📚 Year 13 CCEA Computer Science: Terminology Quick Guide | Year 13 CCEA 计算机：词汇术语速记指南
Mastering computer science terminology is crucial for success in Year 13 CCEA exams. This guide provides memorable explanations for key terms across the syllabus, paired with mnemonic devices and practical contexts to help you retain them faster.
掌握计算机科学术语对于在 Year 13 CCEA 考试中取得成功至关重要。本指南为全课程关键术语提供易记的解释，配合助记技巧和实际语境，帮助你更快记住它们。
1. Data Representation | 数据表示
Bit: Short for binary digit, the smallest unit of data (0 or 1). Think: 'BIt' = BInary digiT.
位 (Bit)：二进制数字的简称，最小的数据单位（0 或 1）。联想：'Bit' = Binary digit 的缩写。
Byte: A group of 8 bits. Mnemonic: "8 bits take a Byte out of data."
字节 (Byte)：由 8 个位组成。助记：“8 个比特一起‘咬’下一大块数据”，英文 Byte 谐音 bite。
Nibble: Half a byte, 4 bits. Think of a 'nibble' as a small bite.
半字节 (Nibble)：4 个位，是字节的一半。英文 nibble 是“小口咬”，正好比 byte 小。
Kilobyte (KB): 1024 bytes, not 1000, due to binary nature (210). Just remember 2¹⁰ = 1024.
千字节 (KB)：1024 字节，不是 1000，因为计算机采用二进制，2¹⁰ = 1024。
Binary: Base-2 number system using 0 and 1. Easy recall: 'bi' means two.
二进制：基数为 2 的数字系统，只用 0 和 1。'bi' 表示二。
Hexadecimal: Base-16 system using 0–9 and A–F. One hex digit represents exactly 4 bits – a nibble.
十六进制：基数为 16，使用 0–9 和 A–F。每一个十六进制位正好代表 4 个二进制位（一个半字节）。
| Decimal | Binary | Hexadecimal |
|---|---|---|
| 10 | 1010 | A |
| 15 | 1111 | F |
Two's complement: Method to represent negative integers in binary. Quick rule: flip all bits and add 1.
二进制补码：表示负整数的方法。速记口诀：所有位取反，再加 1。
Floating point: Stores real numbers as mantissa × 2exponent. Think: 'mantissa' moves the point.
浮点数：用尾数 × 2指数 存储实数。尾数尾数，小数点浮动，指数给出次数。
ASCII: 7-bit character set for English text. Extended to 8 bits. Mnemonic: American Standard Code.
ASCII码：7 位英文字符集，后扩展至 8 位。记法：美国标准信息交换码。
Unicode: Universal character set covering most world scripts. Usage memory: UTF-8 variable 1–4 bytes.
Unicode：通用字符集覆盖大多数文字。UTF-8 变长编码 1–4 字节，节省空间。
Overflow: Error when a calculation result exceeds the allocated bit width. Imagine a cup overflowing.
溢出：计算结果超出分配的位宽时出错。就像杯子水满溢出。
Sampling al by taking amplitude measurements at intervals. Sampling rate = samples per second (Hz).
采样：按固定间隔测量模拟声音的振幅，将其转换为数字信号。采样率单位赫兹。速率越高音质越好。
Resolution: Number of bits per sample; higher resolution captures finer detail. Think: more bits per pixel in images.
分辨率：每个采样的位数；分辨率越高，细节越精细。联想图像中的像素位深。
2. Programming Fundamentals | 编程基础
Variable: A named storage location whose value can change during execution. Think: a labeled box.
变量：命名的存储位置，其值在程序运行中可以改变。想象成一个贴了标签的盒子。
Constant: Similar to a variable but its value cannot be changed after initialisation. Use keyword 'const' or 'final'.
常量：类似于变量，但初始化后值不可更改。联想：“恒定不变”。
Data type: Defines what kind of data a variable can hold (integer, real/float, Boolean, char, string).
数据类型：定义变量可以存放的数据种类，如整型、实型、布尔型、字符、字符串。
Selection: Making decisions using IF, ELSE IF, ELSE, or SWITCH/CASE statements. 'If this, do that'.
