OCR J277 Computer Science Component 1 and 2 Revision Flashcards

Comprehensive vocabulary flashcards covering OCR J277 Computer Science Component 1 (Systems Architecture, Memory, Security, Systems Software, Ethics) and Component 2 (Algorithms, Programming Fundamentals, Robust Design, Search & Sort, Translators).

Central Processing Unit (CPU)

Processes data and instructions by carrying out the fetch–decode–execute cycle.

Control Unit (CU)

Decodes instructions and sends control signals to coordinate data flow in the CPU and other components.

Arithmetic Logic Unit (ALU)

Performs arithmetic calculations and logical operations, such as AND, OR, and comparisons.

Cache

Small, very fast memory on or near the CPU that stores frequently used data and instructions.

Clock Speed

The frequency of the fetch–decode–execute cycle measured in Hertz ($\text{Hz}$), where gigahertz ($\text{GHz}$) represents billions of cycles per second.

Embedded System

A dedicated computer system built into a larger device to perform one specific function.

Von Neumann Architecture

A computer architecture where both data and instructions are stored together in the same memory and processed by the CPU using registers.

Program Counter (PC)

A CPU register that holds the memory address of the next instruction to be fetched.

Memory Address Register (MAR)

A CPU register that holds the memory address of the data or instruction currently being fetched or written.

Memory Data Register (MDR)

A CPU register that holds the data or instruction just fetched from, or waiting to be written to, memory.

Accumulator

A register in the CPU that stores the immediate results of calculations carried out by the ALU.

General Data Protection Regulation (GDPR) / Data Protection Act 2018

UK legislation controlling how organisations collect, store, and process personal data lawfully, fairly, and transparently.

Computer Misuse Act 1990

UK legislation that makes unauthorised access to computer material, unauthorised access with intent to commit offences, and unauthorised modification of data illegal.

Open Source Software

Software whose underlying source code is freely available for anyone to view, modify, and redistribute.

Proprietary Software

Closed-source software distributed under a licence that prevents users from viewing, modifying, or copying the source code.

Digital Exclusion

Being excluded from participating in society due to an inability to access or effectively use digital technology.

Digital Divide

The gap between individuals, households, or regions that have access to modern information and communications technology and those that do not.

E-waste

Discarded electronic devices, such as computers and phones, that often contain toxic materials and require responsible disposal or recycling.

Personal Data

Any information that relates to an identified or identifiable living individual, such as name, address, or date of birth.

Data Subject

The living individual whose personal data is collected, stored, or processed by an organisation.

Copyright, Designs and Patents Act 1988

UK law making it illegal to copy, distribute, or modify creative intellectual property without explicit permission.

Random Access Memory (RAM)

Volatile primary memory that temporarily holds the operating system, currently running programs, and active data.

Read-Only Memory (ROM)

Non-volatile primary memory that permanently stores boot-up instructions, such as the BIOS or bootstrap loader.

Virtual Memory

An allocated area of secondary storage configured to act as supplementary RAM when physical RAM becomes full.

Character Set

A defined standard list of characters recognised by a computer, where each individual character corresponds to a unique binary code.

ASCII

A $7$-bit character set capable of representing $128$ unique characters, with extended ASCII using $8$ bits for $256$ characters.

Unicode

A universal character set using up to $32$ bits per character to represent characters, symbols, and emoji across worldwide languages.

Pixel

The smallest individual addressable point of colour forming a digital bitmap image.

Resolution

The total density or number of pixels composing an image, calculated as $\text{width} \times \text{height}$.

Colour Depth

The number of bits allocated to represent the colour of each individual pixel in an image.

Sample Rate

The number of discrete audio samples recorded per second, measured in Hertz ($\text{Hz}$).

Bit Depth (Audio)

The number of bits used to encode and store each individual sound sample.

Lossless Compression

A compression method that reduces file size without losing any data, allowing the original file to be reconstructed perfectly.

Lossy Compression

A compression method that permanently removes less noticeable data to significantly reduce file size at the cost of slight quality reduction.

Nibble

A binary data unit consisting of exactly $4$ bits.

Overflow Error

An error in binary arithmetic that occurs when an addition result exceeds the maximum number of bits available in the register.

Binary Shift

A bitwise operation that moves bits left to multiply a number by powers of $2$, or right to divide by powers of $2$.

Malware

Hostile or intrusive software intentionally developed to damage, disrupt, or gain unauthorised access to a computer system.

Spyware

Malicious software that operates covertly to record user activity, such as keystrokes, and transmits the collected data to third parties.

Ransomware

Malicious software that encrypts user files and demands financial payment in exchange for the decryption key.

Phishing

A social engineering attack where fraudulent emails or websites impersonate trustworthy entities to deceive victims into revealing credentials.

Social Engineering

The psychological manipulation of individuals into disclosing confidential information or bypassing security controls.

