📚 Year 12 WJEC Computer Science: A Glossary & Rapid Revision Guide | WJEC Year 12 计算机科学：术语速记指南
Mastering WJEC Year 12 Computer Science starts with a firm grip on the subject's core terminology. This rapid revision guide groups essential terms by topic, pairing concise English explanations with their Chinese equivalents to support bilingual learners. Each entry focuses on the definition that matters for the exam, with memory hooks and contextual notes where helpful.
掌握 WJEC Year 12 计算机科学，首先要牢固掌握学科核心术语。本速记指南按主题分组关键术语，提供精准的英文定义与对应中文解释，帮助双语学习者高效复习。每条术语都紧扣考点，并配有记忆技巧与语境说明，让备考更有针对性。
1. Algorithmic Thinking & Problem Solving | 算法思维与问题解决
Algorithm – a finite sequence of unambiguous steps that takes an input, processes it, and produces a valid output in a predictable time.
算法 – 一个有限的、步骤明确的序列，接收输入、进行处理并在可预测的时间内产生有效输出。
Decomposition – the process of breaking a complex problem into smaller, self‑contained sub‑problems, each easier to solve independently. Often paired with modular design.
分解 – 将复杂问题拆分为更小、更独立子问题的过程，每个子问题更容易单独解决，常与模块化设计结合使用。
Abstraction – hiding unnecessary detail while retaining only the features relevant to a particular context; used extensively in data modelling and layered architecture.
抽象 – 隐藏不必要的细节，只保留与特定语境相关的特征；广泛应用于数据建模与分层架构中。
Pattern recognition – identifying similarities among problems or data sets to reuse solutions; the key to reducing redundant coding.
模式识别 – 找出问题或数据集之间的相似性以便复用解决方案，是减少重复编码的关键。
Pseudocode – a notation resembling a simplified programming language, used to express algorithms without strict syntax constraints; ideal for planning logic before coding.
伪代码 – 一种类似简化编程语言的表示法，用于表达算法而无严格语法限制，非常适合在编码前规划逻辑。
Flowchart – a diagrammatic tool that uses standard symbols (ovals, diamonds, rectangles) to represent the sequence of steps and decisions in an algorithm.
流程图 – 一种图解工具，使用标准符号（椭圆、菱形、矩形）来表示算法中的步骤顺序和决策分支。
2. Data Structures & Linear Collections | 数据结构与线性集合
Array – a static, contiguous block of memory holding elements of the same data type, accessed via an index starting from 0. Fast random access, fixed size.
数组 – 一个静态的、连续的内存块，存放相同数据类型的元素，通过从0开始的索引访问。支持快速随机访问，但大小固定。
Linked list – a dynamic collection of nodes, each containing data and a pointer to the next node; efficient insertion/deletion, but slower search.
链表 – 由节点组成的动态集合，每个节点包含数据和指向下一节点的指针；插入和删除高效，但查找较慢。
Stack (LIFO) – a last‑in, first‑out structure with operations push and pop; used for function call management, undo features, and depth‑first search.
栈（后进先出） – 一种后进先出的结构，支持压入和弹出操作；用于函数调用管理、撤销功能和深度优先搜索。
Queue (FIFO) – a first‑in, first‑out structure with enqueue and dequeue; applied in CPU scheduling, print spoolers, and breadth‑first traversal.
队列（先进先出） – 一种先进先出的结构，支持入队和出队操作；应用于CPU调度、打印缓冲和广度优先遍历。
Record (struct) – a composite data type that groups fields of possibly different types under one name; each field has an identifier and a value.
记录（结构体） – 一种复合数据类型，将可能不同类型的数据字段组合在一个名称下；每个字段有标识符和值。
Binary tree – a hierarchical structure where each node has at most two children; used in binary search trees, heaps, and syntax trees.
