📚 CIE Year 11 Computer Science: Vocabulary & Terminology Quick Memory Guide | CIE Year 11 计算机科学：词汇术语速记指南
Terminology is the currency of CIE IGCSE Computer Science. Examiners award marks for precise wording, so a vague phrase such as 'the computer thinks about it' scores nothing, while 'the control unit decodes the instruction' scores immediately. This guide gathers the core vocabulary of the Year 11 syllabus into 12 short sections, each with a plain-English definition, a matching Chinese explanation, and a memory hook that makes the term stick. Use it for quick daily revision rather than one long cramming session.
术语是 CIE IGCSE 计算机科学的“硬通货”。考官是按精确表述给分的：说“电脑会思考一下”不得分，而说“控制器对指令进行译码”立刻得分。本指南把 Year 11 教学大纲的核心词汇整理成 12 个小节，每节包含简明英文定义、对应的中文解释，以及一个让术语牢牢记住的记忆口诀。建议每天用它做短时复习，而不是一次性长时间突击。
1. Algorithm, Program, Pseudocode, Flowchart | 算法、程序、伪代码、流程图
Algorithm: a precise, step-by-step procedure that solves a problem. A valid algorithm must be finite (it stops), unambiguous (only one possible interpretation), and it must have defined inputs and outputs. Picture a recipe: every instruction tells you exactly what to do next, and the result is guaranteed if you follow the steps. Memory hook: 'An algorithm is a recipe for success.'
算法：一种精确的、分步解决问题的过程。有效的算法必须是有穷的（会结束）、无歧义的（只有一种解释），并且有明确的输入和输出。把它想象成食谱：每条指令都清楚告诉你下一步做什么，照着做结果就是确定的。记忆口诀：“算法就是成功的食谱。”
Program: an algorithm written in a programming language so that a computer can execute it. The recipe has been translated into a language the machine can run, such as Python or Java. Memory hook: 'A program is a running recipe.'
程序：用编程语言编写、能被计算机执行的算法。也就是说，食谱被翻译成了机器能运行的语言（如 Python、Java）。记忆口诀：“程序 = 正在运行的食谱。”
Pseudocode: a high-level, human-readable description of an algorithm that follows structural conventions but ignores strict syntax details. 'Pseudo' means fake: it looks like code but cannot be executed. Programmers use it to plan logic before writing real code.
伪代码：一种高级的、人类可读的算法描述，遵循结构化约定但忽略严格语法细节。“Pseudo”意为虚假——它看起来像代码，却不能执行。程序员用它在实际编码前规划逻辑。
Flowchart: a diagrammatic representation of an algorithm using standard symbols. Ovals mark start and end, rectangles show processes, diamonds indicate decisions, and arrows show the direction of flow. Branching and loops become visually obvious.
流程图：使用标准符号对算法进行图形化表示。椭圆表示开始与结束，矩形表示处理，菱形表示判断，箭头表示流向。分支与循环在图中一目了然。
| Term 术语 | Memory hook 记忆钩子 |
| Algorithm 算法 | Recipe 食谱 |
| Program 程序 | Recipe being cooked 正在烹饪的食谱 |
| Pseudocode 伪代码 | Fake code 假代码 |
| Flowchart 流程图 | Picture of the recipe 食谱的图画 |
2. Bit, Byte, Binary, Denary, Hexadecimal | 位、字节、二进制、十进制、十六进制
Bit: a binary digit, the smallest unit of data, holding either 0 or 1. Nibble: 4 bits, exactly one hexadecimal digit. Byte: 8 bits, which can store 256 different values and usually holds one character.
位（bit）：二进制数字，最小的数据单位，只能是 0 或 1。半字节（nibble）：4 位，正好等于一个十六进制数字。字节（byte）：8 位，可表示 256 种不同取值，通常存放一个字符。
1 byte = 8 bits = 2 nibbles; 2⁸ = 256 possible values
Binary to denary: e bits and add the values under every 1. Example: 1011 0011 = 128 + 32 + 16 + 2 + 1 = 179.
