📚 Year 11 WJEC Computer Science: Key Terms Rapid Memorisation Guide | Year 11 WJEC 计算机：词汇术语速记指南
Mastering the vocabulary of computer science is the first step towards exam success. This guide compiles the most essential terms you’ll encounter in the WJEC Year 11 syllabus, along with memorable tips to lock them into your long-term memory. Each key concept is broken down with a definition and a clever memory hook, helping you recall facts quickly during the exam.
掌握计算机科学的词汇是通向考试成功的第一步。本指南整理了 WJEC Year 11 大纲中最关键的术语，并附上记忆技巧，帮助你将其牢固储存在长期记忆中。每个关键概念都配有定义和巧妙的记忆钩子，让你在考试中快速回想起知识点。
1. Data Representation Fundamentals | 数据表示基础
All data inside a computer is stored as binary digits (bits). Understanding how bits combine into nibbles, bytes and larger units, and how numbers can overflow, is the foundation for every topic. Visualise a byte as a tiny box holding 8 switches.
计算机内的所有数据都以二进制数字（比特）形式存储。理解比特如何组成半字节、字节和更大单位，以及数字如何溢出，是所有主题的基础。把字节想象成一个装有8个开关的小盒子。
A bit (binary digit) is the smallest unit of data, holding either 0 or 1. Memory tip: the word ‘bit’ is a contraction of ‘binary digit’ — keep it simple.
比特（二进制位）是最小的数据单位，只能保存0或1。记忆窍门：“bit”是“binary digit”的缩写——就这么简单。
A nibble consists of 4 bits, exactly half a byte. The name suggests a tiny ‘nibble’ of a byte — like taking a small bite of data.
半字节（nibble）由4个比特组成，恰好是半个字节。名称暗示了从字节上咬了一小口——就像轻咬一小口数据。
A byte is a group of 8 bits and commonly represents one character, such as ‘A’ or ‘9’. Use the mnemonic: ‘Eight bits make a byte, just like an octet.’ A kilobyte (KB) is 1024 bytes (2¹⁰ bytes) because binary counts in powers of two, not powers of ten.
字节（byte）是一组8个比特，通常表示一个字符，如“A”或“9”。使用助记诀窍：“八位成一个字节，就像八重奏。” 1 KB 是 1024 字节（2¹⁰ 字节），因为二进制以2的幂计数，而非10的幂。
Overflow occurs when an arithmetic result is too large for the fixed number of bits. For example, adding 1 to 11111111₂ (8 bits) gives 100000000₂, which needs 9 bits and loses the leftmost bit. Think of a car odometer clicking over from 999999 to 000000.
溢出（overflow）发生在算术结果超出规定的位数时。例如，11111111₂（8位）加1得到100000000₂，需要9位，并且最左边的位会丢失。这就像汽车里程表从999999跳到000000。
2. Storing Images & Sound | 图像与声音存储
Images and audio are analogue, so computers must digitise them via sampling. The quality and file size are determined by resolution, colour depth and sample rate. Picture a mosaic — more tiles give a sharper image but demand more memory.
图像和声音都是模拟的，因此计算机必须通过采样将它们数字化。质量和文件大小由分辨率、颜色深度和采样率决定。想象一幅马赛克画——瓦片越多，画面越清晰，但占用内存也更多。
A pixel (picture element) is the smallest addressable point in a digital image. The more pixels, the higher the resolution. Remember: ‘pixel’ = ‘pic’ + ‘el’.
像素（pixel）是数字图像中最小的可寻址点。像素越多，分辨率越高。记住：“pixel”就是“picture element”的组合。
Colour depth is the number of bits used for each pixel. 1 bit gives 2 colours; 8 bits give 256 colours; 24 bits give millions of colours (true colour). The phrase ‘deeper colour, richer picture’ can help you recall that more bits per pixel mean more possible shades.
颜色深度是每个像素使用的比特数。1位显示2色；8位显示256色；24位显示数百万种颜色（真彩色）。“深度越深，画面越浓”这句话能帮你记住每个像素的位数越多，可能的色彩就越多。
Metadata is data about data. An image file stores metadata such as date, camera model and GPS location alongside the pixels. Think of it as the digital label on the back of a photo frame.
元数据（metadata）是关于数据的数据。图像文件除了像素信息，还存有日期、相机型号和GPS位置等元数据。可以把它想象成相框背面的数字标签。
For sound, the sample rate (Hz) is how many times per second the amplitude is measured. Bit rate is the number of bits processed per second, calculated as sample rate × bit depth × number of channels. Higher rates mean richer sound but larger files. Lossy compression (e.g., MP3) discards some data to shrink files, while lossless compression (e.g., FLAC) preserves every bit. Think ‘lossy = loses quality’.
