📚 Year 9 SQA Computing: Key Concepts Checklist | Year 9 SQA 计算机：核心知识点梳理
This article brings together the most important topics covered in the Year 9 SQA Computing curriculum. From how a computer processes data to writing your first programs and staying safe online, each section explains a core concept you need to master. Use this checklist to review your knowledge and identify any gaps before assessments.
本文汇总了 Year 9 SQA 计算机课程中最重要的主题。从计算机如何处理数据，到编写你的第一个程序，再到安全上网，每个部分都解释了你必须掌握的核心概念。利用这份清单来复习知识，并在评估前找出薄弱环节。
1. Introduction to Computing Systems | 计算系统概论
A computing system is more than just the physical machine. It consists of hardware, software, data, and the people who use it. Understanding how these elements work together is the first step in studying computing.
计算系统不仅仅是一台物理机器。它由硬件、软件、数据以及使用它的人组成。理解这些要素如何协同工作，是学习计算机的第一步。
The input-process-output model describes how any computer works. Input devices like a keyboard or a sensor feed data into the system. The central processing unit (CPU) then processes the data, and output devices such as a screen or a printer show the results. Storage devices hold data before or after processing.
输入-处理-输出模型描述了任何计算机的工作方式。键盘或传感器等输入设备将数据送入系统，中央处理器（CPU）对数据进行处理，然后显示器或打印机等输出设备显示出结果。存储设备在处理前后保存数据。
The difference between general-purpose and embedded systems matters. A general-purpose computer, like a laptop, can run many different applications. An embedded system is a computer built into a larger device, such as the control unit inside a washing machine or a car’s engine management system, and it usually performs one dedicated function.
通用系统与嵌入式系统之间的区别很重要。笔记本电脑这类通用计算机可以运行许多不同的应用程序。嵌入式系统则是内置在更大设备中的计算机，比如洗衣机或汽车发动机管理系统里的控制单元，通常只执行一项专用功能。
2. Data Representation | 数据表示
All data inside a computer is stored and processed as binary digits (bits) – 0s and 1s. Knowing how numbers, text, images, and sound are converted into binary is a fundamental skill.
计算机内部的所有数据都以二进制数字（比特）的形式存储和处理——即 0 和 1。理解数字、文字、图像和声音如何转换为二进制，是一项基本技能。
Binary numbers use base 2, while we normally count in base 10 (denary). Converting between denary and binary and back is essential. For example, the denary number 13 is 1101 in binary. You should also be comfortable with hexadecimal (base 16), which is often used to shorten long binary strings, such as representing colours in web design.
二进制数使用基数为 2，而我们通常用十进制（基数为 10）计数。在十进制和二进制之间互相转换非常重要。例如，十进制数 13 在二进制中是 1101。你还应该熟悉十六进制（基数为 16），它常用于缩短长二进制串，比如在网页设计中表示颜色。
Text is stored using character sets like ASCII and Unicode. Each character is assigned a unique binary number. Images are broken into pixels, and each pixel's colour is stored as a binary value – a higher bit depth means more possible colours and larger file sizes. Sound is sampled at regular intervals, with each sample turned into a binary number.
文本使用 ASCII 或 Unicode 等字符集存储，每个字符分配一个唯一的二进制编码。图像被分解为像素，每个像素的颜色存储为二进制值——位深度越高，可能的颜色数越多，文件也越大。声音以固定间隔进行采样，每个样本转化为二进制数值。
3. Computer Architecture | 计算机体系结构
The Von Neumann architecture is the basis for almost all modern computers. It describes a system where program instructions and data share the same memory and are fetched, decoded, and executed by the CPU.
冯·诺依曼体系结构是几乎所有现代计算机的基础。它描述的系统中，程序指令和数据共用同一存储器，由 CPU 完成取指、译码和执行。
The CPU contains several key components. The control unit (CU) directs operations and sends control signals. The arithmetic logic unit (ALU) performs calculations and logical comparisons. Registers are tiny, super-fast memory locations inside the CPU; for example, the program counter holds the address of the next instruction, and the accumulator stores intermediate results.
CPU 包含几个关键部件。控制单元（CU）指导操作并发出控制信号；算术逻辑单元（ALU）执行计算和逻辑比较；寄存器是 CPU 内部极小的超快存储单元，比如程序计数器存放下一条指令的地址，累加器暂存中间结果。
The fetch-decode-execute cycle is the heartbeat of the processor. The CPU fetches an instruction from memory, decodes it to work out what must be done, and then executes it. This cycle repeats billions of times per second. Clock speed, measured in hertz, and the number of cores both affect how quickly a processor can complete cycles.