二进制转十进制：在位上方写上权值 128、64、32、16、8、4、2、1，把每个 1 下方的权值相加。例如：1011 0011 = 128 + 32 + 16 + 2 + 1 = 179。
Hexadecimal: o one byte is always written as two hex digits. Programmers prefer hex because it is far shorter than binary and much less likely to be misread.
十六进制：基数为 16，使用 0-9 与 A-F，其中 A = 10、F = 15。一个十六进制数字等于 4 位二进制，因此一个字节总写成两个十六进制数字。程序员偏爱十六进制，因为它比二进制短得多，也不容易看错。
Binary addition rules: + 1 + 1 = 11 (write 1, carry 1). If the result needs more bits than the register holds, an overflow error occurs. Memory hook: 'Four bits, one hex digit; eight bits, one byte.'
二进制加法规则：0 + 0 = 0，0 + 1 = 1，1 + 1 = 10（写 0 进 1），1 + 1 + 1 = 11（写 1 进 1）。如果结果需要的位数超过寄存器容量，就会发生溢出（overflow）。记忆口诀：“四位一个十六进制数字，八位一个字节。”
3. ASCII, Unicode, Data Units and Compression | ASCII、Unicode、数据单位与压缩
ASCII: the American Standard Code for Information Interchange. Standard ASCII uses 7 bits and represents 128 characters; extended ASCII uses 8 bits and represents 256 characters. Each character has a unique binary code, which is why text can be stored and transmitted reliably.
ASCII：美国信息交换标准代码。标准 ASCII 使用 7 位，表示 128 个字符；扩展 ASCII 使用 8 位，表示 256 个字符。每个字符对应唯一的二进制编码，因此文本可以被可靠地存储和传输。
Unicode: occupy more storage than ASCII files because each character needs more bits. Memory hook: 'Unicode = universal code.'
Unicode：一种每个字符最多使用 4 字节的字符集，几乎涵盖所有语言、符号和表情符号。代价是体积：由于每个字符需要更多位，Unicode 文件比 ASCII 文件占用更多存储空间。记忆口诀：“Unicode = 通用编码。”
Data units: 1 TiB = 1024 GiB. Note that storage manufacturers often use powers of 1000, which is why a '1 TB' drive shows less than 1 TiB.
数据单位：1 KiB = 1024 字节，1 MiB = 1024 KiB，1 GiB = 1024 MiB，1 TiB = 1024 GiB。注意存储厂商常按 1000 的幂计算，这就是“1 TB”硬盘显示容量小于 1 TiB 的原因。
Compression: lossy compression permanently removes data the human eye or ear is unlikely to notice (JPEG, MP3) and cannot restore the original file. Lossless compression (PNG, ZIP, FLAC) rebuilds the original file exactly and is used for text, code and archives.
压缩：有损压缩会永久删除人眼或人耳不易察觉的数据（JPEG、MP3），无法还原原始文件。无损压缩（PNG、ZIP、FLAC）可以精确重建原文件，适用于文本、代码和压缩包。
Image file size = width × height × colour depth ÷ 8 (bytes)
Sound file size = sample rate × duration × sample resolution ÷ 8 (bytes)
These two formulas appear in almost every examination series, so learn them as a pair and always check whether the answer should be in bits or bytes.
这两个公式几乎每轮考试都会出现，请成对记住，并始终检查答案单位是位还是字节。
4. CPU, ALU, Control Unit, Registers and the Fetch-Decode-Execute Cycle | CPU、ALU、控制器、寄存器与取指-译码-执行周期
CPU (Central Processing Unit): the component that processes all instructions and data. ALU (Arithmetic Logic Unit): performs calculations and logical comparisons. Control Unit: decodes instructions and coordinates the flow of data around the processor. Cache: very fast memory inside the CPU that holds frequently used instructions and data.
