📚 GCSE AQA Computer Science: Final Revision Checklist | GCSE AQA 计算机科学：期末复习提纲
This revision checklist summarises the key topics covered in the AQA GCSE Computer Science (8525) specification. Use it to structure your final review, ensuring you can recall definitions, apply concepts to scenarios, and understand how the different areas of the subject fit together. Aim to link theoretical knowledge with practical programming and problem-solving skills.
本复习提纲总结了 AQA GCSE 计算机科学 (8525) 考试大纲的核心主题。用它来规划你的期末复习，确保你能回忆定义、将概念应用于场景，并理解不同知识领域如何相互关联。请将理论知识与实际编程和问题解决能力结合起来。
1. Algorithms and Computational Thinking | 算法与计算思维
An algorithm is a step-by-step procedure for solving a problem. Computational thinking involves decomposition, pattern recognition, abstraction, and algorithm design. Abstraction means removing unnecessary detail to focus on the important parts of a problem. Decomposition breaks a complex problem into smaller, manageable sub-problems.
算法是解决问题的分步过程。计算思维包括分解、模式识别、抽象和算法设计。抽象意味着移除不必要的细节，专注于问题的重要部分。分解则是将复杂问题拆解为更小、更易于管理的子问题。
You should be able to represent algorithms using flowcharts and pseudocode. A flowchart uses standard symbols: ovals for start/stop, parallelograms for input/output, rectangles for processes, and diamonds for decisions. Pseudocode is a readable, language-independent description of an algorithm’s logic. You must be able to trace through an algorithm using a trace table to track variable values step by step, and identify logic errors.
你应该能够使用流程图和伪代码表示算法。流程图使用标准符号：椭圆形表示开始/结束，平行四边形表示输入/输出，矩形表示处理步骤，菱形表示判断。伪代码是一种可读的、独立于编程语言的算法逻辑描述。你必须能够使用追踪表逐步跟踪变量值来模拟算法执行，并识别逻辑错误。
Searching and sorting algorithms are fundamental. Linear search checks each element in turn until the target is found or the list ends; binary search repeatedly divides a sorted list in half, discarding the half that cannot contain the target. Bubble sort repeatedly steps through a list, compares adjacent items and swaps them if they are in the wrong order; merge sort divides a list into smaller sub-lists, sorts them, and then merges them back together. Understand the efficiency trade-offs between these algorithms.
查找和排序算法是基础。线性查找逐个检查每个元素，直到找到目标或列表结束；二分查找反复将已排序列表分成两半，丢弃不包含目标的那一半。冒泡排序反复遍历列表，比较相邻元素并在顺序错误时交换；归并排序将列表分成更小的子列表，排序后再将它们合并回来。要理解这些算法在效率上的权衡。
2. Programming Fundamentals | 编程基础
Programming involves writing instructions in a high-level language such as Python. Key constructs are sequence, selection, and iteration. Sequence means executing instructions one after another. Selection uses IF, ELSE IF, ELSE statements to make decisions based on conditions. Iteration includes definite loops (FOR loops, which repeat a set number of times) and indefinite loops (WHILE loops, which repeat as long as a condition is true).
编程是指用高级语言（如 Python）编写指令。关键结构是顺序、选择和迭代。顺序意味着一条接一条地执行指令。选择使用 IF、ELSE IF、ELSE 语句根据条件做出决策。迭代包括确定循环（FOR 循环，重复固定次数）和不确定循环（WHILE 循环，只要条件为真就重复）。
Variables store data values; they have a data type such as integer, float (real), Boolean (True/False), character, or string. You need to be able to declare variables, assign values, and use arithmetic operators (+, -, *, /, MOD, DIV) and logical operators (AND, OR, NOT). String manipulation includes concatenation (joining strings), slicing, and finding length. Know how to use arrays (lists) to store multiple values under one name, and access elements by index.
变量用于存储数据值；它们具有数据类型，如整数、浮点数（实数）、布尔型（真/假）、字符或字符串。你需要能够声明变量、赋值，并使用算术运算符（+、-、*、/、MOD、DIV）和逻辑运算符（AND、OR、NOT）。字符串操作包括拼接（连接字符串）、切片和获取长度。了解如何使用数组（列表）以一个名字存储多个值，并通过索引访问元素。
Subroutines are blocks of code that perform a specific task. Procedures perform actions but do not return a value; functions perform actions and return a value. Subroutines can take parameters (arguments) to make them more flexible. Using local variables helps avoid unintended side effects. Structured programming makes code easier to read, test, and maintain.
