LC Computer Science flashcards

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

Decomposition

Breaking a complex problem into smaller sub-problems that can be solved, tested and debugged independently, which makes large projects manageable and allows work to be shared across a team.

Abstraction

Removing or hiding detail that is not needed for the current task so a problem can be modelled simply, such as using a route map that omits every individual building.

Algorithm

A finite, unambiguous sequence of steps that transforms given inputs into a required output and always terminates, written in pseudocode, a flowchart or a programming language.

Pattern recognition

Identifying similarities between problems or within data so that a single general solution or rule can be reused instead of solving each case separately from scratch.

Functional requirement

A statement of what a system must do, for example that a user can reset a password by email, written so it can be tested against observable behaviour.

Non-functional requirement

A constraint on how well a system performs, such as a response under two seconds, availability, usability, security or portability; it describes a quality, not a feature.

Unit test

A test that exercises a single function or module in isolation with defined inputs and compares the actual output against the expected output, typically automated.

Black-box testing

Test design based only on the specification, inputs and expected outputs, without knowledge of the internal code, focusing on boundary values and invalid data.

Regression testing

Re-running previously passing tests after code changes to confirm that new or modified code has not broken behaviour that already worked.

Version control commit

A recorded snapshot of project changes stored with an author, timestamp and message, allowing the project to be compared with or reverted to any earlier state.

Two's complement

A signed integer representation where the most significant bit carries a negative weight; eight bits cover minus 128 to 127 and negation is bitwise NOT plus one.

Hexadecimal

A base-16 notation using digits 0-9 and letters A-F; each hex digit maps to exactly four binary bits, so one byte is written as two hex digits.

Unicode

A character encoding standard that assigns a unique code point to characters from most of the world's writing systems; UTF-8 stores each code point in one to four bytes.

Fetch-decode-execute cycle

The repeated CPU process of fetching the instruction addressed by the program counter, decoding its operation, executing it, then storing any result and incrementing the counter.

Von Neumann architecture

A design in which one memory stores both instructions and data and shares a single bus with the CPU, so instruction and data fetches compete for bandwidth.

Cache memory

Small, fast memory between the CPU and RAM that holds recently or frequently used data; it exploits temporal and spatial locality to reduce average memory access time.

TCP

A connection-oriented transport protocol providing ordered, reliable delivery using acknowledgements, sequence numbers and retransmission; used for web, email and file transfer where loss must not occur.

UDP

A connectionless transport protocol with no acknowledgements, ordering or retransmission; its low overhead and latency suit live streaming, online gaming and DNS lookups.

Binary search

Repeatedly halving a sorted list by comparing the target with the middle element; it runs in O(log n) time but requires sorted data that supports direct access.

Recursion base case

The condition that stops a recursive function calling itself; without it, calls continue until the call stack is exhausted and a stack overflow error occurs.

Big O notation

A description of how an algorithm's running time or memory use grows as input size increases, ignoring constant factors, such as O(n log n) for merge sort.

Primary key

A column or combination of columns that uniquely identifies each row of a database table and cannot contain duplicate or null values.

GDPR data minimisation

A data protection principle requiring that personal data collected is adequate, relevant and limited to what is necessary for the stated purpose, and kept no longer than needed.

Right to erasure

A data protection right allowing a person to have personal data deleted when it is no longer necessary, consent is withdrawn or processing was unlawful, subject to legal exceptions.

Open source licence

A licence granting rights to use, modify and redistribute source code; copyleft licences require derivative works to stay open while permissive licences allow closed redistribution.

WCAG POUR principles

Web accessibility guidelines grouped as Perceivable, Operable, Understandable and Robust, forming the basis of accessible design and of many legal accessibility requirements.

Supervised learning

Machine learning trained on labelled examples so the model learns a mapping from inputs to known outputs, then predicts labels or values for new, unseen data.

Digital divide

The gap between people with reliable access to devices, connectivity and digital skills and those without, affecting participation in education, work and public services.

E-waste

Discarded electronic equipment containing both valuable metals and hazardous substances; formal recycling, design for repair and extended device life reduce its environmental harm.

Continuous integration

A practice of merging code changes frequently into a shared repository and running automated builds and tests on each merge so defects are detected early.

Embedded system

A computer dedicated to a specific control function inside a larger device, typically running fixed firmware with real-time deadlines and limited memory, power and processing.

Salted password hash

Storing a one-way hash of each password combined with a unique random salt, so identical passwords produce different hashes and precomputed lookup tables become ineffective.