End of Unit 4: Exam-style Case Study Questions | 单元4复习：考试风格案例研究题

📚 End of Unit 4: Exam-style Case Study Questions | 单元4复习：考试风格案例研究题

Exam-style case study questions in Unit 4 often present a small computer system, such as a vending machine, a greenhouse controller, or a robotic arm, and ask you to apply processor fundamentals to that context. This article helps you revise the core ideas, read scenarios efficiently, and write answers that match Cambridge mark schemes.

单元4的考试风格案例研究题通常会给出一个小型计算机系统，例如自动售货机、温室控制器或机械臂，并要求你把处理器基础知识应用到该情境中。本文帮助你复习核心概念、高效阅读场景，并写出符合剑桥评分标准的答案。

1. What Are Exam-style Case Study Questions? | 什么是考试风格案例研究题

In Cambridge A Level Computer Science (9618), Unit 4 covers processor fundamentals. Exam-style case study questions combine a short narrative with technical tasks such as identifying registers, completing fetch-decode-execute sequences, writing assembly language fragments, or explaining interrupts. The scenario is not decoration – it determines which details matter.

在剑桥A Level计算机科学(9618)中，单元4涵盖处理器基础知识。考试风格案例研究题把简短叙述与技术要求结合起来，例如识别寄存器、补全取指-译码-执行序列、编写汇编语言片段或解释中断。场景不是装饰，它决定了哪些细节重要。

Typical contexts include embedded systems, control systems, and simple CPU simulations. For example, a question might describe a coffee machine that uses a processor to check water temperature every second. You then need to link the description to the accumulator, status register, and interrupt mechanism.

典型情境包括嵌入式系统、控制系统和简单CPU模拟。例如，题目可能描述一台咖啡机使用处理器每秒检测水温。然后你需要把该描述与累加器、状态寄存器和中断机制联系起来。

2. Core Syllabus Focus of Unit 4 | 单元4核心考点

Before tackling a case study, make sure you can define the key components without hesitation: the control unit, arithmetic logic unit (ALU), registers, system buses, and the stored-program concept. Cambridge questions regularly ask you to state the role of the program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR), accumulator (ACC), and status register.

在处理案例研究之前，确保你能毫不犹豫地定义关键部件：控制单元、算术逻辑单元(ALU)、寄存器、系统总线以及存储程序概念。剑桥试题经常要求你说明程序计数器(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)、累加器(ACC)和状态寄存器的作用。

You should also understand how bus width affects performance and addressing capacity. A system with n address lines can address 2ⁿ memory locations. This is a common calculation embedded in case studies.

你还应理解总线宽度如何影响性能和

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