📚 Year 12 CAIE Computer Science: Key Terms Revision Guide | CAIE 计算机 AS 词汇术语速记指南
Mastering technical vocabulary is half the battle in Cambridge AS Computer Science. This guide groups essential Year 12 terms by topic, with clear definitions, memory hooks, and paired English–Chinese explanations to help you recall concepts quickly in exams.
掌握专业术语是攻克剑桥 AS 计算机科学的一半功夫。这本指南按主题将 Year 12 核心词汇分组，配以清晰的定义、记忆技巧以及中英文对照解释，助你在考试中快速回忆起相关概念。
1. Data Representation | 数据表示
Bit: The smallest unit of data in a computer, representing a binary digit 0 or 1.
比特（位）：计算机中最小的数据单位，表示二进制数字 0 或 1。
Byte: A group of 8 bits, treated as a single unit of data. Most characters are stored using one or more bytes.
字节：由 8 个比特组成的一个数据单位。大多数字符用一个或多个字节存储。
Nibble: A group of 4 bits (half a byte). Often used in hexadecimal representation.
半字节：由 4 个比特组成的组（半个字节），常用于十六进制表示。
Binary: A base‑2 number system using only digits 0 and 1.
二进制：基数为 2 的数字系统，仅使用数字 0 和 1。
Denary / Decimal: The base‑10 number system typically used by humans (digits 0‑9).
十进制：人类通常使用的基数为 10 的数字系统（数字 0‑9）。
Hexadecimal: A base‑16 system using digits 0‑9 and letters A‑F. Compact way to represent binary values.
十六进制：基数为 16 的系统，使用数字 0‑9 和字母 A‑F，是表示二进制值的紧凑方式。
Overflow: An error condition that occurs when a calculation produces a result too large to be stored in the allocated number of bits.
溢出：计算结果超出了分配给它的二进制位数所能表示的范围而产生的错误状态。
Two’s complement ing signed integers in binary. The most significant bit acts as a sign bit (1 = negative).
二进制补码：一种用二进制表示有符号整数的方法。最高有效位用作符号位（1 表示负数）。
Fixed point: A representation of real numbers where a fixed number of bits are used for the integer part and the fractional part.
定点数：一种实数表示法，其中整数部分和小数部分各使用固定数量的比特位。
Floating point: A representation of real numbers in the form mantissa × baseexponent, allowing a wide range of values.
浮点数：用尾数 × 基数指数 的形式表示实数，能够表示范围很广的值。
ASCII: American Standard Code for Information Interchange. A 7‑bit character set encoding 128 characters.
美国信息交换标准代码：一种 7 位字符集，可编码 128 个字符。
Unicode: A computing industry standard for consistent encoding, representation, and handling of text expressed in most of the world’s writing systems. Uses variable length encoding (e.g. UTF‑8).
统一码：计算机行业标准，用于对世界上大多数书写系统的文本进行一致的编码、表示和处理，采用变长编码（如 UTF‑8）。
2. Data Storage and Compression | 数据存储与压缩
File: A named collection of data, stored on a disk or other storage medium.
文件：存储在磁盘或其他存储介质上的一组被命名的数据集合。
Lossless compression: Data compression technique where the original data can be perfectly reconstructed from the compressed data (e.g. run‑length encoding, Huffman coding).
无损压缩：能从压缩数据中完全重建原始数据的压缩技术（如行程编码、哈夫曼编码）。
Lossy compression: Data compression technique that reduces file size by permanently eliminating certain information (e.g. JPEG, MP3). Suitable for images and sounds.
有损压缩：通过永久性丢弃部分信息来减小文件大小的压缩技术（如 JPEG、MP3），适用于图像和声音。
Run‑length encoding (RLE) sless compression method that stores runs of data as a single data value and a count (e.g. “AAAA” → “4A”).
行程编码：一种无损压缩方法，将连续重复的数据存储为单个数据值和计数（例如“AAAA” → “4A”）。
Huffman coding: A lossless compression algorithm that uses variable‑ haracters based on their frequency of occurrence (more frequent character = shorter code).
哈夫曼编码：一种无损压缩算法，根据字符出现频率使用不同长度的编码（频率越高，编码越短）。
Sampling (sound): The process of measuring the amplitude of an analogue sound wave at regular time intervals to convert it into digital form.
采样（声音）：以固定时间间隔测量模拟声波的振幅，将其转换为数字形式的过程。
Sampling rate: The number of samples taken per second, measured in Hertz (Hz). Higher rates produce better quality but larger files.
