📚 Year 13 OCR Computer Science: Key Terms & Memorisation Guide | A Level OCR 计算机科学：核心术语速记指南
Mastering the terminology is essential for success in the OCR A Level Computer Science examination. This guide organises the most frequently tested key terms into thematic sections, each presented with a concise English definition followed by its Chinese equivalent. Use these pairings to build a solid mental glossary that will support your understanding across all components — from the inner workings of the processor to abstract problem-solving techniques.
掌握术语是 OCR A Level 计算机科学考试取得成功的关键。本指南将最常考查的核心术语按主题组织章节，每个术语先给出简明的英文定义，再配以对应的中文解释。利用这些中英配对术语，你可以构建扎实的思维词库，支撑从处理器内部机制到抽象问题求解各个模块的理解。
1. Computer Architecture & CPU | 计算机体系结构与中央处理器
The CPU is the heart of any computer system, executing instructions using registers, buses, and control signals. Understanding its internal components and the fetch-decode-execute cycle is foundational for Year 13 topics like pipelining and processor performance.
CPU 是任何计算机系统的心脏，它利用寄存器、总线和控制信号执行指令。理解其内部组件以及取指-译码-执行周期是掌握 Year 13 中诸如流水线和处理器性能等主题的基础。
Central Processing Unit (CPU): The component that fetches, decodes, and executes instructions. It consists of the Control Unit and the Arithmetic Logic Unit.
中央处理器 (CPU)：负责取指、译码和执行指令的部件，由控制单元和算术逻辑单元组成。
Control Unit (CU): Directs the operation of the processor by sending control signals to other components. It coordinates the fetch-decode-execute cycle and manages data flow.
控制单元 (CU)：通过向其他部件发送控制信号来指挥处理器操作，协调取指-译码-执行周期并管理数据流。
Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations, such as addition, subtraction, AND, OR, and comparisons. It receives data from registers and outputs results to the accumulator.
算术逻辑单元 (ALU)：执行算术和逻辑运算，如加、减、与、或及比较操作。它从寄存器获取数据，并将结果输出到累加器。
Program Counter (PC): A register that holds the memory address of the next instruction to be executed. It is incremented automatically after each fetch.
程序计数器 (PC)：存放下一要执行指令的内存地址的寄存器，每次取指后自动递增。
Memory Address Register (MAR): Holds the address of the memory location that is currently being read from or written to.
内存地址寄存器 (MAR)：保存当前正在读取或写入的内存单元的地址。
Memory Data Register (MDR): Temporarily stores the data that has been read from or is about to be written to memory.
内存数据寄存器 (MDR)：临时存储刚从内存读出或即将写入内存的数据。
Current Instruction Register (CIR): Stores the actual instruction currently being decoded and executed by the CPU.
当前指令寄存器 (CIR)：保存 CPU 正在译码并执行的实际指令。
Accumulator (ACC): A register that temporarily holds the results of operations performed by the ALU.
累加器 (ACC)：暂存 ALU 运算结果的寄存器。
Fetch-Decode-Execute Cycle: The continuous process by which the CPU retrieves an instruction from memory, interprets it, and carries out the required action.
取指-译码-执行周期：CPU 从内存取出一条指令、解释该指令并执行相应操作的连续过程。
Pipelining: A technique in which multiple instructions are overlapped in execution by splitting the processor into stages, improving throughput but potentially causing data dependencies.
流水线：一种将处理器划分为多个阶段、使多条指令重叠执行的技术，可提高吞吐量，但可能引发数据依赖问题。
2. Memory & Storage | 内存与存储器
Memory and storage technologies determine how data and instructions are retained, accessed, and managed. Key distinctions between volatile RAM, non-volatile ROM, and secondary storage like SSDs are vital for system optimisation questions.
内存与存储技术决定了数据和指令如何被保存、访问和管理。易失性 RAM、非易失性 ROM 以及 SSD 等辅助存储器之间的关键区别对于系统优化类问题至关重要。
Random Access Memory (RAM): Volatile memory used to store data and programs that are currently in use. It can be read from and written to, and its contents are lost when power is turned off.
