temporal‑difference update | Grid‑world navigation, simple games |
| Policy Gradient | Optimise policy parameters directly using gradient of expected reward | Complex control, continuous action spaces |
| Actor‑Critic | Actor updates policy; Critic evaluates state‑value V(s) | Robotics, Atari games |
2.8 Recursion & Advanced Programming Paradigms
- Recursive problem solving – divide‑and‑conquer, backtracking (e.g., N‑Queens).
- Functional programming concepts – pure functions, higher‑order functions, immutability.
- Event‑driven programming – callbacks, listeners (GUI, network).
- Exception handling – try/catch/finally, custom exception classes.
2.9 Advanced File Processing
- Random‑access files –
seek(), tell(), record locking. - Binary serialization – struct packing, endianness considerations.
- XML/JSON parsing – DOM vs. SAX, schema validation.
3 Assessment Objectives (AO) Alignment
| AO | What it assesses | Relevant topics |
|---|
| AO1 | Knowledge & understanding of concepts | All theory sections – number systems, CPU cycle, AI definitions, security principles. |
| AO2 | Application of knowledge to solve problems | Algorithm design, binary arithmetic, SQL queries, network protocol analysis, AI model selection. |
| AO3 | Design, development and testing of solutions | Programming (functions, OOP, recursion), SDLC, testing strategies, AI model training & evaluation. |
4 Examination Overview (Papers 1‑4)
- Paper 1 – Theory (2 hrs) – AO1 & AO2. Includes short‑answer, extended‑response, and data‑analysis questions covering all syllabus blocks.
- Paper 2 – Problem Solving (2 hrs) – AO2. Requires algorithm design, pseudocode, flowcharts, and analysis of given scenarios.
- Paper 3 – Programming (2 hrs) – AO3. Practical coding in a high‑level language (Python/Java). Tasks may involve data structures, file I/O, recursion, and a small AI component (e.g., implementing a decision tree).
- Paper 4 – Practical (2 hrs, optional A‑Level) – AO3. Hands‑on programming on a computer, testing and debugging a supplied program.
Paper‑specific checklist
| Paper | Key skills to practise |
|---|
| 1 | Definitions, diagram labeling, short calculations (binary, IP subnetting), ethical case analysis. |
| 2 | Write/interpret pseudocode, trace algorithms, calculate complexity, design a simple search or sorting algorithm. |
| 3 | Implement data structures, file handling, OOP classes, a basic ML model (e.g., logistic regression using a library), unit testing. |
| 4 | Debug a provided program, extend functionality, apply version‑control concepts. |
5 Evaluation Metrics for AI & Machine Learning Models
| Metric | Interpretation | When to use |
|---|
| Accuracy | Overall proportion of correct predictions | Balanced classification problems |
| Precision | True Positives / (True Positives + False Positives) | Costly false positives (spam, fraud detection) |
| Recall (Sensitivity) | True Positives / (True Positives + False Negatives) | Missing a positive is critical (medical diagnosis) |
| F1‑score | Harmonic mean of precision & recall | Imbalanced datasets where both errors matter |
| Mean Squared Error (MSE) | Average squared deviation from true value | Regression tasks (price prediction) |
| ROC‑AUC | Area under Receiver Operating Characteristic curve | Evaluating binary classifiers across thresholds |
6 Why Use These Methods? – Comparative Summary
| Method | Strengths | Limitations | Typical Applications |
|---|
| Traditional Machine Learning (ML) | Interpretable models; works with modest data; fast training. | Requires manual feature engineering; limited on raw high‑dimensional data. | Spam filtering, credit scoring, basic image classification. |
| Deep Learning (DL) | State‑of‑the‑art performance on vision, speech, language; learns features automatically. | Data‑hungry; computationally intensive; less transparent. | Image recognition, voice assistants, language translation. |
| Reinforcement Learning (RL) | Learns optimal sequential decisions; handles delayed rewards. | Needs many interactions; exploration‑exploitation balance; often requires simulation. | Game agents (AlphaGo), robotics, autonomous navigation. |
7 Suggested Diagrams (for classroom use)
- Flowchart of the AI hierarchy: AI → Graph‑based techniques → Machine Learning → Deep Learning (ANNs) → Reinforcement Learning, with example applications attached to each node.
- CPU fetch‑decode‑execute pipeline diagram.
- OSI model stack with protocol examples at each layer.
- Decision‑tree split illustration with entropy calculation.
- Q‑learning update equation visualised on a simple grid world.