Cambridge Syllabus Notes

Cambridge IGCSE Computer Science (0478) – Complete Syllabus Notes (2026‑28)

This set of notes covers all required sub‑topics for Topics 1‑10 of the Cambridge IGCSE Computer Science (0478) syllabus. It is written in the Cambridge‑style pseudocode conventions, includes clear examples, tables, and test‑data strategies, and highlights the limits imposed by the syllabus (e.g., parameters, nesting depth, circuit inputs).

1. Algorithm Design & Problem Solving (Topic 7)

Four‑stage problem‑solving cycle (PDLC)
1. Analysis – understand the problem, list inputs, outputs, constraints, and any validation required.
2. Design – decompose the problem into sub‑problems, produce a structure diagram and a clear algorithm (flowchart + pseudocode).
3. Coding – translate the algorithm into pseudocode (or a programming language).
4. Testing & Evaluation – verify correctness (validation) and improve the solution (verification).
Decomposition – break a large problem into smaller, manageable parts. Each part can be expressed as a separate procedure/function.

Structure diagram – a hierarchical block diagram that shows the main program and its sub‑routines. Example:

+-------------------+
|   Main Program    |
+-------------------+
|  Initialise()    |
|  GetData()       |
|  ProcessData()   |
|  OutputResult()  |
+-------------------+

Trace tables – record the values of variables after each step of an algorithm. Example for a FOR loop that adds the numbers 1‑5:

Step	i	sum
Initialise	–	0
1st iteration	1	0 + 1 = 1
2nd iteration	2	1 + 2 = 3
3rd iteration	3	3 + 3 = 6
4th iteration	4	6 + 4 = 10
5th iteration	5	10 + 5 = 15
Loop ends	–	15

Validation vs. Verification
- Validation – checks that input data are sensible (type, range, format). Example:
```
// Validate age input
READ age
IF age < 0 OR age > 120 THEN
    PRINT "Invalid age"
    STOP
END IF
                
```
- Verification – confirms that the program does what the specification requires. Use test‑data categories:
  - Normal data – typical values within the expected range.
  - Boundary data – values at the limits (e.g., 0 and 120 for age).
  - Extreme/invalid data – outside the limits or wrong type (e.g., –5, 999, “abc”).

2. Core Programming Concepts (Topic 8)

2.1 Variables, Constants & Data Types

Variables – named storage locations whose values can change. Types required:
- INTEGER – whole numbers.
- REAL – numbers with a decimal point.
- BOOLEAN – TRUE or FALSE.
- CHARACTER – a single character.
- STRING – a sequence of characters.
Constants – values that never change during execution. Declared with the CONST keyword and written in ALL CAPS:
```
CONST MAX_STUDENTS ← 30
CONST TAX_RATE ← 0.20
        
```
Commenting & Indentation
- Comments begin with // and are ignored by the interpreter.
- Indent one level (four spaces) for each block inside IF, FOR, WHILE, etc.
```
// Calculate average mark
FOR i ← 1 TO n DO
    total ← total + marks[i]
END FOR
average ← total / n
        
```

2.2 Operators

Category	Operator(s)	Example
Arithmetic	+, –, *, /, %	area ← length * width
Relational	=, ≠, <, >, ≤, ≥	IF score ≥ 50 THEN …
Logical	AND, OR, NOT	IF age ≥ 18 AND citizen = TRUE THEN …

2.3 Input / Output

READ variable – obtains a value from the user.
PRINT … – displays text and/or variable values.
Multiple items can be printed in one statement, separated by commas.

2.4 Procedures & Functions

Reusable blocks of code. Syllabus limits:
- Maximum 2 parameters per routine.
- Maximum 3 levels of nesting** (e.g., a loop inside an IF inside another loop).

Syntax (Cambridge style):
// Procedure – no return value PROCEDURE DisplayHeader() PRINT "=== STUDENT MARKS ===" END PROCEDURE // Function – returns a value FUNCTION Max(a, b) RETURNS INTEGER IF a > b THEN RETURN a ELSE RETURN b END IF END FUNCTION

2.5 Pseudocode Conventions (Cambridge style)

IF condition THEN statements END IF IF condition THEN statements1 ELSE statements2 END IF IF cond1 THEN statements1 ELSE IF cond2 THEN statements2 ELSE statements3 END IF FOR i ← start TO end STEP step DO statements END FOR WHILE condition DO statements END WHILE REPEAT statements UNTIL condition

3. Control Structures – Sequence, Selection, Iteration

3.1 Sequence

The default flow of a program – each statement is executed once, top to bottom, unless a later control structure changes the order.

3.2 Selection (Decision Making)

Allows a program to choose actions based on a Boolean condition.

