📚 Year 11 AQA Computer Science: Quick Vocabulary Guide | AQA 计算机科学：词汇术语速记指南
This guide breaks down essential AQA Computer Science terms into easy-to-remember explanations. Each English definition is immediately followed by its Chinese equivalent, helping you build dual-language fluency for the exam. We focus on high-frequency vocabulary you will encounter in papers 1 and 2, from computational thinking to networking.
本指南将 AQA 计算机科学核心术语拆解为易于记忆的解释。每条英文释义后紧跟中文对照，帮助你在备考中培养中英双语理解力。我们聚焦于试卷一和试卷二中的高频词汇，涵盖计算思维到网络等领域。
1. Algorithms & Pseudocode | 算法与伪代码
An algorithm is a step-by-step sequence of instructions designed to solve a problem or perform a task. Think of it like a cooking recipe – precise and unambiguous.
算法是为解决问题或执行任务而设计的一系列分步指令。可以把它想象成烹饪食谱——精确且无歧义。
Pseudocode is a simplified, informal way of writing algorithms using structured English, not tied to any specific programming language. It allows you to plan logic before coding.
伪代码是一种使用结构化英语来编写算法的简化非正式方法，不特定于任何编程语言。你可以在编码前先用它规划逻辑。
Trace tables are used to manually follow the execution of an algorithm, recording variable values step by step to detect errors.
跟踪表用于手动追踪算法的执行过程，逐步记录变量的值，以便发现错误。
- Abstraction: Removing unnecessary details to focus on key aspects of a problem.
- 抽象: 去除不必要的细节，专注于问题的关键方面。
- Decomposition: Breaking a complex problem into smaller, more manageable parts.
- 分解: 将复杂问题拆解成更小、更易处理的部分。
2. Flow of Control | 控制流
Sequence is the default control flow where instructions are executed one after another in the order they are written.
顺序结构是默认的控制流，指令按照编写顺序一条接一条地执行。
Selection allows the program to make decisions using statements like IF, ELSE IF, and ELSE, or CASE/SWITCH constructs.
选择结构使程序能够做出决策，使用 IF、ELSE IF、ELSE 或 CASE/SWITCH 等语句。
Iteration repeats a block of code. Count-controlled iteration (FOR loops) runs a set number of times, while condition-controlled iteration (WHILE, REPEAT UNTIL) runs as long as a condition holds true.
迭代重复执行一段代码。计数控制迭代（FOR 循环）运行固定次数，而条件控制迭代（WHILE、REPEAT UNTIL）只要条件为真就持续运行。
Nested statements occur when one control structure is placed inside another, such as an IF inside a FOR loop.
嵌套语句指一个控制结构放在另一个内部，例如 FOR 循环里嵌套 IF 语句。
3. Data Types & Variables | 数据类型与变量
An integer is a whole number, positive or negative, without a decimal point. In pseudocode, it is written as INTEGER or simply a number like 5.
整数是不带小数点的正负整数。在伪代码中写作 INTEGER 或直接写数字如 5。
A real (or float) is a number that can have a fractional part, e.g., 3.14. It is used when precision is needed.
实数（或浮点数）是可以包含小数部分的数字，例如 3.14，在需要精度时使用。
A Boolean data type stores only two possible values: TRUE or FALSE. It underpins all logical decisions.
布尔数据类型只能存储两个可能的值：TRUE 或 FALSE。它支撑着所有逻辑决策。
A character is a single symbol such as 'A', '7', or '%', while a string is a sequence of characters like "Hello". Strings are often enclosed in double quotes.
字符是单个符号，如 'A'、'7' 或 '%'；而字符串是由字符组成的序列，如 "Hello"。字符串通常用双引号括起。
Variables are named memory locations that store data which can change during program execution. Constants hold values that never change.
变量是命名的内存位置，存储程序运行期间可以改变的数据。常量保存永不改变的值。
4. Data Structures | 数据结构
An array (1D) is an indexed collection of elements of the same data type, stored contiguously. Elements are accessed via an index, usually starting from 0.
一维数组是相同数据类型元素的索引集合，连续存储。通过索引访问元素，通常从 0 开始。
A 2D array is like a table with rows and columns. You refer to elements using two indices, e.g., grid[2,3].
二维数组类似含有行和列的表格。使用两个索引引用元素，例如 grid[2,3]。
Records (similar to structs) group related items of possibly different data types under one name. Each item is called a field.
记录（类似于结构体）将可能属于不同数据类型的相关项组合在一个名称下。每个项称为字段。
Lists are dynamic collections that can grow or shrink, unlike arrays which are usually static in size. Python’s list is a built-in example.
列表是可以动态增减的集合，而数组大小通常是静态的。Python 的 list 就是一个内置例子。
5. Searching & Sorting Algorithms | 查找与排序算法
Linear search checks every element sequentially until the target is found or the list ends. It works on unsorted data but is slow for large lists.