选择结构：使用 if、else if、else 或 switch/case 做判断。就是“如果……就……”。
Iteration: Repeated execution of a block of code – oops (count-controlled), WHILE, DO...WHILE (condition-controlled). Repetition = iteration.
迭代：重复执行一段代码——for 循环（计数控制），while 和 do…while 循环（条件控制）。重复就是迭代。
Subroutine: A named block of code that performs a specific task. Two types: procedures (no return value) and functions (return a value).
子程序：执行特定任务的命名代码块。分为过程（不返回值）和函数（返回值）。
Parameter passing: By value (a copy is passed, original unchanged) vs by reference (address passed, original can change).
参数传递：按值传递（传递副本，原值不变）与按引用传递（传递地址，可改变原值）。
Scope: The region of program where a variable is accessible. Local: inside a subroutine; Global: whole program.
作用域：变量可被访问的程序区域。局部变量在子程序内，全局变量在整个程序。
IDE: Integrated Development Environment – editor, compiler/interpreter, debugger, syntax highlighting, autocomplete in one tool.
集成开发环境：集成编辑器、编译器/解释器、调试器等功能的工具。一站式编程。
3. Data Structures | 数据结构
Array: Fixed-size, contiguous block of elements of the same data type, accessed by index. Think: a row of lockers.
数组：固定大小、连续存储、同类型元素，通过索引访问。像一排储物柜，按号码取物。
Linked list: Dynamic structure where each node contains data and a pointer/address to the next node. Can grow/shrink easily.
链表：动态结构，每个节点含数据和指向下一节点的指针。插入删除灵活，但无法直接随机访问。
Stack: LIFO (Last In First Out) – like a stack of plates. Operations: push (add) and pop (remove). Use for recursion and undo.
栈：后进先出（LIFO），像一叠盘子，入栈 push，出栈 pop。用于递归、撤销操作。
Queue: FIFO (First In First Out) – like a waiting line. Enqueue (add) and dequeue (remove). Think: supermarket checkout.
队列：先进先出（FIFO），像排队买票。入队 enqueue，出队 dequeue。
Binary tree: Hierarchical structure with root, child nodes; each node has at most two children. Binary search tree speeds up searching.
二叉树：分层结构，每个节点最多有两个子节点。二叉搜索树可高效查找，左小右大。
Record: A collection of related fields, possibly of different data types (like a row in a database).
记录：相关字段的集合，字段可以不同类型，类似数据库中的一行。
Dictionary / Map: Key-value pairs for fast lookup. Think: a real dictionary where a word (key) points to definition (value).
字典/映射：键值对结构，通过键快速查找值。如同一本真正的字典，词条索引快速定位释义。
4. Algorithms and Efficiency | 算法与效率
Linear search: Check each element one by one until found. Worst-case O(n). Simple but slow for large data.
线性搜索：从头到尾逐个检查，直到找到。最坏情况 O(n)。数据量大时效率低。
Binary search: On sorted list, repeatedly divide search interval in half. O(log n). Mnemonic: 'binary chop'.
二分搜索：在已排序列表中反复折半比较。时间复杂度 O(log n)。助记：折半查找。
Bubble sort: Repeatedly steps through list, compares adjacent pairs and swaps if out of order. O(n²). Small lists only.
冒泡排序：重复遍历，比较相邻元素并交换。复杂度 O(n²)，适合小数据量。气泡上浮。
Insertion sort: Builds sorted portion by inserting each new element into correct position. O(n²) but efficient for small or nearly sorted data.
插入排序：将每个新元素插入已排序部分的正确位置，O(n²)，对几乎有序数据很快。
Merge sort: Divide and conquer – splits list, sorts halves, merges. Guaranteed O(n log n). Stable. Use extra memory.
归并排序：分治法——先分割再归并。保证 O(n log n)，稳定但需额外内存。
Quick sort: Picks a pivot, partitions array, recursively sorts. Average O(n log n), worst O(n²). Good pivot selection crucial.
快速排序：选基准，分区，递归。平均 O(n log n)，最坏 O(n²)。基准选择是关键。
Big O notation: Describes upper bound of time/space complexity. O(1) constant, O(n) linear, O(n²) quadratic, O(log n) logarithmic. Remember: 'Oh, how bad can it get?'
