📚 Year 7 Edexcel Computer Science: Core Knowledge Review | Edexcel 七年级计算机：核心知识点梳理
This article consolidates the essential knowledge for Year 7 Edexcel Computer Science, covering fundamental concepts from hardware and software to programming and networking. Each section breaks down key ideas into clear, digestible points, helping you build a strong foundation for the rest of the course.
本文梳理了 Edexcel 七年级计算机科学的核心知识点，涵盖硬件与软件、编程基础和网络等基本概念。每个部分将关键内容分解为清晰易懂的要点，帮助你为后续课程打下坚实基础。
1. Hardware and Software | 硬件与软件
Hardware refers to the physical components of a computer system that you can touch. Examples include the processor, memory modules, keyboard, mouse, monitor, and internal storage drives. Hardware is responsible for executing instructions and displaying output.
硬件指计算机系统中可触摸的物理部件，如处理器、内存条、键盘、鼠标、显示器和内置存储驱动器。硬件负责执行指令和显示输出。
Software is the collection of programs and instructions that tell the hardware what to do. It is intangible and includes operating systems like Microsoft Windows and macOS, as well as applications such as word processors and games.
软件是告诉硬件如何工作的程序和指令集合。它是无形的，包括操作系统（如 Windows 和 macOS）以及应用软件（如文字处理器和游戏）。
| Category | Examples |
|---|---|
| System Software | Operating systems, device drivers, utility programs |
| Application Software | Word processors, spreadsheets, web browsers, games |
系统软件 包括操作系统、设备驱动和实用程序；应用软件 包括文字处理器、电子表格、网页浏览器和游戏。两者协同工作，硬件提供物理基础，软件实现具体功能。
2. Input and Output Devices | 输入与输出设备
Input devices allow users to send data or commands to the computer. Common input devices include the keyboard, mouse, touchscreen, microphone, scanner, and webcam. These convert human-readable information into machine-readable signals.
输入设备用于向计算机发送数据或命令。常见输入设备有键盘、鼠标、触摸屏、麦克风、扫描仪和摄像头，它们将人类可读信息转换为机器可读信号。
Output devices present data from the computer to the user. Typical output devices are the monitor (or screen), printer, speakers, and headphones. They convert digital information back into a form humans can perceive.
输出设备将计算机的数据呈现给用户。典型输出设备包括显示器、打印机、扬声器和耳机，它们将数字信息转换回人类能感知的形式。
Some devices can act as both input and output, for example, a touchscreen displays visuals (output) and detects touch (input), or a headset with a microphone (input) and earphones (output).
有些设备兼具输入和输出功能，例如触摸屏既能显示图像（输出）又能检测触摸（输入），带麦克风的耳机同样如此。
3. Storage Devices | 存储设备
Storage devices hold data and programs permanently or temporarily. Primary storage, such as RAM (Random Access Memory), is volatile and loses its contents when the power is turned off. It is used to store currently running programs and data.
存储设备用于永久或临时保存数据和程序。主存储器如 RAM（随机存取存储器）是易失性的，断电后内容丢失，用于存放正在运行的程序和数据。
Secondary storage retains data even without power. Hard Disk Drives (HDDs) use magnetic platters, while Solid-State Drives (SSDs) use flash memory and are faster and more durable. USB flash drives and optical discs (CDs, DVDs) are also common secondary storage options.
辅助存储器在断电后仍能保留数据。硬盘驱动器使用磁性盘片，固态驱动器使用闪存，速度更快、更耐用。U 盘和光盘（CD、DVD）也是常见的辅助存储设备。
Cloud storage lets users save files on remote servers accessed via the internet, providing convenience and backup but requiring an internet connection.
云存储允许用户将文件保存在远程服务器上并通过互联网访问，提供了便利性和备份功能，但需联网。
4. Binary and Data Representation | 二进制与数据表示
Computers use binary, a base-2 number system with only two digits: 0 and 1. These binary digits, or bits, represent all types of data—numbers, text, images, and sound—by combining many bits together.
计算机使用二进制，即只有 0 和 1 两个数字的基数为 2 的计数系统。这些二进制位（比特）通过组合表示数字、文本、图像和声音等所有类型的数据。
Each bit position represents a power of 2. For example, the binary number 1011 can be converted to decimal as follows:
1 × 2³ + 0 × 2² + 1 × 2¹ + 1 × 2⁰ = 8 + 0 + 2 + 1 = 11
每个比特位代表 2 的幂。例如二进制数 1011 转换为十进制：1×2³ + 0×2² + 1×2¹ + 1×2⁰ = 11。
Text is represented using character codes like ASCII or Unicode, where each character has a unique binary value. Images are represented as a grid of pixels, each pixel stored as binary color values. Sound is sampled at regular intervals and each sample is stored as binary numbers.
