Year 10 Cambridge Computer Science: Core Knowledge Review | Year 10 Cambridge 计算机：核心知识点梳理

📚 Year 10 Cambridge Computer Science: Core Knowledge Review | Year 10 Cambridge 计算机：核心知识点梳理

This article provides a structured revision of the core topics covered in the Year 10 Cambridge IGCSE Computer Science syllabus (0478/0984). It is designed to reinforce understanding of key concepts, from data representation to programming fundamentals, helping students build a solid foundation for their final assessments.

本文系统梳理了 Year 10 Cambridge IGCSE 计算机科学课程（0478/0984）的核心知识点，旨在帮助学生巩固从数据表示到编程基础等关键概念，为最终的考试评估打下坚实基础。

1. Data Representation | 数据表示

Computers process all data in binary, a base-2 number system using only 0s and 1s. The smallest unit of data is a bit (binary digit), and a group of 8 bits forms a byte. Understanding how numbers, text, images, and sound are converted into binary is fundamental.

计算机使用二进制处理所有数据，二进制是一种只使用 0 和 1 的基数为 2 的数字系统。数据的最小单位是位（比特），8 个位组成一个字节。理解数字、文本、图像和声音如何转换为二进制形式是基础。

Binary numbers follow place values that double from right to left: … 2, 1. A binary number like 1101 represents 1×8 + 1×4 + 0×2 + 1×1 = 13 in denary (base-10).

二进制数遵循从右向左依次加倍的位值规律：... 128, 64, 32, 16, 8, 4, 2, 1。例如二进制数 1101 表示 1×8 + 1×4 + 0×2 + 1×1，换算为十进制是 13。

2. Binary Arithmetic and Overflows | 二进制运算与溢出

h a carry of 1. When adding two 8-bit numbers, the result may exceed 255, causing an overflow error if the hardware cannot store the 9th bit.

二进制加法遵循简单规则：0+0=0，0+1=1，1+0=1，1+1=0 并向高位进 1。当两个 8 位二进制数相加，结果可能超过 255，如果硬件无法存储第 9 位，就会发生溢出错误。

Shifting binary digits left multiplies a number by 2 for each shift; shifting right divides by 2 (integer division). For example, 00001100 (12) shifted left once becomes 00011000 (24).

二进制左移一位相当于乘以 2，右移一位相当于除以 2（整数除法）。例如 00001100 (12) 左移一位变成 00011000 (24)。

3. Hexadecimal System | 十六进制系统

adecimal (base-16) is used as a more human-friendly shorthand for binary. It uses digits 0–9 and letters A– 5. One hex digit represents exactly 4 bits (a nibble), making conversions straightforward.

十六进制（基数为 16）用作更易读的二进制简写形式，使用数字 0–9 和字母 A–F，其中 A=10，F=15。一位十六进制刚好表示 4 个二进制位（一个半字节），因此转换非常直接。

12 remainder 8, and 12 is C. Hex is widely used for memory addresses, colour codes (e.g., #FF5733), and MAC addresses.

十进制转十六进制通过不断除以 16 并记录余数来实现。例如十进制 200 转换为十六进制是 C8，因为 200 ÷ 16 = 12 余 8，而 12 对应 C。十六进制广泛用于内存地址、颜色代码（如 #FF5733）和 MAC 地址。

4. Representing Text, Sound and Images | 文本、声音和图像的表示

Text is encoded using character sets such as ASCII (7-bit, encoding 128 characters) and Unicode (multiple bytes, supporting global scripts). An ASCII 'A' is 65 in denary, or 01000001 in binary. Unicode (e.g., UTF-8) extends this to cover emojis and thousands of languages.

文本使用字符集编码，如 ASCII（7 位，编码 128 个字符）和 Unicode（多字节，支持全球文字）。ASCII 的 'A' 在十进制中为 65，二进制为 01000001。Unicode（如 UTF-8）对此进行扩展，涵盖表情符号和数千种语言。

Sound is analogue and must be sampled for digital use. Analogue-to-digital conversion measures amplitude at regular intervals (sample rate) and records values as binary. Higher sample rates and bit depths increase quality but also file size.

声音是模拟信号，必须通过采样才能数字化。模数转换以固定间隔（采样率）测量振幅，并将数值记录为二进制。更高的采样率和位深度会提升音质，但同时增加文件大小。

bit (0 or 1). Colour images use bit depth to define the range of colours; for example, 24-bit colour uses 8 bits each for red, green, and blue (RGB). Resolution (total pixel count) and colour depth determine image quality and file size.

