📚 GCSE AQA Computer Science: Mind Map Quick Revision | GCSE AQA 计算机科学：思维导图速记
Mind maps are powerful tools for visualising and memorising key concepts in GCSE AQA Computer Science. This article presents a structured mind map covering all major topics, helping you revise efficiently for your exams.
思维导图是可视化和记忆 GCSE AQA 计算机科学关键概念的强大工具。本文提供了一个结构化的思维导图，涵盖所有主要主题，帮助你高效备考。
1. Algorithms | 算法
An algorithm is a set of step-by-step instructions to solve a problem or perform a task.
算法是一组用于解决问题或执行任务的分步骤指令。
Algorithms can be represented using flowcharts (graphical) and pseudocode (text-based).
算法可以用流程图（图形化）和伪代码（基于文本）来表示。
The basic building blocks are sequence (one step after another), selection (IF…THEN…ELSE), and iteration (FOR, WHILE, REPEAT loops).
基本构建块包括顺序（一步步执行）、选择（IF…THEN…ELSE）和迭代（FOR、WHILE、REPEAT 循环）。
Linear search examines each item in turn; binary search repeatedly halves a sorted list, requiring comparisons of log₂ n.
线性搜索逐个检查每一项；二分查找反复将已排序列表对半分，比较次数约为 log₂ n。
Bubble sort compares and swaps adjacent items; merge sort splits lists and merges sorted sublists, having O(n log n) complexity.
冒泡排序比较并交换相邻项；归并排序拆分列表再合并已排序子列表，复杂度为 O(n log n)。
Algorithm efficiency is measured by time and space complexity; trace tables help verify correctness.
算法效率通过时间复杂度和空间复杂度衡量；跟踪表有助于验证正确性。
2. Programming | 编程
Data types include integer, float, Boolean, character, and string. Declaration initialises a variable with a type.
数据类型包括整型、浮点型、布尔型、字符和字符串。声明用于初始化变量并指定类型。
Variables store values that can change; constants hold fixed values set once. Input receives data, output displays results.
变量存储可变的值；常量保存设定后不可更改的固定值。输入接收数据，输出显示结果。
Operators: arithmetic (+, −, ×, ÷), comparison (==, !=, <, >, <=, >=), logical (AND, OR, NOT).
运算符：算术（+、−、×、÷）、比较（==、!=、<、>、<=、>=）、逻辑（AND、OR、NOT）。
Sequence, selection (if-elif-else), and iteration (for and while loops) structure code. Nested constructs are common.
顺序、选择（if-elif-else）和迭代（for 和 while 循环）构成代码结构；嵌套结构十分常见。
Subroutines: procedures perform actions, functions return a value. Parameters pass data; scope controls visibility of variables.
子程序：过程执行操作，函数返回值。参数传递数据；作用域控制变量的可见性。
String manipulation includes concatenation, slicing, and functions like len(), substring. Arrays/lists hold multiple items under one name.
字符串操作包括连接、切片以及 len()、子串等函数。数组/列表用一个名称存储多个数据项。
3. Data Representation | 数据表示
Units: bit (b), nibble (4 bits), byte (B, 8 bits). Larger units use powers of 2: 1 KB = 2¹⁰ bytes = 1024 B; 1 MB = 2²⁰ B; 1 GB = 2³⁰ B; 1 TB = 2⁴⁰ B.
单位：位 (bit)、半字节 (4 位)、字节 (B, 8 位)。更大单位使用 2 的幂：1 KB = 2¹⁰ B = 1024 B；1 MB = 2²⁰ B；1 GB = 2³⁰ B；1 TB = 2⁴⁰ B。
Binary numbers: denary to binary uses repeated division by 2; binary to denary sums place values (e.g., 1011₂ = 8+0+2+1 = 11). Binary addition follows 0+0=0, 0+1=1, 1+0=1, 1+1=10 (carry 1).