子程序是执行特定任务的代码块。过程执行操作但不返回值；函数执行操作并返回一个值。子程序可以接收参数（实际参数）以增加灵活性。使用局部变量有助于避免意外的副作用。结构化编程使代码更易于阅读、测试和维护。
3. Data Representation | 数据表示
Computers use binary (base-2) to represent all data. A single binary digit is a bit; 8 bits make a byte. Larger units are kilobyte (kB, 10³ bytes), megabyte (MB, 10⁶ bytes), gigabyte (GB, 10⁹ bytes) and so on, though some contexts use binary powers (kibibyte, mebibyte). You must be able to convert between binary, denary (decimal, base-10), and hexadecimal (base-16). Denary to binary uses successive division by 2; binary to hexadecimal groups bits into nibbles (4 bits) and replaces each with the equivalent hex digit. Understand why hexadecimal is used by humans as a more compact, readable representation of binary.
计算机使用二进制（基数为 2）表示所有数据。一个二进制数字是一个位（比特）；8 位组成一个字节。更大单位有千字节（kB, 10³ 字节）、兆字节（MB, 10⁶ 字节）、吉字节（GB, 10⁹ 字节）等，尽管某些上下文使用二进制幂（kibibyte、mebibyte）。你必须能够在二进制、十进制（基数为 10）和十六进制（基数为 16）之间转换。十进制转二进制使用除 2 取余法；二进制转十六进制将位按半个字节（4 位）分组，并用等效的十六进制数字替换。理解为什么人类使用十六进制作为二进制更紧凑、可读的表示形式。
Binary addition is performed column by column, carrying over to the next column when the sum reaches 2. Overflow occurs when the result of an addition exceeds the number of bits available. Binary shifts (left and right) multiply or divide a binary number by powers of 2. You also need to understand how characters are represented using character sets like ASCII (7/8-bit) and Unicode (up to 32-bit), which allows a much wider range of characters.
二进制加法逐列进行，当和达到 2 时向下一列进位。当加法结果超出可用位数时，发生溢出。二进制移位（左移和右移）可将二进制数乘以或除以 2 的幂。你还需要理解字符如何用字符集表示，如 ASCII（7/8 位）和 Unicode（最多 32 位），后者支持更广泛的字符。
Images can be represented as bitmaps, where each pixel’s colour is stored as a binary number. The colour depth (bits per pixel) determines the number of colours. Higher resolution (more pixels) and higher colour depth improve quality but increase file size. Sound is represented by sampling the analogue wave at regular intervals; sample rate (Hz) and bit depth affect quality and size. Calculate file sizes for images, sound, and text using appropriate formulas.
图像可以表示为位图，每个像素的颜色存储为二进制数。颜色深度（每像素位数）决定颜色数量。更高的分辨率（更多像素）和更高的颜色深度可提升质量，但增加文件大小。声音通过对模拟波形进行等间隔采样来表示；采样率（Hz）和位深度会影响质量和文件大小。使用适当的公式计算图像、声音和文本的文件大小。
4. Computer Architecture | 计算机体系结构
The Von Neumann architecture stores both program instructions and data in the same memory. The central processing unit (CPU) executes instructions following the fetch-decode-execute cycle. The CPU contains the control unit (CU), which coordinates the processor, the arithmetic logic unit (ALU), which performs calculations and logical operations, and registers — small, fast storage locations.
冯·诺依曼体系结构将程序指令和数据存储在同一个内存中。中央处理器 (CPU) 遵循取指-译码-执行周期来执行指令。CPU 包含控制单元 (CU)（协调处理器）、算术逻辑单元 (ALU)（执行计算和逻辑操作）以及寄存器——小而快的存储位置。
Key registers include the program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR), and accumulator (ACC). The PC holds the address of the next instruction. The MAR holds the address being read from or written to. The MDR holds the data being transferred. Clock speed (GHz), number of cores, and cache memory are factors that affect CPU performance.
