📚 Year 8 Cambridge Computing: Core Knowledge Review | Year 8 Cambridge 计算机：核心知识点梳理
In Year 8 of the Cambridge Lower Secondary Computing curriculum, students build on foundational knowledge and delve deeper into how computer systems work, how data is represented, and how to think computationally. This article provides a comprehensive review of the core topics, from hardware components to programming fundamentals, networking, and digital safety.
在剑桥初中计算机课程八年级（Year 8）中，学生们在基础知识之上进一步学习计算机系统的工作原理、数据的表示方式以及计算思维方法。本文全面梳理了从硬件组件到编程基础、网络和数字安全等核心知识点。
1. Computer Systems and Components | 计算机系统与组件
A computer system is made up of hardware and software working together. The central processing unit (CPU) is the 'brain' that executes program instructions. The motherboard connects all internal components and allows communication between them.
计算机系统由协同工作的硬件和软件组成。中央处理器（CPU）是执行程序指令的“大脑”。主板连接所有内部组件，使它们能够相互通信。
The CPU contains the control unit (CU), which manages instruction execution, and the arithmetic logic unit (ALU), which performs calculations. Data and instructions are moved between the CPU, memory, and storage via buses.
CPU 包含控制单元（CU），负责管理指令执行，以及算术逻辑单元（ALU），负责执行计算。数据和指令通过总线在 CPU、内存和存储设备之间传输。
Key differences between RAM and ROM are summarised below.
| Characteristic | RAM | ROM |
|---|---|---|
| Volatility | Volatile (data lost when powered off) | Non-volatile (retains data) |
| Purpose | Stores currently running programs and data | Stores firmware/boot instructions (BIOS) |
| Speed | Fast read/write | Slower read, rarely written to |
RAM 和 ROM 的主要区别总结如下。
| 特性 | RAM | ROM |
|---|---|---|
| 易失性 | 易失（断电后数据丢失） | 非易失（保留数据） |
| 用途 | 存储当前运行的程序和数据 | 存储固件/启动指令（BIOS） |
| 速度 | 快速读/写 | 读取较慢，很少写入 |
2. Input and Output Devices | 输入与输出设备
Input devices let users give commands and data to the computer. Output devices show the results of processing to the user.
输入设备使用户能够向计算机下达命令和输入数据。输出设备则将处理结果展示给用户。
Common input devices include:
- Keyboard – text and command input
- Mouse – pointing, selecting, dragging
- Microphone – audio capture
- Touchscreen – direct screen interaction (acts as both input and output)
常见输入设备包括：
- 键盘 – 文本和命令输入
- 鼠标 – 指向、选择、拖放
- 麦克风 – 捕捉音频
- 触摸屏 – 直接与屏幕交互（兼具输入与输出功能）
Common output devices include:
- Monitor – displays visual information
- Printer – produces hard copies
- Speakers/headphones – output sound
常见输出设备包括：
- 显示器 – 显示视觉信息
- 打印机 – 生成硬拷贝
- 扬声器/耳机 – 输出声音
3. Storage Devices | 存储设备
Primary storage (RAM) is fast but temporary. Secondary storage holds data permanently or for long periods. Examples include hard disk drives (HDDs), solid-state drives (SSDs), USB flash drives, and optical discs.
主存储（RAM）速度快但是临时的。辅助存储则可以永久或长期保存数据。例如硬盘（HDD）、固态硬盘（SSD）、U盘和光盘。
Data storage units, from smallest to largest:
| Unit | Abbreviation | Equivalent |
|---|---|---|
| bit | b | smallest unit (0 or 1) |
| byte | B | 8 bits |
| kilobyte | KB | 1024 bytes |
| megabyte | MB | 1024 KB |
| gigabyte | GB | 1024 MB |
| terabyte | TB | 1024 GB |
数据存储单位（从小到大）：
| 单位 | 缩写 | 等值 |
|---|---|---|
| 比特 | b | 最小单位（0或1） |
| 字节 | B | 8比特 |
| 千字节 | KB | 1024字节 |
| 兆字节 | MB | 1024 KB |
| 吉字节 | GB | 1024 MB |
| 太字节 | TB | 1024 GB |
4. Binary and Data Representation | 二进制与数据表示
Computers use binary (base-2) because their electronic components have two states: off (0) and on (1). All data – numbers, text, images, sound – is stored as sequences of bits.
计算机使用二进制（基数为2），因为电子元件有开（1）和关（0）两种状态。所有数据——数字、文本、图像、声音——都以比特序列的形式存储。
To convert a decimal number to binary, use the column headings for powers of 2. For example, to convert 13 to binary:
8 4 2 1
1 1 0 1
the binary value is 1101. You can also check by adding the place values where a 1 appears.
将十进制数转换为二进制数时，使用2的幂次作为位权。例如把13转换为二进制：
8 4 2 1
1 1 0 1
因为8+4+1=13，所以二进制表示为1101。你也可以通过将所有置1的位权相加来验证。
Characters are represented by codes. ASCII uses 7 bits to represent 128 characters (English letters, digits, symbols). Unicode, such as UTF-8, extends this to cover characters from all writing systems and uses variable byte lengths.
字符通过编码表示。ASCII使用7比特表示128个字符（英文字母、数字和符号）。Unicode（如UTF-8）对此进行了扩展，能够表示所有书写系统的字符，并使用变长字节。
urs can be represented. Resolution is the number of pixels in an image (e.g. 1920 × 1080).
图像由称为像素的微小点组成。每个像素的颜色以二进制数存储；每像素的比特数越多（颜色深度越高），可表示的颜色就越多。分辨率是图像中像素的数量（例如1920×1080）。
Sound is captured by sampling the sound wave at regular intervals. The sample rate (e.g. 44.1 kHz) and bit depth affect sound quality and file size.
声音是通过按固定时间间隔对声波进行采样来记录的。采样率（如44.1kHz）和位深度会影响音质和文件大小。
5. Networks and the Internet | 网络与互联网
A network connects two or more computers to share resources and data. A Local Area Network (LAN) covers a small area like a school or office. A Wide Area Network (WAN) spans large distances, such as the Internet.
网络连接两台或更多计算机以共享资源和数据。局域网（LAN）覆盖较小区域，如学校或办公室。广域网（WAN）跨越长距离，例如互联网。
Networking hardware includes:
- Network Interface Card (N
Published by TutorHao | Year 8 Computer Science Revision Series | aleveler.com
广告 / Sponsored现货 Cambridge International AS & ALevel IT Coursebook剑桥国际IGC…计算机 备考教辅 · 正版现货 · 与本文内容相关查看详情 / View on Taobao参考价 ¥467.0更多咨询请联系16621398022（同微信）
备考资讯每日更新，关注不错过考纲变化 · 科目分析 · 学习方法
在微信里长按二维码识别关注
或截图后用「扫一扫 → 相册」选择本图公众号：tutorhao