图像由像素组成，每个像素分配一个表示颜色的二进制值。在黑白位图中，1 个像素 = 1 位（0 或 1）。彩色图像使用色彩深度定义颜色范围；例如 24 位色彩中，红、绿、蓝（RGB）各占 8 位。分辨率（总像素数）和色彩深度决定了图像质量和文件大小。

5. Data Storage and Compression | 数据存储与压缩

, and beyond. Calculating file size is essential: a 10-second sound clip with 44.1 kHz sample rate and 16-bit sample depth in stereo requires 10 × 44100 × 16 × 2 = 14112000 bits, or about 1.68 MB.

数据量以位、字节、千字节（KB，存储中为 10³ 字节，内存中为 1024）、兆字节（MB）、吉字节（GB）、太字节（TB）等单位衡量。计算文件大小很重要：一段 10 秒、采样率 44.1 kHz、16 位采样位深的立体声片段需要 10 × 44100 × 16 × 2 = 14112000 位，约 1.68 MB。

Compression reduces file size. Lossless compression (e.g., run-length encoding, ZIP) preserves all original data. Lossy compression (e.g., JPEG for images, MP3 for audio) permanently removes some data, exploiting human perceptual limits to maintain acceptable quality while drastically reducing size.

压缩可减小文件体积。无损压缩（如行程编码、ZIP）保留所有原始数据。有损压缩（如 JPEG 图片、MP3 音频）会永久移除部分数据，利用人类感知局限，在保持可接受质量的同时大幅缩减体积。

6. Computer Architecture: CPU and Memory | 计算机体系结构：CPU 与存储器

The central processing unit (CPU) follows the fetch-decode-execute cycle. Key components include the control unit (CU), arithmetic logic unit (ALU), and registers such as the program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR), and accumulator (ACC).

中央处理器（CPU）遵循“取指–译码–执行”周期。关键组件包括控制单元（CU）、算术逻辑单元（ALU），以及程序计数器（PC）、内存地址寄存器（MAR）、内存数据寄存器（MDR）、当前指令寄存器（CIR）和累加器（ACC）等寄存器。

Factors affecting CPU performance are clock speed (cycles per second, GHz), number of cores, and cache size. Cache memory provides high-speed data access and reduces the need to fetch from slower main memory (RAM). Primary storage includes RAM (volatile, work space) and ROM (non-volatile, stores firmware/BIOS). Secondary storage devices (HDD, SSD, optical) hold data permanently.

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影响 CPU 性能的因素包括时钟速度（每秒周期数，GHz）、核心数量以及缓存大小。缓存内存提供高速数据访问，减少了从较慢的主存（RAM）读取数据的需要。主存储器包括 RAM（易失性，工作空间）和 ROM（非易失性，存储固件/BIOS）。辅助存储设备（HDD、SSD、光盘）用于永久保存数据。

7. Input and Output Devices | 输入与输出设备

Input devices transfer data from the outside world into the computer. Common examples include keyboards, mice, touchscreens, microphones, sensors (temperature, light, pressure), and barcode readers. Sensors continuously capture analogue signals; an ADC converts them to digital for processing.

输入设备将外界数据传输到计算机中。常见例子有键盘、鼠标、触摸屏、麦克风、传感器（温度、光、压力）和条形码阅读器。传感器持续采集模拟信号；模数转换器（ADC）将其转换为数字信号供处理。

Output devices present the processed data. Monitors (LCD, LED), printers (inkjet, laser), speakers, and actuators are typical. An actuator takes a digital signal and produces physical movement, such as opening a valve or turning a motor.

输出设备呈现处理后的数据。典型的设备有显示器（LCD、LED）、打印机（喷墨、激光）、扬声器和执行器。执行器接收数字信号并产生物理动作，例如打开阀门或转动马达。

8. Software and Operating Systems | 软件与操作系统

Software is divided into system software and application software. System software includes the operating system (OS), utilities, and translators (compilers, interpreters, assemblers). The OS manages hardware, provides a user interface, handles file management, and oversees multitasking and memory management.

软件分为系统软件和应用软件。系统软件包括操作系统（OS）、实用工具和翻译器（编译器、解释器、汇编器）。操作系统管理硬件、提供用户界面、处理文件管理，并负责多任务和内存管理。

Application software performs specific user-oriented tasks: word processors, spreadsheets, web browsers, and database management systems. High-level languages (Python, Java) are translated into machine code by compilers (whole program at once) or interpreters (line by line).