关键寄存器包括程序计数器 (PC)、存储地址寄存器 (MAR)、存储数据寄存器 (MDR)、当前指令寄存器 (CIR) 和累加器 (ACC)。PC 保存下一条指令的地址。MAR 保存被读或写的地址。MDR 保存正在传输的数据。时钟速度 (GHz)、核心数量和缓存内存是影响 CPU 性能的因素。
Embedded systems are computers built into larger devices to perform a dedicated function, such as in washing machines or car engine management. Primary memory (RAM and ROM) is directly accessible by the CPU. RAM is volatile and holds data and programs currently in use; ROM is non-volatile and stores the bootstrap program (BIOS). Virtual memory uses a portion of secondary storage as if it were RAM when memory is full.
嵌入式系统是内置在更大设备中执行专用功能的计算机，例如洗衣机或汽车引擎管理。主存储器（RAM 和 ROM）可由 CPU 直接访问。RAM 是易失性的，保存当前使用的数据和程序；ROM 是非易失性的，存储引导程序 (BIOS)。虚拟内存在内存满时将部分辅助存储当作 RAM 使用。
5. System Software | 系统软件
System software manages and controls the computer hardware so that application software can perform tasks. The operating system (OS) provides a user interface, manages memory, manages peripherals (device drivers), manages processor scheduling (multitasking), and manages file storage and security (user access rights). Utility software performs maintenance tasks, such as encryption, defragmentation, compression, and backup.
系统软件管理和控制计算机硬件，以便应用软件能够执行任务。操作系统 (OS) 提供用户界面、管理内存、管理外设（设备驱动程序）、管理处理器调度（多任务处理）以及管理文件存储和安全（用户访问权限）。实用工具软件执行维护任务，如加密、碎片整理、压缩和备份。
Know the difference between open source and proprietary software, and the implications of each for copyright, cost, and support. Low-level languages (assembly language) use mnemonics that are translated into machine code by an assembler; they are specific to one processor family. High-level languages are translated by compilers (translates entire source code before execution) or interpreters (translates line by line during execution). Understanding this translation process helps explain how programs execute on hardware.
了解开源软件与专有软件的区别，以及各自对版权、成本和售后支持的影响。低级语言（汇编语言）使用助记符，由汇编器翻译成机器码；它们特定于一种处理器系列。高级语言由编译器（执行前翻译整个源代码）或解释器（执行期间逐行翻译）翻译。理解这个翻译过程有助于解释程序如何在硬件上执行。
6. Networks and Protocols | 网络与协议
A network is two or more computers connected together to share resources. LANs (Local Area Networks) cover a small geographical area, usually using Ethernet or Wi-Fi. WANs (Wide Area Networks) cover a large geographical area, such as the Internet. Factors affecting network performance include bandwidth, number of users, transmission media (wired vs wireless), and error rate.
网络是连接在一起以共享资源的两台或多台计算机。局域网 (LAN) 覆盖小地理区域，通常使用以太网或 Wi-Fi。广域网 (WAN) 覆盖广泛的地理区域，例如互联网。影响网络性能的因素包括带宽、用户数量、传输介质（有线与无线）和错误率。
Network topologies describe how devices are connected. In a star topology, each node connects to a central switch or hub; if one cable fails, only that node is affected, but the central device is a single point of failure. In a mesh topology, nodes are interconnected; it is robust but expensive. You should also understand client-server and peer-to-peer network models, and where each is suitable.
网络拓扑描述设备如何连接。在星型拓扑中，每个节点连接到中央交换机或集线器；如果一根电缆故障，仅影响该节点，但中央设备是单点故障。在网状拓扑中，节点互相连接；它很健壮但成本高。你还应理解客户端-服务器和对等网络模型，以及各自适合的场景。
Protocols are agreed rules for communication. Key protocols include TCP/IP (Transmission Control Protocol/Internet Protocol, used for routing and reliable delivery of data packets over the Internet), HTTP/HTTPS (Hypertext Transfer Protocol Secure, for web pages), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol, for sending email), POP/IMAP (for retrieving email), and Ethernet/Wi-Fi for the link layer. The concept of layering (e.g., TCP/IP 4-layer model) helps in designing and troubleshooting networks.
