GCE A/L General Information Technology flashcards

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

Data versus information

Data are raw, unprocessed facts and figures. Information is data that has been processed, organised and presented in a meaningful form so it can support decisions.

IPO model

Input–Process–Output describes any computing system: input devices capture data, the processor transforms it, and output devices present the result. Storage holds data between stages.

Bit and byte

A bit is a single binary digit, 0 or 1. A byte is a group of 8 bits and is the standard unit for storing one character in ASCII encoding.

Bandwidth

The maximum data-carrying capacity of a communication channel, usually measured in bits per second. Higher bandwidth allows more data to be transferred in a given time.

Von Neumann architecture

A computer design in which the CPU, memory, input and output units are connected by buses, and program instructions and data are stored together in the same memory.

CPU fetch-decode-execute cycle

The CPU fetches an instruction from memory using the program counter, decodes it in the control unit, executes it in the ALU, and stores the result before repeating.

RAM versus ROM

RAM is volatile read/write memory holding running programs and data, losing contents when power is off. ROM is non-volatile, normally read-only, and stores firmware such as the boot program.

Cache memory

A small, very fast memory between the CPU and main memory that holds recently or frequently used instructions and data, reducing average access time.

Operating system functions

An operating system manages processes, memory, files and devices, enforces security and access rights, and provides the user interface through which programs run.

Virtual memory

A memory-management technique that uses part of secondary storage as an extension of RAM, allowing programs larger than physical memory to run, though access is slower.

Open-source software

Software whose source code is published so anyone may inspect, modify and redistribute it under its licence, often at no cost, for example Linux and LibreOffice.

Round-robin scheduling

A pre-emptive CPU scheduling method giving each ready process a fixed time slice in turn, which is fair and responsive but adds context-switching overhead.

Binary to decimal conversion

Convert by summing place values of positions containing 1, using powers of two from the right. For example, 1101 equals 8+4+1, which is 13.

Two's complement

A signed binary representation in which a negative number is formed by inverting all bits and adding one. In n bits the range is −2^(n−1) to +2^(n−1)−1.

Hexadecimal notation

A base-16 number system using digits 0–9 and letters A–F. Each hex digit represents exactly four binary bits, so it shortens long binary values.

Unicode

A character-encoding standard that assigns a unique code point to characters of all the world's writing systems, overcoming the limited 128-character range of basic ASCII.

LAN versus WAN

A LAN connects devices within a limited area such as a building and is usually privately owned. A WAN spans large distances, often using public or leased telecommunication links.

TCP versus UDP

TCP is connection-oriented and reliable, acknowledging and retransmitting lost segments. UDP is connectionless and faster but does not guarantee delivery or ordering.

DNS

The Domain Name System translates human-readable domain names into numeric IP addresses, so browsers can reach servers without users remembering addresses.

IP address and subnet mask

An IP address identifies a device on a network. The subnet mask separates the network portion from the host portion, determining which addresses are local.

Primary key

A field or combination of fields that uniquely identifies each record in a table. It cannot contain duplicate values or nulls, ensuring entity integrity.

Foreign key

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

Third normal form

A table is in 3NF when it is in 2NF and no non-key attribute depends transitively on the primary key, removing redundancy and update anomalies.

ACID properties

Atomicity, Consistency, Isolation and Durability: transaction properties ensuring all-or-nothing execution, valid states, non-interference between concurrent transactions, and survival of committed data.

Binary search

A search algorithm that repeatedly halves a sorted list by comparing the target with the middle element, giving O(log n) time but requiring sorted data.

Iteration versus selection

Iteration repeats a block of statements using loops such as WHILE, REPEAT and FOR. Selection chooses between alternative paths using IF or CASE statements.

Syntax versus logic error

A syntax error breaks the grammar rules of a programming language and stops compilation. A logic error is valid code that produces incorrect output.

Trace table

A manual testing tool listing each variable as columns and each algorithm step as rows, recording values so the logic of an algorithm can be verified without a computer.

B2C and B2B

B2C e-commerce sells from businesses to individual consumers, such as online retail. B2B e-commerce handles transactions between businesses, such as wholesale ordering.

Transaction processing system

An information system that records and processes routine daily transactions such as sales, payments and bookings, emphasising speed, accuracy and reliability.

Phishing

A social-engineering attack using fraudulent emails, messages or websites that impersonate a trusted party to trick users into revealing passwords or financial details.

Symmetric versus asymmetric encryption

Symmetric encryption uses one shared secret key for both encryption and decryption and is fast. Asymmetric encryption uses a public key to encrypt and a matching private key to decrypt.