📚 Year 11 SQA Computing: Core Knowledge Review | 苏格兰SQA计算机：核心知识点梳理
Year 11 SQA Computing Science gives students a solid foundation in how computer systems work, how software is designed and built, and how data is managed and presented on the web. This article reviews the core knowledge areas you need to master for success in the National 5 course, blending essential theory with practical insight.
Year 11 SQA 计算机科学课程为学生们打下坚实基础，涵盖计算机系统工作原理、软件设计与构建方法，以及数据如何被管理和呈现在网络中。本文梳理了 National 5 课程中必须掌握的核心知识领域，将基础理论与实用见解相结合。
1. Understanding Binary & Data Representation | 理解二进制与数据表示
All data inside a computer is stored as binary digits (bits) – sequences of 0s and 1s. A single bit can represent two states, such as off and on. By grouping bits together, computers can represent numbers, text, images and sound.
计算机内部的所有数据都以二进制数字（比特）存储，即 0 和 1 的序列。一个比特可以表示两种状态，比如关和开。通过将比特组合在一起，计算机能够表示数字、文本、图像和声音。
The smallest addressable unit of memory is the byte, which contains 8 bits. For example, the denary number 65 is stored as 01000001 in binary. Larger units include kilobyte (1024 bytes), megabyte, gigabyte and terabyte.
内存中最小的可寻址单位是字节，1 字节包含 8 个比特。例如，十进制数 65 存储为二进制 01000001。更大的单位有千字节（1024 字节）、兆字节、吉字节和太字节。
Text is encoded using standards like ASCII (7 bits per character, extended to 8 bits) and Unicode (up to 32 bits per character) to support global languages. Images are represented as a grid of pixels, where each pixel’s colour is stored as a binary number; higher bit depths give more colour possibilities.
文本使用 ASCII（每字符 7 比特，可扩展至 8 比特）和 Unicode（每字符最多 32 比特）等标准进行编码，以支持全球语言。图像表示为像素网格，每个像素的颜色以二进制数存储；更高的位深带来更多颜色可能。
epth bits per pixel: 1 bit → 2 colours; 8 bit → 256 colours; 24 bit → 16.7 million colours
颜色位深每像素：1 比特 → 2 种颜色；8 比特 → 256 种颜色；24 比特 → 1670 万种颜色
2. The CPU and Memory | 中央处理器与内存
The Central Processing Unit (CPU) is the brain of the computer. It follows the fetch-decode-execute cycle: the control unit fetches an instruction from RAM, decodes it, and the arithmetic logic unit (ALU) executes it. The speed is measured in gigahertz (GHz) – billions of cycles per second.
中央处理器（CPU）是计算机的大脑。它遵循取指-解码-执行周期：控制单元从 RAM 中取出指令，解码后由算术逻辑单元（ALU）执行。速度以吉赫兹（GHz）为单位，即每秒数十亿次周期。
The CPU contains registers – very fast memory locations inside the processor – such as the Program Counter, Memory Address Register, Memory Data Register, and Accumulator. Cache memory is high-speed memory inside the CPU that stores frequently used data for quicker access.
CPU 内部包含寄存器——处理器内部极快的内存位置，如程序计数器、内存地址寄存器、内存数据寄存器和累加器。高速缓存是 CPU 内部的高速内存，存储常用数据以便更快访问。
Main memory is divided into RAM (Random Access Memory) and ROM (Read Only Memory). RAM is volatile – its contents are lost when power is turned off – and holds the programs and data currently in use. ROM is non-volatile and stores the bootstrap loader that starts the system.
主存分为 RAM（随机存取存储器）和 ROM（只读存储器）。RAM 是易失性的——断电后内容丢失——用于保存当前正在使用的程序和数据。ROM 是非易失性的，存储启动系统的引导加载程序。
| Memory Type | Volatile? | Purpose |
|---|---|---|
| RAM | Yes | Running programs & data |
| ROM | No | Start-up instructions |
3. Storage Devices and Input/Output | 存储设备与输入输出
Computers need secondary storage to keep data permanently. Magnetic storage (e.g., hard disk drives) uses magnetic platters and read/write heads. Optical storage (e.g., CDs, DVDs) uses lasers to read pits and lands on a reflective surface. Solid-state storage (e.g., SSDs, USB flash drives) uses flash memory chips with no moving parts, making it faster and more durable.