对于声音，采样率（Hz）表示每秒测量振幅的次数。比特率是每秒处理的比特数，计算为采样率×位深×声道数。速率越高，音质越细腻，但文件也越大。有损压缩（如MP3）会丢弃部分数据来缩小文件，而无损压缩（如FLAC）则保留每一个比特。记住“lossy = lose（丢失）”。
3. CPU Architecture | 中央处理器架构
The CPU is the brain of the computer. It follows the Von Neumann stored-program concept and runs the fetch-decode-execute cycle billions of times per second. Imagine a chef reading a recipe, understanding the steps, and then cooking.
CPU是计算机的大脑。它遵循冯·诺依曼的存储程序概念，并每秒运行数十亿次取指-译码-执行周期。想象厨师阅读菜谱、理解步骤、然后烹饪。
The Control Unit (CU) directs the operation of all other parts by sending timing and control signals. The Arithmetic Logic Unit (ALU) performs calculations and logical operations. Use the rhyme: ‘CU controls, ALU adds.’
控制单元（CU）通过发送时序和控制信号指挥其他部件工作。算术逻辑单元（ALU）执行运算和逻辑操作。用顺口溜记住：“CU控制，ALU算数。”
A register is an ultra-fast memory location inside the CPU. Key registers include the Program Counter (PC), Memory Address Register (MAR), Memory Data Register (MDR) and Accumulator (ACC). Think of them as the chef’s tiny, instant-access workbench.
寄存器（register）是CPU内部超快的内存位置。关键寄存器包括程序计数器(PC)、存储器地址寄存器(MAR)、存储器数据寄存器(MDR)和累加器(ACC)。将它们想象成厨师手边可以即时取用的小工作台。
Cache is a small amount of high-speed memory located near the CPU that stores frequently used instructions and data. Caches are compared by levels: L1 is smallest and fastest, L2 larger but slightly slower. The mnemonic ‘Cache speeds up the race’ reminds you it reduces the need to fetch from slower RAM.
缓存（cache）是CPU附近的小容量高速存储器，存放常用指令和数据。缓存按级别比较：L1最小最快，L2较大但略慢。助记口诀“缓存加速竞赛”提醒你，它减少了对较慢RAM的访问需求。
4. Memory & Storage | 内存与存储
Primary memory (RAM and ROM) is directly accessible by the CPU, while secondary storage holds data permanently. RAM is the desk where you work; ROM is the sealed instruction manual.
主存储器（RAM和ROM）由CPU直接访问，而辅助存储器永久保存数据。RAM好比你的办公桌，ROM好比密封的说明手册。
RAM (Random Access Memory) is volatile — all data is lost when power is turned off. It stores the operating system, applications and data currently in use. Think ‘RAM remembers while you ram about, but forgets when the power’s out.’
RAM（随机存取存储器）是易失性的——断电后所有数据都会丢失。它存储当前使用的操作系统、应用程序和数据。可以这样记：“RAM在你忙碌时记得，一断电它就忘。”
ROM (Read Only Memory) is non-volatile and contains the BIOS/bootstrap program needed to start the computer. The word ‘Read Only’ tells you it cannot be easily changed — it’s permanently baked in, like a recipe carved in stone.
ROM（只读存储器）是非易失性的，存有启动计算机所需的BIOS/引导程序。“只读”一词告诉你它无法轻易更改——就像刻在石头上的食谱，永久固化在内。
Virtual memory uses part of the hard drive/SSD as extra RAM when the actual RAM is full. Because secondary storage is far slower, overusing virtual memory leads to disk thrashing and sluggish performance. Picture an overflowing desk spilling documents onto a huge but slow cabinet.
虚拟内存（virtual memory）在物理RAM已满时，将硬盘/SSD的一部分当作额外RAM使用。由于辅助存储慢得多，过度使用虚拟内存会导致磁盘颠簸和性能低下。想象一张堆满文件的桌子，溢出的文件堆到了一个庞大但缓慢的柜子里。
Secondary storage falls into three types: magnetic (hard disk drive with spinning platters), solid-state (SSD, USB flash, no moving parts, faster, more durable) and optical (CD, DVD, Blu-ray). The phrase ‘SSD silently speeds, magnetic mechanically moves’ helps distinguish them.
辅助存储分为三种：磁存储（带旋转磁盘的机械硬盘）、固态存储（SSD、U盘，无活动部件、更快、更耐用）和光存储（CD、DVD、蓝光）。“固态静静加速，磁碟机械转动”有助于区分。
5. System Software | 系统软件
System software controls the hardware and provides a platform for applications. The operating system (OS) is the chief conductor, while utility software handles housekeeping tasks.
系统软件控制硬件并为应用程序提供平台。操作系统
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