Brute Force Attack

An attack method that uses automated trial-and-error to cycle through every conceivable character combination until a password is found.

Denial of Service (DoS) Attack

A cyberattack designed to overwhelm a network or server with redundant requests, rendering it inaccessible to legitimate users.

SQL Injection

A security exploit where malicious SQL commands are inserted into input entry fields to view or modify database records.

Penetration Testing

An authorised, controlled simulation of a cyberattack against a system to discover vulnerabilities before malicious actors exploit them.

Firewall

A network security device or software that inspects incoming and outgoing packet traffic to block unauthorised access according to security rules.

Operating System

System software that coordinates computer hardware, allocates system resources, and provides an interface for software applications.

Utility Software

Specialised system programs that perform housekeeping, maintenance, and optimisation tasks on a computer.

Defragmentation

The process of rearranging fragmented data on a hard disk drive so that individual file sectors reside in contiguous storage locations.

Algorithm

A finite sequence of well-defined, step-by-step instructions designed to solve a specific computational problem.

Decomposition

The computational thinking technique of breaking a complex problem down into smaller, simpler, and more manageable constituent parts.

Abstraction

The process of filtering out unnecessary details from a problem to concentrate solely on the essential components.

Algorithmic Thinking

The cognitive skill of identifying the precise logical steps required to reach an effective solution to a problem.

Pseudocode

A plain-text notation that outlines the operational logic of an algorithm without conforming to strict programming syntax.

Variable

A named memory location assigned an identifier that holds a data value capable of altering during program execution.

Constant

A named memory location assigned an identifier that holds a fixed data value that cannot be overwritten during runtime.

Sequence

A fundamental programming construct where instructions execute sequentially in the exact chronological order in which they appear.

Selection

A programming construct where conditions are evaluated to determine which path of execution the program follows.

Iteration

A programming construct where a block of code repeats multiple times through a count-controlled or condition-controlled loop.

Trace Table

A structured auditing grid used to manually step through an algorithm line by line to track changes in variable states and detect errors.

Truth Table

A mathematical table detailing the resulting boolean logic output for every possible binary input combination.

Syntax Error

A code fault that violates the grammatical constructs of the programming language, preventing the translator from executing the code.

Logic Error

A programming mistake that allows the program to run without crashing but causes it to produce incorrect or unexpected output.

Runtime Error

An error encountered while a program is running that forces it to terminate unexpectedly, such as a division-by-zero operation.

Casting

The programmatic conversion of an explicit value from one primitive data type into another data type.

Concatenation

The operation of linking two or more alphanumeric character strings end to end to produce a single continuous string.

Validation

An automated program routine that checks incoming user data against predefined criteria to confirm it is sensible and reasonable.

Verification

The practice of ensuring that data matches its original source and has been transcribed accurately without human data-entry mistakes.

Authentication

The security mechanism responsible for verifying the claimed identity of a user or system process before granting access rights.

Array

A static data structure capable of storing an ordered collection of elements of the same data type under a shared identifier.

Defensive Design

The practice of constructing robust software that anticipates potential misuse, validates all inputs, and prevents unhandled system crashes.

Boundary Test Data

Test values that sit on the immediate outer and inner boundaries of acceptable ranges to test conditional edge limits.

Erroneous Test Data

Test input consisting of completely incompatible data types designed to verify that the program rejects illegal data cleanly.

Maintainability

The structural quality of source code written with indentation, comments, meaningful identifiers, and modular subprograms to simplify upkeep.

Linear Search

A basic search algorithm that inspects each element of a collection sequentially from beginning to end until a match is discovered.

Binary Search

An efficient logarithmic search algorithm that repeatedly halves an ordered list by checking the middle item until the target key is located.

Bubble Sort

A sorting algorithm that passes through a list comparing adjacent pairs of values and swapping them if they are in the wrong order.

Merge Sort

A recursive divide-and-conquer algorithm that breaks an array down into individual elements before merging adjacent sorted sub-lists.

Insertion Sort

A sorting algorithm that builds a final sorted array by taking one element at a time and inserting it into its correct position.

Subprogram

A self-contained named unit of executable code that can be called repeatedly to execute a specific task within a program.

Procedure

A type of subprogram that executes a series of commands without returning a value back to the calling instruction.

Function

A type of subprogram that calculates and returns an explicit result value back to the calling environment.

Parameter

A placeholder variable declared inside a subprogram header that receives an incoming value during execution.

Argument

The concrete value passed into a subprogram parameter when that subprogram is formally called by the main code.

Compiler

A translator that converts an entire high-level program into standalone machine code before execution, providing a list of all errors.

Interpreter

A translator that reads, translates, and executes high-level source code line by line, pausing execution immediately when an error is encountered.

Integrated Development Environment (IDE)

A unified software suite providing integrated utilities, such as an editor, debugger, and translator, to support application development.