协议是通信的约定规则。关键协议包括 TCP/IP（传输控制协议/互联网协议，用于在互联网上路由和可靠传输数据包）、HTTP/HTTPS（安全超文本传输协议，用于网页）、FTP（文件传输协议）、SMTP（简单邮件传输协议，用于发送邮件）、POP/IMAP（用于接收邮件），以及用于链路层的以太网/Wi-Fi。分层概念（如 TCP/IP 4 层模型）有助于网络设计和故障排除。
7. Cyber Security | 网络安全
Cyber security aims to protect systems, networks, and data from attack. Common threats include malware (viruses, worms, trojans), social engineering (phishing, blagging, shouldering), brute-force attacks, denial-of-service (DoS) attacks, and SQL injection. You must be able to describe how each threat works and the potential damage it can cause.
网络安全旨在保护系统、网络和数据免受攻击。常见威胁包括恶意软件（病毒、蠕虫、特洛伊木马）、社会工程学（网络钓鱼、冒充、窥视）、暴力破解攻击、拒绝服务 (DoS) 攻击和 SQL 注入。你必须能够描述每种威胁如何运作以及可能造成的损害。
Preventive measures include penetration testing (ethical hacking) to identify weaknesses, anti-malware software, firewalls (which filter incoming and outgoing traffic based on rules), user access levels, encryption, and physical security. Strong password policies and two-factor authentication (2FA) add extra layers of security. Be able to recommend appropriate protection strategies for given scenarios.
预防措施包括渗透测试（道德入侵）以识别弱点、反恶意软件、防火墙（基于规则过滤进出流量）、用户访问级别、加密和物理安全。强密码策略和双因素身份验证 (2FA) 增加了额外的安全层。要能够针对给定情境推荐合适的保护策略。
Encryption transforms plaintext into ciphertext using an algorithm and a key. Symmetric encryption uses the same key to encrypt and decrypt; asymmetric encryption uses a public key to encrypt and a private key to decrypt. This underpins secure web transactions (SSL/TLS). Understanding these threats and defences is crucial for analysing real-world security issues.
加密使用算法和密钥将明文转换为密文。对称加密使用相同的密钥加密和解密；非对称加密使用公钥加密和私钥解密。这构成了安全网络交易 (SSL/TLS) 的基础。理解这些威胁和防御对于分析现实世界安全问题至关重要。
8. Relational Databases and SQL | 关系数据库与 SQL
A database is a structured collection of data. A relational database stores data in tables, where each table consists of records (rows) and fields (columns). Each field has a data type (text, number, date, Boolean). A primary key uniquely identifies each record in a table. A foreign key is a field in one table that refers to the primary key in another table, creating relationships between tables.
数据库是结构化的数据集合。关系数据库将数据存储在表中，每个表由记录（行）和字段（列）组成。每个字段有数据类型（文本、数字、日期、布尔）。主键唯一标识表中的每条记录。外键是一个表中的字段，引用另一个表中的主键，从而创建表之间的关系。
Structured Query Language (SQL) is used to query and manipulate relational databases. You must be able to write SQL statements: SELECT to retrieve specified fields, FROM to specify the table, WHERE to filter records, ORDER BY to sort, and INSERT INTO, UPDATE, DELETE to modify data. For example, SELECT name, price FROM products WHERE category = ‘Electronics’ ORDER BY price DESC; retrieves products sorted by price descending.
结构化查询语言 (SQL) 用于查询和操作关系数据库。你必须能编写 SQL 语句：SELECT 检索指定字段，FROM 指定表，WHERE 过滤记录，ORDER BY 排序，以及 INSERT INTO、UPDATE、DELETE 修改数据。例如，SELECT name, price FROM products WHERE category = ‘Electronics’ ORDER BY price DESC; 检索产品并按价格降序排列。
Normalisation is the process of organising data to reduce redundancy. Know the first normal form (1NF): each field contains atomic values, and there is no repeating groups. Second normal form (2NF) requires 1NF and all non-key attributes are fully dependent on the whole primary key (no partial dependencies). Understand why reducing data duplication improves data integrity and efficiency.
规范化是组织数据以减少冗余的过程。了解第一范式 (1NF)：每个字段包含原子值，没有重复组。第二范式 (2NF) 要求满足 1NF 且所有非键属性完全依赖于整个主键（无部分依赖）。理解为什么减少数据重复可以提高数据完整性和效率。
9. Ethical, Legal and Environmental Issues | 伦理、法律与环境问题
Technology brings ethical questions about fairness, privacy, and the digital divide. Automated decision-making and artificial intelligence can lead to bias if based on flawed data. The use of personal data by social media and companies raises privacy concerns. The digital divide refers to the gap between those who have access to technology and those who do not, influenced by factors such as location, income, and disability.
