All Keywords 11-12 Grade

Data Privacy and Security

Data privacy
Data stored about a person or an organisation must remain private and unauthorised access to the data must be prevented.

Data protection laws
Laws which govern how data should be kept private and secure.

Data security
Refers to the methods used to prevent unauthorised access to data, as well as to the data recovery methods if it is lost.

Data integrity
The accuracy, completeness and consistency of data.

Data backup
An additional copy of data that can be used to restore and recover data if it was lost or corrupted.

Data mirroring
A way of storing the same data in different places on multiple hard disks to protect data in the case of a drive failure.

User accounts
Used to authenticate a user (prove that a user is who they say they are). User accounts control access rights.

Access rights (data security)
Use of access levels to ensure only authorised users can gain access to certain data.

Encryption
The use of encryption keys to make data meaningless without the correct decryption key.

Validation
Method used to ensure entered data is reasonable and meets certain input criteria.
Validation check types: range, type, length, presence, format.

Verification
Method used to ensure data is correct by using double entry or visual checks.
Verification check types: visual check, double entry, check digit.

Passwords
Used to restrict access to data or systems.

Digital signatures
Protect data by providing a way of identifying the sender of, for example, an email.

Biometrics
Rely on the unique characteristics of human beings.

Legal, Moral, Ethical and Cultural Issues

Legal
Covers the law, whether or not an action is punishable by law.

Morality
Concerns questions of right and wrong, and is more often thought of in relation to personal or individual choices.

Ethics
Also concerns questions of right and wrong, but is more often used in a professional context.

Culture
Refers to the attitudes, values and practices shared by a society or group of people.

Plagiarism
When a person takes another person’s idea or work and claims it was their own.

Piracy
The practice of using or making illegal copies of, for example, software, digital products such as movies, music.

Copyright
A type of intellectual property that gives its owner the exclusive legal right to copy, distribute, adapt, display, and perform a creative work.

Software Types and Licensing

Open-source software
Gives users the freedom to run, copy, change and adapt software.

Commercial software
Available to customers for a fee, providing a licence for one genuine copy to be used on a single device, or a multi-use licence for multiple users.

Shareware
Allows users to try out some software free of charge for a trial period.

Freeware
Software a user can download from the internet free of charge.

Cyber Threats

Hacking
Illegal access to a computer system without the owner’s permission.

Cracking
Refers to the intentional, illegal, or malicious process of bypassing security controls, copy protection, or cryptographic protections in computer software, networks, or systems.

Difference: While “hacking” can sometimes have neutral or positive connotations (ethical hacking), cracking is almost always associated with malicious intent, such as stealing data, bypassing licensing, or gaining unauthorized access.

Malware
Malicious software that seeks to damage or gain unauthorised access to a computer system.

Viruses
Programs or program code that can replicate and/or copy themselves with the intention of deleting or corrupting files or causing the computer to malfunction.

Worms
A type of stand-alone virus that can replicate themselves with the intention of spreading to other computers; they often use networks to search out computers with weak security.

Trojan horses
Malicious programs often disguised as legitimate software.

Spyware
Software that gathers information by monitoring, for example, key presses on the user’s keyboard.

Phishing
When someone sends legitimate-looking emails to users. They may contain links or attachments which, when clicked, take the user to a fake website, or they may trick the user into responding with personal data such as bank account details or credit card numbers.

Pharming
Malicious code installed on a user’s computer or on a web server. The code re-directs the user to a fake website without their knowledge (the user does not have to take any action, unlike phishing).

System / Program Development Lifecycle (SDLC)

SDLC
The process of developing a program set out in five stages: analysis, design, coding, testing and maintenance.

• Analysis – investigation leading to the specification of what a program is required to do.
• Design – uses the program specification to show how the program should be developed.
• Coding – the writing of the program or suite of programs.
• Testing – testing the program to make sure that it works under all conditions.
• Maintenance – making sure that the program continues to work during use.

The Waterfall Model

Linear sequential development cycle; each stage is completed and signed off before the next begins. Suitable for smaller projects with well-known, stable requirements.

The Agile (Iterative) Model

Develops a simple subset first, then expands in repeated cycles. Suitable for projects where major requirements are known but details may evolve.

The Spiral Model

Focuses on managing risk-heavy projects; if too risky at any point, the project is terminated. Suited to very large-scale projects.

Fact-Finding Methods in Analysis

Analysis employs fact-finding methods: observation, questionnaires, document collection, interview/meeting.

Observation – shadowing employees and noting how they work.

Questionnaires – gathering opinions from many people; challenging to design well.

Document collection – gathering business documents (orders, invoices, financial records).

Interviewing – quick collection of detailed information; often the starting point.

Advantages and Disadvantages of Fact-Finding Methods

Data Flow Diagram (DFD)

A way of representing a flow of data through a process or system.

DFD Symbols

1. Process – transformation or manipulation of data.
2. Data Flow – movement of data from one process to another or to/from a data store.
3. Data Store – storage location for data.
4. Entity / Source Sink – external source or destination of data.

DFD Level 0 (Context Diagram) – highest-level overview; single process, two entities, no data stores.

DFD Level 1 – detailed view; breaks down the major process into sub-processes; includes multiple processes, entities, and data stores.

Flowchart

A diagrammatic representation of an algorithm using symbols linked with flow lines.