大 O 表示法：描述时间/空间复杂度的上界。O(1) 常数，O(n) 线性，O(n²) 平方，O(log n) 对数。调侃记忆：'Oh' 多糟糕。
| Algorithm | Best | Average | Worst |
|---|---|---|---|
| Linear Search | O(1) | O(n) | O(n) |
| Binary Search | O(1) | O(log n) | O(log n) |
| Merge Sort | O(n log n) | O(n log n) | O(n log n) |
| Quick Sort | O(n log n) | O(n log n) | O(n²) |
Recursion: A function that calls itself. Needs a base case to stop. Think: Russian dolls. Stack overflow possible if no base case.
递归：函数调用自身，必须有终止条件。像俄罗斯套娃，层层深入，触底返回。缺终止会栈溢出。
5. Computer Architecture | 计算机体系结构
CPU components: ALU (Arithmetic Logic Unit – does maths), Control Unit (CU – directs operations), Registers (fast storage inside CPU).
CPU 组成：ALU 算术逻辑单元（运算），控制单元 CU（指挥），寄存器（临时高速存储）。
Von Neumann architecture: Shared memory for instructions and data. Stored program concept. Remember: 'one bus for both'.
冯·诺依曼体系：指令和数据共用同一内存和总线。存储程序概念。标志：统一的总线。
Fetch-Decode-Execute cycle: CPU fetches instruction from memory, decodes it, executes. Repeats. Mnemonic: FDE forever.
取指-解码-执行周期：CPU 从内存取指令、解码、执行，无限循环。缩写 FDE。
Cache: Small, very fast memory near CPU storing frequently used data. Levels L1, L2, L3. Cache hit vs miss.
缓存：靠近 CPU 的超高速小容量内存，存常用数据。命中率高则速度快，未命中则去主存。
Pipelining: Overlapping instruction execution: while one is decoded, next fetched. Improves throughput. Think: assembly line.
流水线：指令执行重叠，一条解码时下一条已取指。像工厂流水线，提升吞吐量。
CISC vs RISC: CISC (Complex) – many instructions, complex operations; RISC (Reduced) – simple, fixed-length instructions, fast. Remember: 'C' for complex, 'R' for reduced.
CISC 与 RISC：CISC 复杂指令集，指令多多样；RISC 精简指令集，指令简单规整，执行快。
6. System Software and OS | 系统软件与操作系统
Operating System: Manages hardware, runs applications, provides user interface. Functions: memory management, processor scheduling, file management, I/O.
操作系统：管理硬件、运行应用、提供用户界面。功能：内存管理、进程调度、文件系统、输入输出控制。
Memory management: Paging (divides memory into fixed-size pages), Segmentation (divides into logical segments), virtual memory (using disk as extension).
内存管理：分页（固定大小的页框），分段（逻辑段），虚拟内存（用磁盘扩展内存）。
Interrupt: Signal to CPU that needs immediate attention; current task suspended, then resumed. ISR (Interrupt Service Routine).
中断：发给 CPU 的需立即响应的信号，当前任务挂起，执行中断服务程序 ISR 后恢复。
Scheduling: Deciding order of process execution: Round Robin, First Come First Served, Shortest Job First, Priority.
调度：决定进程执行顺序：轮转调度、先来先服务、最短作业优先、优先级调度。
Translators: Compiler translates whole source code to machine code at once (fast execution). Interpreter runs line-by-line (easier debugging). Assembler for assembly code.
翻译器：编译器整篇翻译成机器码（执行快但调试慢），解释器逐行执行（调试方便），汇编器处理汇编语言。
Virtual machine: Software emulating a computer, allowing isolation and running different OS. Think: a computer inside a computer.
虚拟机：软件模拟出计算机，能隔离运行不同操作系统。相当于计算机里再造一台电脑。
7. Networking | 网络
LAN vs WAN: Local Area Network (small area, high speed) vs Wide Area Network (large geographical area, slower).
局域网与广域网：LAN 小范围高速，WAN 大面积连接，通常需租用线路。
Protocols: Set of rules for communication. TCP/IP (Transmission Control Protocol/Internet Protocol) ensures reliable delivery. HTTP for web, FTP for files, SMTP for sending email, POP3/IMAP for receiving.