采样率：每秒采集的样本数量，单位是赫兹（Hz）。采样率越高，音质越好，但文件越大。
Bit depth: The number of bits used to record each sample. Higher bit depth gives more accurate representation of amplitude.
位深度：用于记录每个样本的比特数。位深度越高，对振幅的表示越精确。
3. Hardware | 硬件
CPU (Central Processing Unit): The part of a computer that fetches, decodes, and executes instructions. Often called the “brain” of the computer.
中央处理器：计算机中取指、译码和执行指令的部分，常被称作计算机的“大脑”。
ALU (Arithmetic Logic Unit): A component inside the CPU that performs arithmetic and logical operations.
算术逻辑单元：CPU 内部执行算术和逻辑运算的部件。
CU (Control Unit): The CPU component that directs the operation of the processor, fetching instructions and controlling the flow of data.
控制单元：CPU 中指挥处理器操作的部件，负责取指令并控制数据流动。
Register: A small high‑speed storage location inside the CPU used to hold data, addresses, or instructions temporarily.
寄存器：CPU 内部的高速小型存储单元，用于临时保存数据、地址或指令。
PC (Program Counter): A register that holds the memory address of the next instruction to be fetched.
程序计数器：保存下一条待取指令所在内存地址的寄存器。
MAR (Memory Address Register): A register that holds the address of the memory location that is to be read from or written to.
存储器地址寄存器：保存将要读取或写入的内存单元地址的寄存器。
MDR (Memory Data Register): A register that holds the data that has been read from or is to be written to a memory address.
存储器数据寄存器：保存从内存地址读取到的数据或待写入数据的寄存器。
CIR (Current Instruction Register): A register that holds the actual instruction currently being executed.
当前指令寄存器：保存当前正被执行的实际指令的寄存器。
Bus: A set of parallel wires used to transfer data, addresses, or control signals between components. Three types: data bus, address bus, control bus.
总线：一组并行导线，用于在组件之间传输数据、地址或控制信号。分三类：数据总线、地址总线、控制总线。
Clock speed: The number of cycles a CPU can perform per second, measured in Hertz (GHz on modern CPUs).
时钟速度：CPU 每秒能够执行的周期数，以赫兹为单位（现代 CPU 用 GHz）。
Core: An individual processing unit within a CPU. Multi‑core processors can execute multiple instructions simultaneously.
核心：CPU 内部的一个独立处理单元。多核处理器可以同时执行多条指令。
Von Neumann architecture: A computer architecture where instructions and data share the same memory and buses, resulting in the von Neumann bottleneck.
冯·诺依曼架构：指令和数据共用同一内存和总线的计算机架构，由此产生“冯·诺依曼瓶颈”。
Harvard architecture: A computer architecture that uses separate memories and buses for instructions and data, allowing simultaneous access.
哈佛架构：使用独立的存储器和总线分别存储指令和数据，从而允许同时访问的计算机架构。
4. Memory and Storage Devices | 存储器与存储设备
RAM (Random Access Memory): Volatile memory that holds data and instructions currently being used by the CPU. Data is lost when power is turned off.
随机存取存储器：易失性存储器，保存 CPU 当前正在使用的数据和指令，断电后数据消失。
ROM (Read Only Memory): Non‑volatile memory that stores firmware and the bootstrap loader. Data is not lost when power is turned off.
只读存储器：非易失性存储器，用于存储固件和引导加载程序，断电后数据不会丢失。
Volatile memory: Memory that requires a constant power supply to retain data. RAM is volatile.
易失性存储器：需要持续供电才能保持数据的存储器，如 RAM。
Non‑volatile memory: Memory that retains data even without power. ROM, flash memory, and hard disks are examples.
非易失性存储器：即使断电也能保持数据的存储器，如 ROM、闪存和硬盘。
Cache memory: A small amount of high‑speed memory placed close to the CPU to store frequently accessed instructions and data, reducing average access time.
高速缓存：靠近 CPU 的一小块高速存储器，存储频繁使用的指令和数据，以减少平均访问时间。
Secondary storage: Non‑volatile storage used for long‑term data retention. Examples: HDD, SSD, optical discs.
辅助存储器：用于长期保存数据的非易失性存储器，如机械硬盘、固态硬盘和光盘。
HDD (Hard Disk Drive): A magnetic storage device with spinning platters and a read/write head. Slower but cheap and high capacity.
机械硬盘：一种带有旋转盘片和读写头的磁性存储设备，速度较慢但成本低、容量大。
SSD (Solid State Drive): A storage device using NAND flash memory. Faster, more durable, and consumes less power than HDDs.