二进制数：十进制转二进制用除 2 取余法；二进制转十进制累加位值（如 1011₂ = 8+0+2+1 = 11）。二进制加法规则：0+0=0, 0+1=1, 1+0=1, 1+1=10（进位 1）。
Hexadecimal (base 16) uses digits 0−9 and A−F. It provides a compact way to represent binary (each hex digit = 4 bits). Convert via grouping bits or via denary.
十六进制（基数为 16）使用 0−9 和 A−F。它提供了一种紧凑表示二进制的方法（每个十六进制位 = 4 位）。通过分组或十进制进行转换。
Character sets: ASCII uses 7 bits for 128 characters; Unicode extends this to cover global scripts with up to 32 bits per character (UTF-8 variable length).
字符集：ASCII 使用 7 位表示 128 个字符；Unicode 扩展至覆盖全球文字，每个字符最多 32 位（UTF-8 变长）。
Images: made of pixels; colour depth (bits per pixel) determines number of colours (2ⁿ). Resolution is width × height. File size = width × height × colour depth (bits). Convert to bytes: ÷8.
图像：由像素构成；颜色深度（每像素位数）决定颜色数（2ⁿ）。分辨率为宽×高。文件大小 = 宽 × 高 × 颜色深度（位）。转换为字节：÷8。
Sound: analogue sound is sampled at a sample rate (Hz); bit depth determines amplitude precision. File size = sample rate × bit depth × duration (seconds) × channels.
声音：模拟声音以采样率（Hz）采样；位深度决定振幅精度。文件大小 = 采样率 × 位深度 × 时长（秒）× 声道数。
Compression: lossless reduces file size without losing data (e.g., run-length encoding); lossy permanently removes some data (e.g., JPEG, MP3).
压缩：无损压缩减小文件大小但不丢失数据（如游程编码）；有损压缩永久移除部分数据（如 JPEG、MP3）。
4. Computer Systems | 计算机系统
Hardware is the physical components; software is the programs. System software includes OS and utility programs.
硬件是物理组件；软件是程序。系统软件包括操作系统和实用程序。
CPU executes instructions via the fetch-decode-execute cycle. Components: Control Unit (CU) directs operations, Arithmetic Logic Unit (ALU) performs calculations, registers store temporary data.
CPU 通过取指-解码-执行循环运行指令。组件：控制单元 (CU) 指挥操作，算术逻辑单元 (ALU) 执行计算，寄存器存储临时数据。
Key registers: PC (program counter) holds address of next instruction; MAR (memory address register) holds address to read/write; MDR (memory data register) holds the data; ACC (accumulator) stores results.
关键寄存器：PC（程序计数器）存放下一条指令地址；MAR（存储器地址寄存器）存放读写地址；MDR（存储器数据寄存器）存放数据；ACC（累加器）存储计算结果。
Factors affecting CPU performance: clock speed (GHz), number of cores (parallel execution), and cache size (fast memory reducing RAM access).
影响 CPU 性能的因素：时钟速度 (GHz)、核心数（并行执行）和缓存大小（快速存储器减少 RAM 访问）。
Primary memory: RAM (volatile, fast) holds currently running programs/data; ROM (non-volatile) stores firmware/bootstrap. Virtual memory uses disk space when RAM is full.
主存：RAM（易失，快速）存放当前运行的程序/数据；ROM（非易失）存储固件/引导程序。虚拟内存当 RAM 满时使用磁盘空间。
Secondary storage: magnetic (HDD, high capacity, mechanical), optical (CD/DVD, low capacity, portable), solid state (SSD, fast, no moving parts). Compare by capacity, speed, portability, durability, cost.
辅助存储：磁性（HDD，大容量，机械式）、光学（CD/DVD，低容量，便携）、固态（SSD，快速，无移动部件）。比较维度：容量、速度、便携性、耐用性、成本。
Embedded systems are dedicated computers inside larger devices (e.g., microwave, car). They have limited functions, low power, real-time operation.
嵌入式系统是位于大型设备内的专用计算机（如微波炉、汽车）。功能有限、低功耗、实时操作。
Operating system functions: manages hardware, provides user interface, memory management, process scheduling, file management, security.
