100+ Free IGCSE Computer Science Practice Questions

Data Representation

Binary, denary and hex conversion; two's complement; binary addition; logical and arithmetic shifts; ASCII vs Unicode UTF-8/UTF-16; sound sampling rate and bit depth; image resolution and colour depth; lossy vs lossless compression including run-length encoding and Huffman coding; bit/byte/KiB/MiB/GiB units

Data Transmission

Serial vs parallel transmission; simplex, half-duplex and full-duplex; packet switching with header/payload/trailer; error detection by parity bit, ARQ, checksum and echo check; USB; HTTP vs HTTPS; URL components (protocol, domain, path)

Hardware

CPU components (control unit, ALU, registers MAR/MDR/PC/CIR/Accumulator, buses); fetch-execute cycle; factors affecting CPU performance; embedded vs general-purpose systems; RAM vs ROM and virtual memory; primary, secondary and off-line storage (HDD, SSD, optical, cloud); input and output devices including sensors

Software

System vs application software; operating system functions (multitasking, memory/file/peripheral/process management, UI, security); utility programs (antivirus, defragmenter, backup, compression); high-level vs low-level languages; compiler vs interpreter vs assembler; IDE features (editor, run-time environment, error diagnostics, auto-completion)

Internet and its Uses

URL structure; HTML structure and presentation; CSS; client-side vs server-side scripting; session vs persistent cookies; digital currency and blockchain basics; cyber security threats (brute force, DDoS, malware types, pharming, phishing, social engineering); solutions (access levels, anti-malware, authentication, firewalls, proxy servers, SSL/TLS)

Algorithm Design and Problem Solving

Computational thinking (decomposition, pattern recognition, abstraction); pseudocode and flowchart symbols; trace tables; identifying syntax, logic and runtime errors; structure diagrams; validation (range, type, length, presence, format) vs verification (visual, double entry); test data types; linear search, binary search, bubble sort, insertion sort

Programming

Cambridge pseudocode constructs (DECLARE, INPUT/OUTPUT, IF/THEN/ELSE, CASE OF, FOR/NEXT, WHILE, REPEAT/UNTIL); data types (INTEGER, REAL, STRING, CHAR, BOOLEAN); arithmetic and comparison operators including MOD and DIV; logical operators; string functions LENGTH, SUBSTRING, UCASE, LCASE; 1D and 2D arrays indexed from 1; procedures and functions; reading and writing files

Databases

Flat files vs relational databases; tables, records and fields; primary key and foreign key; one-to-one, one-to-many and many-to-many relationships; SQL basics (SELECT, FROM, WHERE, ORDER BY ASC/DESC, AND, OR, LIKE with wildcards); first normal form to remove repeating groups