Form Pseudocode Typical Use

Simple IF
IF condition THEN statements END IF
Execute a block only when the condition is true.

IF‑ELSE
IF condition THEN statements1 ELSE statements2 END IF
Choose between two alternatives.

Nested selection
IF cond1 THEN IF cond2 THEN statements END IF END IF
Decision inside another decision (max 3 levels).

Multiple selection (ELSE IF)
IF cond1 THEN statements1 ELSE IF cond2 THEN statements2 ELSE statements3 END IF
More than two alternatives.

3.3 Iteration (Loops)

Repeats a block of statements. Choose the loop type that best matches the known information about the number of repetitions.

Loop type Pseudocode When to use

WHILE (pre‑test)
WHILE condition DO statements END WHILE
Number of repetitions unknown; loop may execute zero times.

FOR (counter‑controlled)
FOR i ← start TO end STEP step DO statements END FOR
Exact number of repetitions known; i is the loop counter.

REPEAT‑UNTIL (post‑test)
REPEAT statements UNTIL condition
Loop must execute at least once.

4. Arrays (Topic 8)

Only **one‑dimensional arrays** are required for IGCSE.

Declaration syntax (Cambridge style):
DECLARE Scores : ARRAY[1:10] OF INTEGER // 10 elements, indexed 1‑10

Accessing elements – use Scores[i] where i is an integer within the declared bounds.

Typical iteration – reading values into an array:
FOR i ← 1 TO 10 DO READ Scores[i] END FOR

Common array operations

Find maximum:
max ← Scores[1] FOR i ← 2 TO 10 DO IF Scores[i] > max THEN max ← Scores[i] END IF END FOR

Calculate average:
total ← 0 FOR i ← 1 TO 10 DO total ← total + Scores[i] END FOR average ← total / 10

Search for a value:
found ← FALSE FOR i ← 1 TO 10 DO IF Scores[i] = target THEN found ← TRUE EXIT FOR END IF END FOR

5. File Handling (Topic 8)

Cambridge pseudocode distinguishes between INPUT (reading) and OUTPUT (writing) modes. A file must be opened before any read/write operation and closed afterwards.

Statement Purpose

OPEN file_name FOR INPUT Open an existing text file for reading.

OPEN file_name FOR OUTPUT Create a new file (or overwrite an existing one) for writing.

READ file_name, variable Read the next record from the file into variable.

WRITE file_name, variable Write the value of variable as a new record.

CLOSE file_name Close the file and release the resource.

Example – Store 5 marks in a file and then display them:

// Write marks to file OPEN "marks.txt" FOR OUTPUT FOR i ← 1 TO 5 DO READ mark WRITE "marks.txt", mark END FOR CLOSE "marks.txt" // Read marks back and display OPEN "marks.txt" FOR INPUT FOR i ← 1 TO 5 DO READ "marks.txt", mark PRINT "Mark", i, "=", mark END FOR CLOSE "marks.txt"

6. Databases & SQL (Topic 9)

6.1 Defining a Single‑Table Database

A table consists of fields (columns) and records (rows).

Each field has a name and a data type (INTEGER, REAL, CHAR, VARCHAR, BOOLEAN).

One field must be designated as the primary key – it uniquely identifies each record.

Example – Table definition (Cambridge style description)

Table: Students Fields: StudentID : INTEGER // Primary key, >0, unique Name : VARCHAR(30) Age : INTEGER // 5 ≤ Age ≤ 120 Mark : INTEGER // 0 ≤ Mark ≤ 100

6.2 Basic SQL Statements

Purpose SQL (Cambridge style)

List all records ordered by a field SELECT * FROM Students ORDER BY Mark DESC;

Count records that meet a condition SELECT COUNT(*) FROM Students WHERE Mark ≥ 80;

Sum a numeric field SELECT SUM(Mark) FROM Students;

Find a specific record SELECT * FROM Students WHERE StudentID = 3;

Insert a new record INSERT INTO Students (StudentID, Name, Age, Mark) VALUES (4, 'David', 17, 73);

Update a field UPDATE Students SET Mark = 88 WHERE StudentID = 2;

Delete a record DELETE FROM Students WHERE StudentID = 5;

6.3 Validation Rules for Tables

Field‑level validation (e.g., Age must be between 5 and 120).

Primary‑key uniqueness is automatically enforced.

Data‑type consistency – a VARCHAR field cannot store a numeric value without conversion.

7. Boolean Logic & Logic‑Gate Circuits (Topic 9)

7.1 Logical Operators & Truth Tables

Operator Symbol Result

AND ∧ TRUE only when both operands are TRUE

OR ∨ TRUE when at least one operand is TRUE

NOT ¬ Inverts the operand

7.2 Building Circuits from Boolean Expressions

Each gate can have **a maximum of three inputs** (as required by the syllabus).

