Cambridge International AS & A Level Computer Science - Vocabulary

Vocabulary flashcards covering core concepts, definitions, and technical terms from Cambridge International AS & A Level Computer Science.

Binary

A base two number system based on the values 0 and 1 only.

Bit

Abbreviation for binary digit.

One's complement

A representation in which each binary digit in a number is reversed to allow both negative and positive numbers to be represented.

Two's complement

A method of representing positive and negative numbers where each binary digit is reversed and 1 is added in the right-most position.

Sign and magnitude

A binary number system where the left-most bit represents the sign ($0 = +$ and $1 = -$) and the remaining bits represent the binary value.

Hexadecimal

A number system based on the value 16, using denary digits 0 to 9 and letters A to F.

Memory dump

The contents of a computer memory output to a screen or printer.

Binary-coded decimal (BCD)

A number system that uses 4 bits to represent each denary digit.

ASCII code

A coding system for all the characters on a keyboard and control codes.

Character set

A list of characters that have been defined by computer hardware and software so that the computer can understand human characters.

Unicode

A coding system which represents all the languages of the world, where the first 128 characters are the same as ASCII code.

Bit-map image

A system that uses pixels arranged in a grid to make up an image.

Pixel

The smallest picture element that makes up an image.

Colour depth

The number of bits used to represent the colours in a pixel, e.g., an 8-bit depth represents $2^8 = 256$ colours.

Bit depth

The number of bits used to represent the smallest unit in a sound or image file.

Image resolution

The number of pixels that make up an image, e.g., $4096 \times 3192$ pixels.

Screen resolution

The number of horizontal and vertical pixels that make up a screen display.

Pixel density

The number of pixels per square unit (e.g., per square centimetre or square inch).

Vector graphics

Images that use 2D points to describe lines and curves and their properties, grouped to form geometric shapes.

Sampling resolution

The number of bits used to represent sound amplitude (also known as bit depth).

Sampling rate

The number of sound samples taken per second.

Lossless file compression

A file compression method where the original file can be completely restored following decompression.

Lossy file compression

A file compression method where parts of the original file cannot be recovered during decompression, resulting in lost detail.

Run length encoding (RLE)

A lossless file compression technique used to reduce the size of a string of adjacent, identical data.

Local Area Network (LAN)

A network covering a small geographical area, such as a single building.

Wide Area Network (WAN)

A network covering a very large geographical area, typically made up of interconnected LANs.

Metropolitan Area Network (MAN)

A network larger than a LAN but smaller than a WAN, covering several buildings in a single city or campus.

Client-server model

A network architecture that uses separate dedicated servers and specific client workstations.

Peer-to-peer network

A network in which each node can share its files with all other nodes without a central server.

Thin client

A device or software that heavily depends on a connection to a server to work and perform processing.

Thick client

A device or software that can perform processing independently, whether connected to a server/network or offline.

Cloud storage

A method of data storage where data is saved on off-site physical servers owned and managed by a hosting company.

Data redundancy

A situation in which the same data is stored on several servers in case of maintenance or hardware failure.

Router

A network device that enables data packets to be routed between different networks.

Modem

Modulator demodulator; a device that converts digital data to analogue data for transmission over telephone wires, and vice versa.

Ethernet

A standard protocol (IEEE 802.3) used by many wired local area networks.

CSMA/CD

Carrier Sense Multiple Access with Collision Detection; a protocol used in wired networks to detect collisions and resolve them using random back-off times.

Bit streaming

A contiguous sequence of digital bits sent over a network or the internet.

Domain Name Service (DNS)

A system that translates domain names into IP addresses for internet hosts.

Random Access Memory (RAM)

A volatile primary memory unit that can be written to and read from directly by the CPU.

Read-Only Memory (ROM)

A non-volatile primary memory unit that can only be read from and cannot be altered.

Dynamic RAM (DRAM)

A type of RAM chip consisting of transistors and capacitors that needs to be constantly refreshed to retain data.

Static RAM (SRAM)

A type of high-speed RAM chip that uses flip-flops to hold bits and does not require constant refreshing.

Hard Disk Drive (HDD)

A magnetic storage device that uses spinning platters and read-write heads to store data digitally.

Solid State Drive (SSD)

A non-volatile storage device with no moving parts that relies on controlling the movement of electrons in flash memory chips.

Sensor

An input device that reads or measures physical properties from its surroundings.

Logic gate

An electronic circuit component that relies on 'on/off' logic to take binary inputs and produce a binary output.

Logic circuit

A circuit formed from a combination of logic gates designed to carry out a specific function.

Truth table

A table used to check and display all possible binary input combinations and corresponding outputs for a logic gate or circuit.

Von Neumann architecture

A computer architecture based on the concept of the stored program, featuring a CPU, memory, and shared bus structures.