操作系统功能：管理硬件、提供用户界面、内存管理、进程调度、文件管理、安全控制。
Logic gates: AND (A∧B, output 1 only if both 1), OR (A∨B, 1 if at least one 1), NOT (¬A, inverts input). Combined to create circuits for addition, control.
逻辑门：与门 (A∧B，仅当两个输入均为 1 时输出 1)、或门 (A∨B，至少一个 1 则输出 1)、非门 (¬A，反转输入)。可组合构成加法器、控制电路。
5. Networks | 网络
LAN (Local Area Network) covers a small area, often using Ethernet/Wi-Fi; WAN (Wide Area Network) spans large distances, e.g., the internet, connecting LANs.
LAN（局域网）覆盖小范围，常使用以太网/Wi-Fi；WAN（广域网）跨越长距离，如互联网，连接多个 LAN。
Client-server model: clients request services from a central server. Peer-to-peer: each node acts as both client and server, sharing resources directly.
客户端-服务器模型：客户端向中央服务器请求服务。对等网络：每个节点既作客户端又作服务器，直接共享资源。
Network hardware: router (connects different networks, directs packets), switch (connects devices within a LAN, smarter than hub), NIC (network interface card), cables (ethernet twisted-pair, fibre optic), wireless (Wi-Fi, Bluetooth).
网络硬件：路由器（连接不同网络，定向数据包）、交换机（在 LAN 内连接设备，比集线器智能）、网卡 (NIC)、线缆（以太网双绞线、光纤）、无线（Wi-Fi、蓝牙）。
Protocols: TCP/IP (transmission control/internet protocol, splits data into packets, reassembles), HTTP/HTTPS (web transfer, secure with encryption), FTP (file transfer), SMTP/IMAP/POP (email send/receive).
协议：TCP/IP（传输控制/互联网协议，将数据分为包并重组）、HTTP/HTTPS（网页传输，HTTPS 加密安全）、FTP（文件传输）、SMTP/IMAP/POP（电子邮件发送/接收）。
Layered model: application layer (HTTP, FTP), transport layer (TCP), network layer (IP), link layer (Ethernet, Wi-Fi). Each layer provides services to the one above.
分层模型：应用层 (HTTP、FTP)、传输层 (TCP)、网络层 (IP)、链路层 (以太网、Wi-Fi)。每一层为上一层提供服务。
Topologies: star (all nodes connect to central switch, easy isolation of faults), mesh (fully connected for redundancy, very reliable).
拓扑结构：星型（所有节点连接到中央交换机，故障易隔离）、网状（全连接，冗余度高，非常可靠）。
Domain Name System (DNS) translates domain names (e.g., example.com) to IP addresses. Cloud hosting provides remote storage and computing services.
域名系统 (DNS) 将域名（如 example.com）转换为 IP 地址。云托管提供远程存储和计算服务。
6. Cyber Security | 网络安全
Malware threats: virus (attaches to programs, spreads), worm (self-replicates across networks), trojan (disguised as legitimate software), ransomware (encrypts files for ransom), spyware (secretly monitors).
恶意软件威胁：病毒（附加到程序上传播）、蠕虫（在网络中自我复制）、木马（伪装成合法软件）、勒索软件（加密文件索要赎金）、间谍软件（暗中监视）。
Social engineering tricks people, e.g., phishing (fake emails/websites to steal credentials), pretexting, baiting.
社会工程学欺骗人们，例如网络钓鱼（伪造电子邮件/网站窃取凭证）、借口欺骗、诱饵攻击。
Other attacks: brute force (trying all possible passwords), denial of service (DoS, flood a server with traffic), data interception (eavesdropping on unencrypted traffic).
其他攻击：暴力破解（尝试所有可能的密码）、拒绝服务 (DoS，用流量淹没服务器)、数据拦截（窃听未加密通信）。
Detection and prevention: anti-malware software, firewalls (filter incoming/outgoing traffic), user access levels, strong password policies, encryption (e.g., AES), penetration testing, physical security (locks, biometrics).