随机存取存储器 (RAM)：用于存储当前正在使用的数据和程序的易失性存储器，可读写，断电后内容丢失。
Read-Only Memory (ROM): Non-volatile memory that retains its contents when the power is off. It typically stores the bootstrap loader and firmware.
只读存储器 (ROM)：非易失性存储器，断电后仍保留内容，通常存储引导程序和固件。
Virtual Memory: A technique that uses a portion of secondary storage as if it were RAM, allowing the system to run larger programs or multiple programs simultaneously when physical memory is insufficient.
虚拟内存：利用部分辅助存储空间模拟 RAM 的技术，当物理内存不足时，使系统能运行更大的程序或同时运行多个程序。
Cache Memory: A small, high-speed memory located close to the CPU that stores frequently accessed instructions and data to reduce average memory access time.
高速缓存：位于 CPU 附近的小容量高速存储器，存放频繁访问的指令和数据，以降低平均内存访问时间。
Solid State Drive (SSD): Non-volatile storage that uses flash memory to store data. It has no moving parts, resulting in faster access times and lower power consumption compared to magnetic hard drives.
固态硬盘 (SSD)：采用闪存存储数据的非易失性设备，无移动部件，访问速度更快，功耗比机械硬盘更低。
Magnetic Hard Disk Drive (HDD): A storage device that uses spinning platters coated with magnetic material and a read/write head to access data. It offers high capacity at lower cost but is slower than SSDs.
机械硬盘 (HDD)：通过涂覆磁性材料的旋转盘片和读写头访问数据的存储设备，容量大、成本低，但速度慢于 SSD。
Cloud Storage: Remote storage provided by third-party servers accessed over the internet, offering scalability, accessibility, and off-site backup.
云存储：由第三方服务器通过互联网提供的远程存储服务，具有可扩展性、便捷访问和异地备份等优点。
3. Systems Software & Operating Systems | 系统软件与操作系统
The operating system is the supervisor that manages hardware resources, provides a user interface, and enables application execution. Together with utilities, compilers, and interpreters, systems software forms the essential bridge between user and machine.
操作系统是管理硬件资源、提供用户界面并支持应用程序运行的监管者。连同实用程序、编译器和解释器在内，系统软件构成了用户与机器之间必不可少的桥梁。
Operating System (OS): Software that manages computer hardware, runs application programs, and provides common services such as file management, memory management, and process scheduling.
操作系统 (OS)：管理计算机硬件、运行应用程序并提供文件管理、内存管理和进程调度等公共服务的软件。
Kernel: The core of the operating system that remains in main memory and controls all critical operations, including process management, memory allocation, and I/O handling.
内核：操作系统的核心，常驻内存，控制进程管理、内存分配和 I/O 处理等所有关键操作。
Device Driver: A specialized program that allows the operating system to communicate with and control a specific hardware device, such as a printer or graphics card.
设备驱动程序：使操作系统能够与特定硬件设备（如打印机或显卡）通信并控制其工作的专用程序。
Virtual Machine: A software emulation of a physical computer that runs an operating system and applications as if they were on separate hardware, enabling isolation and cross-platform execution.
虚拟机：对物理计算机的软件仿真，可运行操作系统和应用程序，仿佛它们位于独立硬件上，实现隔离和跨平台执行。
Compiler: Translates the entire source code of a high-level language into machine code or object code in one batch, generating an executable file that can run independently of the compiler.
编译器：将高级语言的全部源代码一次性翻译为机器码或目标代码，生成可独立于编译器运行的可执行文件。
Interpreter: Executes source code line by line, translating and carrying out each instruction immediately without producing a standalone executable. This allows easier debugging but results in slower overall execution.
解释器：逐行执行源代码，即时翻译并执行每条指令，不生成独立可执行文件，便于调试但整体执行速度较慢。
Assembler: Converts assembly language mnemonics into machine code. Each assembly instruction typically represents one machine instruction.
汇编器：将汇编语言助记符转换为机器码，每条汇编指令通常对应一条机器指令。
Interrupt: A signal sent to the CPU by hardware or software indicating an event that needs immediate attention. The CPU suspends the current task, saves its state, and executes an interrupt service routine.
