📚 IGCSE WJEC Computer Science: Exam Specification Unpacked | IGCSE WJEC 计算机：考试大纲解读
Are you preparing for the IGCSE WJEC Computer Science exam? Understanding the specification is the first and most important step to success. This guide breaks down the entire course structure, assessment objectives, key topics, and question styles so you know exactly what to expect and how to prepare efficiently.
您正在备考IGCSE WJEC计算机科学考试吗？理解考试大纲是通往成功的第一步，也是最重要的一步。本文详细拆解了课程结构、评估目标、核心主题以及题型风格，让您清楚了解考试内容和高效备考的方法。
1. Exam Overview | 考试概览
The WJEC IGCSE Computer Science qualification is assessed entirely through two external written examinations. There is no controlled assessment or coursework component. Unit 1: Computer Systems lasts 1 hour 30 minutes and contributes 50% of the final grade. Unit 2: Computational Thinking, Programming and Algorithms lasts 2 hours and makes up the remaining 50%.
WJEC IGCSE计算机科学资格完全通过两场外部笔试进行评估，没有课程作业或内部评估。单元一：计算机系统考试时长为1小时30分钟，占总成绩的50%。单元二：计算思维、编程与算法考试时长为2小时，同样占剩余的50%。
Both papers are set and marked by WJEC, ensuring a uniform standard. Candidates are expected to demonstrate a range of skills, from factual recall in Unit 1 to applied problem-solving and programming in Unit 2. The papers are available in a linear format, typically taken at the end of the course.
两份试卷均由WJEC出题和评分，保证了统一的评估标准。考生需要展现多种能力，单元一侧重知识记忆，单元二则侧重应用型问题解决和编程技能。两场考试通常在课程结束时以线性方式进行。
2. Assessment Objectives | 评估目标
WJEC identifies three main assessment objectives (AOs) that underpin every question in the examinations. AO1 targets knowledge and understanding: you must recall facts, terminology, principles and concepts accurately. Questions may ask for definitions, explanations of hardware components, or descriptions of network models.
WJEC明确了三大评估目标，贯穿所有试题。AO1考查知识与理解：要求准确复述事实、术语、原理和概念。题目可能要求定义术语、解释硬件组件或描述网络模型。
AO2 focuses on application of knowledge. Here you are required to use computing concepts, methods and techniques to solve problems or respond to structured scenarios. For example, you might be asked to convert a binary number to hexadecimal, trace a given algorithm, or apply security measures to a case study.
AO2侧重于知识的应用。要求您运用计算机科学的概念、方法与技术来解决实际问题或回应结构化场景。例如，您可能需要将二进制数转换为十六进制、追踪给定算法，或将安全措施应用于某个案例。
AO3 involves analysis, evaluation and making reasoned judgements. These higher-order skills are typically tested through longer-answer questions where you compare technologies, assess the impact of computing solutions on society, or justify a choice of data structure. The weighting across the two papers is balanced, but Unit 1 places more emphasis on AO1 and AO2, while Unit 2 significantly rewards AO3 skills through algorithm design and evaluation tasks.
AO3涉及分析、评估与理性判断。这些高阶技能通常通过较长的问答题来考查，您需要比较技术方案、评价计算解决方案对社会的影响，或论证所选数据结构的合理性。两份试卷的权重分布平衡，但单元一更侧重AO1和AO2，而单元二通过算法设计与评估任务着重奖励AO3技能。
3. Exam Paper Structure | 试卷结构
Understanding the layout of each paper helps you manage time and expectations on exam day. The table below summarises the key features of both units.
了解每份试卷的布局有助于您在考试当天有效管理时间和预期。下表总结了两份试卷的主要特征。
| Feature | Unit 1: Computer Systems | Unit 2: Computational Thinking |
|---|---|---|
| Duration | 1 hour 30 minutes | 2 hours |
| Total Marks | 100 | 100 |
| Question Types | Short-answer, structured, extended response | Short-answer, structured, extended response, pseudocode tracing and writing |
| Weighting | 50% | 50% |
Unit 1 questions are usually arranged by topic, progressing from simpler recall to more complex applied questions. Expect diagrams of logic circuits, memory hierarchies, or network topologies that require labelling or explanation. Unit 2 begins with smaller programming and algorithm questions, then moves into longer problem-solving tasks where you design, write and evaluate pseudocode. A pseudocode reference sheet is not always provided, so you must be fluent in the expected syntax.