二叉树 – 一种层次结构，每个节点最多有两个子节点；用于二叉搜索树、堆和语法树。
3. Programming Concepts & Constructs | 编程概念与构造
Sequence, selection, iteration – the three fundamental control structures of structured programming. Selection often involves if‑else, switch; iteration covers for, while, do‑while loops.
顺序、选择、循环 – 结构化编程的三大基本控制结构。选择通常涉及if‑else、switch语句；循环包括for、while和do‑while。
Variable scope (local/global) – a local variable is declared inside a subroutine and only accessible there; a global variable is declared outside and visible to the whole program. Minimising global use reduces side effects.
变量作用域（局部/全局） – 局部变量在子程序内部声明，只能在该处访问；全局变量在外部声明，对整个程序可见。减少全局变量可使副作用最小化。
Parameter passing (by value / by reference) – pass by value sends a copy, leaving the original unchanged; pass by reference sends the memory address, allowing the subroutine to modify the actual parameter.
参数传递（按值/按引用） – 按值传递发送一份副本，原始值不变；按引用传递发送内存地址，允许子程序修改实际参数。
Recursion – a technique where a subroutine calls itself; needs a base case to terminate. Elegant for tree traversal, factorial calculation, but can be memory intensive.
递归 – 子程序调用自身的技术；需要基线条件来终止。适合树遍历、阶乘计算，但可能消耗较多内存。
String manipulation – operations such as concatenation, substring extraction, length measurement, and pattern matching (using wildcards or regex). Essential for parsing input and formatting output.
字符串操作 – 包括连接、取子串、求长度以及模式匹配（使用通配符或正则表达式）。解析输入和格式化输出时不可或缺。
Exception handling – structured ways (try‑catch) to manage runtime errors gracefully, preventing abrupt program termination while logging diagnostic information.
异常处理 – 以结构化方式（try‑catch）优雅地管理运行时错误，避免程序突然中止并记录诊断信息。
4. Computer Architecture & CPU Components | 计算机体系结构与CPU组件
Von Neumann architecture – a design where both data and instructions share the same memory and single bus system; the fetch‑decode‑execute cycle underpins program execution.
冯·诺依曼体系结构 – 数据与指令共用同一内存和单一总线系统的设计；取指‑译码‑执行周期是程序运行的基础。
Control Unit (CU) – directs operations of the CPU by sequencing instruction execution and coordinating the movement of data in/out of the processor.
控制器 – 通过排序指令执行和协调查处理器数据进出以指挥CPU操作。
Arithmetic Logic Unit (ALU) – performs arithmetic (add, subtract) and logical (AND, OR, NOT) operations, as well as comparison; its status flags (zero, carry) influence branching.
算术逻辑单元 – 执行算术（加、减）和逻辑（与、或、非）运算以及比较；其状态标志（零、进位）影响分支决策。
Registers (MAR, MDR, PC, ACC) – tiny, very fast storage locations inside the CPU: Memory Address Register, Memory Data Register, Program Counter, Accumulator. Each plays a critical role in the FDE cycle.
寄存器（MAR、MDR、PC、ACC） – CPU内部极小且极快的存储位置：内存地址寄存器、内存数据寄存器、程序计数器、累加器。每个都在FDE周期中起关键作用。
Clock speed – measured in Hz (cycles per second), determines how many FDE cycles the CPU can attempt per second; higher speed generally means faster processing but more heat.
时钟频率 – 以赫兹（每秒周期数）衡量，决定CPU每秒能尝试完成多少个FDE周期；频率越高通常处理越快，但产生更多热量。
Cache memory – a small, high‑speed SRAM pool close to the CPU that stores frequently accessed instructions and data, reducing average memory access time (L1, L2, L3 hierarchy).
高速缓存 – 位于CPU附近的小容量高速SRAM池，存储频繁访问的指令和数据，降低平均内存访问时间（L1、L2、L3层级）。
5. Memory, Storage & I/O | 内存、存储与输入输出
RAM (volatile) – random access memory that loses its content when power is off; used as main memory for currently running programs and the OS.