中断：由硬件或软件向 CPU 发送的信号，指示有事件需立即处理。CPU 暂停当前任务，保存状态并执行中断服务程序。
4. Data Representation & Compression | 数据表示与压缩
Numbers, text, sound, and images are encoded in binary. Understanding positional number systems like binary and hexadecimal, together with concepts such as two’s complement and floating-point representation, is crucial for analysing how data is stored and transmitted.
数字、文本、声音和图像均以二进制编码。理解二进制和十六进制等位置记数系统，以及补码和浮点表示等概念，对分析数据的存储与传输至关重要。
Binary: A base-2 number system using only the digits 0 and 1. All data in a computer is ultimately represented as sequences of binary digits (bits).
二进制：仅使用数字 0 和 1 的基-2 计数系统，计算机中所有数据最终均表示为二进制位序列。
Hexadecimal: A base-16 number system employing digits 0-9 and letters A-F to represent values 0-15. It provides a compact human-readable shorthand for binary sequences, with each hex digit representing four bits.
十六进制：基-16 计数系统，使用数字 0-9 和字母 A-F 表示 0-15 的值，每十六进制位代表四个二进制位，是二进制序列的紧凑可读简写。
Two’s Complement: A method of representing signed integers in binary, where the most significant bit acts as the sign bit. Negative values are formed by inverting all bits and adding 1, which simplifies arithmetic operations in hardware.
二进制补码：一种用二进制表示有符号整数的方法，最高位为符号位，负值通过将所有位取反再加 1 得到，简化了硬件中的算术运算。
Floating-Point Representation: Stores real numbers using a mantissa (the significant digits) and an exponent (the power of two by which the mantissa is multiplied). The binary point ‘floats’ according to the exponent, allowing a wide dynamic range.
浮点表示：使用尾数（有效数字）和指数（尾数乘以2的幂）存储实数，小数点根据指数“浮动”，以提供宽广的动态范围。
ASCII: A 7-bit or 8-bit standard code that represents English characters, digits, and punctuation as binary numbers. It forms the basis of many text encoding schemes.
ASCII：一种 7 位或 8 位标准编码，用二进制数表示英文字符、数字和标点符号，是众多文本编码方案的基础。
Unicode: A comprehensive character set designed to represent text from all writing systems worldwide. Common encodings include UTF-8 and UTF-16, which use variable-length byte sequences to accommodate thousands of characters.
Unicode：为表示全球所有书写系统文本而设计的综合字符集，常用编码有 UTF-8 和 UTF-16，使用变长字节序列容纳数千种字符。
Lossy Compression: Reduces file size by permanently discarding some data that is deemed less perceptible, such as high-frequency sound details in MP3 or colour variations in JPEG. The original data cannot be perfectly reconstructed.
有损压缩：通过永久丢弃某些感知度较低的数据（如 MP3 中的高频声音细节或 JPEG 中的色彩变化）减小文件大小，原始数据无法无失真地重建。
Lossless Compression: Shrinks file size by encoding patterns without losing any original information. Run-length encoding and Huffman coding are typical examples; the decompressed file is identical to the original.
无损压缩：通过编码模式减小文件大小但不丢失任何原始信息，游程编码和霍夫曼编码为典型例子，解压后文件与原始文件完全一致。
Huffman Coding: A lossless compression algorithm that assigns variable-length binary codes to symbols based on their frequency of occurrence. More frequent symbols receive shorter codes, optimising overall bit count.
霍夫曼编码：一种无损压缩算法，根据符号出现频率分配变长二进制代码，高频符号获得较短编码，从而优化总比特数。
5. Boolean Algebra & Logic Gates | 布尔代数与逻辑门
Boolean algebra underpins digital circuit design and programming conditions. Logic gates like AND, OR, NOT, NAND, and XOR implement these functions in hardware. De Morgan’s laws and truth tables are frequently assessed tools for simplification and equivalence proofs.