线性查找逐一检查每个元素，直到找到目标或列表结束。它适用于未排序数据，但大型列表较慢。
Binary search requires a sorted list. It repeatedly divides the search interval in half, comparing the middle element to the target. Much faster than linear search on large datasets.
二分查找要求列表已排序。它反复将搜索区间对半分，将中间元素与目标比较。大规模数据集上比线性查找快得多。
Bubble sort repeatedly steps through the list, compares adjacent items and swaps them if they are in the wrong order. Simple but inefficient.
冒泡排序反复遍历列表，比较相邻项，若顺序错误则交换。简单但效率低。
Merge sort is a divide-and-conquer algorithm that splits the list into halves, recursively sorts them, then merges the sorted halves. It is efficient with time complexity O(n log n).
归并排序是一种分治算法，将列表对半拆分，递归排序，再合并已排序的两半。时间复杂度 O(n log n)，效率高。
6. Binary, Hex & Data Units | 二进制、十六进制与数据单位
Binary uses a base-2 system with digits 0 and 1. Each binary digit is a bit. Computers use binary because they rely on two-state logic (on/off).
二进制使用基数为 2 的系统，数字 0 和 1。每个二进制数字是一位。计算机使用二进制因其依赖双态逻辑（开/关）。
Hexadecimal (base-16) uses digits 0-9 and letters A-F to represent values compactly. One hex digit represents four binary bits (nibble).
十六进制（基数为 16）使用 0-9 和 A-F 紧凑表示值。一位十六进制表示四个二进制位（半字节）。
erabyte (TB) = 10¹² bytes. In exam contexts, be aware of binary prefixes (Kibibyte = 2¹⁰).
数据大小：1 字节 = 8 位。1 千字节 (KB) = 10³ 字节，1 兆字节 (MB) = 10⁶ 字节，1 吉字节 (GB) = 10⁹ 字节，1 太字节 (TB) = 10¹² 字节。考试中注意二进制前缀（如 Kibibyte = 2¹⁰）。
Overflow occurs when a calculation produces a value that exceeds the allocated number of bits. The result wraps around incorrectly.
溢出（上溢）发生在计算结果超过分配的位数时，结果会错误地绕回。
7. Computer System Components | 计算机系统组件
The CPU (Central Processing Unit) executes instructions. It contains the ALU (Arithmetic Logic Unit) for calculations, the CU (Control Unit) for directing operations, and registers.
CPU（中央处理器）执行指令。内含 ALU（算术逻辑单元）进行计算、CU（控制单元）指导操作，以及寄存器。
Von Neumann architecture stores both data and instructions in the same memory unit. Programs are fetched, decoded, executed in a cycle.
冯·诺依曼架构将数据和指令存储在同一内存单元中。程序在取指、解码、执行周期中运行。
Key registers: PC (Program Counter) holds the address of next instruction; MAR (Memory Address Register) holds the address being read/written; MDR (Memory Data Register) holds the data; ACC (Accumulator) stores results of ALU operations.
关键寄存器：PC（程序计数器）存放下一条指令地址；MAR（内存地址寄存器）存放读写地址；MDR（内存数据寄存器）存放数据；ACC（累加器）存储 ALU 运算结果。
Clock speed (measured in Hz) determines how many fetch-decode-execute cycles can be performed per second. A higher clock speed generally means faster performance.
时钟速度（以赫兹 Hz 计量）决定每秒可完成的取指-解码-执行周期数。时钟速度越高通常性能越快。
8. Memory & Storage | 内存与存储
RAM (Random Access Memory) is volatile, fast memory that holds the operating system, programs, and data currently in use. Content is lost when power is off.
RAM（随机存取存储器）是易失性快速内存，存储当前运行的操作系统、程序和数据。断电后内容丢失。
ROM (Read Only Memory) is non-volatile and stores the boot program (BIOS) needed to start the computer. Content is retained without power.
ROM（只读存储器）是非易失性的，存储启动计算机所需的引导程序（BIOS）。断电保留内容。
Cache is a small, high-speed memory inside or near the CPU that stores frequently used instructions and data to reduce access time.
缓存是 CPU 内部或附近的小容量高速内存，存储经常使用的指令和数据以缩短访问时间。
Virtual memory uses a section of the hard disk/SSD as an extension of RAM when RAM is full. It allows more programs to run but is slower.
虚拟内存在 RAM 满时使用硬盘/固态硬盘的一部分作为 RAM 扩展。允许运行更多程序，但速度较慢。
Solid State Drives (SSDs) use flash memory with no moving parts, making them faster, quieter, and more durable than magnetic Hard Disk Drives (HDDs).