RAM（易失性存储器） – 随机存取存储器，断电后内容丢失；用作当前运行程序和操作系统的主存。
ROM (non‑volatile) – read‑only memory that retains data permanently; commonly holds the BIOS/bootstrap loader to initialise hardware on startup.
ROM（非易失性存储器） – 只读存储器，永久保存数据；通常存放BIOS/引导加载器，在启动时初始化硬件。
Virtual memory – a technique that uses a portion of secondary storage (HDD/SSD) as an extension of RAM, swapping pages in and out; allows running larger programs but slows access.
虚拟内存 – 利用部分辅助存储器（HDD/SSD）作为RAM的扩展，通过页面换入换出实现；允许运行更大程序，但访问速度变慢。
Secondary storage types – magnetic (HDD, large capacity, slower), solid‑state (SSD, faster, no moving parts, wear levelling), optical (CD, DVD, Blu‑ray). Each is non‑volatile and used for long‑term data retention.
辅助存储器类型 – 磁性（HDD，大容量、速度较慢）、固态（SSD，速度快，无活动部件，需磨损均衡）、光学（CD、DVD、蓝光）。都是非易失性，用于长期数据保存。
Interrupt – a signal to the CPU indicating an event that needs immediate attention, causing the current instruction stream to be suspended and an Interrupt Service Routine (ISR) to execute.
中断 – 发给CPU的信号，指示需要立即处理的事件，导致当前指令流暂停并执行中断服务程序。
DMA (Direct Memory Access) – allows certain hardware subsystems to transfer data directly to/from memory without constant CPU involvement, improving overall system efficiency.
直接存储器访问 – 允许某些硬件子系统直接将数据传输到内存或从内存读取，减少CPU参与，提升系统整体效率。
6. Systems Software & Operating Systems | 系统软件与操作系统
Operating System (OS) – a low‑level software that manages hardware resources, provides a user interface, and enables execution of applications; includes kernel, device drivers, and utility programs.
操作系统 – 管理硬件资源、提供用户界面并允许应用程序执行的底层软件；包括内核、设备驱动程序和实用程序。
Multitasking – the OS concurrently running multiple tasks by rapidly switching the CPU among processes; each process gets a time slice so the system appears responsive.
多任务处理 – 操作系统通过在进程间快速切换CPU来实现同时运行多个任务；每个进程获得一个时间片，使系统看起来响应迅速。
Paging and segmentation – memory management techniques: paging divides physical memory into fixed‑size blocks; segmentation uses variable‑sized logical units. Both help prevent memory fragmentation.
分页与分段 – 内存管理技术：分页将物理内存分为固定大小的块；分段使用可变大小的逻辑单元。两者都有助于防止内存碎片。
File system – the method and data structure that an OS uses to store, organise, and retrieve files on a storage device; examples include FAT, NTFS, ext4. Manages directories, permissions, and metadata.
文件系统 – 操作系统用来在存储设备上存储、组织和检索文件的方法与数据结构；例如FAT、NTFS、ext4。管理目录、权限和元数据。
Utility software – programmes that perform maintenance or housekeeping tasks: disk defragmentation, backup, compression, antivirus, firewall, and encryption utilities.
实用软件 – 执行维护或管理任务的程序：磁盘碎片整理、备份、压缩、防病毒、防火墙和加密工具。
Assembler, compiler, interpreter – translators: an assembler converts assembly code to machine code; a compiler translates the whole high‑level source into an executable beforehand; an interpreter executes line by line at runtime.
汇编器、编译器、解释器 – 翻译器：汇编器将汇编代码转换为机器码；编译器提前把整个高级源代码翻译成可执行文件；解释器在运行时逐行执行。
7. Networking Fundamentals | 网络基础
LAN vs WAN – a Local Area Network spans a small geographic area (building/campus) with privately owned infrastructure; a Wide Area Network covers large distances, often relying on leased telecommunications lines.
