Reference

Computer Science Glossary

39 terms from the Cambridge O Level 2210 / IGCSE 0478 and AS & A Level 9618 syllabuses, defined in the words that earn the mark. Each one links to the topic where it is taught — and the flashcards drill 1,600 more.

AbstractionAll levels: Removing unnecessary detail to focus on what matters for solving the problem.; Algorithm Design and Problem-Solving · O Level / IGCSE Algorithm Design and Problem-Solving · AS Level
AlgorithmAll levels: An ordered set of unambiguous steps that solves a problem or performs a task.; Algorithm Design and Problem-Solving · O Level / IGCSE Algorithm Design and Problem-Solving · AS Level
Backus-Naur FormA2 Level: A formal notation for describing the syntax of a language using production rules.
Big O notationA2 Level: Describes how an algorithm's time or space grows with input size (O(1), O(log n), O(n), O(n²)).; Computational Thinking and Problem-Solving · A2 Level
BYREFAS Level: Parameter passed by reference — the procedure works on the caller's actual variable.; Programming · AS Level
BYVALAS Level: Parameter passed by value — the procedure works on a copy.; Programming · AS Level
ChecksumAll levels: A value calculated from a block of data and sent with it; the receiver recalculates to detect errors.; Data Transmission · O Level / IGCSE Security, Privacy and Data Integrity · AS Level
CompilerAll levels: Translates the whole high-level program into machine code before it runs; produces an executable and a list of all errors.; Software · O Level / IGCSE System Software · AS Level
De Morgan's lawsA2 Level: NOT(A AND B) = NOT A OR NOT B; NOT(A OR B) = NOT A AND NOT B — 'break the bar, change the sign' (9618 §15.2).; Data Representation · O Level / IGCSE Hardware · O Level / IGCSE Software · O Level / IGCSE
DecompositionAll levels: Breaking a problem down into smaller sub-problems that are easier to solve.; Algorithm Design and Problem-Solving · O Level / IGCSE Algorithm Design and Problem-Solving · AS Level
Digital certificateA2 Level: An electronic document from a Certificate Authority binding a public key to an identity.; Security · A2 Level
Dijkstra's algorithmA2 Level: Finds the shortest path from a source node to all other nodes in a weighted graph.
Embedded systemO Level / IGCSE: A computer system with a dedicated function built into a larger device (e.g. a washing machine).; Hardware · O Level / IGCSE Hardware · AS Level
EncryptionAll levels: Scrambling data with a key so that it is meaningless if intercepted.; Data Transmission · O Level / IGCSE Security · A2 Level
Expert systemO Level / IGCSE: AI that mimics a human expert using a knowledge base, rule base, inference engine and user interface.; Automated and Emerging Technologies · O Level / IGCSE
FirewallAll levels: Monitors and filters network traffic between a computer/network and the internet according to rules.; The Internet and Its Uses · O Level / IGCSE
Flip-flopA2 Level: A logic circuit with two stable states that stores one bit; SR and JK types are the building blocks of registers and SRAM (9618 §15.2).; Hardware and Virtual Machines · A2 Level
Full adderA2 Level: A logic circuit that adds two bits plus a carry-in, producing a sum and a carry-out; built from two half adders and an OR gate.; Hardware and Virtual Machines · A2 Level
InterpreterAll levels: Translates and executes a high-level program one line at a time; stops at the first error.; Software · O Level / IGCSE System Software · AS Level
InterruptAll levels: A signal to the processor that an event needs immediate attention; the current task is paused and an ISR runs.; Software · O Level / IGCSE Processor Fundamentals · AS Level
Karnaugh mapA2 Level: A grid method for simplifying Boolean expressions by grouping adjacent 1s (9618 §15.2).; Hardware and Virtual Machines · A2 Level
Mantissa & exponentA2 Level: The two parts of a floating-point number: significant digits (mantissa) and the power of two scale (exponent).; Data Representation · A2 Level
Normalisation (databases)AS Level: Organising tables to remove redundancy and update anomalies (1NF, 2NF, 3NF).; Databases · AS Level Data Representation · A2 Level
OverflowAll levels: When a calculation produces a result too large to be stored in the available number of bits.; Data Representation · O Level / IGCSE Data Representation · A2 Level
Packet switchingAll levels: Data split into packets that may take different routes and are reassembled at the destination.; Data Transmission · O Level / IGCSE
ParityAll levels: An extra bit added so the number of 1s is even (or odd), used to detect single-bit errors.; Data Transmission · O Level / IGCSE Security, Privacy and Data Integrity · AS Level
PipeliningA2 Level: Overlapping the fetch, decode and execute stages of successive instructions to increase throughput.; Hardware and Virtual Machines · A2 Level
PolymorphismA2 Level: Objects of different classes responding to the same method call in class-specific ways.; Further Programming · A2 Level
PseudocodeAll levels: A structured, language-independent way of writing an algorithm using programming-like statements.; Algorithm Design and Problem-Solving · O Level / IGCSE Algorithm Design and Problem-Solving · AS Level
RecursionA2 Level: A function that calls itself, with a base case to stop and a general case that moves towards it.; Computational Thinking and Problem-Solving · A2 Level
Register Transfer NotationAS Level: Notation describing data movement between registers, e.g. MAR ← [PC].; Processor Fundamentals · AS Level
Reverse Polish NotationA2 Level: Postfix notation where operators follow operands; evaluated with a stack without brackets.
RISC / CISCA2 Level: Reduced vs Complex Instruction Set Computer — few simple fixed-length instructions vs many complex ones.; Hardware and Virtual Machines · A2 Level
Stub testingAS Level: Replacing an unfinished module with a simple placeholder so the rest can be tested.; Software Development · AS Level
Trace tableAll levels: A table used to dry-run an algorithm, recording the value of each variable at each step.; Algorithm Design and Problem-Solving · O Level / IGCSE Software Development · AS Level
Two's complementAll levels: A method of representing signed integers where the MSB has a negative place value.; Data Representation · O Level / IGCSE Information Representation · AS Level
ValidationAll levels: Automated checks that input data is reasonable (range, type, length, presence, format, check digit).; Algorithm Design and Problem-Solving · O Level / IGCSE Security, Privacy and Data Integrity · AS Level
VerificationAll levels: Checking data has been transferred/entered accurately (double entry, visual check).; Algorithm Design and Problem-Solving · O Level / IGCSE Security, Privacy and Data Integrity · AS Level
Virtual machineA2 Level: Software emulation of a computer system, allowing multiple OSs to run on one physical machine.; Hardware · O Level / IGCSE Hardware and Virtual Machines · A2 Level System Software · A2 Level