Flowchart Symbols

• Start/End (Terminator) – marks starting or ending point; usually contains “Start” or “End”.
• Action or Process (Box) – a single step or sub-process.
• Decision / Loop (Diamond) – decision or branching point.
• Input/Output (Parallelogram) – material or information entering/leaving the process.

Implementation and Changeover

Implementation – installing the new system and putting it into use after software and documentation are produced.

Changeover – switching from one system to another.

Changeover Types

Prototyping

Combines iterative and incremental development by providing a cut-down version for client feedback, then improving or adding functionality.

• Advantage: Quickly demonstrate ideas; high flexibility; react to changing requirements.
• Disadvantage: Difficult to manage; few concrete deadlines; mission creep possible.

Operating Systems

Software providing an environment for applications and an interface between hardware and users.

• Memory management – optimising, organising, and protecting main memory.
• Security management – ensuring integrity, confidentiality, and availability of data.
• Process management – allocating resources and synchronising processes.
• Hardware management – managing input/output peripheral devices.
• File management – defining naming conventions, directory structures, and file operations (create, open, close, delete, rename, copy, move).

GUI vs CLI

Types of Operating Systems

Advanced Interface Types

System Software: Translators and Utilities

Utility program – OS component performing functions like virus checking, defragmentation, disk formatting.

Library program – stored in a library for future use (e.g., DLLs).

Translator – translates source code into machine code.

Machine code – binary instructions executed by the processor.

Compiler

Translates high-level language to machine code all at once.

Interpreter

Analyses and executes high-level code line by line.

Assembler

Translates assembly language into machine code.

Comparison of Translators

Integrated Development Environment (IDE)

A suite of programs for writing and testing high-level programs. Includes: source code editor; compiler/interpreter; run-time environment with debugger; auto-documenter.

Debugging – finding logic errors by running/tracing.

Breakpoint – deliberate pause during testing.

Computer Architecture

Von Neumann Architecture

Introduced the stored program concept. Features:

• Central Processing Unit (CPU)
• Processor can access memory directly
• Memory stores both programs and data
• Stored programs consist of instructions executed sequentially

CPU Components

• ALU (Arithmetic Logic Unit) – performs arithmetic and logic operations.
• Accumulator (ACC) – temporary general-purpose register storing numerical values.
• Control Unit – synchronises data flow and programs via control signals on the control bus.
• System Clock – produces timing signals on the control bus for synchronisation.
• Registers – temporary storage; types: PC, MAR, MBR/MDR, CIR, IX, SR.

System Buses

Parallel transmission components; each wire carries one bit.

• Address bus – carries addresses.
• Data bus – carries data between processor, memory, and I/O devices.
• Control bus – carries control signals from the control unit to other components.

Key Terms

• Clock cycle – speed measured in GHz; vibrational frequency of the clock.
• Bus width – number of parallel wires in a bus.
• Word length – group of bits a computer uses as a single unit.
  • Difference: Word length is the amount of data CPU processes at once (e.g., 64-bit); bus width is bits transferred simultaneously over physical connections.
• Core – unit comprising ALU, control unit, and registers within a CPU.
• Cache memory – high-speed memory for fast data transfer.
• Interrupt – signal from device/software requesting processor attention; suspends current operations.

Fetch-Decode-Execute Cycle (Simplified)

CISC vs RISC Processors

Pipelining – allows several instructions to be processed simultaneously.

Memory

RAM vs ROM

Other Memory Concepts

• Virtual memory – paging technique giving the illusion of unlimited memory.
• Virtual machine – emulation of a computer system; an OS running within another OS.

Addressing Modes

• Direct addressing – contents of memory location in operand are used.
• Indirect addressing – contents of the contents of memory location in operand are used.
• Indexed addressing – adds contents of index register to operand address.
• Immediate addressing – value of operand only is used.

Paging vs Segmentation

Databases

Database – structured collection of data accessible by different applications.

Relational database – data items linked by internal pointers.

Table – group of data with rows (instances) and columns (attributes).

Record – a row in a table.

Attribute – individual data item stored for an entity (e.g., name, address).

Field – a column in a table.

Tuple – one instance of an entity (a row).

Entity – anything that can have data stored about it (person, place, event, thing).

Index – data structure built from columns to speed up searching.

Relationship – one table has a foreign key referring to a primary key in another table.

Primary key – unique identifier for a table; special candidate key.

Composite key – set of attributes forming a primary key.

Foreign key – attribute(s) in one table referring to a primary key in another.

Entity-Relationship (E-R) Model / ERD – graphical representation of database and relationships.

Normalisation

Process of organising data to minimise redundancy.

• 1NF – no repeated groups of attributes.
• 2NF – 1NF + non-key attributes depend on the primary key.
• 3NF – 2NF + all non-key attributes are independent.

DBMS and Data Management

Database Management System (DBMS) – software for defining, creating, and manipulating databases; solves redundancy, inconsistency, and dependency issues.

Data management – organisation and maintenance of data.

Data dictionary – contains metadata (data about data).

Common Data Types

Structured Query Language (SQL)

Standard language for relational databases.

Data Definition Language (DDL) Commands

Data Manipulation Language (DML) – Query Commands

DML – Maintenance Commands

Artificial Intelligence, VR and AR

Artificial Intelligence (AI) – machine or application performing tasks requiring human-like intelligence.

Virtual Reality (VR) vs Augmented Reality (AR)