单元一的题目通常按主题排列，从简单记忆逐步过渡到较复杂的应用题。您会遇到逻辑电路图、存储器层次结构或网络拓扑图，需要加注标签或进行解释。单元二以较小的编程和算法问题开头，然后进入较长的解决问题任务，需要设计、编写并评价伪代码。考试不一定会提供伪代码参考页，因此您必须熟练掌握预期的语法。
4. Computer Systems Fundamentals | 计算机系统基础
This topic forms the backbone of Unit 1. You need a solid grasp of the Von Neumann architecture, which defines how a CPU fetches, decodes and executes instructions. Key components include the control unit (CU), arithmetic logic unit (ALU), program counter (PC), memory address register (MAR), memory data register (MDR) and accumulator.
本主题是单元一的骨架。您需要牢固掌握冯诺依曼架构，该架构定义了CPU如何取指、译码和执行指令。关键组件包括控制单元(CU)、算术逻辑单元(ALU)、程序计数器(PC)、内存地址寄存器(MAR)、内存数据寄存器(MDR)和累加器。
The fetch-decode-execute cycle describes the continuous repetition of these steps. Understanding how the address bus, data bus and control bus work together is essential. You should also distinguish between primary memory (RAM and ROM) and secondary storage. RAM is volatile and holds data currently in use, while ROM is non-volatile and stores boot instructions. Secondary storage such as magnetic hard disks, solid-state drives and optical discs provides long-term data retention. Factors like capacity, speed, durability and cost per unit must be compared.
取指-译码-执行周期描述了这些步骤的不断重复。理解地址总线、数据总线和控制总线如何协同工作至关重要。您还应区分主存储器(RAM和ROM)与辅助存储器。RAM是易失性的，存放当前使用的数据；ROM是非易失性的，存放引导指令。辅助存储器，如磁性硬盘、固态硬盘和光盘，提供长期数据保存。需要比较的因素包括容量、速度、耐用性和单位成本。
5. Data Representation | 数据表示
All data in a computer is stored as binary digits (bits). You must be able to convert between denary (base 10), binary (base 2) and hexadecimal (base 16) fluently. For example, 1101 01102 is equivalent to D616 and 214 in denary. The syllabus also covers binary addition, overflow errors and two’s complement representation for negative numbers, though the latter may vary in depth.
计算机中的所有数据都以二进制位存储。您必须能熟练地在十进制、二进制和十六进制之间转换。例如，1101 0110₂ 等于 D6₁₆ 和十进制 214。大纲还包括二进制加法、溢出错误以及用补码表示负数，不过后者的深度可能有所变化。
Character sets such as ASCII and Unicode are used to represent text. ASCII uses 7 or 8 bits per character, while Unicode uses up to 32 bits to support many languages. The exam expects you to calculate text file sizes: number of characters x bits per character. For images, you need to understand pixels, resolution and colour depth. An image with a resolution of 800 x 600 and a colour depth of 24 bits would have a file size of 800 x 600 x 24 = 11,520,000 bits, which is 1.44 MB (dividing by 8 to get bytes, then by 1024 twice).
字符集如ASCII和Unicode用于表示文本。ASCII每个字符用7或8位，而Unicode最多可用32位以支持众多语言。考试要求您计算文本文件大小：字符数 x 每字符位数。对于图像，您需要理解像素、分辨率和颜色深度。一幅分辨率为 800 x 600、颜色深度为 24 位的图像，文件大小为 800 x 600 x 24 = 11,520,000 位，即 1.44 MB（除以 8 得到字节，再除以两次 1024）。
Sound is represented by sampling the analogue waveform at regular intervals. The sampling rate and bit depth determine the quality and file size. A typical calculation would be: sample rate x bit depth x duration (seconds) for mono recordings, doubled for stereo.
