📚 Year 9 Cambridge Computing: Core Knowledge Review | Year 9 Cambridge 计算机：核心知识点梳理
This article provides a comprehensive overview of the essential topics covered in the Year 9 Cambridge Computing curriculum. It is designed to help students consolidate their understanding of computer systems, data representation, programming, networks, cybersecurity and the broader implications of digital technology. By revisiting these core areas, learners can build a strong foundation for further study in IGCSE Computer Science and beyond.
本文全面梳理了 Year 9 Cambridge 计算机课程的核心知识点，旨在帮助学生巩固对计算机系统、数据表示、程序设计、网络、网络安全以及数字技术影响的理解。通过回顾这些关键领域，学习者可以为后续 IGCSE 计算机科学及其他相关学习打下坚实的基础。
1. The Central Processing Unit (CPU) and Memory | 中央处理器与存储器
The CPU is often described as the "brain" of the computer. Its primary job is to process instructions from programs by repeatedly carrying out a sequence known as the fetch-decode-execute cycle. The control unit (CU) manages the flow of data and instructions, while the arithmetic logic unit (ALU) performs calculations and logical comparisons. Registers inside the CPU provide the fastest form of storage, holding the data and instructions currently being worked on.
CPU 通常被描述为计算机的"大脑"。它的主要任务是通过反复执行一个称为"取指-解码-执行"的周期来处理程序指令。控制单元 (CU) 管理数据与指令的流动，而算术逻辑单元 (ALU) 执行计算和逻辑比较。CPU 内部的寄存器提供了速度最快的存储形式，用于保存正在处理的数据和指令。
Memory can be divided into two main types: RAM (Random Access Memory) and ROM (Read Only Memory). RAM is volatile, meaning it loses its contents when the power is turned off; it stores the operating system, applications and data that are currently in use. ROM is non-volatile and typically holds the firmware or boot instructions needed to start the computer. Cache memory is a small, high-speed memory located close to the CPU, used to speed up access to frequently used data and instructions.
存储器主要分为两类：RAM（随机存取存储器）和 ROM（只读存储器）。RAM 是易失性的，这意味着断电后其中的内容会丢失；它存储当前正在使用的操作系统、应用程序和数据。ROM 是非易失性的，通常保存启动计算机所需的固件或引导指令。高速缓冲存储器 (Cache) 是一种位于 CPU 附近的小容量高速存储器，用于加快对频繁使用的数据和指令的访问速度。
2. Input, Output and Storage Devices | 输入、输出与存储设备
Input devices allow users to send data and control signals to a computer. Common examples include keyboards, mice, touchscreens, microphones and scanners. Output devices communicate the results of processing to the user, such as monitors, printers and speakers. Some devices, like touchscreens and headsets with microphones, can perform both input and output functions.
输入设备允许用户向计算机发送数据和控制信号。常见的例子有键盘、鼠标、触摸屏、麦克风和扫描仪。输出设备将处理结果呈现给用户，例如显示器、打印机和扬声器。有些设备，如触摸屏和带麦克风的耳机，可以同时实现输入和输出功能。
st amounts of data at relatively low cost, while solid-state drives (SSDs) rely on flash memory and offer much faster read/write speeds with no moving parts. Optical discs (CD, DVD, Blu-ray) use lasers to read and write data. Storage capacity is measured in bytes, with common multiples such as kilobyte (1 KB = 2¹⁰ bytes), megabyte (1 MB = 2²⁰ bytes) and gigabyte (1 GB = 2³⁰ bytes).
辅助存储设备能永久保存数据和程序，即使断电也不会丢失。硬盘驱动器 (HDD) 使用磁性盘片以较低成本存储大量数据，而固态驱动器 (SSD) 采用闪存技术，没有移动部件，读写速度更快。光盘（CD、DVD、蓝光）使用激光读取和写入数据。存储容量以字节为单位，常用的倍数包括千字节（1 KB = 2¹⁰ 字节）、兆字节（1 MB = 2²⁰ 字节）和吉字节（1 GB = 2³⁰ 字节）。
3. Binary and Data Representation | 二进制与数据表示
re represented using place values that are powers of 2. For example, the binary number 1101₂ can be converted to decimal by calculating (1 × 2³) + (1 × 2²) + (0 × 2¹) + (1 × 2⁰) = 8 + 4 + 0 + 1 = 13.
计算机内部的所有数据都用二进制数字（位）表示，每个位的值只能是 0 或 1。8 个位组成一个字节。数字使用以 2 的幂为权值的位值来表示。例如，二进制数 1101₂ 可以通过计算 (1 × 2³) + (1 × 2²) + (0 × 2¹) + (1 × 2⁰) = 8 + 4 + 0 + 1 = 13 转换为十进制。
Text is encoded using standard systems such as ASCII, which originally assigned a unique 7‑bit binary code to each English letter, digit and symbol. Extended ASCII uses 8 bits to include more characters. Unicode was developed to handle a much broader range of characters from different languages and writing systems, often using 16 bits or more per character. Images are typically represented as a grid of pixels, with each pixel assigned a binary value for its colour. Sound is represented by sampling the analogue wave at regular intervals and converting each sample into a binary number.
