GCSE CCEA Computer Science: Mind Map Rapid Revision | GCSE CCEA 计算机：思维导图速记

📚 GCSE CCEA Computer Science: Mind Map Rapid Revision | GCSE CCEA 计算机：思维导图速记

This mind map style revision guide distils the CCEA GCSE Computer Science specification into bite-sized, bilingual nodes. Each concept is paired in English and Chinese to help you build a strong mental map, making last-minute revision faster and more effective.

这份思维导图式速记指南将 CCEA GCSE 计算机科学大纲浓缩为简短的中英双语节点。每个核心概念都配有英文和中文解释，帮助你构建清晰的知识网络，让考前冲刺复习更快速、更高效。

1. Computer Hardware and Architecture | 计算机硬件与架构

The CPU executes instructions through the fetch-decode-execute cycle, using the system bus with separate address, data and control lines.

CPU 通过取指–译码–执行周期执行指令，借助地址总线、数据总线和控制总线进行通信。

Von Neumann architecture stores both data and programs in a single memory unit. Essential registers include PC (program counter), MAR, MDR, CIR and ACC.

冯·诺依曼架构将数据和程序存储在同一内存中；关键寄存器包括程序计数器（PC）、存储器地址寄存器（MAR）、存储器数据寄存器（MDR）、当前指令寄存器（CIR）和累加器（ACC）。

CPU performance is influenced by clock speed in GHz, the number of processor cores and cache memory size.

CPU 性能受时钟速度（GHz）、核心数量和高速缓存大小的影响。

Embedded systems are dedicated computers inside devices like microwaves, digital watches and car engine management units; they are often low-power and run a single program.

嵌入式系统是内置在微波炉、电子手表和汽车发动机管理系统等设备中的专用计算机；它们通常功耗低且只运行单一程序。

Secondary storage devices include magnetic HDDs, solid-state drives (SSDs), optical discs and cloud storage. Key comparisons are capacity, speed, durability and portability.

辅助存储设备包括机械硬盘 (HDD)、固态硬盘 (SSD)、光盘和云存储；主要比较指标有容量、速度、耐用性和便携性。

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2. System Software | 系统软件

The operating system (OS) manages hardware resources, provides a user interface, handles peripheral management, memory management and multitasking.

操作系统 (OS) 管理硬件资源、提供用户界面、处理外设管理、内存管理和多任务处理。

Utility software includes disk defragmenters, backup tools, encryption software and antivirus programs, all designed to maintain system health.

实用程序包括磁盘碎片整理工具、备份软件、加密软件和防病毒程序，用于维护系统健康。

A compiler translates an entire high-level source code into machine code before execution, whereas an interpreter translates and executes line by line, making debugging easier but runtime slower.

编译器在执行前将整个高级语言源代码翻译为机器码；解释器则逐行翻译并执行，调试更方便但运行速度较慢。

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3. Number Systems and Text Representation | 数制与文本表示

Binary uses a base of 2 with digits 0 and 1. Hexadecimal (base 16) uses 0-9 and A-F, where one hex digit represents a nibble (4 bits).

二进制基数为 2，使用 0 和 1；十六进制基数为 16，使用 0-9 和 A-F，一个十六进制位表示 4 个比特（半字节）。

To convert binary to denary, sum the place values (e.g., 128, 64, 32, 16, 8, 4, 2, 1) for every 1. Denary to binary uses successive subtraction of the largest power of 2.

二进制转十进制：将所有值为 1 的位权（如 128, 64, 32, 16, 8, 4, 2, 1）相加；十进制转二进制：连续减去可容纳的最大 2 的幂。

Binary addition follows the rules 0+0=0, 0+1=1, 1+1=0 carry 1, 1+1+1=1 carry 1. Overflow occurs when a calculation produces a result larger than the allocated number of bits can store.

二进制加法规则：0+0=0, 0+1=1, 1+1=0 进位 1, 1+1+1=1 进位 1。当运算结果超出分配位数可存储的范围时会产生溢出。

The ASCII character set uses 7 bits to encode 128 characters; extended ASCII uses 8 bits (256 characters). Unicode (e.g., UTF-8) supports a huge range of symbols and international characters.

ASCII 字符集用 7 位编码 128 个字符；扩展 ASCII 用 8 位（256 个字符）。Unicode（如 UTF-8）支持海量符号和多国文字。

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4. Image and Sound Representation | 图像与声音表示

A bitmap image is a grid of pixels; its resolution is width × height. Colour depth measured in bits per pixel determines the number of colours possible: 2ᵇ colours for b-bit depth.

位图图像是像素网格，分辨率为宽度 × 高度。以每像素位数为单位的颜色深度决定了可能的颜色数：b 位深度可显示 2ᵇ 种颜色。

Bitmap file size (bytes) = (width × height × colour depth) ÷ 8. Metadata stores additional properties such as dimensions and colour depth.

位图文件大小（字节）= (宽 × 高 × 颜色深度) ÷ 8。元数据存储尺寸和颜色深度等附加属性。

Sound is digitised by sampling the analogue signal at regular intervals. Sample rate measured in Hz and bit depth together determine the accuracy and file size.

声音通过定期对模拟信号采样实现数字化；采样率（Hz）和位深度共同决定声音的精确度和文件大小。

Sound file size (bits) = sample rate × bit depth × duration in seconds × number of channels. Higher sample rates and bit depths produce truer recordings but result in larger files.

声音文件大小（位）= 采样率 × 位深度 × 时长（秒）× 声道数。更高的采样率和位深度能生成更逼真的录音，但文件也会更大。

Compression can be lossless (reduces file size without quality loss, e.g., PNG, FLAC) or lossy (permanently removes some data, e.g., JPEG, MP3).

压缩分为无损压缩（减小文件但无质量损失，如 PNG、FLAC）和有损压缩（永久移除部分数据，如 JPEG、MP3）。

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5. Logic Gates and Truth Tables | 逻辑门与真值表

A NOT gate outputs the logical opposite: input 0 gives 1, input 1 gives 0. An AND gate outputs 1 only when every input is 1.

非门输出逻辑相反值：输入 0 得 1，输入 1 得 0。与门仅在所有输入均为 1 时输出 1。

An OR gate outputs 1 if at least one input is 1. A NAND gate is an AND followed by NOT, and a NOR gate is an OR followed by NOT.

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