GCE A/L Information & Communication Technology flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Digitisation

Conversion of analogue information such as text, sound or images into discrete binary digits that a computer can store and process.

Digital divide

The gap between groups in access to, and effective use of, information and communication technology, driven by income, infrastructure, skills and geography.

Moore's law

The observation that the number of transistors that can be placed on an integrated circuit roughly doubles every two years at similar cost.

Von Neumann architecture

A computer design in which instructions and data share the same memory and bus, processed through repeated fetch, decode and execute cycles.

Two's complement

A signed binary representation formed by inverting all bits and adding one, giving a single zero and a range of minus two to the power n minus one.

Cache memory

Small, very fast volatile memory close to the CPU that holds recently used instructions and data to reduce average access time from main memory.

Lossy compression

A compression method that permanently discards data judged less perceptible, achieving small files but preventing exact reconstruction of the original.

Hexadecimal place value

A base-16 system using digits 0 to 9 and letters A to F, where each digit position represents a power of sixteen and one digit equals four bits.

Universal gates

NAND and NOR gates, each of which can be combined with itself to construct any other Boolean function, including NOT, AND and OR.

De Morgan's theorems

Boolean identities stating that the complement of a conjunction equals the disjunction of complements, and the complement of a disjunction equals the conjunction of complements.

Karnaugh map

A grid arrangement of truth table values used to group adjacent ones in powers of two and derive a simplified sum-of-products Boolean expression.

Packet switching

A transmission technique that splits messages into independently routed packets, allowing shared links and resilient delivery without a reserved end-to-end path.

OSI reference model

A seven-layer framework for network functions: application, presentation, session, transport, network, data link and physical, each providing services to the layer above.

Subnet mask

A 32-bit pattern that identifies which bits of an IPv4 address denote the network and which denote hosts, enabling subnetting and address planning.

Simplex transmission

A communication mode in which data travels in one direction only, such as a keyboard sending input to a computer.

DNS

The Domain Name System, a hierarchical distributed database that translates human-readable domain names into the IP addresses used for routing.

HTTPS

HTTP carried over Transport Layer Security, providing encryption, integrity checking and server authentication through digital certificates.

Stateless protocol

A protocol such as HTTP in which each request is independent and the server keeps no memory of earlier requests, so cookies or sessions maintain state.

Client-side scripting

Code such as JavaScript that executes in the user's browser to provide interaction and validation, reducing server load but visible to the user.

Normalisation to third normal form

A design process removing repeating groups, then partial key dependencies, then transitive dependencies, so non-key attributes depend only on the whole primary key.

Foreign key

An attribute in one relation that references the primary key of another relation, enforcing referential integrity between related tables.

ACID properties

Transaction guarantees: atomicity, consistency, isolation and durability, ensuring database changes are all-or-nothing, valid, independent and permanent.

Binary search

A search that repeatedly halves a sorted list by comparing the middle element with the target, running in logarithmic time.

Stack data structure

A last-in-first-out collection where items are added with push and removed with pop at the same end, used for recursion and expression evaluation.

Big-O notation

A notation describing the upper bound on how an algorithm's time or space requirement grows as the input size increases.

Data flow diagram

A modelling tool showing external entities, processes, data stores and data flows, describing what a system does rather than how it is implemented.

Critical path

The longest chain of dependent project activities, whose total duration determines the shortest possible completion time for the whole project.

Parallel changeover

An implementation strategy where old and new systems run simultaneously for a period, reducing risk but duplicating cost and effort.

Digital signature

A cryptographic value created with a sender's private key that lets receivers verify message integrity and authenticity and supports non-repudiation.

Phishing

A social engineering attack using fraudulent messages that impersonate trusted parties to trick users into revealing credentials or installing malware.

Platform as a Service

A cloud model providing a managed runtime, development tools and services so developers deploy applications without managing servers or operating systems.

Internet of Things

A network of physical devices embedded with sensors and connectivity that collect and exchange data, often analysed in cloud or edge systems.