文本使用标准系统进行编码，例如 ASCII 最初为每个英文字母、数字和符号分配了唯一的 7 位二进制码。扩展 ASCII 使用 8 位以包含更多字符。Unicode 则被开发用于处理更广泛范围的语言和书写系统，通常每个字符使用 16 位或更多位数。图像通常表示为像素网格，每个像素被分配一个表示其颜色的二进制值。声音的表示方式是对模拟声波进行定期采样，并将每个采样值转换为二进制数。
4. Programming Essentials: Sequence, Selection, Iteration | 编程基础：顺序、选择与迭代
The three fundamental building blocks of any program are sequence, selection and iteration. Sequence means that instructions are executed in the order they are written, one after another. Selection allows the program to make decisions based on conditions, typically using if, else if and else statements. Iteration (looping) enables a block of code to be repeated, either a fixed number of times (count‑controlled, using for loops) or until a condition changes (condition‑controlled, using while loops).
任何程序的三个基本构造块是顺序、选择和迭代。顺序意味着指令按照编写顺序一条接一条地执行。选择允许程序根据条件做出决策，通常使用 if、else if 和 else 语句。迭代（循环）使一段代码能重复执行，可以是固定次数（计数控制，使用 for 循环），也可以是直到某个条件改变为止（条件控制，使用 while 循环）。
Programs work with data stored in variables. Each variable has a data type that determines what kind of data it can hold. Common data types include integer (whole numbers), float or real (decimal numbers), string (text) and Boolean (true or false). Choosing meaningful variable names and using comments makes code easier to read and debug.
程序处理存储在变量中的数据。每个变量都有一个数据类型，决定了它可以保存何种数据。常见的数据类型包括整型（整数）、浮点型或实型（小数）、字符串（文本）和布尔型（真或假）。选择有意义的变量名并添加注释可以使代码更易于阅读和调试。
5. Algorithms, Pseudocode and Flowcharts | 算法、伪代码与流程图
An algorithm is a step‑by‑step procedure for solving a problem or completing a task. A good algorithm is precise, unambiguous, has a clear start and end, and should eventually stop. Algorithms can be represented in different ways, including written descriptions, pseudocode and flowcharts.
算法是解决某个问题或完成某项任务的分步过程。一个好的算法应该精确、无歧义，有明确的开始和结束，并且最终能够终止。算法可以用不同的方式表示，包括文字描述、伪代码和流程图。
Flowcharts use standard symbols to visualise the flow of an algorithm: an oval marks the start or end, a rectangle represents a process or calculation, a diamond indicates a decision (with branches for true/false), and a parallelogram is used for input and output operations. Arrows show the direction of flow. Pseudocode is a way of writing algorithms using plain language mixed with programming keywords; it mimics the structure of real code without worrying about strict syntax rules, making it a useful planning tool.
流程图使用标准符号将算法的流程可视化：椭圆形表示开始或结束，矩形表示处理或计算，菱形表示决策（带有真/假分支），平行四边形用于输入和输出操作。箭头指示流程方向。伪代码是一种使用通俗语言和编程关键词相结合的方式来书写算法的方法；它模仿真实代码的结构，无需遵守严格的语法规则，因此是一种有用的规划工具。
6. Computer Networks: LAN, WAN and the Internet | 计算机网络：局域网、广域网与互联网
A computer network connects two or more devices so that they can share resources and communicate. A Local Area Network (LAN) covers a small geographical area, such as a single building or campus, and is typically owned and managed by a single organisation. A Wide Area Network (WAN) spans large distances, often connecting multiple LANs across cities or countries; the largest WAN is the Internet.
计算机网络将两个或更多设备连接起来，使它们能够共享资源并进行通信。局域网 (LAN) 覆盖较小的地理区域，例如单栋建筑或校园，通常由单个组织拥有和管理。广域网 (WAN) 跨越较长距离，通常连接多个位于不同城市或国家的局域网；最大的广域网就是互联网。
Common network hardware includes switches that connect devices within a LAN and routers that direct data between different networks. Data is transmitted in small units called packets. Network protocols, such as TCP/IP, define the rules for how data is formatted, addressed, transmitted and received. Many networks follow the client‑server model, where a central server provides services (such as web pages or file storage) and clients request those services.
常见的网络硬件包括在局域网内连接设备的交换机，以及在不同网络之间引导数据的路由器。数据以称为数据包的小单元进行传输。网络协议，例如 TCP/IP，定义了数据的格式、寻址、传输和接收规则。许多网络采用客户端-服务器模型，其中中央服务器提供服务（如网页或文件存储），客户端则请求这些服务。
7. Network Security and Safe Online Practices | 网络安全与安全上网实践
Being connected to networks exposes computer systems to various security threats. Malware is malicious software designed to damage, disrupt or gain unauthorised access; it includes viruses, worms, Trojans and spyware. Phishing attacks attempt to trick users into revealing sensitive information, often through emails or fake websites that appear legitimate.
