GCE O/L Information & Communication Technology flashcards

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

Data vs information

Data is raw unprocessed facts without context. Information is data that has been processed and organised so it has meaning and can support decisions.

ICT definition

Information and Communication Technology: the set of hardware, software, networks and procedures used to capture, store, process, transmit and present data.

Von Neumann architecture

Computer design where CPU and memory share a single store for both instructions and data, executed in a fetch-decode-execute cycle.

RAM vs ROM

RAM is volatile read/write memory holding running programs and data. ROM is non-volatile read-only memory storing firmware such as the boot program.

SSD vs HDD

An SSD stores data in flash memory with no moving parts, giving fast access. An HDD uses spinning magnetic platters, offering more capacity per unit cost.

Cache memory

Small, very fast memory between CPU and RAM that holds frequently used instructions and data, reducing average access time.

Binary to decimal

Multiply each bit by its place value (powers of 2 from the right) and add the results. Example: 1011 = 8 + 0 + 2 + 1 = 11.

Hexadecimal conversion

Each hex digit maps to a 4-bit binary group. Convert binary to hex by grouping bits in fours from the right, then reading each group as a digit.

Two's complement

Method for signed binary: the leftmost bit is the sign. To negate a number, invert all bits and add one. An 8-bit signed range is −128 to +127.

Bitmap file size

Approximate uncompressed size = width × height × colour depth ÷ 8 bytes. Higher colour depth or resolution increases file size.

ASCII vs Unicode

ASCII encodes 128 characters in 7 bits, mainly English. Unicode assigns a unique code point to characters of all world scripts, commonly stored as UTF-8.

LAN vs WAN

A LAN covers a small area such as a building and is usually owned by one organisation. A WAN spans large distances, often using public infrastructure; the Internet is a WAN.

Router vs switch

A switch forwards frames within a LAN using MAC addresses. A router forwards packets between different networks using IP addresses.

DNS function

The Domain Name System translates human-readable domain names into IP addresses so browsers can locate the correct server.

TCP vs UDP

TCP is connection-oriented and reliable, retransmitting lost packets. UDP is connectionless and faster but does not guarantee delivery, used for streaming and voice.

IP address and subnet mask

An IP address identifies a host on a network. The subnet mask separates the network portion from the host portion of the address.

Operating system functions

An OS manages processes, memory, files and devices, provides a user interface and enforces security and access control.

Absolute vs relative reference

In a spreadsheet, a relative reference such as A1 changes when copied. An absolute reference such as $A$1 stays fixed.

Open source software

Software whose source code is publicly available so users can study, modify and redistribute it, often free of charge under a licence.

Primary key

A field or combination of fields that uniquely identifies each record in a table and cannot contain duplicate or null values.

Foreign key

A field in one table that references the primary key of another table, creating a relationship and enforcing referential integrity.

Validation vs verification

Validation checks that data is sensible and within rules (range, type, presence). Verification checks that data was entered or copied correctly, e.g. by double entry.

Normalisation purpose

Structuring tables to remove redundant data and update anomalies. First normal form removes repeating groups; third normal form removes transitive dependencies.

Algorithm definition

A finite, ordered set of unambiguous steps that solves a problem or performs a task, often shown as pseudocode or a flowchart.

Iteration structures

Loops that repeat steps: FOR repeats a fixed number of times, WHILE repeats while a condition is true, REPEAT-UNTIL repeats until a condition becomes true.

Binary search

Search algorithm that repeatedly halves a sorted list, comparing the middle item, until the target is found or the range is empty. Faster than linear search on large data.

SDLC phases

Systems development life cycle: analysis, design, development, testing, deployment and maintenance, each producing documentation and review points.

Waterfall vs Agile

Waterfall is sequential with fixed requirements and heavy documentation. Agile delivers in short iterative sprints with continuous customer feedback and changing requirements.

Parallel changeover

Running the old and new systems together for a period so results can be compared. It is the safest but most costly changeover method.

Digital divide

The gap between people who have effective access to ICT and the skills to use it and those who do not, often due to income, location or education.

Phishing

A social-engineering attack using fake emails or websites that imitate trusted organisations to trick users into revealing passwords or financial details.

Cloud service models

IaaS provides virtual infrastructure, PaaS provides a development platform, SaaS provides ready-to-use applications, all delivered over the Internet on demand.