固态硬盘：使用 NAND 闪存的存储设备，比机械硬盘更快、更耐用、更省电。
Cloud storage: Data storage where data is stored on remote servers accessed via the Internet, managed by a third party.
云存储：数据保存在通过互联网访问的远程服务器上的存储方式，由第三方管理。
5. Systems Software and Operating Systems | 系统软件与操作系统
Operating system (OS): Software that manages hardware, runs applications, and provides a user interface. Key functions: memory management, processor scheduling, file management, security.
操作系统：管理硬件、运行应用程序并提供用户界面的软件。主要功能：内存管理、处理器调度、文件管理、安全管理。
Utility software: Programs designed to help analyse, configure, optimise, or maintain a computer system. Examples: antivirus, defragmentation, backup software.
实用工具软件：旨在帮助分析、配置、优化或维护计算机系统的程序，如杀毒软件、磁盘碎片整理、备份软件。
Library / Software library: A collection of pre‑written functions and routines that can be used by other programs, promoting reusability.
程序库：一组预先编写好的函数和例程，可被其他程序使用，以促进代码复用。
Compiler: A program that translates high‑level source code into machine code all at once, producing an executable file.
编译器：将高级语言源代码一次性翻译成机器码并生成可执行文件的程序。
Interpreter: A program that translates and executes high‑level source code line by line, without producing a separate executable.
解释器：逐行翻译并执行高级语言源代码，且不生成独立可执行文件的程序。
Assembler: A program that translates assembly language code into machine code.
汇编器：将汇编语言代码翻译成机器码的程序。
Translation (code): The process of converting a program written in one programming language into another language, typically from high‑level to machine code.
代码翻译：将用一种编程语言编写的程序转换为另一种语言的过程，通常是从高级语言到机器码。
6. Networks and the Internet | 网络与互联网
LAN (Local Area Network): A network that connects computers within a small geographical area, such as a school or office building.
局域网：连接小型地理区域内计算机的网络，如学校或办公楼内。
WAN (Wide Area Network): A network that covers a broad geographical area, often made up of several LANs connected together. The Internet is the largest WAN.
广域网：覆盖广泛地理区域的网络，常由多个局域网互连而成。互联网是最大的广域网。
Client‑server model: A networking architecture where clients request services and servers provide them.
客户端-服务器模型：一种网络架构，其中客户端请求服务，服务器提供这些服务。
Peer‑to‑peer (P2P) network: A network where all computers have equal status and can act as both client and server, sharing resources directly.
对等网络：所有计算机地位平等，均可同时充当客户端和服务器，直接共享资源的网络。
Router: A network device that forwards data packets between different networks, using IP addresses to find the best path.
路由器：在不同网络之间转发数据包的网络设备，利用 IP 地址寻找最佳路径。
Switch: A device that connects devices together on a LAN, forwarding data frames using MAC addresses.
交换机：在局域网中连接各类设备，使用 MAC 地址转发数据帧的设备。
MAC address: A unique hardware identifier assigned to a network interface controller (NIC), used for communication within a local network segment.
MAC 地址：分配给网络接口控制器的唯一硬件标识符，用于网段内的本地通信。
IP address: A numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. IPv4: 32‑bit; IPv6: 128‑bit.
IP 地址：为参与使用互联网协议的计算机网络的每台设备分配的数字标签。IPv4：32 位；IPv6：128 位。
Protocol: A set of rules governing the exchange or transmission of data between devices. Examples: HTTP, TCP, IP, FTP.
协议：管理设备之间数据交换或传输的一套规则，如 HTTP、TCP、IP、FTP。
TCP/IP stack: A suite of protocols organised in layers: Application, Transport, Internet, and Network Access. Each layer performs specific tasks.
TCP/IP 协议栈：分层组织的一组协议：应用层、传输层、互联网层和网络接入层，每层完成特定任务。
7. Databases | 数据库
Database: A structured collection of related data held in a computer system, typically organised into tables.
数据库：计算机系统中存放的有组织、相互关联的数据集合，通常以表格形式组织。
DBMS (Database Management System): Software that enables users to define, create, maintain, and control access to the database. Examples: MySQL, Microsoft Access.
数据库管理系统：使用户能够定义、创建、维护和控制数据库访问的软件，如 MySQL、Microsoft Access。
Relational database: A database structured to recognise relations among stored items of information, using tables of rows (records) and columns (fields). Foreign keys link tables.
关系数据库：通过行（记录）和列（字段）组成的表来识别存储信息项之间关系的数据库。外键用于连接表。
Primary key: A unique identifier for each record in a database table. No two rows can have the same primary key value.