计算机需要辅助存储器来永久保存数据。磁存储（如硬盘驱动器）使用磁盘盘片和读写头。光存储（如 CD、DVD）使用激光读取反射面上的凹坑和平面。固态存储（如 SSD、USB 闪存盘）使用闪存芯片，无活动部件，速度更快且更耐用。
Input devices allow users to send data into the computer – keyboard, mouse, touchscreen, microphone, scanner. Output devices display or produce the results – monitor, printer, speakers. Touchscreen technology combines both input and output by sensing touch on a display.
输入设备允许用户将数据送入计算机——键盘、鼠标、触摸屏、麦克风、扫描仪。输出设备显示或生成结果——显示器、打印机、音箱。触摸屏技术通过在显示器上感应触控，将输入与输出合二为一。
A key factor in storage choice is capacity versus speed. SSDs have no moving parts, giving faster boot times and lower power consumption, but cost more per gigabyte than magnetic HDDs.
选择存储器的一个关键因素是容量与速度的权衡。SSD 无活动部件，启动更快且功耗更低，但每吉字节成本高于磁性硬盘。
4. System Performance and Environmental Impact | 系统性能与环境影响
System performance can be improved by increasing clock speed, adding more cores, or increasing cache on the CPU. However, higher performance often generates more heat, requiring better cooling solutions. Adding more RAM can also reduce the need for virtual memory, which uses slow hard drive space as overflow for RAM.
系统性能可以通过提高时钟频率、增加内核数量或增加 CPU 缓存来提升。但性能越高往往产生更多热量，需要更好的散热方案。增加 RAM 也能减少对虚拟内存的需求，虚拟内存是将速度较慢的硬盘空间作为 RAM 溢出的缓冲区。
Virtual memory allows a computer to run when RAM is full by swapping data to the hard disk, but because disk access is much slower than RAM, excessive paging leads to a noticeable slowdown known as thrashing.
虚拟内存在 RAM 已满时，通过将数据交换到硬盘来维持计算机运行，但由于磁盘访问远慢于 RAM，过度的页面交换会导致明显变慢，称为抖动。
Computers have an environmental impact from manufacturing through disposal. Energy-efficient devices, power management settings (e.g., sleep mode), and recycling of e-waste help reduce this impact. The WEEE directive in Europe promotes responsible disposal of electronic equipment.
计算机从制造到废弃都对环境产生影响。节能设备、电源管理设置（如睡眠模式）以及电子垃圾回收有助于减少影响。欧洲的 WEEE 指令鼓励对电子设备进行负责任的处置。
5. Software Development Process | 软件开发流程
Software is created through a structured development process: analysis, design, implementation, testing, documentation, and evaluation. During analysis, the developer understands the problem by identifying the inputs, processes and outputs (IPO). A clear specification is agreed with the client.
软件通过结构化的开发流程创建：分析、设计、实现、测试、文档和评估。在分析阶段，开发者通过识别输入、处理和输出来理解问题，并与客户商定清晰的规格说明。
Design uses tools such as pseudocode, flowcharts, and structure diagrams to plan the solution. Pseudocode is a simplified textual description of the algorithm using common programming keywords like IF, WHILE, and FOR. Flowcharts use standard symbols: oval for start/end, parallelogram for input/output, rectangle for process, diamond for decision.
设计阶段使用伪代码、流程图和结构图等工具规划解决方案。伪代码是一种简化的算法文本描述，使用常见编程关键字，如 IF、WHILE、FOR。流程图使用标准符号：椭圆表示开始/结束，平行四边形表示输入/输出，矩形表示处理，菱形表示判断。
Example pseudocode: IF temperature > 30 THEN OUTPUT “Hot day” ELSE OUTPUT “Mild”
伪代码示例：如果 温度 > 30 则 输出 “炎热” 否则 输出 “温和”
6. Programming Fundamentals and Algorithms | 编程基础与算法
At the heart of software development are algorithms – step-by-step sequences of operations that solve a problem. They use sequence, selection (conditional statements such as IF...THEN...ELSE) and iteration (loops: fixed FOR loops and conditional WHILE loops).
软件开发的核心是算法——逐步解决问题的操作序列。它们使用顺序、选择（条件语句如 IF...THEN...ELSE）和迭代（循环：固定循环 FOR 和条件循环 WHILE）。
Variables are named storage locations whose value can change during execution. They have data types: integer, real (float), string, Boolean. Arrays (lists) store multiple values of the same type under one identifier, accessed via an index.