Arithmetic Logic Unit (ALU)

A component in the CPU that performs arithmetic and logical operations.

Control Unit (CU)

A CPU component that reads instructions from memory, decodes them, and manages data flow by sending control signals.

Program Counter (PC)

A register in the CPU that stores the address of the next instruction to be fetched and executed.

Memory Address Register (MAR)

A CPU register that stores the address of the memory location currently being read from or written to.

Memory Data Register (MDR)

A CPU register that stores data just read from memory or data about to be written to memory.

Current Instruction Register (CIR)

A CPU register that holds the instruction currently being decoded and executed.

Accumulator (ACC)

A general-purpose register in the CPU used to temporarily store numerical values during arithmetic/logic calculations.

Fetch-Execute Cycle

The continuous cycle in which instructions are fetched from memory, decoded, and executed by the CPU.

Interrupt

A signal sent from a hardware device or software to the CPU requesting immediate attention.

Machine code

The low-level binary programming language that a CPU directly understands and executes.

Assembly language

A low-level, machine-specific programming language that uses mnemonics instead of binary code.

Opcode

Short for operation code; the part of an instruction that specifies the operation to be performed.

Operand

The part of an instruction that contains data or the memory address of data to be used.

Assembler

A computer program that translates source code written in assembly language into machine code.

Operating system (OS)

Systems software that provides an environment for applications to run and acts as an interface between hardware and the user.

Compiler

A translator program that converts a high-level language source program into an entire executable object program in machine code.

Interpreter

A translator program that translates and executes a high-level language program line-by-line without producing an object program.

Data privacy

The right to keep personal information stored on computers secret and protected from unauthorized access.

Data security

Methods taken to prevent unauthorized access to data and to recover data if lost or corrupted.

Data integrity

The accuracy, completeness, and consistency of data.

Validation

An automated check performed by computer software to ensure that entered data is reasonable and meets defined criteria.

Verification

A check to ensure that data has been entered or transferred correctly without errors (e.g., via double entry or visual checks).

Plagiarism

The act of taking another person's work or ideas and claiming them as one's own.

Artificial Intelligence (AI)

A machine or software application that performs tasks requiring cognitive abilities similar to human intelligence.

Relational database

A database where data is organised into tables that are linked together using primary and foreign keys.

Primary key

An attribute or set of attributes in a relational database table that uniquely identifies each tuple (record).

Foreign key

An attribute in one table that references the primary key in another table to establish a relationship.

Normalisation

The process of structuring data in a relational database to reduce data redundancy and improve data integrity.

Abstraction

The computational thinking process of extracting essential details while ignoring irrelevant details to create a simplified model.

Decomposition

The computational thinking process of breaking a complex problem down into smaller, more manageable sub-problems.

Array

A data structure containing a fixed number of elements of the same data type, accessed using index values.

Linear search

A searching algorithm that checks every element in a list sequentially from start to end until the item is found or the end is reached.

Bubble sort

A sorting algorithm that repeatedly steps through a list, compares adjacent elements, and swaps them if they are out of order.

Stack

An abstract data type operating on a Last In, First Out (LIFO) structure where items are added (pushed) and removed (popped) from the top.

Queue

An abstract data type operating on a First In, First Out (FIFO) structure where items are added at the rear and removed from the front.

Linked list

An abstract data type containing nodes where each node contains data and a pointer pointing to the next node in the list.

Procedure

A defined block of programming code that performs a specific task without returning a value to the calling program.

Function

A defined block of programming code that performs a task and always returns a single value to the calling program.

Structure chart

A design diagram used to decompose a system into a hierarchy of sub-tasks and show the data passed between modules.

Dry run

A manual testing process where a programmer steps line-by-line through an algorithm recording variable values in a trace table.

User-defined data type

A custom data type constructed by a programmer based on existing primitive data types or previously defined types.

Serial file organisation

A file organisation method where records are stored physically one after another in the order they were added.

Sequential file organisation

A file organisation method where records are stored physically one after another in a specific sorted order based on a key field.

Random file organisation

A file organisation method where records are stored in available memory locations determined by a hashing algorithm.

Binary floating-point number

A representation of real numbers in binary expressed in the form $M \times 2^E$, where $M$ is the mantissa and $E$ is the exponent.

Circuit switching

A transmission method in which a dedicated physical path or channel is established and maintained for the entire duration of communication.

Packet switching

A transmission method where messages are divided into independent packets that are routed across a network via different paths.

CISC

Complex Instruction Set Computer; a processor architecture designed to execute complex multi-cycle instructions directly in hardware.

RISC

Reduced Instruction Set Computer; a processor architecture optimized to execute simple, single-cycle instructions using pipelining.

Pipelining

A technique in processor design that allows multiple instruction execution stages to overlap and execute simultaneously.