主键：数据库表中每条记录的唯一标识符，任何两行都不能有相同的主键值。
Foreign key: A field in one table that refers to the primary key in another table, creating a relationship between the two tables.
外键：一张表中引用另一张表主键的字段，用于在两张表之间建立关系。
Normalisation: The process of organising data in a database to reduce redundancy and improve data integrity. Forms: 1NF, 2NF, 3NF.
规范化：在数据库中组织数据以减少冗余并提高数据完整性的过程，包括第一范式、第二范式、第三范式。
SQL (Structured Query Language): A standard language for managing relational databases, used to query, insert, update, and delete data.
结构化查询语言：管理关系数据库的标准语言，用于查询、插入、更新和删除数据。
8. Algorithm Design and Problem Solving | 算法设计与问题求解
Algorithm: A step‑by‑step procedure for solving a problem in a finite number of steps. Characteristics: definiteness, input, output, finiteness, effectiveness.
算法：在有限步骤内解决问题的一步一步的过程。特性：确定性、有零或多个输入、至少一个输出、有限性、有效性。
Abstraction: The process of removing unnecessary details so that you can focus on the characteristics needed to solve the problem.
抽象化：去除不必要的细节，以便专注于解决问题所需特征的过程。
Decomposition: Breaking down a complex problem into smaller, more manageable parts.
分解：将一个复杂问题分解为更小、更易管理的部分。
Pattern recognition: Identifying common characteristics and patterns that can be used to solve the problem efficiently, often using ideas from previous solutions.
模式识别：识别可以用来高效解决问题的共同特性和模式，常常借鉴以往解决方案的思路。
Pseudocode: A notation resembling a simplified programming language, used to design algorithms without worrying about syntax of a specific language.
伪代码：一种类似简化编程语言的表示法，用于设计算法，无需考虑特定语言的语法。
Flowchart: A graphical representation of an algorithm using standard symbols (ovals for start/stop, rectangles for processes, diamonds for decisions).
流程图：使用标准符号（椭圆表示开始/结束，矩形表示处理步骤，菱形表示判断）的算法图形表示。
Trace table: A manual technique used to test an algorithm by tracking the values of variables step by step.
跟踪表：一种通过逐步跟踪变量值来测试算法的手工技术。
Search algorithm: An algorithm that finds an item with specific properties in a collection. Linear search (check each item) vs binary search (divide and conquer, requires sorted list).
查找算法：在集合中寻找具有特定属性的项的算法。线性搜索（逐个检查）与二分搜索（分而治之，要求预排序列表）。
Sorting algorithm: An algorithm that puts elements in a certain order. Bubble sort and insertion sort are standard AS examples.
排序算法：将元素按一定顺序排列的算法。冒泡排序和插入排序是 AS 阶段的典型示例。
9. Programming Concepts | 编程概念
Variable: A named storage location in memory whose value can change during program execution.
变量：内存中一个被命名的存储位置，其值在程序执行过程中可以改变。
Constant: A named memory location whose value cannot be changed during program execution.
常量：在程序执行过程中值不可更改的命名内存位置。
Data type: A classification that specifies which kind of value a variable can hold (e.g. Integer, Real, Boolean, Char, String).
数据类型：规定变量可以存储何种数值的分类（如整型、实型、布尔型、字符型、字符串型）。
Array: A data structure that stores a fixed‑size sequential collection of elements of the same data type. Index starts at 0 in many languages.
数组：一种存放固定大小、相同数据类型元素序列的数据结构。索引通常从 0 开始。
Parameter (actual vs formal): Formal parameters are variables listed in a procedure’s definition; actual parameters are the values passed when the procedure is called.
参数（实际参数与形式参数）：形式参数是过程定义中列出的变量；实际参数是调用过程时传入的值。
Function vs Procedure: A function returns a single value and can be used in expressions; a procedure performs a task but does not return a value.
函数与过程：函数返回一个值并可用于表达式中；过程执行任务但不返回值。
Recursion: A method where a function calls itself with a smaller problem, until a base case is met.
递归：函数通过调用自身解决规模更小的问题，直到达到基案的方法。
IDE (Integrated Development Environment): Software that combines a code editor, debugger, and build automation tools. Common features: syntax highlighting, auto‑complete, debugging.
集成开发环境：集代码编辑器、调试器和构建自动化工具于一体的软件。常见功能：语法高亮、自动补全、调试。
10. Program Testing and Maintenance | 程序测试与维护
Testing: The process of evaluating a program to find errors and verify that it meets its requirements. Types: white‑box (structural), black‑box (functional).