声音通过按固定间隔对模拟波形采样来表示。采样率和采样精度决定了音质和文件大小。一个典型的计算是：采样率 x 采样精度 x 时长（秒）为单声道文件大小，立体声需乘以 2。
6. Networks and Communication | 网络与通信
Networks allow computers to share resources and communicate. You need to distinguish between LAN (Local Area Network) and WAN (Wide Area Network). Common topologies include star, bus and mesh, each with its own advantages and disadvantages in terms of cost, reliability and performance. The exam may ask you to draw and label a topology or explain why a school might choose a star network.
网络让计算机能够共享资源并通信。您需要区分LAN（局域网）和WAN（广域网）。常见拓扑结构包括星形、总线和网状，每种在成本、可靠性和性能方面各有优缺点。考试可能要求您画出并标注一种拓扑，或者解释某所学校为什么选择星形网络。
Networking hardware includes routers, switches, hubs and network interface cards (NICs). Protocols are sets of rules governing communication. The TCP/IP stack is fundamental: IP handles addressing and routing, while TCP ensures reliable data delivery. Other key protocols are HTTP/HTTPS for web browsing, FTP for file transfer, SMTP for sending emails and IMAP/POP3 for receiving them. You should also understand the role of MAC addresses (unique hardware identifiers) and how they differ from IP addresses.
网络硬件包括路由器、交换机、集线器和网络接口卡(NIC)。协议是管理通信的规则集。TCP/IP协议栈是基础：IP负责寻址和路由，TCP负责确保数据可靠交付。其他关键协议包括用于网页浏览的HTTP/HTTPS、文件传输的FTP、发送电子邮件的SMTP以及接收邮件的IMAP/POP3。您还需要理解MAC地址（唯一硬件标识）的作用及其与IP地址的区别。
7. Information Security | 信息安全
Threats to computer systems and data are a major focus. You must identify malware types such as viruses, worms, Trojan horses, ransomware and spyware, explaining how each operates and how they can be combated. Phishing, social engineering and denial-of-service (DoS) attacks are also examinable.
对计算机系统和数据的威胁是重点内容。您必须识别恶意软件类型，如病毒、蠕虫、特洛伊木马、勒索软件和间谍软件，解释每种如何运作以及如何应对。网络钓鱼、社会工程和拒绝服务(DoS)攻击也在考查范围内。
Protective measures include firewalls, which monitor incoming and outgoing traffic; encryption, which scrambles data using symmetric or asymmetric keys; and two-factor authentication (2FA), which adds an extra verification step. Penetration testing and network forensics are more advanced concepts that may appear in extended answers. You should also be aware of biometric security and physical security methods.
防护措施包括防火墙，用来监控进出流量；加密，使用对称或非对称密钥对数据进行加扰；以及双因素认证(2FA)，增加额外的验证步骤。渗透测试和网络取证是更高阶的概念，可能出现在扩展回答中。您还应当了解生物识别安全和物理安全方法。
Vulnerabilities often arise from poor password hygiene, unpatched software and misconfigured systems. Case studies may ask you to recommend a tailored security strategy for a given scenario, linking to the principles of confidentiality, integrity and availability (CIA).
漏洞常因密码习惯不良、软件未打补丁和系统配置错误而产生。案例题可能要求您为特定场景推荐针对性的安全策略，并关联到机密性、完整性和可用性(CIA)原则。
8. Programming Fundamentals | 编程基础
Unit 2 relies on your ability to read, write and interpret pseudocode. The syllabus expects familiarity with common data types: integer, real (or float), character, string and Boolean. You must be able to declare variables and constants, understand assignment statements, and construct input/output commands. While no specific IDE is mandated, you will be tested on your understanding of sequence, selection and iteration.
单元二依赖于您阅读、编写和解释伪代码的能力。大纲要求熟悉常见数据类型：整型、实型（浮点型）、字符、字符串和布尔型。您必须能够声明变量和常量，理解赋值语句，并构造输入/输出命令。虽然不指定特定 IDE，但会考查您对顺序、选择和循环的理解。
Selection is handled by IF…THEN…ELSE…ENDIF structures; nested conditions are common. Iteration uses FOR loops (when the number of repetitions is known), WHILE loops (condition checked at the start) and REPEAT…UNTIL loops (condition checked at the end). You need to know how to use arrays (1D and 2D) to store multiple data items and how to access elements by index.
