📚 Year 12 Cambridge Computer Science: Key Terminology Quick-Memorization Guide | 剑桥12年级计算机科学：词汇术语速记指南
Mastering the technical vocabulary of Cambridge AS & A Level Computer Science (9618) is half the battle. This guide breaks down essential Year 12 terms into digestible, paired explanations with memory hooks, so you can recall them confidently in exams. Each term is presented first in English, then in Chinese, ensuring bilingual clarity.
掌握剑桥AS和A Level计算机科学（9618）的技术词汇是成功的一半。本指南将Year 12的关键术语拆解为易消化的中英双语配对解释，并附上记忆技巧，帮助你在考试中自信地回忆。每个术语都先提供英文释义，再紧跟中文阐述，确保双语清晰。
1. Data Representation Basics | 数据表示基础
Bit – the smallest unit of data, a binary digit 0 or 1. Think of it as a light switch: on or off.
比特 – 数据的最小单位，一个二进制数字0或1。可以把它想象成一个电灯开关：开或关。
Byte – a group of 8 bits. Memory trick: '8 bits make a byte, just like 8 tentacles of an octopus.'
字节 – 由8个比特组成的组。记忆技巧：“8个比特组成一个字节，就像章鱼的8条触手。”
Nibble – half a byte, i.e., 4 bits. It's a 'nibble' of the byte, as a playful parallel to 'bite'.
半字节 – 半个字节，即4个比特。它是字节的一小口（nibble），与“咬”（bite）形成俏皮的对应。
Overflow error – occurs when a number is too large to be represented with the given number of bits. Imagine a mileage counter that rolls back to zero after exceeding its maximum.
溢出错误 – 当一个数字太大，无法用给定位数表示时发生。就像一个里程表在超过最大值后归零。
Two's complement – a method to represent negative integers in binary. The most significant bit acts as the sign bit; invert all bits and add 1 to flip sign.
二进制补码 – 用二进制表示负整数的方法。最高位作为符号位；将所有位取反再加1即可翻转符号。
2. Multimedia and Compression | 多媒体与压缩
Bitmap image – each assigned a colour value. Resolution = width × height, colour depth = bits per pixel.
位图图像 – 由像素网格组成的图像，每个像素被赋予一个颜色值。分辨率 = 宽 × 高，颜色深度 = 每像素比特数。
Vector graphic – stores drawing instructions (lines, curves, shapes) using mathematical formulas. Scalable without losing quality, but cannot store realistic photos.
矢量图形 – 使用数学公式存储绘图指令（线条、曲线、形状）。可以缩放而不损失质量，但不能存储逼真照片。
Lossless compression – reduces file size without losing any data, e.g., run-length encoding and Huffman coding. Perfect for text and programs.
无损压缩 – 在不丢失任何数据的情况下减小文件大小，例如行程编码和哈夫曼编码。适合文本和程序。
Lossy compression – permanently removes some (less perceptible) data to achieve higher compression, e.g., JPEG for images, MP3 for audio. Quality vs. size trade-off.
有损压缩 – 永久移除一些（不太可察觉的）数据以获得更高压缩率，例如图像的JPEG和音频的MP3。在质量与大小之间权衡。
3. Processor Architecture | 处理器架构
Central Processing Unit (CPU) – the brain of the computer, executing instructions via the fetch-decode-execute cycle. Key components: Control Unit (CU), Arithmetic Logic Unit (ALU), and registers.
中央处理器 (CPU) – 计算机的大脑，通过取指-译码-执行周期运行指令。关键部件：控制单元 (CU)、算术逻辑单元 (ALU) 和寄存器。
Von Neumann architecture – a stored-program concept where both instructions and data share the same memory and bus pathways. Most modern computers follow this model.
冯·诺依曼架构 – 一种存储程序概念，指令和数据共享同一内存和总线通道。大多数现代计算机都遵循这种模型。
Harvard architecture – physically separate storage and buses for instructions and data, allowing simultaneous access. Used in embedded systems for speed.