连接到网络会使计算机系统面临各种安全威胁。恶意软件是旨在造成破坏、中断或获取未经授权访问的恶意程序，包括病毒、蠕虫、特洛伊木马和间谍软件。网络钓鱼攻击试图诱骗用户泄露敏感信息，通常通过看似合法的电子邮件或虚假网站实施。
Staying safe online requires a combination of technical measures and sensible behaviour. Firewalls monitor and control incoming and outgoing network traffic. Antivirus software detects and removes malicious programs. Using strong, unique passwords and enabling two‑factor authentication greatly reduces the risk of unauthorised access. It is also important to keep software updated, avoid clicking on unknown links, and never share personal details with untrusted sources.
安全上网需要技术手段与明智行为的结合。防火墙监控并控制进出网络流量。防病毒软件检测并清除恶意程序。使用高强度、独一无二的密码并启用双重认证可大大降低未经授权访问的风险。同样重要的是，保持软件更新，避免点击不明链接，绝不要向不可信来源透漏个人信息。
8. System Software and Application Software | 系统软件与应用软件
Software can be divided into two broad categories: system software and application software. System software includes the operating system (OS) and utility programs that manage and maintain the computer's resources. The operating system performs essential tasks such as managing the processor, memory and storage, providing a user interface, handling input and output, and enabling multitasking. Examples of utility software include disk defragmenters, backup tools and file compression programs.
软件可以划分为两大类：系统软件和应用软件。系统软件包括操作系统 (OS) 以及管理和维护计算机资源的实用程序。操作系统执行关键任务，例如管理处理器、内存和存储，提供用户界面，处理输入输出以及实现多任务处理。实用软件的例子有磁盘碎片整理程序、备份工具和文件压缩程序。
Application software is designed to help users perform specific tasks. Common types include word processors (for creating documents), spreadsheets (for organising and calculating data), presentation software (for slideshows) and web browsers (for accessing the Internet). Software can also be classified as general‑purpose (suited to a wide range of tasks), special‑purpose (built for a single, focused activity) or custom‑written (tailored for a particular organisation's needs).
应用软件旨在帮助用户执行特定任务。常见的类型包括文字处理软件（用于创建文档）、电子表格软件（用于组织与计算数据）、演示软件（用于幻灯片展示）和网页浏览器（用于访问互联网）。软件还可以分为通用软件（适合多种任务）、专用软件（为单一聚焦活动而构建）或定制软件（为特定组织需求专门开发）。
9. Computational Thinking Skills | 计算思维技能
Computational thinking involves a set of problem‑solving skills that are central to computer science. Decomposition means breaking a complex problem into smaller, more manageable sub‑problems. Pattern recognition involves identifying similarities or common characteristics among problems, which allows solutions to be reused. Abstraction is the process of focusing on the important details while filtering out irrelevant information, creating a simplified model of the problem.
计算思维包含一组计算机科学的核心问题解决技能。分解意味着将一个复杂问题拆分成更小、更易于处理的子问题。模式识别指识别问题之间的相似性或共同特征，从而可以重用解决方案。抽象是专注于重要细节而过滤掉无关信息的过程，从而创建问题的简化模型。
Algorithmic thinking is the ability to define a clear, step‑by‑step solution to a problem. Together, these four pillars enable us to tackle challenges in a logical and structured way, whether we are writing code, designing a system or making everyday decisions. Developing computational thinking helps students become more effective problem solvers across many subjects and in real life.
算法思维是定义清晰、分步骤的解决方案的能力。这四个支柱共同作用，使我们能够以逻辑化和结构化的方式应对挑战，无论我们是在编写代码、设计系统还是做出日常决策。培养计算思维有助于学生在许多学科和现实生活中成为更高效的问题解决者。
10. Digital Citizenship and Ethics | 数字公民与伦理
Digital citizenship is about using technology responsibly, respectfully and safely. It covers how we behave online, how we communicate with others, and how we protect our own and other people's digital well‑being. Good digital etiquette includes showing respect in online discussions, not cyberbullying and thinking before sharing content.
数字公民是指负责任、尊重且安全地使用技术。它涵盖我们的在线行为方式、与他人的沟通方式，以及如何保护自己与他人的数字福祉。良好的数字礼仪包括在网络讨论中表现出尊重、不进行网络欺凌以及在分享内容前三思。
Ethical issues in computing involve respecting intellectual property and understanding copyright. Plagiarism, illegal file sharing and using someone else's work without permission are unacceptable. Students should learn to cite sources and recognise the impact of a permanent digital footprint. Protecting privacy by adjusting social media settings and thinking critically about the information we share online are vital skills for life in a connected world.
计算机领域的伦理问题涉及尊重知识产权和理解版权。抄袭、非法文件共享以及未经许可使用他人作品都是不可接受的。学生应学习引用来源，并认识到永久数字足迹的影响。通过调整社交媒体设置来保护隐私，批判性地思考我们在网上分享的信息，这些都是互联世界生活中至关重要的技能。
Published by TutorHao | Computing Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图