选择结构用 IF…THEN…ELSE…ENDIF 实现，嵌套条件很常见。迭代使用 FOR 循环（次数已知时）、WHILE 循环（条件前置检查）和 REPEAT…UNTIL 循环（条件后置检查）。您需要知道如何使用数组（一维和二维）存储多项数据，以及如何通过索引访问元素。
Subroutines, including functions that return a value and procedures that do not, are essential for modular code. Parameters can be passed by value or by reference. Tracing code with a trace table to track variable values is a key skill that helps with debugging and understanding algorithm logic.
子程序包括有返回值的函数和无返回值的过程，对模块化编码至关重要。参数可以通过值传递或引用传递。使用跟踪表追踪变量值是关键技能，有助于调试和理解算法逻辑。
9. Algorithms and Problem Solving | 算法与问题解决
Algorithms are step-by-step procedures for solving problems. The specification covers standard searching algorithms (linear search and binary search) and sorting algorithms (bubble sort, insertion sort and possibly merge sort). You should be able to describe each algorithm, write it in pseudocode, and evaluate its efficiency, often using Big O notation informally (e.g., binary search is faster than linear search on a sorted list).
算法是解决问题的步骤化程序。大纲涵盖标准搜索算法（线性搜索和二分搜索）和排序算法（冒泡排序、插入排序，还可能包括归并排序）。您应该能描述每种算法，用伪代码编写，并评价其效率，经常非正式地使用大O表示法（例如，在有序列表中二分搜索比线性搜索更快）。
Algorithm design is often expressed through flowcharts and pseudocode. You may be asked to complete or correct a flowchart, or to derive an algorithm from a written problem description. Problem decomposition and abstraction are key computational thinking skills that help manage complexity. The exam may present a real-world scenario—such as a ticketing system or a simple game—and ask you to design a solution.
算法设计通常通过流程图和伪代码来表达。您可能被要求完成或纠正流程图，或根据书面问题描述推导算法。问题分解和抽象是管理复杂度的关键计算思维技能。考试可能给出一个真实场景，比如售票系统或简单游戏，要求您设计解决方案。
Testing is integral: you must understand the difference between syntax errors, logic errors and runtime errors. Using test data—normal, boundary, invalid and extreme cases—is a key approach to verifying algorithm correctness. Trace tables are the primary tool to identify logic errors in pseudocode.
测试不可或缺：您必须理解语法错误、逻辑错误和运行时错误的区别。使用测试数据——正常、边界、无效和极端情况——是验证算法正确性的关键方法。跟踪表是识别伪代码中逻辑错误的主要工具。
10. Software Development and Life Cycle | 软件开发与生命周期
System software, particularly operating systems, performs functions such as memory management, file management, hardware peripheral control and providing a user interface. You may be asked to compare graphical user interfaces (GUIs) with command-line interfaces (CLIs). Utility software, like antivirus programs, disk defragmentation and backup tools, also fall under system software.
系统软件，尤其是操作系统，执行内存管理、文件管理、硬件外设控制和提供用户界面等功能。您可能被要求比较图形用户界面(GUI)和命令行界面(CLI)。工具软件，如杀毒程序、磁盘碎片整理和备份工具，也属于系统软件。
The software development life cycle (SDLC) provides a structured approach to creating software. The main stages are: analysis (defining requirements), design (planning data structures, interfaces and algorithms), implementation (coding and building), testing (checking each module and system), evaluation (assessing against user needs) and maintenance (ongoing updates). You should be prepared to explain the purpose of each stage and the deliverables produced, such as requirement specifications, design documents and test plans.
软件开发周期(SDLC)为软件创建提供结构化方法。主要阶段包括：分析（定义需求）、设计（规划数据结构、接口和算法）、实现（编码与构建）、测试（检查每个模块和系统）、评估（对照用户需求进行评价）和维护（持续更新）。您应能解释每个阶段的目的是什么，以及产生的交付物，如需求规格说明书、设计文档和测试计划。
Different development methodologies, including the waterfall model and agile methods, may be discussed in terms of their suitability for certain projects. The spiral model and rapid application development (RAD) are less common but could appear as extension knowledge.