哈佛架构 – 指令和数据使用物理上独立的存储和总线，允许同时访问。用于嵌入式系统以提高速度。
Register – a small, high-speed storage location inside the CPU. Examples: Program Counter (PC), Memory Address Register (MAR), Memory Data Register (MDR), Current Instruction Register (CIR), Accumulator (ACC).
寄存器 – CPU内部的小型高速存储位置。例如：程序计数器 (PC)、内存地址寄存器 (MAR)、内存数据寄存器 (MDR)、当前指令寄存器 (CIR)、累加器 (ACC)。
Program Counter – holds the address of the next instruction to be fetched. Incremented after fetching, unless a jump occurs.
程序计数器 – 存放待取出的下一条指令的地址。取指后递增，除非发生跳转。
4. Buses and Data Transfer | 总线与数据传输
Address bus – carries memory addresses from the CPU to other components (unidirectional). Its width determines the maximum addressable memory (2n locations).
地址总线 – 将内存地址从CPU传送到其他部件（单向）。其宽度决定了最大可寻址内存（2n个位置）。
Data bus – emory, and I/O devices (bidirectional). Wider data bus = faster transfer of larger chunks.
数据总线 – 在CPU、内存和I/O设备之间传输实际数据（双向）。更宽的数据总线意味着更快地传输更大的数据块。
Control bus – carries control signals like read, write, clock, and interrupt requests. Coordinates activities across the system.
控制总线 – 传输读写、时钟和中断请求等控制信号。协调系统各部分的动作。
System bus – the collection of address, data, and control buses; the main communication backbone of a computer.
系统总线 – 地址总线、数据总线和控制总线的集合；是计算机的主要通信骨干。
5. Memory and Storage | 内存与存储
RAM (Random Access Memory) – volatile, fast memory that holds data and instructions currently in use. Loses contents when power is off.
随机存取存储器 (RAM) – 易失性、快速的内存，保存当前正在使用的数据和指令。断电后内容丢失。
ROM (Read Only Memory) – non-volatile memory that stores firmware (e.g., BIOS). Cannot be easily modified; retains data without power.
只读存储器 (ROM) – 非易失性存储器，存放固件（如BIOS）。不易修改；断电后数据保持。
Cache memory – extremely fast, small-capacity memory located close to the CPU, storing frequently accessed instructions and data to reduce latency. Levels: L1 (fastest, smallest), L2, L3.
高速缓存 (Cache) – 位于CPU附近的超快速、小容量存储器，存放经常访问的指令和数据以减少延迟。级别：L1（最快、最小）、L2、L3。
Secondary storage – non-volatile storage like HDD, SSD, optical discs; much larger and slower than primary memory. Used for long-term data retention.
辅助存储 – 非易失性存储器，如HDD、SSD、光盘；容量远大于主存，但速度更慢，用于长期保存数据。
6. Operating Systems and Software | 操作系统与软件
Operating System (OS) – system software that manages hardware resources, provides user interface, and enables applications to run. Functions: memory management, process scheduling, file management, security, device drivers.
操作系统 (OS) – 管理硬件资源、提供用户界面并让应用程序运行的系统软件。功能：内存管理、进程调度、文件管理、安全性、设备驱动。
Kernel – the core of the OS, always resident in memory; handles low-level tasks like process/ memory management and hardware communication.
内核 – 操作系统的核心，常驻内存；处理诸如进程/内存管理和硬件通信等底层任务。
Interrupt – a signal to the processor that requires immediate attention, e.g., keyboard press or disk I/O complete. Handled by the Interrupt Service Routine (ISR).
中断 – 一个需要处理器立即处理的信号，例如键盘按键或磁盘I/O完成。由中断服务程序 (ISR) 处理。
Utility software – programs that help maintain the system, e.g., antivirus, defragmentation, backup software. Not fundamental to OS operation but enhance usability.
实用软件 – 帮助维护系统的程序，例如防病毒、碎片整理、备份软件。并非OS运行的基础，但增强了可用性。
7. Networks and the Internet | 网络与互联网
LAN (Local Area Network) – a network covering a small geographical area, like a home or school; typically high speed, private ownership.