变量是有名称的存储位置，其值可在执行期间改变。它们有数据类型：整数、实数（浮点）、字符串、布尔型。数组（列表）在一个标识符下存储多个同类型的值，通过索引访问。
Common algorithms include input validation (checking data is sensible before processing), maintaining a running total inside a loop, and finding the maximum or minimum value in a list. Trace tables are used to manually work through an algorithm to spot errors.
常见算法包括输入验证（在处理前检查数据是否合理）、在循环中维护累加和，以及找到列表中的最大值或最小值。跟踪表用于手工执行算法以发现错误。
| Construct | Symbol in flowchart | Pseudocode |
|---|---|---|
| Sequence | Downward arrows | line by line |
| Selection | Diamond | IF...THEN...ELSE |
| Iteration | Loop back arrow | WHILE / FOR |
7. Testing, Debugging and Language Types | 测试、调试与语言类型
Testing verifies that the software works as intended. Test data should include normal data (expected, valid), extreme data (boundary values), and exceptional data (invalid inputs). A test table documents the input, expected output, actual output, and pass/fail result for each test case.
测试验证软件是否按预期工作。测试数据应包括正常数据（预期有效）、极端数据（边界值）和异常数据（无效输入）。测试表记录每个测试用例的输入、预期输出、实际输出和通过/失败结果。
Debugging means finding and fixing errors (bugs). Three common error types: syntax errors (mistakes in the language rules), execution errors (runtime errors, e.g., dividing by zero), and logic errors (the program runs but gives wrong results). A trace table helps uncover logic errors.
调试指发现并修复错误。三种常见错误类型：语法错误（语言规则错误）、执行错误（运行时错误，如除以零）和逻辑错误（程序能运行但结果错误）。跟踪表有助于暴露逻辑错误。
Programming languages can be high-level (like Python, Java) which are easier for humans to read and write and require a translator, or low-level (assembly, machine code) which are closer to hardware. High-level languages are portable across platforms.
编程语言可以是高级语言（如 Python、Java），易于人类阅读和编写，需要翻译器；也可以是低级语言（汇编、机器码），更接近硬件。高级语言可跨平台移植。
8. Database Concepts and SQL Queries | 数据库概念与 SQL 查询
A database is a structured collection of data stored in tables. Each table contains records (rows) and fields (columns). A field is the smallest piece of data – such as a person’s surname. Every table must have a primary key that uniquely identifies each record, e.g., StudentID.
数据库是存储在表中的结构化数据集合。每张表包含记录（行）和字段（列）。字段是最小的数据片段——如某人的姓氏。每张表必须有一个主键来唯一标识每条记录，如 StudentID。
Relationships between tables are created using foreign keys. For example, an Orders table might include a CustomerID field that links to the Customers table. This avoids data duplication and maintains referential integrity.
表与表之间的关系通过外键建立。例如，订单表可能包含一个 CustomerID 字段来链接到客户表。这避免了数据重复，并保持参照完整性。
Structured Query Language (SQL) is used to retrieve and manipulate data. Key commands:
结构化查询语言（SQL）用于检索和操作数据。关键命令：
SELECT * FROM Pupils; – retrieves all fields from the Pupils table.
SELECT * FROM Pupils; – 从 Pupils 表中检索所有字段。
SELECT name, age FROM Pupils WHERE age >= 12; – filters results with a condition.
SELECT name, age FROM Pupils WHERE age >= 12; – 使用条件筛选结果。
ORDER BY surname ASC; – sorts results ascendingly.
ORDER BY surname ASC; – 按升序排序结果。
INSERT INTO Pupils VALUES (...); – adds a new record.
INSERT INTO Pupils VALUES (...); – 添加新记录。
9. Web Design with HTML and CSS | 用 HTML 和 CSS 进行网页设计
Modern web pages are built using Hypertext Markup Language (HTML) for structure and Cascading Style Sheets (CSS) for presentation. HTML uses tags enclosed in angle brackets, such as <h1> for the main heading and <p> for paragraphs. The file begins with <!DOCTYPE html> and the <html> element.