布尔代数支撑着数字电路设计和程序中的条件表达式。与、或、非、与非及异或等逻辑门在硬件中实现这些函数。德·摩根定律和真值表是简化与等价证明中常考的工具。
Logic Gate: An elementary building block of a digital circuit that performs a basic Boolean function on one or more binary inputs and produces a single binary output.
逻辑门：数字电路的基本构建块，对一个或多个二进制输入执行基本的布尔函数并产生单个二进制输出。
AND Gate: Outputs 1 if and only if all inputs are 1. Symbol: A∧B; often drawn as a flat-ended wedge shape.
与门：当且仅当所有输入为1时输出1。符号：A∧B，常用平头楔形符号表示。
OR Gate: Outputs 1 if at least one input is 1. Symbol: A∨B; represented by a curved wedge shape with the output on the pointed side.
或门：至少一个输入为1时输出1。符号：A∨B，用带弧形的楔形表示。
NOT Gate: An inverter that outputs the complement of its single input. Symbol: ¬A or a triangle with a bubble.
非门：取反器，输出其单个输入的补值。符号：¬A 或带小圆圈的三角形。
NAND Gate: Outputs 0 only when all inputs are 1; it is the inverse of the AND gate. NAND is functionally complete, meaning any Boolean function can be constructed using only NAND gates.
与非门：仅当所有输入为1时输出0，是与门的取反。与非门是功能完备的，意味着仅用与非门就可以构建任何布尔函数。
XOR Gate: Outputs 1 if an odd number of inputs are 1; for two inputs, it acts as a selective switch, giving 1 when inputs differ.
异或门：输入中1的个数为奇数时输出1；对于两个输入，当输入相异时输出1，起到选择性开关作用。
Truth Table: A systematic table listing all possible input combinations and the corresponding output for a Boolean expression or logic circuit. Used for verification and simplification.
真值表：列出布尔表达式或逻辑电路所有可能输入组合及相应输出的系统表，用于验证和化简。
De Morgan’s Laws: ¬(A ∧ B) = ¬A ∨ ¬B and ¬(A ∨ B) = ¬A ∧ ¬B. These rules enable the transformation of AND/NAND expressions into their OR/NOR equivalents, which is useful for minimising gate count.
德·摩根定律：¬(A ∧ B) = ¬A ∨ ¬B 以及 ¬(A ∨ B) = ¬A ∧ ¬B。这些规则可将“与/与非”表达式转换为对应的“或/或非”表达式，有助于减少门电路数量。
Half Adder: A combinational circuit that adds two single binary digits and produces a sum bit and a carry bit. It lacks a carry-in input and often serves as a building block for full adders.
半加器：将两个二进制数字相加并产生和位与进位位的组合电路，没有进位输入，常用作全加器的构建模块。
6. Networks & the Internet | 网络与互联网
A firm grasp of networking concepts—from protocols like TCP/IP and HTTP to devices such as switches and routers—enables you to analyse how data travels across LANs and the Internet. The OSI and TCP/IP models provide a layered framework for understanding communication.
牢固掌握网络概念——从 TCP/IP、HTTP 等协议到交换机、路由器等设备——能帮助你分析数据如何在局域网和互联网中传输。OSI 和 TCP/IP 模型为理解通信提供了分层框架。
LAN (Local Area Network): A network that connects computers and devices within a limited geographical area, such as a single building, using Ethernet or Wi-Fi.
局域网 (LAN)：在有限地理范围（如单幢建筑）内使用以太网或 Wi-Fi 连接计算机设备的网络。
WAN (Wide Area Network): A network that spans a large geographical area, often comprising multiple LANs connected by leased lines, fibre, or satellite links. The Internet is the largest WAN.
广域网 (WAN)：覆盖广大地理区域的网络，通常由多个局域网通过租用线路、光纤或卫星链路互联而成，互联网是最大的广域网。
TCP/IP Stack: A suite of communication protocols organised into four layers: Application, Transport, Internet, and Link. It forms the foundation of the Internet, with TCP ensuring reliable, ordered delivery and IP handling addressing and routing.