文本使用 ASCII 或 Unicode 等字符编码表示，每个字符对应唯一的二进制值。图像表示为像素网格，每个像素以二进制颜色值存储。声音则按固定间隔采样，每个样本存储为二进制数。
5. Algorithms and Flowcharts | 算法与流程图
An algorithm is a step-by-step set of instructions to solve a problem or perform a task. Algorithms can be expressed in plain language, pseudocode, or as flowcharts. They must be precise, unambiguous, and finite.
算法是解决问题或执行任务的分步指令集，可以用自然语言、伪代码或流程图表示。算法必须精确、无歧义且有限。
Flowcharts use standard symbols to visually represent algorithms:
流程图使用标准符号直观表示算法：
- Oval (Terminator) — indicates Start or End | 椭圆形（终止符） — 表示开始或结束
- Rectangle (Process) — represents a calculation or action | 矩形（处理框） — 表示计算或操作
- Diamond (Decision) — shows a yes/no or true/false condition | 菱形（判断框） — 表示是/否或真/假条件
- Parallelogram (Input/Output) — used for entering data or displaying results | 平行四边形（输入/输出） — 用于输入数据或显示结果
- Arrows — indicate the flow of control | 箭头 — 表示控制流向
Flowcharts help programmers plan and debug logic before writing actual code.
流程图帮助程序员在编写代码前规划和调试逻辑。
6. Programming Basics: Sequence, Selection, Iteration | 编程基础：顺序、选择、迭代
Sequence means executing instructions one after another in the order they are written. This is the simplest control structure and is the default flow in most programs.
顺序 指按照书写顺序逐条执行指令。这是最简单的控制结构，也是大多数程序的默认执行方式。
Selection allows the program to make decisions and choose different paths based on conditions. It uses if, else, and elif statements. For example: “if score >= 50, print ‘Pass’; else, print ‘Fail’”.
选择 让程序根据条件做出决策并选择不同路径，使用 if、else 和 elif 语句。例如：“如果分数 ≥ 50，输出‘通过’；否则输出‘未通过’”。
Iteration repeats a block of code multiple times. There are two main types: count-controlled loops (e.g., for loop) that repeat a set number of times, and condition-controlled loops (e.g., while loop) that continue as long as a condition is true.
迭代 让一段代码重复执行。主要有两种类型：计数控制循环（如 for 循环）按设定次数重复；条件控制循环（如 while 循环）在条件为真时持续执行。
7. Scratch Programming | Scratch 编程
Scratch is a block-based visual programming language designed for beginners. It allows students to create animations, games, and interactive stories by dragging and snapping together code blocks, eliminating the need to type syntax.
Scratch 是一种面向初学者的积木式可视化编程语言，通过拖拽和拼接代码块即可创作动画、游戏和交互故事，无需输入语法。
Key features of Scratch include:
Scratch 的主要特性包括：
- Sprites — the characters or objects that perform actions | 角色（Sprites） — 执行动作的人物或对象
- Backdrops — the stage background | 背景（Backdrops） — 舞台背景
- Scripts — the code blocks attached to sprites or the stage | 脚本（Scripts） — 附加到角色或舞台的代码块
- Events — triggers like “when green flag clicked” | 事件（Events） — 如“当绿旗被点击”的触发条件
- Loops, conditions, and variables — programming concepts built into the blocks | 循环、条件和变量 — 内置于积木中的编程概念
Scratch reinforces computational thinking while making programming accessible and engaging.
Scratch 强化了计算思维，同时使编程易于上手且充满乐趣。
8. Networking Basics | 网络基础
A network is a collection of two or more computers connected together to share resources such as files, printers, and internet connections. Networks can be classified by their geographical range.
网络是两台或更多计算机连接在一起的集合，用于共享文件、打印机和互联网连接等资源。网络可根据地理范围分类。
| Type | Coverage |
|---|---|
| PAN (Personal Area Network) | Small area around a person (e.g., Bluetooth connection between phone and earphones) |
| LAN (Local Area Network) | A single site, such as a school or office building |
| WAN (Wide Area Network) | Large geographical area, such as the internet connecting networks worldwide |
个域网 (PAN) 覆盖个人周围小范围（如手机与耳机蓝牙连接）；局域网 (LAN) 连接单一场所，如学校或办公楼；广域网 (WAN) 覆盖大范围区域，如连接全球网络的互联网。
Common network hardware includes routers, which direct data packets between networks, switches that connect devices within a LAN, and network interface cards (NICs) that allow a device to connect to a network.