不同的开发方法，包括瀑布模型和敏捷方法，可能会就其是否适合特定项目进行讨论。螺旋模型和快速应用开发(RAD)不太常见，但可能作为扩展知识出现。
11. Ethical, Legal, and Environmental Impacts | 伦理、法律与环境影响
Computing technologies have far-reaching consequences, and the syllabus requires you to evaluate them. Data protection legislation, such as the UK Data Protection Act and the EU’s GDPR, governs how personal data must be collected, stored and processed. Principles include obtaining consent, ensuring data accuracy and keeping data secure. The Computer Misuse Act makes unauthorised access, modification and malware distribution illegal.
计算技术影响深远，大纲要求对此进行评价。数据保护法规，如英国《数据保护法》和欧盟的《通用数据保护条例》(GDPR)，规定了个人数据收集、存储和处理的方式。原则包括获取同意、确保数据准确性和保护数据安全。《计算机滥用法》规定未经授权的访问、修改和传播恶意软件为非法。
Copyright and intellectual property laws protect software and digital content, raising issues around plagiarism and licensing. Open-source and proprietary software represent two contrasting models. Ethical dilemmas include automated decision-making, algorithmic bias and the impact of AI on employment. You should be able to discuss both sides of such debates.
版权和知识产权法保护软件和数字内容，由此引发关于抄袭和许可的问题。开源和专有软件代表了两种对立的模式。伦理困境包括自动化决策、算法偏见以及人工智能对就业的影响。您应能讨论这类辩论的正反两面。
The environmental footprint of computing is significant. Manufacturing devices consumes rare materials and energy, while discarded electronics (e-waste) create pollution. You should explore ways organisations and individuals can reduce environmental impact, such as virtualisation, longer device usage, and responsible recycling. The digital divide—unequal access to technology—is another social concern that may be assessed through AO3 style questions.
计算产业的环境足迹不可忽视。制造设备消耗稀有材料和能源，而废弃电子产品（电子垃圾）造成污染。您应探讨组织和个人如何减轻环境影响，例如采用虚拟化、延长设备使用期限和负责任回收。数字鸿沟——技术接入不平等——是另一个可能通过AO3型问题评估的社会问题。
12. Top Revision Tips | 备考建议
Start your revision by obtaining the latest WJEC specification from the official website and use it as a checklist. Tick off each topic as you master it. Past papers are the most valuable resource; aim to complete at least three years’ worth under timed conditions. Analyse the mark schemes to understand how examiners award points, particularly for longer written answers and pseudocode correctness.
备考应从WJEC官网下载最新的考试大纲，并将其作为核对清单。每掌握一个主题，就打勾标记。历年真题是最宝贵的资源；争取在限时条件下至少完成近三年的试卷。仔细分析评分方案，理解考官如何给分，尤其是长篇书面回答和伪代码正确性方面的评分标准。
For Unit 1, create concise revision cards for hardware, networking and security topics. Use diagrams to explain the fetch-decode-execute cycle and network topologies. Practice binary, hexadecimal and file size calculations repeatedly until you can perform them accurately and quickly. For Unit 2, write pseudocode daily. Set yourself small problems—like reversing a string or finding the maximum in an array—and solve them on paper. Build a library of standard algorithm implementations in pseudocode and memorise their patterns.
对于单元一，为硬件、网络和安全等主题制作简明复习卡片。用图表解释取指-译码-执行周期和网络拓扑。反复练习二进制、十六进制和文件大小计算，直到能又快又准地完成。对于单元二，每天写伪代码。给自己设定小问题——比如反转字符串或找出数组中最大值——并在纸上解答。建立一个标准算法伪代码实现库并记住其模式。
Regularly self-assess your AO3 skills by discussing the pros and cons of real-world technologies in writing. Choose an issue—like the use of facial recognition in schools—and draft a balanced argument using facts from your notes. Finally, maintain a steady revision timetable over several weeks rather than cramming, ensuring that each session includes a mix of theory and practical algorithm work.
定期自我评估AO3技能：书面讨论真实技术的利弊。选择一个话题——如学校中使用面部识别——利用笔记中的事实撰写一份正反论证。最后，保持数周内稳定的复习时间表而非考前突击，确保每次复习都包含理论知识和实践算法练习。
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