CPU（中央处理器）：处理所有指令与数据的部件。ALU（算术逻辑单元）：执行运算与逻辑比较。控制器：对指令译码并协调数据在处理器内部的流动。高速缓存：CPU 内部速度极快的存储器，保存经常使用的指令和数据。
Registers: tiny, extremely fast storage locations inside the CPU. The PC (program counter) holds the address of the next instruction, the MAR holds that address while memory is accessed, the MDR holds the data or instruction transferred, the CIR/IR holds the current instruction, and the accumulator holds the result of the ALU's calculations.
寄存器：CPU 内部极小、极快的存储单元。PC（程序计数器）保存下一条指令的地址，MAR在访问内存时保存该地址，MDR保存被传送的数据或指令，CIR/IR保存当前指令，累加器保存 ALU 的计算结果。
Fetch-Decode-Execute cycle: the instruction address in the PC is copied to the MAR; the instruction is fetched from RAM into the MDR and then into the CIR; the PC is incremented; the control unit decodes the instruction; finally the instruction is executed and any result is written back.
取指-译码-执行周期：PC 中的指令地址被复制到 MAR；指令从内存取出送入 MDR，再送入 CIR；PC 递增；控制器对指令译码；最后执行指令并写回结果。
Performance factors: clock speed (cycles per second, measured in GHz), number of cores (more cores allow parallel processing), and cache size (a larger cache reduces the slower access to RAM). Memory hook: 'Fetch the address, decode the meaning, execute the action.'
性能因素：时钟频率（每秒周期数，单位为 GHz）、核心数量（核心越多越能并行处理）以及缓存容量（缓存越大，访问较慢内存的次数越少）。记忆口诀：“取来地址，译出含义，执行动作。”
5. RAM, ROM, Cache and Virtual Memory | 随机存储器、只读存储器、缓存与虚拟内存
RAM (Random Access Memory): volatile main memory that stores currently running programs and data. Its contents are lost when power is switched off, and it can be read from and written to at any time. More RAM allows more applications to run smoothly at once.
RAM（随机存取存储器）：易失性主存，存放当前运行的程序和数据。断电后内容全部丢失，任何时刻都可读写。RAM 越大，可同时流畅运行的应用程序越多。
ROM (Read-Only Memory): non-volatile memory that keeps its contents when power is removed. It stores the bootstrap loader (BIOS/UEFI) that starts the computer and runs the power-on self-test. Memory hook: 'RAM forgets, ROM remembers.'
ROM（只读存储器）：非易失性存储器，断电后内容仍然保留。它存放启动计算机并执行开机自检的引导程序（BIOS/UEFI）。记忆口诀：“RAM 会忘，ROM 记得。”
Cache: small, very fast memory located in or close to the CPU. Level 1 is fastest and smallest, Level 3 is slower and larger. Frequently used data is copied into the cache so that the CPU does not have to wait for slower RAM.
缓存：位于 CPU 内部或附近的小容量高速存储器。一级缓存最快最小，三级缓存较慢较大。常用数据被复制进缓存，使 CPU 不必等待较慢的 RAM。
Virtual memory: when RAM is full, sections of data that are not currently needed are moved to a swap file or page file on secondary storage, freeing space for active programs. It prevents crashes but slows the machine down because secondary storage is far slower than RAM; excessive swapping is called disk thrashing.
虚拟内存：当 RAM 被占满时，当前不需要的数据段被移到辅助存储器上的交换文件（页面文件）中，为活跃程序腾出空间。它能避免程序崩溃，但会降低速度，因为辅助存储器远慢于 RAM；过度交换称为磁盘抖动（thrashing）。
6. Secondary Storage, Input/Output Devices and Sensors | 辅助存储、输入输出设备与传感器
Magnetic storage (HDD): stores data as magnetised areas on spinning platters. It offers a very low cost per gigabyte and large capacity, but it contains moving parts, so it is slower, noisier and more easily damaged by impact.
磁存储（HDD）：以旋转盘片上的磁化区域存储数据
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