固态硬盘 (SSD) 使用闪存且无活动部件，比磁性硬盘 (HDD) 更快、更安静、更耐用。
9. Networks & Topologies | 网络与拓扑
A network is a collection of interconnected computers and devices that can share resources. LAN (Local Area Network) covers a small area; WAN (Wide Area Network) spans large distances.
网络是一组互联计算机和设备，可共享资源。LAN（局域网）覆盖小区域；WAN（广域网）跨越长距离。
A protocol is a set of rules governing how data is transmitted and received. Key examples: TCP/IP (Internet communication), HTTP/HTTPS (web), FTP (file transfer), SMTP (email send).
协议是一套控制数据传输和接收的规则。常见例子：TCP/IP（互联网通信）、HTTP/HTTPS（网页）、FTP（文件传输）、SMTP（邮件发送）。
Star topology connects all devices to a central switch or hub. If one cable fails, only that station is affected. Bus topology uses a single backbone cable; a break can disrupt entire network.
星型拓扑将所有设备连接到中央交换机或集线器。一根电缆故障仅影响该站。总线拓扑使用单根主干电缆，断裂可能导致全网中断。
IP address: a unique identifier for a device on a network. MAC address: a hardware address embedded in the network interface card, usually fixed.
IP 地址：网络设备的唯一标识符。MAC 地址：嵌入网卡的硬件地址，通常是固定的。
Packet switching breaks data into small packets, each routed independently across the network and reassembled at the destination.
分组交换将数据拆分成小数据包，每个包独立路由，在目的地重新组装。
10. Network Security | 网络安全
Malware is malicious software including viruses, worms, trojans, spyware, and ransomware. Social engineering tricks users into revealing secure information, e.g., phishing emails.
恶意软件包括病毒、蠕虫、木马、间谍软件和勒索软件。社交工程诱骗用户泄露安全信息，例如钓鱼邮件。
Encryption scrambles data so that only authorised parties with a key can read it. Plaintext becomes ciphertext. Symmetric encryption uses the same key; asymmetric uses a public/private key pair.
加密打乱数据，只有持有密钥的授权方才能读取。明文变为密文。对称加密使用同一密钥；非对称加密使用公钥/私钥对。
A firewall monitors and controls incoming and outgoing network traffic based on predetermined security rules, blocking unauthorised access.
防火墙根据预设安全规则监视和控制进出网络流量，阻止未授权访问。
Authentication verifies a user’s identity. Multi-factor authentication uses two or more factors (something you know, have, or are) to improve security.
认证验证用户身份。多因素认证使用两个或多个因素（你知道的、你拥有的、你本身的）提高安全性。
11. Ethical, Legal & Environmental Issues | 伦理、法律与环境问题
The Data Protection Act (2018/GDPR) governs how personal data can be collected, used, and stored, requiring consent and strong security measures.
数据保护法（2018/GDPR）规范个人数据的收集、使用和存储，要求征得同意并采取安全措施。
Computer Misuse Act (1990) makes it illegal to gain unauthorised access to computer material (hacking), or to create and distribute malware.
计算机滥用法（1990）将未经授权访问计算机资料（黑客）或创建散布恶意软件定为非法。
Copyright, Designs and Patents Act protects intellectual property, preventing software piracy and unauthorized copying.
版权、设计和专利法保护知识产权，防止软件盗版和未经授权的复制。
Digital divide refers to the gap between those with access to modern technology and those without, often due to economic or geographical factors.
数字鸿沟指能够使用现代技术的人与无法使用的人之间的差距，常因经济或地理因素导致。
E-waste is discarded electronic devices. Computing poses environmental challenges, but can also help through remote work and digital documents reducing paper and travel.
电子垃圾是废弃的电子设备。计算带来环境挑战，但也可通过远程工作和数字文档减少纸张和出行。
12. Software & Development Lifecycle | 软件与开发生命周期
System software includes the operating system (manages hardware, provides UI), utility programs (antivirus, disk defragmentation), and translators (compilers, interpreters).
系统软件包括操作系统（管理硬件、提供用户界面）、实用程序（防病毒、磁盘碎片整理）和翻译器（编译器、解释器）。
Application software performs specific tasks for users, such as word processors, browsers, and games.
应用软件为用户执行特定任务，如文字处理器、浏览器和游戏。
A compiler translates the entire high-level source code into machine code at once, producing an executable. An interpreter translates and executes line by line.
编译器一次将整个高级源代码翻译为机器码，生成可执行文件。解释器逐行翻译执行。
The software development lifecycle includes analysis, design, implementation, testing, and maintenance. Testing strategies: iterative testing during development, final/terminal testing at end. Test data includes normal, boundary, and erroneous inputs.
软件开发生命周期包括分析、设计、实现、测试和维护。测试策略：开发期间的迭代测试和最后的终局测试。测试数据包含正常、边界和错误输入。
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