测试：评估程序以发现错误并验证其是否满足需求的过程。类型：白盒测试（结构测试）和黑盒测试（功能测试）。
Syntax error: An error that occurs when the rules of the programming language are broken; the program cannot be translated.
语法错误：违反编程语言规则时发生的错误；程序无法被翻译运行。
Logic error: An error where the program runs but produces incorrect results because of a flaw in the algorithm.
逻辑错误：程序能够运行但因算法缺陷而产生不正确结果的错误。
Run‑time error: An error that occurs during program execution, causing the program to crash or behave unexpectedly (e.g. division by zero).
运行时错误：程序执行过程中发生的错误，导致程序崩溃或行为异常（如除以零）。
Normal / Boundary / Erroneous test data: Normal data is valid and expected; boundary data is at the limits of valid ranges; erroneous data is invalid and should be rejected.
正常 / 边界 / 异常测试数据：正常数据是有效且预期的；边界数据处于有效范围的极限；异常数据无效，应被程序拒绝。
Dry run: Manually stepping through a program or algorithm using pen and paper to trace variable values and logic flow. Often done using a trace table.
白盒走查：用手工方式在纸上逐步执行程序或算法以跟踪变量值和逻辑流程，通常借助跟踪表完成。
Maintenance: The modification of a software product after delivery to correct faults, improve performance, or adapt to a changed environment. Types: corrective, adaptive, perfective.
维护：软件交付后对其进行的修改，以纠正错误、提升性能或适应环境变化。分为纠错性、适应性、完善性维护。
11. Security and Ethics | 安全与伦理
Malware: Malicious software designed to disrupt, damage, or gain unauthorised access to a computer system. Includes viruses, worms, trojans, ransomware.
恶意软件：旨在干扰、破坏或未经授权访问计算机系统的软件，包括病毒、蠕虫、特洛伊木马、勒索软件等。
Phishing: A social engineering technique that uses deceptive emails or websites to trick users into revealing personal information like passwords.
网络钓鱼：一种利用欺骗性电子邮件或网站诱骗用户泄露个人信息（如密码）的社会工程手段。
Encryption: The process of converting plaintext data into ciphertext using an algorithm and a key, so that only authorised parties can decipher it.
加密：使用算法和密钥将明文数据转换为密文的过程，只有经授权方才能解密。
Firewall: A network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.
防火墙：根据预设安全规则监控并控制网络进出流量的网络安全系统。
Cookies: Small text files stored on a user’s computer by a web browser, used to track user preferences or login sessions.
Cookie（小文本文件）：由网页浏览器存储在用户计算机上的小型文本文件，用于跟踪用户偏好或登录会话。
Ethics: Moral principles that govern a person’s behaviour in computing, such as respecting intellectual property, privacy, and avoiding harm.
计算机伦理：指导人们在计算机领域行为的道德原则，如尊重知识产权、隐私和避免伤害。
Acceptable Use Policy (AUP): A set of rules applied by a network or website owner that restrict the ways in which the network or site may be used.
可接受使用政策：由网络或网站所有者制定的一套规则，限制该网络或网站的使用方式。
12. Communication and Internet Technologies | 通信与互联网技术
Packet switching: A method of data transmission where data is broken into smaller packets, which are sent independently across a network and reassembled at the destination.
分组交换：一种数据传输方法，将数据分割成较小的包，各包独立在网络上传输，在目的地重新组装。
Circuit switching: A method where a dedicated communication path is established between two nodes for the entire duration of the connection (e.g. traditional landline phone).
电路交换：在两个节点之间为连接的整个持续时间内建立专用通信路径的方法（如传统固定电话）。
DNS (Domain Name System): A hierarchical naming system that translates human‑friendly domain names into IP addresses (e.g. www.example.com → 93.184.216.34).
域名系统：将人类友好的域名翻译为 IP 地址的分层命名系统（如 www.example.com → 93.184.216.34）。
HTML (HyperText Markup Language): The standard markup language used to create web pages, using tags to define structure and content.
超文本标记语言：用于创建网页的标准标记语言，通过标签定义结构和内容。
CSS (Cascading Style Sheets): A style sheet language used for describing the presentation of a document written in HTML, controlling layout, colours, fonts.
层叠样式表：用于描述 HTML 文档呈现方式的样式表语言，控制布局、颜色和字体。
URL (Uniform Resource Locator): A reference (address) that specifies the location of a resource on the internet. Contains protocol, domain, path.
统一资源定位符：指定互联网上资源位置的引用（地址），包含协议、域名和路径。
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