常见网络硬件包括：路由器（在网络间导引数据包）、交换机（连接局域网内设备）和网卡（使设备能接入网络）。
9. The Internet and World Wide Web | 互联网与万维网
The Internet is a global network of interconnected computers and devices that communicate using standard protocols (TCP/IP). It is the physical infrastructure that carries data worldwide.
互联网是由相互连接的计算机和设备组成的全球网络，使用标准协议（TCP/IP）进行通信。它是承载全球数据的物理基础设施。
The World Wide Web (WWW) is a service that runs on top of the internet, consisting of web pages accessed through browsers using HTTP/HTTPS. The web is a collection of linked documents and multimedia files, not the internet itself.
万维网是运行在互联网之上的一项服务，由通过浏览器使用 HTTP/HTTPS 访问的网页组成。网络是相互链接的文档和多媒体文件的集合，而非互联网本身。
Web addresses, or URLs (Uniform Resource Locators), typically include the protocol (https://), domain name (example.com), and path to a specific page. A web browser interprets HTML code to display the page.
网址即 URL（统一资源定位符），通常包含协议（https://）、域名（example.com）和特定页面路径。网络浏览器解析 HTML 代码以显示页面。
10. Cybersecurity and Ethics | 网络安全与伦理
Cybersecurity involves protecting systems, networks, and data from digital attacks. Common threats include malware (viruses, worms, ransomware), phishing emails that trick users into revealing passwords, and hacking.
网络安全涉及保护系统、网络和数据免受数字攻击。常见威胁包括恶意软件（病毒、蠕虫、勒索软件）、诱骗用户泄露密码的网络钓鱼邮件以及黑客入侵。
Strong passwords — long, using a mix of uppercase letters, lowercase letters, numbers, and symbols — help prevent unauthorized access. Never share passwords and always lock devices when not in use.
强密码（长度足够且包含大小写字母、数字和符号混合）有助于防止未经授权的访问。切勿分享密码，并在不用时锁定设备。
Ethical considerations in computing include respecting privacy, not spreading misinformation, acknowledging the intellectual property of others (copyright), and using technology responsibly. Digital footprints are the traces we leave online, which can be permanent.
计算机伦理包括尊重隐私、不传播错误信息、承认他人知识产权（版权）以及负责任地使用技术。数字足迹是我们留在网络上的痕迹，可能是永久性的。
11. Computational Thinking | 计算思维
Computational thinking is a problem-solving approach that uses concepts essential to computing. It involves four core techniques: decomposition, pattern recognition, abstraction, and algorithm design.
计算思维是运用计算机科学基本概念解决问题的方法，包括四项核心技术：分解、模式识别、抽象和算法设计。
- Decomposition — breaking a complex problem into smaller, manageable parts | 分解 — 将复杂问题分解为更小、更易处理的部分
- Pattern recognition — identifying similarities and trends among problems to reuse solutions | 模式识别 — 找出问题间的相似性和趋势，以重用解决方案
- Abstraction — focusing on important details while ignoring irrelevant information | 抽象 — 关注重要细节，忽略无关信息
- Algorithm design — creating step-by-step instructions to solve the problem | 算法设计 — 制定分步指令来解决问题
These skills are not only useful in programming but also in everyday decision-making and other subjects.
这些技能不仅在编程中有用，在日常决策和其他学科中同样适用。
12. History and Impact of Computers | 计算机的历史与影响
Computing devices have evolved from early mechanical calculators to modern electronic computers. Key milestones include Charles Babbage’s Analytical Engine (a conceptual mechanical computer), Alan Turing’s theoretical work on computation, and the development of the first electronic general-purpose computer, ENIAC.
计算设备从早期机械计算器演进为现代电子计算机。关键里程碑包括查尔斯·巴贝奇的分析机（概念机械计算机）、艾伦·图灵在计算理论上的贡献，以及第一台通用电子计算机 ENIAC 的诞生。
The invention of the transistor and integrated circuits made computers smaller, faster, and more affordable, leading to personal computers in the 1970s and 80s. The rise of the internet in the 1990s transformed how people communicate and access information.
晶体管和集成电路的发明使计算机更小、更快、更便宜，推动 1970 年代和 80 年代个人计算机的出现。1990 年代互联网的兴起彻底改变了人们交流与获取信息的方式。
Today, computers are embedded in everyday devices (smartphones, home appliances, cars) and drive advances in artificial intelligence, robotics, and scientific research. Understanding the history helps us appreciate the rapid pace of technological change.
如今，计算机嵌入日常设备（智能手机、家电、汽车），并推动人工智能、机器人和科学研究的进步。了解历史有助于我们体会技术变革的迅猛步伐。
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