取指-译码-执行循环是处理器的心跳。CPU 从内存中取出一条指令，译码以决定要做什么，然后执行该指令。此循环每秒重复数十亿次。时钟频率（以赫兹为单位）以及核心数量都会影响处理器完成循环的速度。
4. Software Concepts | 软件概念
Software is divided into system software and application software. System software includes the operating system (OS) and utility programs that manage the computer’s resources. Application software lets users perform specific tasks, such as writing a document or editing a photo.
软件分为系统软件和应用软件。系统软件包括操作系统（OS）以及管理计算机资源的实用程序。应用软件让用户完成特定任务，比如写文档或编辑照片。
The operating system has many vital roles: managing the user interface, handling memory and processor scheduling, controlling peripherals through device drivers, and organising files on storage devices. A real-time OS might be used in a braking system where response must be immediate, while a multi-user OS supports many people at once.
操作系统有许多关键角色：管理用户界面，处理内存和处理器调度，通过设备驱动程序控制外设，以及在存储设备上组织文件。实时操作系统可能用于必须立即响应的刹车系统，而多用户操作系统同时支持许多人。
Utility software performs maintenance tasks. File compression reduces storage size, disk defragmentation reorganises scattered data for faster access, backup utilities protect against data loss, and antivirus software defends against malware. Low-level and high-level formatting prepare storage media for use.
实用软件执行维护任务。文件压缩能减少存储空间，磁盘碎片整理可重组分散的数据以实现更快访问，备份实用程序防止数据丢失，杀毒软件防御恶意软件。低级格式化和高级格式化为存储介质的使用做好准备。
5. Networks and the Internet | 网络与互联网
A network connects two or more computing devices so they can share data and resources. LANs (Local Area Networks) cover a small geographical area like a school, while WANs (Wide Area Networks) connect devices across cities or countries – the Internet is the largest WAN.
网络连接两台或多台计算设备，以便它们共享数据和资源。局域网（LAN）覆盖学校这样的小地理范围，而广域网（WAN）连接跨越城市或国家的设备——互联网是最大的广域网。
Network hardware includes switches, routers, and network interface cards (NICs). A switch connects devices within a LAN and forwards data intelligently to the correct destination. A router connects different networks together and directs packets between them, often using IP addresses. Transmission media can be wired (copper cable, fibre optic) or wireless (Wi‑Fi, Bluetooth).
网络硬件包括交换机、路由器和网络接口卡（NIC）。交换机连接局域网内的设备，并智能地将数据转发到正确目的地。路由器将不同网络连接起来，并在它们之间根据 IP 地址转发数据包。传输介质可以是有线的（铜缆、光纤）或无线的（Wi‑Fi、蓝牙）。
The client-server model is common: a server provides services (like hosting a website), and clients request those services. Peer-to-peer networks have no central server; each device can share resources directly. Protocols are the rules that enable communication – HTTP for web pages, FTP for file transfer, SMTP for sending email, and TCP/IP as the foundation of Internet data delivery.
客户端-服务器模型很常见：服务器提供服务（如托管网站），客户端请求这些服务。对等网络没有中央服务器，每台设备可直接共享资源。协议是实现通信的规则——HTTP 用于网页，FTP 用于文件传输，SMTP 用于发送电子邮件，而 TCP/IP 是互联网数据传输的基础。
6. Cybersecurity Basics | 网络安全基础
Cybersecurity is about protecting systems, networks, and data from digital attacks. Threats such as malware, phishing, and brute-force attacks are constantly evolving, so understanding them is crucial.
网络安全关乎保护系统、网络和数据免受数字攻击。恶意软件、网络钓鱼和暴力破解等威胁不断演变，因此理解它们至关重要。
Malware is malicious software designed to cause harm. Viruses attach themselves to clean files and spread. Worms replicate without user action. Trojans disguise themselves as legitimate programs. Ransomware encrypts files and demands payment. Spyware secretly monitors user activity. Phishing attacks use fake emails or websites to trick people into revealing passwords or financial details.
恶意软件是旨在造成危害的恶意程序。病毒附着在干净文件上并传播；蠕虫无需用户操作即可自我复制；木马伪装成合法程序；勒索软件加密文件并要求赎金；间谍软件暗中监视用户活动。网络钓鱼攻击利用虚假电子邮件或网站诱骗人们泄露密码或财务信息。
Defensive measures include using strong passwords and multi-factor authentication, installing firewalls to filter incoming and outgoing traffic, keeping software updated, and encrypting sensitive data. The importance of regular backups cannot be overstated – if ransomware strikes, having a recent backup can save your data. Ethical and legal responsibilities require everyone to respect data privacy.
防御措施包括使用强密码和多因素认证，安装防火墙过滤进出流量，保持软件更新，以及对敏感数据进行加密。定期备份的重要性怎么强调都不为过——如果遭到勒索软件攻击，拥有最近的备份可以保住你的数据。道德和法律责任要求每个人都尊重数据隐私。
7. Programming Fundamentals | 编程基础
Programming means writing instructions that a computer can execute. All programs are built from core constructs: sequence, selection, and iteration. Mastering these allows you to design solutions for a wide range of problems.
