AS OCR Computer Science: Core Knowledge Points Review | AS OCR 计算机核心知识点梳理

📚 AS OCR Computer Science: Core Knowledge Points Review | AS OCR 计算机核心知识点梳理

This article summarises the core knowledge points of the AS OCR Computer Science specification, covering both the Computing Principles and Algorithms and Problem Solving components. It provides a bilingual revision guide to help students consolidate their understanding of hardware, software, data, networks, programming, and ethical issues.

本文梳理了 AS OCR 计算机科学课程的核心知识点，涵盖计算机原理以及算法与问题求解两大组成部分。通过双语复习指南，帮助学生巩固对硬件、软件、数据、网络、编程与伦理问题的理解。

1. Processor Architecture and the FDE Cycle | 处理器架构与取指-译码-执行周期

The classic von Neumann architecture stores both instructions and data in the same memory, using a single shared bus. Key special-purpose registers include the Program Counter (PC) that holds the address of the next instruction, the Memory Address Register (MAR) that holds the address of the memory location to be read or written, the Memory Data Register (MDR) that stores the data being transferred to or from memory, the Current Instruction Register (CIR) that holds the current instruction being executed, and the Accumulator (ACC) that stores results of arithmetic and logic operations.

经典的冯·诺依曼架构将指令和数据存储在同一内存中，使用一条共享总线。关键专用寄存器包括：程序计数器 (PC) 保存下一条指令的地址；内存地址寄存器 (MAR) 保存要读或写的内存单元地址；内存数据寄存器 (MDR) 存储与内存之间传输的数据；当前指令寄存器 (CIR) 保存正在执行的指令；累加器 (ACC) 存储算术逻辑运算的结果。

The Fetch-Decode-Execute (FDE) cycle continuously repeats: Fetch – the instruction addressed by PC is loaded into the CIR via MAR and MDR, and PC is incremented. Decode – the control unit interprets the opcode and operand. Execute – the relevant circuitry carries out the operation, which may involve the ALU and ACC.

取指-译码-执行 (FDE) 周期不断重复：取指 – 通过 MAR 和 MDR 将 PC 所指指令加载至 CIR，PC 自增；译码 – 控制单元解释操作码和操作数；执行 – 相应电路执行

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