局域网 (LAN) – 覆盖较小地理区域的网络，如家庭或学校；通常高速度、私有。
WAN (Wide Area Network) – connects LANs over large areas, often using leased telecommunications lines. The Internet is the largest WAN.
广域网 (WAN) – 连接广大区域内局域网的网络，常使用租用的电信线路。互联网是最大的广域网。
Packet switching – data is split into packets, each with header (source/destination address, sequence number) and payload. Routers forward packets independently; reassembly at destination.
分组交换 – 数据被分割成分组，每个分组包含头部（源/目的地址、序列号）和有效载荷。路由器独立转发分组；在目的地重新组装。
Protocol – a set of rules governing data communication. Key protocols: TCP (reliable transmission), IP (addressing/routing), HTTP (web), FTP (file transfer), SMTP (email).
协议 – 管理数据通信的一组规则。关键协议：TCP（可靠传输）、IP（寻址/路由）、HTTP（网页）、FTP（文件传输）、SMTP（电子邮件）。
MAC address – a unique 48-bit hardware identifier assigned to a network interface card (NIC). Used within a local network segment.
MAC地址 – 分配给网络接口卡 (NIC) 的唯一48位硬件标识符。在局域网段内使用。
8. Database Fundamentals | 数据库基础
Database – a structured collection of data, organized for efficient retrieval and manipulation. Managed by a Database Management System (DBMS).
数据库 – 结构化的数据集合，为高效检索和操作而组织。由数据库管理系统 (DBMS) 管理。
Table (Relation) – a set of rows (tuples/records) and columns (attributes/fields). Each column has a specific data type.
表（关系） – 由行（元组/记录）和列（属性/字段）组成的集合。每个列都有特定的数据类型。
Primary key – a unique identifier for each record in a table (e.g., student ID). Cannot be null. Ensures entity integrity.
主键 – 表中每条记录的唯一标识符（如学号）。不能为空。确保实体完整性。
Foreign key – a column that links two tables by referencing the primary key of another table, enforcing referential integrity.
外键 – 通过引用另一张表的主键来连接两张表的列，强制执行引用完整性。
Normalization – process of organizing data to reduce redundancy and improve integrity. 1NF: atomic values; 2NF: full functional dependency on whole key; 3NF: remove transitive dependency.
规范化 – 组织数据以减少冗余并提高完整性的过程。1NF：原子值；2NF：完全函数依赖于整个键；3NF：消除传递依赖。
9. Algorithms and Programming Concepts | 算法与编程概念
Algorithm – a step-by-step procedure to solve a problem, with properties: finiteness, definiteness, input, output, effectiveness.
算法 – 解决问题的逐步步骤，具有特性：有穷性、确定性、输入、输出、有效性。
Variable – a named storage location in memory that can hold a value, which may change during program execution. Has a data type.
变量 – 内存中一个命名的存储位置，可保存一个值，在程序执行期间可能改变。具有数据类型。
Constant – a named value that cannot be altered during runtime. Improves readability and maintainability.
常量 – 在运行时不能被修改的命名值。提高可读性和可维护性。
Array – a data structure holding a fixed number of elements of the same data type, accessed by index (e.g., marks[3]).
数组 – 一种存放固定数量、相同数据类型元素的数据结构，通过索引访问（如 marks[3]）。
Recursion – a technique where a subroutine calls itself. Must have a base case to terminate. Suited for problems like factorials, tree traversal.
递归 – 子程序调用自身的技术。必须有基例才能终止。适用于阶乘、树遍历等问题。
Iteration – repetition of a block of code using loops: FOR (count-controlled), WHILE, REPEAT-UNTIL (condition-controlled).
迭代 – 使用循环重复执行代码块：FOR（计数控制），WHILE、REPEAT-UNTIL（条件控制）。
10. Security and Encryption | 安全与加密
Malware – malicious software including viruses, worms, trojans, ransomware. Spreads and damages systems.
