Secondary 4 Information & Communication Technology

Raw facts, figures, text or symbols that have not been processed and have no clear meaning on their own.

Data processed into a meaningful and useful form that helps people understand situations and make decisions.

The basic model of data processing: data is input, processed by the computer, and output as information.

Gathering raw data through questionnaires, interviews, observation or existing records.

Checks applied to input data so that unreasonable or impossible values are rejected.

If the input data is wrong, the output information will be wrong too, no matter how precise the processing.

Application software that organises data in rows and columns and performs calculations and charts.

A chart that uses the lengths of bars to compare quantities across categories.

Information absorbed through human understanding, experience and thinking, and applied to explain and decide.

The smallest unit of data in a computer, holding either 0 or 1.

A group of 8 bits able to represent 256 different values; the basic unit of storage.

The base-2 number system using only 0 and 1, the form in which computers store all data.

The base-16 system using 0–9 and A–F; one hexadecimal digit stands for exactly four bits.

A storage unit equal to 1024 bytes.

The scheme that assigns a numeric value to each character so text can be stored digitally.

A 7-bit character code assigning values such as 65 for capital A, covering 128 characters.

An encoding giving every character in every language a unique number, including Chinese characters and emoji.

The smallest unit of a digital image, its colour stored as binary values.

Measuring a sound wave's amplitude at fixed intervals to turn sound into a sequence of numbers.

A collection of related records stored together under one name.

A set of related fields describing one object, such as one book in a catalogue file.

A single item of data within a record, such as a title or a phone number.

The field whose value is unique within the file and identifies each record.

The key that uniquely identifies each record, such as a student number or call number.

A file whose records are stored one after another in key order and read by scanning from the beginning.

A file whose record locations are computed from the key, allowing direct access.

A search that checks records one by one from the start until the target is found, averaging half the records.

Reaching a record immediately by computing its address from the key, without scanning other records.

The main file holding relatively permanent data, updated periodically by merging transaction records.

The physical components of a computer system, such as the processor, memory and storage devices.

The chip that executes instructions, containing the arithmetic and logic unit and the control unit.

The part of the processor that performs arithmetic and logical comparisons.

High-speed storage inside the processor holding the instructions and data being worked on.

Readable and writable main memory that programs must be loaded into; contents are lost when power is off.

Memory holding boot-up firmware written at the factory; contents survive power loss.

The processor's repeating sequence of fetching an instruction, decoding it and executing it.

Small, very fast memory between the processor and main memory holding frequently used data.

Long-term storage such as hard disks and solid-state drives that keeps data without power.

Non-volatile memory used in solid-state drives and USB storage.

The programs and data that instruct a computer what to do.

Software that manages the computer itself, including the operating system, utilities and drivers.

Software that helps users perform specific tasks, such as word processing and spreadsheets.

The core system software that manages hardware resources and provides the platform applications run on.

An interface using windows, icons and pointers so users operate by clicking.

An interface where users type text commands to control the computer — precise and fast but requiring syntax.

The operating system sharing processor time among programs so they appear to run at once.

System software that maintains and optimises the computer, such as antivirus, backup and defragmentation tools.

Software that lets the operating system control a specific hardware device.

A utility that rearranges scattered file fragments into contiguous space to speed up reading.

The ability to recognise information needs, search effectively, evaluate sources and use information ethically.

A service that indexes web pages and returns links matching the keywords entered.

A precise word or phrase entered into a search engine to find relevant pages — concrete rather than a whole sentence.

A symbol that narrows a search, such as quotes for exact phrases, a minus sign to exclude, and site: for one domain.

Words such as AND, OR and NOT used to combine or exclude search terms.

The criterion of how credible a source is, judged by the publisher's expertise and reputation.

How up to date the information is, judged by its publication or revision date.

False or inaccurate content spread without checking, whether or not intended to deceive.

Using others' work or ideas without acknowledging the source.

The legal right of creators over the use of their original works.