Example – XOR expressed as (A AND NOT B) OR (B AND NOT A):
A ──► AND ──► OR ──► Output │ │ NOT B B │ NOT A

To simplify an expression, use Boolean algebra rules (e.g., De Morgan’s laws, absorption).

7.3 Writing Expressions from Truth Tables

Given a truth table, write the minimal Boolean expression and then draw the corresponding circuit.

Exercise – Complete the truth table for (A AND NOT B) OR (B AND NOT A). The completed table is the XOR function:

A B NOT B A AND NOT B NOT A B AND NOT A Result

0 0 1 0 1 0 0

0 1 0 0 1 1 1

1 0 1 1 0 0 1

1 1 0 0 0 0 0

8. Data Representation (Topic 9)

Binary ↔ Decimal – each binary digit (bit) represents a power of 2.
Decimal 13 = 1·2³ + 1·2² + 0·2¹ + 1·2⁰ → 1101₂

Binary ↔ Hexadecimal – group binary digits in fours (nibbles).
1011 1100₂ = BC₁₆

Two’s‑complement (signed integers) – used to represent negative numbers.
+7 = 0000 0111₂ -7 = invert bits → 1111 1000₂ add 1 → 1111 1001₂

Floating‑point (real numbers) – stored in scientific notation: ± mantissa × 2^exponent. IGCSE expects only a conceptual understanding.

9. Computer Systems (Topics 1‑6)

9.1 Hardware

CPU – central processing unit; performs arithmetic, logic, control, and I/O operations.

Memory

RAM – volatile, stores data and instructions while a program runs.

ROM – non‑volatile, stores firmware.

Storage devices – magnetic (HDD), solid‑state (SSD), optical (CD/DVD), and flash (USB).

Input devices – keyboard, mouse, scanner, microphone.

Output devices – monitor, printer, speaker.

9.2 Software

System software – operating system (OS) manages hardware resources.

Application software – programs that perform specific tasks (e.g., word processor, database).

Utility software – antivirus, backup, file‑compression tools.

9.3 Data Representation & Communication

Characters are stored using ASCII (7‑bit) or Unicode (16‑bit). Example: 'A' = 65₁₀ = 01000001₂.

Images: raster (bitmap) vs. vector; colour depth expressed in bits per pixel.

Sound: sampled at a rate (e.g., 44 kHz) and stored with a bit depth (e.g., 16‑bit).

Network basics – LAN, WAN, Internet, protocols (TCP/IP, HTTP, FTP).

9.4 Networking & Cyber‑Security

Common network topologies: star, bus, ring.

Security measures: firewalls, encryption, authentication, anti‑malware.

Legal and ethical issues – copyright, data protection, responsible use.

9.5 Automated Technologies

Embedded systems – microcontrollers in appliances, vehicles, and IoT devices.

Robotics – sensors, actuators, and control algorithms.

Artificial intelligence basics – rule‑based systems, machine learning concepts.

10. Summary of Key Limits Imposed by the Syllabus

Maximum 2 parameters per procedure/function.

Maximum 3 levels of nesting** (loops/selection inside another).

Arrays are limited to one dimension and index range must be specified.

Logic‑gate circuits may have up to three inputs per gate.

All pseudocode must use the exact keywords and indentation rules shown above.

Useful Revision Checklist

Can you write a complete PDLC for a given problem?

Can you produce a structure diagram and translate it into pseudocode?

Are you comfortable with the correct declaration syntax for variables, constants, arrays, and files?

Do you know the exact limits on parameters and nesting depth?

Can you design and trace IF‑ELSE, FOR, WHILE and REPEAT‑UNTIL loops?

Can you write, read, and close files correctly?

Can you define a single‑table database, choose appropriate field types, and write basic SQL statements?

Can you construct truth tables, simplify Boolean expressions, and draw the corresponding gate circuits (max 3 inputs per gate)?

Do you understand binary, hexadecimal, two’s‑complement, and basic floating‑point concepts?

Are you familiar with the hardware, software, networking, and security concepts listed in Topics 1‑6?

Use this checklist to identify any weak areas before the exam. Good luck!