协议：通信规则集合。TCP/IP 提供可靠传输；HTTP 超文本传输，FTP 文件传输；SMTP 发邮件，POP3/IMAP 收邮件。
TCP/IP layers vs OSI: 4 layers: Application, Transport, Internet, Network Access. Mnemonic: 'All Turtles In Nets'.
TCP/IP 层次：4 层：应用层、传输层、网际层、网络接入层。助记：All Tigers In Nets。
IP address: Unique logical address (IPv4: 32-bit, IPv6: 128-bit). Like postal address on internet.
IP 地址：互联网上每台设备的逻辑地址，IPv4 32 位，IPv6 128 位，好比网络门牌号。
MAC address: Unique hardware identifier burned into NIC. 48-bit hexadecimal. Think: physical identity.
MAC 地址：网卡出厂全球唯一的物理地址，48 位十六进制。硬件身份证。
DNS: Domain Name System translates human-readable names (like google.com) to IP addresses. Like a phonebook.
域名系统 DNS：将域名转换为 IP 地址的电话簿。
Packet switching: Data split into packets, sent independently across network, reassembled at destination. Efficient and robust.
包交换：数据分包独立传输，依据路由到达后重组。高效容错。
Firewall: Monitors and controls incoming/outgoing network traffic based on security rules. Think: a security guard.
防火墙：基于规则监控进出流量，如同安检门。
Encryption: Symmetric uses same key for encrypt/decrypt; asymmetric (public/private key pair) uses different keys. HTTPS uses both.
加密：对称加密用同一密钥加解密；非对称加密用公钥加密、私钥解密。HTTPS 结合两者。
8. Databases | 数据库
Relational database: Organised into tables (relations) with rows (records/tuples) and columns (fields/attributes). Uses keys for linking.
关系型数据库：用表组织数据，表由行（记录/元组）和列（字段/属性）组成，通过键关联。
Primary key: Unique identifier for each record in a table. Cannot be null. Often auto-increment integer.
主键：表中唯一标识每条记录的字段，不可为空，常自增。
Foreign key: A field in one table that refers to the primary key in another table, creating relationships.
外键：一张表中的字段，引用另一张表的主键，实现表间关联。
SQL basics ES (...); UPDATE table SET field=value WHERE condition; DELETE FROM table WHERE condition.
SQL 基础：查询 SELECT，插入 INSERT，更新 UPDATE，删除 DELETE。筛选靠 WHERE。
Normalisation: Process to reduce redundancy and anomalies. 1NF (atomic values, no repeating groups), 2NF (removes partial dependencies), 3NF (removes transitive dependencies).
规范化：减少冗余和异常的过程。1NF 字段原子性，消重复组；2NF 消除部分依赖；3NF 消除传递依赖。
| Normal Form | Key Rule |
|---|---|
| 1NF | Each column contains atomic values; no repeating groups |
| 2NF | 1NF + no partial dependencies on part of composite primary key |
| 3NF | 2NF + no transitive dependencies on non-key attributes |
Index: Data structure that speeds up searching on a specific column, similar to a book index. Improves read, may slow writes.
索引：加速某列查找的结构，如书后索引。提升查询，但增删改会稍慢。
9. Software Development | 软件开发
Waterfall model: Linear sequential phases – requirements, design, implementation, testing, maintenance. Easy to manage, not flexible.
瀑布模型：线性顺序阶段：需求、设计、实现、测试、维护。易管理但难回退。
Agile: Iterative development with short sprints, continuous feedback, and incremental delivery. Emphasis on collaboration.
敏捷开发：迭代增量，短周期冲刺，持续反馈交付。重协作轻文档。
Pseudocode: Informal, language-agnostic description of algorithm steps. Not executable, but explains logic.
伪代码：非正式、编程语言无关的算法描述，阐明逻辑而不运行。
Flowchart: Diagram using shapes to represent steps, decisions, loops. Oval start/end, rectangle process, diamond decision.
流程图：用图形表示流程步骤，椭圆起止，矩形处理，菱形判断，箭头流向。
Testing levels: Unit (individual components), Integration (combined modules), System (whole system), Acceptance (user testing). UISA mnemonic.
测试级别：单元测试（独立模块）、集成测试、系统测试、验收测试。可记为 UISA。
Test data: Normal data, boundary data, erroneous data. Boundary analysis essential.
测试数据：正常、边界、异常数据。边界测试总能发现缺陷。
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