TCP/IP 协议栈：一套分为应用层、传输层、互联网层和链路层四层的通信协议，是互联网的基础，其中 TCP 确保可靠有序传输，IP 处理寻址和路由。
IP Address: A numeric label assigned to each device connected to a network that uses the Internet Protocol for communication. IPv4 addresses are 32-bit, while IPv6 uses 128 bits to accommodate more devices.
IP 地址：分配给使用互联网协议通信的每个网络设备的数字标签，IPv4 地址为 32 位，IPv6 采用 128 位以容纳更多设备。
MAC Address: A unique 48-bit hardware identifier assigned to a network interface controller, used for communication within the same local network segment.
MAC 地址：分配给网络接口控制器的唯一 48 位硬件标识符，用于同一局域网段内的通信。
DNS (Domain Name System): A hierarchical naming system that translates human-friendly domain names (e.g., aleveler.com) into IP addresses, acting as the internet’s phonebook.
域名系统 (DNS)：将易于记忆的域名（如 aleveler.com）转换为 IP 地址的分层命名系统，充当互联网的电话簿。
Packet Switching: A network communication method where data is split into small packets that travel independently across the network. Each packet may follow a different route and is reassembled at the destination, using information in the packet header.
分组交换：一种网络通信方式，数据被拆分为独立传输的小数据包，每个包可能经由不同路径，在目的地根据包头信息重新组装。
Firewall: A hardware or software security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules, blocking unauthorised access.
防火墙：基于预定义安全规则监控并控制进出网络流量的硬件或软件安全系统，可阻止未授权访问。
HTTP/HTTPS: Hypertext Transfer Protocol is the foundation of data communication on the web. HTTPS adds a layer of encryption via SSL/TLS to secure the connection, indicated by a padlock icon in the browser.
HTTP/HTTPS：超文本传输协议是 Web 数据通信的基础，HTTPS 通过 SSL/TLS 增加加密层以保护连接安全，浏览器地址栏中显示挂锁图标。
7. Databases & SQL | 数据库与结构化查询语言
Relational databases organise data into tables linked by keys, ensuring data integrity through normalisation. SQL is the standard language for querying and manipulating these databases. Recognising primary and foreign keys, JOIN operations, and normal forms is essential for the exam.
关系数据库通过键将数据组织成相互关联的表，并通过规范化保证数据完整性。SQL 是查询和操作这些数据库的标准语言。识别主键、外键、连接操作以及范式对考试至关重要。
Relational Database: A database structured to recognise relations among stored items of information, using tables with rows (records) and columns (fields). Data is accessed without reorganising the database tables.
关系数据库：一种结构化的数据库，能够识别存储信息项之间的关联，使用由行（记录）和列（字段）组成的表，可在不重新组织表的情况下访问数据。
Primary Key: A field or combination of fields that uniquely identifies each record in a table. It must contain unique, non-null values for every row.
主键：一个或一组字段，唯一标识表中每条记录，必须包含唯一且非空的值。
Foreign Key: A field in one table that refers to the primary key of another table, establishing a link between the two tables and enforcing referential integrity.
外键：一张表中的字段，引用另一张表的主键，建立两表之间的关联并强制执行引用完整性。
Normalisation: The process of organising data to reduce redundancy and dependency. Successive normal forms (1NF, 2NF, 3NF) eliminate repeating groups, partial dependencies, and non-key dependencies.
规范化：通过减少冗余和依赖来组织数据的过程，依次达到 1NF、2NF、3NF 等范式，以消除重复组、部分依赖和非主键依赖。
SQL (Structured Query Language): A declarative language used to interact with relational databases, supporting data definition, manipulation, and control via commands such as SELECT, INSERT, UPDATE, DELETE, and CREATE.
结构化查询语言 (SQL)：一种用于与关系数据库交互的声明式语言，通过 SELECT、INSERT、UPDATE、DELETE、CREATE 等命令支持数据定义、操作和控制。
JOIN Clause: An SQL operation that combines rows from two or more tables based on a related column. Common types include INNER JOIN (returns matching rows only), LEFT JOIN, RIGHT JOIN, and FULL JOIN.
连接子句 (JOIN)：根据相关列组合两个或多个表中行的 SQL 操作，常见类型有 INNER JOIN（只返回匹配行
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