Understand and use sequence, selection, and iteration

Cambridge IGCSE Computer Science (0478) – Complete Syllabus Notes (2026‑28)

1. Algorithm Design & Problem Solving (Topic 7)

2. Core Programming Concepts (Topic 8)

2.1 Variables, Constants & Data Types

2.2 Operators

2.3 Input / Output

2.4 Procedures & Functions

2.5 Pseudocode Conventions (Cambridge style)

3. Control Structures – Sequence, Selection, Iteration

3.1 Sequence

3.2 Selection (Decision Making)

3.3 Iteration (Loops)

4. Arrays (Topic 8)

5. File Handling (Topic 8)

6. Databases & SQL (Topic 9)

6.1 Defining a Single‑Table Database

6.2 Basic SQL Statements

6.3 Validation Rules for Tables

7. Boolean Logic & Logic‑Gate Circuits (Topic 9)

7.1 Logical Operators & Truth Tables

7.2 Building Circuits from Boolean Expressions

7.3 Writing Expressions from Truth Tables

8. Data Representation (Topic 9)

9. Computer Systems (Topics 1‑6)

9.1 Hardware

9.2 Software

9.3 Data Representation & Communication

9.4 Networking & Cyber‑Security

9.5 Automated Technologies

10. Summary of Key Limits Imposed by the Syllabus

Useful Revision Checklist

Support e-Consult Kenya

Form	Pseudocode	Typical Use
Simple `IF`	IF condition THEN statements END IF	Execute a block only when the condition is true.
`IF‑ELSE`	IF condition THEN statements1 ELSE statements2 END IF	Choose between two alternatives.
Nested selection	IF cond1 THEN IF cond2 THEN statements END IF END IF	Decision inside another decision (max 3 levels).
Multiple selection (`ELSE IF`)	IF cond1 THEN statements1 ELSE IF cond2 THEN statements2 ELSE statements3 END IF	More than two alternatives.

Loop type	Pseudocode	When to use
WHILE (pre‑test)	WHILE condition DO statements END WHILE	Number of repetitions unknown; loop may execute zero times.
FOR (counter‑controlled)	FOR i ← start TO end STEP step DO statements END FOR	Exact number of repetitions known; `i` is the loop counter.
REPEAT‑UNTIL (post‑test)	REPEAT statements UNTIL condition	Loop must execute at least once.

Statement	Purpose
`OPEN file_name FOR INPUT`	Open an existing text file for reading.
`OPEN file_name FOR OUTPUT`	Create a new file (or overwrite an existing one) for writing.
`READ file_name, variable`	Read the next record from the file into `variable`.
`WRITE file_name, variable`	Write the value of `variable` as a new record.
`CLOSE file_name`	Close the file and release the resource.

Purpose	SQL (Cambridge style)
List all records ordered by a field	SELECT * FROM Students ORDER BY Mark DESC;
Count records that meet a condition	SELECT COUNT(*) FROM Students WHERE Mark ≥ 80;
Sum a numeric field	SELECT SUM(Mark) FROM Students;
Find a specific record	SELECT * FROM Students WHERE StudentID = 3;
Insert a new record	INSERT INTO Students (StudentID, Name, Age, Mark) VALUES (4, 'David', 17, 73);
Update a field	UPDATE Students SET Mark = 88 WHERE StudentID = 2;
Delete a record	DELETE FROM Students WHERE StudentID = 5;

Operator	Symbol	Result
AND	∧	TRUE only when both operands are TRUE
OR	∨	TRUE when at least one operand is TRUE
NOT	¬	Inverts the operand

Understand and use sequence, selection, and iteration

Cambridge IGCSE Computer Science (0478) – Complete Syllabus Notes (2026‑28)

1. Algorithm Design & Problem Solving (Topic 7)

2. Core Programming Concepts (Topic 8)

2.1 Variables, Constants & Data Types

2.2 Operators

2.3 Input / Output

2.4 Procedures & Functions

2.5 Pseudocode Conventions (Cambridge style)

3. Control Structures – Sequence, Selection, Iteration

3.1 Sequence

3.2 Selection (Decision Making)

3.3 Iteration (Loops)

4. Arrays (Topic 8)

5. File Handling (Topic 8)

6. Databases & SQL (Topic 9)

6.1 Defining a Single‑Table Database

6.2 Basic SQL Statements

6.3 Validation Rules for Tables

7. Boolean Logic & Logic‑Gate Circuits (Topic 9)

7.1 Logical Operators & Truth Tables

7.2 Building Circuits from Boolean Expressions

7.3 Writing Expressions from Truth Tables

8. Data Representation (Topic 9)

9. Computer Systems (Topics 1‑6)

9.1 Hardware

9.2 Software

9.3 Data Representation & Communication

9.4 Networking & Cyber‑Security

9.5 Automated Technologies

10. Summary of Key Limits Imposed by the Syllabus

Useful Revision Checklist

Support e-Consult Kenya

1. Algorithm Design & Problem Solving (Topic 7)

2. Core Programming Concepts (Topic 8)

4. Arrays (Topic 8)

5. File Handling (Topic 8)

6. Databases & SQL (Topic 9)

7. Boolean Logic & Logic‑Gate Circuits (Topic 9)

8. Data Representation (Topic 9)

9. Computer Systems (Topics 1‑6)