【IGCSE计算机】9608理论卷一真题精讲：内存、图像与网络 | IGCSE CS 9608 Paper 1: Memory, Graphics & Networks

📘 引言 | Introduction

Cambridge IGCSE / AS-Level 计算机科学9608 Paper 1（Theory Fundamentals）是考试中的理论核心卷。本文基于2021年冬季真题（9608/w21/qp/12），逐题解析内存架构、图像编码、网络拓扑等高频考点，助你考前冲刺。

Cambridge IGCSE / AS-Level Computer Science 9608 Paper 1 (Theory Fundamentals) is the theoretical core of the exam. Based on the October/November 2021 past paper (9608/w21/qp/12), this article breaks down high-frequency topics like memory architecture, image encoding, and network topologies to boost your exam readiness.

🔑 核心考点解析 | Key Exam Topics

1. RAM vs ROM：内存基础 | Memory Fundamentals

考试必考！需牢记：RAM是易失性（volatile）主存，存储当前运行的应用和数据；ROM是非易失性，存储启动指令（BIOS/UEFI）。两者都直接由CPU访问，都属于主存（Main Memory）。RAM还可分为静态RAM（SRAM）和动态RAM（DRAM）。

A must-know topic! Remember: RAM is volatile main memory storing currently running applications and data; ROM is non-volatile, storing boot instructions (BIOS/UEFI). Both are directly accessed by the CPU and are types of main memory. RAM further splits into static RAM (SRAM) and dynamic RAM (DRAM).

2. 位图图像编码 | Bitmap Image Encoding

位图由像素（Pixels）组成。每个像素所需的位数（bit depth）决定可显示的颜色数：n bits → 2ⁿ 种颜色。例如，3位可表示8色，8位可表示256色。考试中常要求计算图像文件大小：宽度×高度×位深（bits），再转换为字节。

A bitmap consists of pixels. The bit depth per pixel determines the number of displayable colors: n bits → 2ⁿ colors. For example, 3 bits = 8 colors, 8 bits = 256 colors. Exams often ask for file size calculation: width × height × bit depth (in bits), then convert to bytes.

3. 网络拓扑与数据传输 | Network Topologies & Data Transmission

常见考点包括：星型拓扑（Star）——所有节点连接至中心交换机，单点故障不影响其他节点；总线拓扑（Bus）——共享通信线路，成本低但冲突多。理解串行 vs 并行传输的适用场景，以及半双工 vs 全双工的区别。

Common topics: Star topology — all nodes connect to a central switch, single node failure doesn’t affect others; Bus topology — shared communication line, low cost but more collisions. Understand serial vs parallel transmission use cases and the difference between half-duplex and full-duplex communication.

4. 逻辑门与布尔代数 | Logic Gates & Boolean Algebra

9608 Paper 1 经常出现AND、OR、NOT、NAND、NOR、XOR等逻辑门相关的真值表和电路图题目。掌握德摩根定律（De Morgan’s Laws）和布尔表达式化简技巧至关重要。

9608 Paper 1 frequently features truth tables and circuit diagrams involving AND, OR, NOT, NAND, NOR, XOR gates. Mastering De Morgan’s Laws and Boolean expression simplification is crucial for scoring well.

5. 考试技巧 | Exam Technique

9608 Paper 1 共75分，1小时30分钟，平均每题约1.2分钟。注意：软件/硬件品牌名称不得分——必须使用通用术语（如”word processor”而非”Microsoft Word”）。答题时看清分值（括号内数字）决定详略程度。

9608 Paper 1 is 75 marks in 1 hour 30 minutes, averaging ~1.2 minutes per mark. Critical tip: brand names of software or hardware earn zero marks — use generic terms (e.g., “word processor” not “Microsoft Word”). Check the mark allocation in brackets to gauge required detail level.

💡 备考建议 | Study Tips

• ✅ 熟记RAM/ROM对比表——几乎每卷必出
• ✅ 练熟位图文件大小计算公式：W × H × bit depth / 8 = bytes
• ✅ 绘制并标注常见网络拓扑图（Star, Bus, Mesh）
• ✅ 掌握逻辑门符号和真值表，练习电路→表达式→真值表的完整流程
• ✅ 刷近3年Past Papers，注意评分标准中的关键词
• ✅ Memorize the RAM/ROM comparison table — appears in almost every paper
• ✅ Master bitmap file size: W × H × bit depth / 8 = bytes
• ✅ Draw and label common network topologies (Star, Bus, Mesh)
• ✅ Drill logic gate symbols, truth tables, and the full circuit→expression→truth table workflow
• ✅ Practice the last 3 years of past papers, paying attention to mark scheme keywords

📚 相关资源 | Past Papers

访问本站IGCSE / GCSE计算机科学专栏，下载完整9608 Past Papers及详细答案解析！

Visit our IGCSE / GCSE Computer Science section to download full 9608 past papers with detailed answer breakdowns!

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