编程就是编写计算机可以执行的指令。所有程序都由基本结构构成：顺序、选择和迭代。掌握这些结构，你就能为各种问题设计解决方案。
, and else statements, often comparing values with relational operators like >, <, ==, and !=. Iteration repeats a block of code – hile condition-controlled loops (e.g., WHILE) keep running as long as a condition is true.
顺序是最简单的结构：语句按先后顺序一条接一条地执行。选择结构让程序可以通过 if、else if 和 else 语句做出决策，通常会结合 >、<、== 和 != 等关系运算符来比较数值。迭代重复执行一段代码——计数控制循环（如 FOR）运行特定次数，条件控制循环（如 WHILE）则只要条件为真就会继续运行。
Data types are central. Integer holds whole numbers, real (float) holds decimals, Boolean can be True or False, and string stores text. Variables are named containers for data. Arrays (or lists) store multiple values under one name. Writing clean, well-commented code and using meaningful variable names are good practices that aid debugging and readability.
数据类型是核心。整型存放整数，实型（浮点型）存放小数，布尔型可以是 True 或 False，字符串存放文本。变量是存放数据的命名容器，数组（或列表）用一个名称存储多个值。编写整洁、注释良好的代码，并使用有意义的变量名，都是有助于调试和提升可读性的好习惯。
8. Algorithms and Flowcharts | 算法与流程图
An algorithm is a step-by-step procedure for solving a problem. Before writing any code, it is wise to plan the logic with an algorithm. Flowcharts and pseudocode are two useful tools for planning.
算法是解决问题的分步过程。在编写任何代码之前，最好先用算法规划逻辑。流程图和伪代码是两种有用的规划工具。
Flowcharts use standard symbols: an oval for start/end, a rectangle for a process, a diamond for a decision, and a parallelogram for input/output. Arrows show the flow of control. A simple flowchart might ask for two numbers, compare them, and output the larger one. Pseudocode describes algorithm steps in plain, structured English – it is not strict code but is clear enough to be translated into any programming language.
流程图使用标准符号：椭圆形表示开始/结束，矩形表示处理步骤，菱形表示判断，平行四边形表示输入/输出。箭头表示控制流向。一个简单的流程图可能会要求输入两个数字，进行比较，然后输出较大的数。伪代码用清晰的结构化英文描述算法步骤——它不是严格意义上的代码，但足够清晰，可转换为任何编程语言。
Testing algorithms with trace tables helps identify errors. A trace table records the values of variables after each step. Common searching algorithms include linear search (checking each item one by one) and binary search (repeatedly halving a sorted list). Basic sorting algorithms like bubble sort compare adjacent items and swap them if they are in the wrong order until the list is sorted.
使用追踪表测试算法有助于发现错误。追踪表记录每一步之后各变量的值。常见的搜索算法包括线性搜索（逐个检查项目）和二分查找（在有序列表中反复对半查找）。基本排序算法如冒泡排序，会依次比较相邻项目，若顺序错误则交换，直到整个列表有序。
9. Web Development | 网页开发
Web pages are built using HTML (HyperText Markup Language), which defines the structure of content, and CSS (Cascading Style Sheets), which controls presentation and layout. Understanding how these work together allows you to create functional, attractive websites.
网页使用 HTML（超文本标记语言）构建内容结构，使用 CSS（层叠样式表）控制表现和布局。理解两者如何协同工作，你就能创建功能齐全且吸引人的网站。
HTML uses tags enclosed in angle brackets. Essential tags include ,
, ,for paragraphs,
to for headings, for hyperlinks, and ![]()
for images. Attributes provide additional information: the 'href' attribute of an anchor tag sets the link destination, and the 'src' attribute of an image tag points to the image file.
HTML 使用尖括号内的标签。基本标签包括 、
、、段落标签 、标题标签
到 、超链接标签 ，以及图片标签 ![]()
。属性提供额外信息：锚标签的 'href' 属性设置链接目标，图片标签的 'src' 属性指向图像文件。
CSS rules select an element and declare styles. A rule like p { color: blue; font-size: 16px; } changes all paragraphs to blue text with a 16-pixel font. CSS can be written inline, embedded in a
HTML 使用尖括号内的标签。基本标签包括 、
、、段落标签、标题标签
到 、超链接标签 ，以及图片标签 ![]()
。属性提供额外信息：锚标签的 'href' 属性设置链接目标，图片标签的 'src' 属性指向图像文件。
CSS rules select an element and declare styles. A rule like p { color: blue; font-size: 16px; } changes all paragraphs to blue text with a 16-pixel font. CSS can be written inline, embedded in a
CSS rules select an element and declare styles. A rule like p { color: blue; font-size: 16px; } changes all paragraphs to blue text with a 16-pixel font. CSS can be written inline, embedded in a