恶意软件 – 恶意软件，包括病毒、蠕虫、特洛伊木马、勒索软件。传播并破坏系统。
Phishing – a social engineering attack where fake emails/websites trick users into revealing sensitive information. 'Fishing' for credentials.
网络钓鱼 – 一种社会工程攻击，利用虚假电子邮件/网站诱骗用户泄露敏感信息。“钓”取凭据。
Encryption – converting plaintext into ciphertext using an algorithm and key. Ensures confidentiality.
加密 – 使用算法和密钥将明文转换为密文。确保机密性。
Symmetric encryption – same key is used for both encryption and decryption. Fast but requires secure key exchange. Example: AES.
对称加密 – 加密和解密使用相同的密钥。速度快，但需要安全的密钥交换。例如AES。
Asymmetric encryption – uses a key pair: public key (for encryption) and private key (for decryption). Solves key distribution problem. Example: RSA.
非对称加密 – 使用密钥对：公钥（用于加密）和私钥（用于解密）。解决了密钥分发问题。例如RSA。
Firewall – a hardware or software system that monitors and controls incoming/outgoing network traffic based on security rules. Barrier between trusted and untrusted networks.
防火墙 – 基于安全规则监控并控制进出网络流量的硬件或软件系统。在可信网络和不可信网络之间建立屏障。
11. Ethics and Legislation | 伦理与法律
Data protection – laws regulating the collection, storage, and use of personal data. Principles: fair and lawful processing, data minimization, accuracy, security. Example: GDPR, UK Data Protection Act 2018.
数据保护 – 规范个人数据的收集、存储和使用的法律。原则：公平合法处理、数据最小化、准确性、安全性。例如：GDPR、英国2018年数据保护法。
Computer Misuse Act – UK legislation that criminalizes unauthorized access to computer material (hacking), unauthorized modification (e.g., viruses), and unauthorized access with intent to commit further offences.
计算机滥用法 – 英国立法，将未经授权访问计算机材料（黑客行为）、未经授权修改（如病毒）以及意图实施进一步犯罪的未经授权访问定为刑事犯罪。
Copyright, Designs and Patents Act – protects intellectual property such as software code, music, and digital media. Covers illegal copying and distribution.
版权、外观设计和专利法 – 保护软件代码、音乐和数字媒体等知识产权。涵盖非法复制和分发。
Plagiarism – presenting someone else's work or ideas as your own without proper acknowledgement. Academic and professional dishonesty.
抄袭 – 在未适当致谢的情况下将他人的作品或想法作为自己的呈现。学术和职业不诚实。
12. Quick Mnemonics and Memory Aids | 快速助记与记忆助手
Registers (PC MAR MDR CIR ACC) – 'Politely Many Ducks Cackle And Chirp' (PC, MAR, MDR, CIR, ACC). Silly but effective.
寄存器 (PC MAR MDR CIR ACC) – “礼貌的许多鸭子咯咯笑和喳喳叫” (PC, MAR, MDR, CIR, ACC)。虽然傻气，但很有效。
OS functions – MPM FS (Memory, Process, File, Security) or think 'My Pet Frog Sings'.
操作系统功能 – MPM FS（内存、进程、文件、安全）或者想成“我的宠物青蛙唱歌”。
Primary key vs Foreign key – Primary is at home (in its own table), Foreign travels abroad (references another table).
主键 vs 外键 – 主键在自己家里（自己的表中），外键出国旅行（引用另一张表）。
1NF, 2NF, 3NF – '1-Atomic, 2-Full dependency, 3-No transitive'. The numbers increase as you remove more anomalies.
1NF, 2NF, 3NF – “1-原子性，2-完全依赖，3-无传递”。随着异常被消除，数字递增。
Packet switching – Like sending a book page by page through different postal routes; reassembled at the receiver.
分组交换 – 像通过不同的邮路一页一页寄送一本书；在接收端重新组装。
Lossless vs lossy – Lossless = 'Less loss, no loss'; Lossy = 'Lose some, more space'.
无损 vs 有损 – 无损 = “更少损失，没有损失”；有损 = “损失一些，更多空间”。
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