应用软件执行面向用户的特定任务：文字处理器、电子表格、网页浏览器和数据库管理系统。高级语言（Python、Java）由编译器（一次性翻译整个程序）或解释器（逐行翻译）转换为机器码。

9. Networks and Internet | 网络与互联网

A network connects devices to share resources and data. Network types include LAN (local area network) and WAN (wide area network). Network hardware involves routers, switches, hubs, and network interface cards (NICs). Transmission media can be wired (copper cable, fibre optic) or wireless (Wi-Fi, Bluetooth).

网络将设备连接起来以共享资源和数据。网络类型包括局域网（LAN）和广域网（WAN）。网络硬件涉及路由器、交换机、集线器和网络接口卡（NIC）。传输介质可以是有线（铜线电缆、光纤）或无线（Wi-Fi、蓝牙）。

Data is transmitted using protocols, sets of rules ensuring properly ordered communication. The TCP/IP model has four layers: application, transport, internet, and link. Packet switching breaks messages into packets, each containing source/destination addresses and a payload, which are reassembled at the destination.

数据使用协议进行传输，协议是确保有序通信的一套规则。TCP/IP 模型有四层：应用层、传输层、互联网层和链路层。分组交换将信息拆分成数据包，每个包包含源/目的地址和有效载荷，在目的地重新组装。

10. Cybersecurity | 网络安全

Cybersecurity aims to protect systems, networks, and data from digital attacks. Threats include malware (viruses, worms, ransomware), phishing, social engineering, denial-of-service (DoS) attacks, and SQL injection. Understanding these threats is essential for designing secure systems.

网络安全旨在保护系统、网络和数据免受数字攻击。威胁包括恶意软件（病毒、蠕虫、勒索软件）、网络钓鱼、社会工程、拒绝服务（DoS）攻击和 SQL 注入。理解这些威胁对于设计安全系统至关重要。

Defence mechanisms involve firewalls (filtering traffic based on rules), encryption (scrambling data with keys), anti-malware software, and robust password policies. Symmetric encryption uses the same key for encryption and decryption; asymmetric encryption uses a public/private key pair. Digital certificates verify the authenticity of websites and users.

防御机制包括防火墙（基于规则过滤流量）、加密（用密钥打乱数据）、反恶意软件以及强健的密码策略。对称加密使用相同密钥进行加密和解密；非对称加密使用公钥/私钥对。数字证书验证网站和用户的真实性。

11. Algorithms and Problem Solving | 算法与问题解决

An algorithm is a step-by-step procedure to solve a problem. It can be expressed using flowcharts, pseudocode, or structured English. Key constructs include sequence, selection (IF-THEN-ELSE), and iteration (FOR, WHILE). Abstraction simplifies a problem by focusing on essential details and ignoring irrelevant ones.

算法是解决问题的分步过程。可以用流程图、伪代码或结构化英语表示。关键结构包括顺序、选择（IF-THEN-ELSE）和迭代（FOR、WHILE）。抽象是通过聚焦于核心细节而忽略无关细节来简化问题的方法。

Common algorithms include linear search (checking each element sequentially) and binary search (repeatedly dividing a sorted list). Sorting algorithms like bubble sort and insertion sort are also studied. Trace tables track variable values during dry runs to validate algorithm correctness.

常见算法包括线性搜索（顺序检查每个元素）和二分搜索（不断将有序列表对半分）。还学习诸如冒泡排序和插入排序等排序算法。跟踪表在纸面运行时跟踪变量值，以验证算法的正确性。

12. Programming Concepts | 编程概念

Cambridge IGCSE Computer Science uses a high-level language (typically Python) to demonstrate programming principles. Core concepts include variables and data types (integer, float, string, Boolean), assignment, input/output, conditional statements, loops, and arrays (lists).

剑桥 IGCSE 计算机科学常使用高级语言（通常为 Python）来演示编程原理。核心概念包括变量和数据类型（整型、浮点型、字符串、布尔型）、赋值、输入/输出、条件语句、循环和数组（列表）。

Procedures and functions promote modular, reusable code. A procedure performs a task, while a function returns a value. Parameter passing (by value/by reference) affects how arguments are treated. Basic file handling (opening, reading, writing, closing text files) is also introduced.

过程和函数有助于实现模块化、可复用的代码。过程执行一项任务，而函数返回一个值。参数传递（按值/按引用）影响实参的处理方式。还会介绍基本的文件处理（打开、读取、写入、关闭文本文件）。

Testing and debugging are vital. Test data should include normal, boundary (e.g., just inside/outside limits), and erroneous/invalid values. Logic errors may produce wrong outputs without crashing, so thorough testing is required.

测试和调试至关重要。测试数据应当包括正常数据、边界数据（恰好处于临界值内侧/外侧）以及错误/无效值。逻辑错误可能导致输出错误而不会引起崩溃，因此需要进行全面测试。

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