局域网与广域网 – 局域网覆盖小范围地理区域（楼宇/校园），使用私有基础设施；广域网覆盖远距离，常依赖租用的电信线路。
Client‑server vs peer‑to‑peer – in client‑server, a central server provides resources to clients; in P2P, each node acts as both client and server, sharing resources directly without a central controller.
客户‑服务器与对等网络 – 客户‑服务器模式中，中央服务器向客户提供资源；P2P中每个节点既作客户也作服务器，直接共享资源而无中央控制器。
Protocols (TCP/IP stack) – layered model: Application (HTTP, FTP, SMTP), Transport (TCP/UDP), Internet (IP), Link (Ethernet/Wi‑Fi). TCP provides reliable, ordered delivery; UDP is connectionless but faster.
协议（TCP/IP协议栈） – 分层模型：应用层（HTTP、FTP、SMTP）、传输层（TCP/UDP）、网络层（IP）、链路层（以太网/Wi‑Fi）。TCP提供面向连接、可靠有序传输；UDP无连接但速度更快。
IP addressing & subnet mask – an IP address uniquely identifies a host on a network; the subnet mask splits the address into network and host portions, helping routers forward packets correctly.
IP地址与子网掩码 – IP地址唯一标识网络上的主机；子网掩码将地址分为网络部分和主机部分，帮助路由器正确转发数据包。
MAC address – a hardware‑embedded, 48‑bit identifier that uniquely identifies each network interface card (NIC); used for frame delivery within a local segment.
MAC地址 – 硬件嵌入的48位标识符，唯一标识每个网络接口卡（NIC）；用于本地网段内的帧传递。
Packet switching – data is split into packets, routed independently across the network, and reassembled at the destination; makes efficient use of bandwidth and provides redundancy.
分组交换 – 数据被分成数据包，独立地在网络上路由，并在目的地重新组装；有效利用带宽并提供冗余。
8. Databases & SQL | 数据库与SQL
Relational database – data organised into tables (relations) with rows (tuples) and columns (attributes); linked by primary and foreign keys to avoid redundancy through normalisation.
关系数据库 – 数据组织成表（关系），包含行（元组）和列（属性）；通过主键和外键连接，经由规范化避免数据冗余。
Primary key / foreign key – a primary key uniquely identifies each record in a table; a foreign key refers to a primary key in another table, enforcing referential integrity.
主键/外键 – 主键唯一标识表中的每条记录；外键引用另一表的主键，强制参照完整性。
Normalisation (1NF, 2NF, 3NF) – a systematic process to reduce data redundancy: 1NF eliminates repeating groups, 2NF removes partial dependencies, 3NF removes transitive dependencies.
规范化（1NF, 2NF, 3NF） – 减少数据冗余的系统过程：1NF消除重复组，2NF消除部分依赖，3NF消除传递依赖。
SQL SELECT, INSERT, UPDATE, DELETE – DML commands: SELECT retrieves data with WHERE, ORDER BY; INSERT adds new rows; UPDATE modifies existing data; DELETE removes rows.
SQL SELECT, INSERT, UPDATE, DELETE – 数据操作语言命令：SELECT用WHERE, ORDER BY检索数据；INSERT添加新行；UPDATE修改已有数据；DELETE删除行。
Entity‑relationship (E‑R) diagram – a visual model showing entities, attributes, and relationships (one‑to‑one, one‑to‑many, many‑to‑many) used in database design.
实体关系图 – 展示实体、属性及关系（一对一、一对多、多对多）的可视化模型，用于数据库设计。
Data warehouse vs data mining – a data warehouse stores historical, aggregated data from multiple sources; data mining analyses this data to discover patterns and trends.
数据仓库与数据挖掘 – 数据仓库存储来自多个源的历史聚合数据；数据挖掘分析这些数据以发现模式和趋势。
9. Cybersecurity Threats & Measures | 网络安全威胁与措施
Malware types – virus (attaches to files, needs user action), worm (self‑replicates across networks), trojan (disguised as legitimate software), ransomware (encrypts data for ransom), spyware (covertly monitors user activity).