检测与预防：反恶意软件、防火墙（过滤进出流量）、用户访问级别、强密码策略、加密（如 AES）、渗透测试、物理安全（锁具、生物识别）。
Encryption: plaintext is converted to ciphertext using a key; symmetric encryption uses same key, asymmetric uses public/private key pairs. HTTPS uses SSL/TLS encryption.
加密：使用密钥将明文转换为密文；对称加密使用相同密钥，非对称加密使用公钥/私钥对。HTTPS 使用 SSL/TLS 加密。
Backup and recovery policies ensure data can be restored; part of a layered security approach.
备份与恢复策略确保数据可恢复；是分层安全方法的一部分。
7. Software Development | 软件开发
The software development life cycle: analysis (requirements gathering), design (structure, algorithms, UI), implementation (coding), testing (verification), evaluation (review against criteria).
软件开发生命周期：分析（需求收集）、设计（结构、算法、界面）、实现（编码）、测试（验证）、评估（对照标准审查）。
Testing types: unit testing (individual modules), integration testing (combined modules), system testing (whole system), acceptance testing (client approval). Test data uses normal, boundary, and erroneous inputs.
测试类型：单元测试（单个模块）、集成测试（组合模块）、系统测试（整个系统）、验收测试（客户批准）。测试数据使用正常、边界和异常输入。
Translators: assembler (converts assembly to machine code), compiler (translates entire high-level source code to machine code, produces standalone executable), interpreter (translates and executes line by line, slower).
翻译器：汇编器（将汇编语言转换为机器代码）、编译器（将整个高级源代码翻译为机器代码，生成独立可执行文件）、解释器（逐行翻译执行，较慢）。
Integrated Development Environment (IDE) features: code editor with auto-completion, error diagnostics (highlighting syntax errors), run-time environment (executes code within IDE), translator tools, debugger (step-through).
集成开发环境 (IDE) 功能：带自动补全的代码编辑器、错误诊断（高亮语法错误）、运行时环境（在 IDE 内执行代码）、翻译工具、调试器（单步执行）。
Maintainability: code should be readable (comments, indentation, meaningful identifiers) and modular so it can be updated easily.
可维护性：代码应可读（注释、缩进、有意义的标识符）并模块化，以便轻松更新。
8. Ethical, Legal and Environmental Impacts | 伦理、法律与环境影响
Data Protection Act (DPA) / GDPR principles: data must be processed fairly, kept secure, used only for stated purposes, and not kept longer than necessary.
数据保护法 (DPA) / GDPR 原则：数据必须公平处理、安全保存、仅用于声明的目的，且保存时间不长于必要期限。
Computer Misuse Act makes unauthorised access to computers, modification of data, and creation of malware illegal.
计算机滥用法将未经授权访问计算机、修改数据以及制造恶意软件定为非法。
Copyright Designs and Patents Act protects intellectual property; software and digital content cannot be copied without permission.
著作权与专利法保护知识产权；未经许可不得复制软件和数字内容。
Freedom of Information Act grants public access to information held by public authorities.
信息自由法赋予公众访问公共机构持有的信息的权利。
Ethical issues: privacy (collection and use of personal data), surveillance (government or corporate monitoring), digital divide (unequal access to technology), AI bias and decision-making.
伦理问题：隐私（个人数据的收集和使用）、监控（政府或企业监视）、数字鸿沟（技术接入不平等）、人工智能偏见与决策。
Environmental impact: e-waste from discarded devices contains toxic materials; manufacturing and data centres consume huge energy. Green computing promotes energy-efficient hardware and recycling.
环境影响：废弃设备产生的电子垃圾含有有毒物质；制造和数据中心消耗大量能源。绿色计算倡导节能硬件和回收利用。
Open source software can be freely used, modified, and distributed (e.g., Linux). Proprietary software restricts access to source code and requires licensing (e.g., Microsoft Windows).
开源软件可自由使用、修改和分发（如 Linux）。专有软件限制源代码访问并需要授权许可（如 Microsoft Windows）。
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