现代网页使用超文本标记语言（HTML）构建结构，用层叠样式表（CSS）控制呈现。HTML 使用尖括号包裹的标签，如 <h1> 表示主标题，<p> 表示段落。文件以 <!DOCTYPE html> 和 <html> 元素开始。
CSS can be internal (inside a <style> tag), inline (inside an element’s style attribute), or external (a separate .css file linked with <link>). External CSS is preferred because it separates content from design, making maintenance easier.
CSS 可以是内部样式（在 <style> 标签内）、内联样式（在元素的 style 属性中）或外部样式（通过 <link> 链接的独立 .css 文件）。推荐使用外部 CSS，因为它将内容与设计分离，更易于维护。
Key CSS properties control colour (color, background-color), font (font-family, font-size), layout (margin, padding, width, float). Responsive design uses relative units like percentages and media queries to adapt layouts on different devices.
关键的 CSS 属性控制颜色（color、background-color）、字体（font-family、font-size）和布局（margin、padding、width、float）。响应式设计使用百分比等相对单位以及媒体查询，使布局适应不同设备。
Example CSS: h1 { color: navy; font-family: Arial; }
CSS 示例：h1 { color: navy; font-family: Arial; }
10. Networking and Internet Communication | 网络与互联网通信
A network allows computers to share resources and communicate. In a client-server network, one or more servers provide services (file storage, email, web pages) to client devices. A peer-to-peer network allows equal devices to share resources directly.
网络使计算机能共享资源并进行通信。在客户-服务器网络中，一台或多台服务器向客户端设备提供服务（文件存储、电子邮件、网页）。对等网络允许同等地位的设备直接共享资源。
Data is transferred in packets, each containing a header (with source and destination IP addresses, packet number) and payload. Routers forward packets across interconnected networks using IP addresses. The transmission media can be wired (copper, fibre optic) or wireless (Wi‑Fi, Bluetooth).
数据以数据包形式传输，每个包包含报头（含源和目标 IP 地址、包编号）与有效载荷。路由器使用 IP 地址在互联网络中转发数据包。传输介质可以是有线（铜缆、光纤）或无线（Wi‑Fi、蓝牙）。
Common protocols include HTTP/HTTPS for web pages, FTP for file transfer, SMTP for sending emails, and TCP/IP as the foundational suite that ensures reliable delivery. IP addresses (IPv4 like 192.168.1.10) identify devices; DNS translates human-friendly domain names to IP addresses.
常见协议包括用于网页的 HTTP/HTTPS、用于文件传输的 FTP、用于发送电子邮件的 SMTP，以及确保可靠交付的基础协议族 TCP/IP。IP 地址（IPv4 如 192.168.1.10）标识设备；DNS 将人类友好的域名转换为 IP 地址。
| Protocol | Function |
|---|---|
| HTTP | Transfer web pages |
| HTTPS | Secure web transfer (encrypted) |
| FTP | File upload/download |
| SMTP | Send emails |
11. Computer Security and Legal Issues | 计算机安全与法律问题
Cybersecurity threats include malware (viruses, worms, trojans), phishing (fake emails that trick users into revealing data), denial-of-service attacks (flooding a server), and social engineering (manipulating people). Protection measures include firewalls, anti-malware software, strong passwords, and encryption.
网络安全威胁包括恶意软件（病毒、蠕虫、木马）、网络钓鱼（诱骗用户泄露数据的虚假邮件）、拒绝服务攻击（淹没服务器）和社会工程（操纵人）。防护措施包括防火墙、反恶意软件、强密码和加密。
Encryption scrambles data so that only authorised parties with the correct key can read it. For example, HTTPS uses SSL/TLS to encrypt web traffic, protecting sensitive information like credit card numbers during online transactions.
加密将数据打乱，只有拥有正确密钥的授权方才能读取。例如，HTTPS 使用 SSL/TLS 加密网络流量，保护信用卡号等敏感信息在在线交易时不被窃取。
Relevant laws include the Computer Misuse Act (unauthorised access to systems is illegal) and the Data Protection Act (organisations must handle personal data fairly and keep it secure). Copyright law applies to software, images, and music used without permission.
相关法律包括《计算机滥用法》（未经授权访问系统是违法的）和《数据保护法》（组织必须公平处理个人数据并确保其安全）。版权法适用于未经许可使用的软件、图像和音乐。
Principle: CIA triad – Confidentiality, Integrity, Availability – guides security design.
原则：CIA 三元组——保密性、完整性、可用性——指导安全设计。
Published by TutorHao | Computer Science 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