技术带来了关于公平、隐私和数字鸿沟的伦理问题。自动化决策和人工智能如果基于有缺陷的数据，可能导致偏见。社交媒体和公司对个人数据的使用引发隐私担忧。数字鸿沟指能够使用技术的人与不能使用技术的人之间的差距，受地理位置、收入和残障等因素影响。
Legislation protects individuals and data. The key UK laws you need to know: The Data Protection Act 2018 (incorporating GDPR) sets principles for processing personal data (lawful, fair, transparent, purpose limitation, accuracy, storage limitation, security). The Computer Misuse Act 1990 makes unauthorised access to computer material (hacking) and creating/distributing malware illegal. The Copyright, Designs and Patents Act 1988 protects intellectual property including software. The Freedom of Information Act 2000 gives public access to information held by public authorities.
立法保护个人和数据。你需要了解的关键英国法律：2018 年数据保护法（包含 GDPR）规定了处理个人数据的原则（合法、公平、透明、目的限制、准确性、存储限制、安全）。1990 年计算机滥用法将未经授权访问计算机材料（黑客）和创建/传播恶意软件定为非法。1988 年版权、设计和专利法保护包括软件在内的知识产权。2000 年信息自由法赋予公众获取公共机构所持信息的权利。
Environmental impacts include the energy consumption of data centres and the problem of electronic waste (e-waste). Manufacturing, use, and disposal of devices contribute to carbon emissions and toxic waste. The circular economy and e-waste recycling schemes aim to mitigate these effects. Sustainable design considers durability, repairability, and energy efficiency.
环境影响包括数据中心的能源消耗和电子废物问题。设备的制造、使用和处置导致碳排放和有毒废物。循环经济和电子废物回收计划旨在减轻这些影响。可持续设计考虑耐用性、可维修性和能源效率。
10. Boolean Logic and Truth Tables | 布尔逻辑与真值表
Boolean logic deals with TRUE and FALSE values. The basic logic gates are NOT (inverts input), AND (outputs true only if all inputs are true), and OR (outputs true if at least one input is true). Logic circuits can be built by combining gates. Each gate has a symbol and a truth table that shows all possible input combinations and the corresponding output.
布尔逻辑处理 TRUE 和 FALSE 值。基本逻辑门包括 NOT（反转输入）、AND（仅当所有输入为真时输出真）和 OR（至少一个输入为真时输出真）。逻辑电路可通过组合门来构建。每个门有符号和真值表，显示所有可能的输入组合及相应的输出。
You must be able to complete truth tables for given circuits, and to draw circuits from Boolean expressions. Boolean algebra uses notation: A . B for AND (A AND B), A + B for OR (A OR B), and an overbar or ~A for NOT A. Worked example: the expression Q = (A . B) + ~C means Q is true if both A and B are true, or if C is false. You can simplify expressions using Boolean laws like De Morgan’s Law: ~(A . B) = ~A + ~B and ~(A + B) = ~A . ~B.
你必须能够完成给定电路的真值表，并从布尔表达式绘制电路。布尔代数使用记法：A . B 表示 A AND B，A + B 表示 A OR B，上划线或 ~A 表示 NOT A。实例：表达式 Q = (A . B) + ~C 意味着如果 A 和 B 均为真，或 C 为假，则 Q 为真。你可以使用布尔定律简化表达式，如德摩根定律：~(A . B) = ~A + ~B 和 ~(A + B) = ~A . ~B。
A simple truth table for a half adder is often examined. A half adder adds two single binary digits, producing a SUM and a CARRY. SUM is A XOR B (or (A . ~B) + (~A . B)); CARRY is A . B. Applying logic to real-world problems includes creating simple control systems, e.g., a heating system turns on when temperature is low and the timer is active.
半加器的简单真值表经常被考查。半加器将两个单独的二进制数字相加，产生和 (SUM) 与进位 (CARRY)。SUM 是 A XOR B（或 (A . ~B) + (~A . B)）；CARRY 是 A . B。将逻辑应用于现实问题包括创建简单的控制系统，例如，当温度低且定时器活动时加热系统开启。
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