恶意软件类型 – 病毒（附着于文件，需用户执行）、蠕虫（在网络中自我复制）、特洛伊木马（伪装成合法软件）、勒索软件（加密数据索要赎金）、间谍软件（隐蔽监视用户活动）。
Phishing / social engineering – fraudulent attempts to obtain sensitive information by masquerading as a trustworthy entity; often exploits human psychology rather than technical weaknesses.
网络钓鱼/社会工程 – 通过伪装成可信实体来获取敏感信息的欺诈行为；常利用人类心理而非技术漏洞。
Firewall – a barrier (hardware/software) that filters incoming and outgoing traffic based on predefined rules, protecting a network from unauthorised access.
防火墙 – 根据预定义规则过滤进出流量的屏障（硬件/软件），保护网络免受未授权访问。
Encryption (symmetric / asymmetric) – symmetric uses the same key for encryption and decryption; asymmetric uses a public‑key pair, solving the key distribution problem and enabling digital signatures.
加密（对称/非对称） – 对称加密使用相同密钥进行加密和解密；非对称加密使用公钥对，解决了密钥分发问题并支持数字签名。
Penetration testing – authorised simulated attack on a system to identify vulnerabilities before malicious hackers can exploit them; includes black‑box, white‑box, and grey‑box approaches.
渗透测试 – 经授权的模拟攻击，在恶意黑客利用之前识别系统漏洞；包括黑盒、白盒和灰盒方法。
Authentication factors – something you know (password), something you have (token), something you are (biometrics). Two‑factor authentication (2FA) combines two for stronger security.
身份验证因素 – 你知道的（密码）、你拥有的（令牌）、你是什么（生物特征）。双因素认证结合两个因素以增强安全性。
10. Software Development Lifecycle & Ethics | 软件开发生命周期与伦理
Waterfall model – a linear, sequential approach: requirements, design, implementation, testing, deployment, maintenance. Each phase must complete before the next begins; suited for stable requirements.
瀑布模型 – 线性顺序方法：需求、设计、实现、测试、部署、维护。每个阶段必须在下一阶段开始前完成；适合需求稳定的项目。
Agile methodology – iterative development with short sprints, constant feedback, and adaptive planning; values individuals and interactions over rigid processes. Scrum and Kanban are frameworks.
敏捷方法 – 具有短迭代、持续反馈和自适应规划的迭代开发；重视个体和互动而非僵化流程。Scrum和Kanban是常用框架。
Alpha / beta testing – alpha testing is internal, performed by developers; beta testing involves a limited group of real users in a real environment, helping uncover unforeseen issues.
Alpha/ Beta测试 – Alpha测试是内部测试，由开发人员执行；Beta测试涉及有限的实际用户在真实环境中使用，帮助发现未预见问题。
Maintenance types – corrective (fixing bugs), adaptive (adjusting to new platforms), perfective (adding features, improving performance), preventive (updating documentation, restructuring code).
维护类型 – 纠正性（修复错误）、适应性（适应新平台）、完善性（添加功能、提升性能）、预防性（更新文档、重构代码）。
Computer Misuse Act – UK legislation that criminalises unauthorised access to computers, unauthorised access with intent to commit further offences, and unauthorised acts with intent to impair operation.
计算机滥用法 – 英国立法，将未经授权访问计算机、意图实施进一步犯罪的未经授权访问，以及意图损害计算机运行的未经授权行为定为刑事犯罪。
Data Protection Act / GDPR – laws governing how personal data can be collected, processed, and stored. Principles include lawfulness, fairness, transparency, purpose limitation, and data minimisation.
数据保护法/GDPR – 管辖个人数据如何收集、处理和存储的法律。原则包括合法性、公平性、透明性、目的限制和数据最小化。
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