📚 Year 11 AQA Computer Science: Core Knowledge Review | Year 11 AQA 计算机核心知识点梳理
This comprehensive guide summarises the essential topics covered in the Year 11 AQA GCSE Computer Science specification (8525). By breaking down each core area, you can strengthen your understanding and prepare effectively for your exams.
本综合指南总结了 AQA GCSE 计算机科学（8525）Year 11 涵盖的核心主题。通过梳理每个核心领域，你可以加深理解并有效备考。
1. Algorithms and Problem Solving | 算法与问题求解
Computational thinking involves decomposition (breaking a problem into smaller parts), pattern recognition, abstraction (focusing on key details while ignoring irrelevant information), and algorithm design. These skills form the foundation of solving problems computationally.
计算思维包括分解（将问题拆分为更小的部分）、模式识别、抽象（关注关键细节而忽略无关信息）以及算法设计。这些技能构成了用计算机解决问题的基石。
Linear search examines each element of a list one by one until the target value is found or the end is reached. It works on unsorted data and has a time complexity of O(n).
线性搜索逐个检查列表中的每个元素，直到找到目标值或到达末尾。它适用于未排序的数据，时间复杂度为 O(n)。
Binary search repeatedly divides a sorted list in half, comparing the middle element with the target. It is much faster with a time complexity of O(log n) but requires the list to be pre-sorted.
二分搜索反复将有序列表对半分，比较中间元素与目标值。它的速度要快得多，时间复杂度为 O(log n)，但要求列表预先排序。
Two common sorting algorithms are bubble sort and merge sort. Bubble sort repeatedly steps through the list, compares adjacent items and swaps them if they are in the wrong order; it is simple but inefficient (O(n²)). Merge sort divides the list into halves, sorts them recursively and merges the sorted halves; it is efficient (O(n log n)) and suited for large datasets.
两种常见的排序算法是冒泡排序和归并排序。冒泡排序反复遍历列表，比较相邻元素并在顺序错误时交换它们；它简单但效率较低（O(n²)）。归并排序将列表分成两半，递归排序后再合并有序的两半；它效率高（O(n log n)）且适合大数据集。
Algorithms can be represented using flowcharts (with symbols for start/stop, process, decision, input/output) or pseudocode (a textual description that resembles code).
算法可以用流程图（使用起止、处理、判断、输入/输出符号）或伪代码（类似于代码的文本描述）来表示。
2. Programming Fundamentals | 编程基础
Programs use data types such as integer, real/float, Boolean, character and string. Variables must be declared with a data type in many languages (statically typed), and each type determines what operations can be performed.
程序使用整数、实型/浮点型、布尔型、字符和字符串等数据类型。在许多语言中，变量需声明数据类型（静态类型），每种类型决定了可执行的操作。
The three fundamental programming constructs are sequence (instructions executed in order), selection (if-else, switch-case) and iteration (for, while loops). They are the building blocks of any algorithm.
三种基本编程结构是顺序（指令按序执行）、选择（if-else、switch-case）和迭代（for、while 循环）。它们是任何算法的构建块。
Subroutines (procedures and functions) allow modular code reuse. A function returns a value, while a procedure does not. Parameters can be passed by value or by reference.
子程序（过程和函数）允许模块化代码重用。函数返回一个值，而过程不返回值。参数可按值传递或按引用传递。
Arrays (or lists) store multiple data items of the same type under a single identifier with index-based access. A two-dimensional array is analogous to a table with rows and columns.
数组（或列表）在同一标识符下存储多个相同类型的数据项，并通过索引访问。二维数组类似于包含行和列的表格。
Common operators include arithmetic (+, -, *, /, MOD, DIV), relational (==, ! . String handling operations such as concatenation, length and sub-string are also tested.
常用运算符包括算术（+、-、*、/、MOD、DIV）、关系（==、!=、<、>、<=、>=）和逻辑（AND、OR、NOT）。字符串操作如连接、长度和子串也在考查范围内。
3. Data Representation in Computers | 计算机中的数据表示
All data is stored as binary digits (bits). The binary number system uses base 2. Converting between denary and binary, and performing binary addition, are key skills. Overflow occurs when the result of addition exceeds the available bit-width.
所有数据都以二进制数字（比特）存储。二进制数制采用基数为 2。十进制与二进制之间的转换以及二进制加法运算是关键技能。当加法结果超出可用位宽时会发生溢出。
Hexadecimal (base 16) is a shorthand for binary, often used to represent memory addresses and colour codes. One hex digit represents four bits (a nibble).
十六进制（基数为 16）是二进制的简写形式，常用于表示内存地址和颜色代码。一位十六进制数字表示四位二进制（半字节）。
Characters are represented by binary codes. ASCII uses 7 bits (128 characters), while Unicode can encode thousands of characters using up to 4 bytes, supporting multiple languages and symbols.
字符用二进制编码表示。ASCII 使用 7 位（128 个字符），而 Unicode 可使用多达 4 字节来编码数千个字符，支持多种语言和符号。
Images are stored as a grid of pixels, each assigned a binary colour value. The resolution (pixels per inch) and colour depth (bits per pixel) determine image quality and file size. Metadata records dimensions and colour information.
图像以像素网格的形式存储，每个像素分配一个二进制颜色值。分辨率（每英寸像素数）和颜色深度（每像素位数）决定了图像质量和文件大小。元数据记录尺寸和颜色信息。
Sound is digitised by sampling the amplitude at regular intervals. Sample rate (Hz) and bit depth affect sound quality and file size. Higher sample rates reproduce frequencies more accurately.
声音通过定期对振幅进行采样来数字化。采样率（赫兹）和位深度影响音质和文件大小。更高的采样率可以更准确地还原频率。
Compression reduces file size. Lossless compression (e.g., run-length encoding, Huffman coding) preserves all original data, whereas lossy compression (e.g., JPEG, MP3) permanently removes some data, usually imperceptible to humans.
压缩可减小文件大小。无损压缩（如游程编码、霍夫曼编码）保留所有原始数据，而有损压缩（如 JPEG、MP3）会永久删除一些通常人类无法察觉的数据。
4. Computer Architecture | 计算机体系结构
The Von Neumann architecture stores both data and instructions in the same memory. Key components include the Control Unit (CU), Arithmetic Logic Unit (ALU), registers, and buses (address, data, control).
冯·诺依曼体系结构将数据和指令存储在同一个内存中。关键组件包括控制器（CU）、算术逻辑单元（ALU）、寄存器和总线（地址总线、数据总线、控制总线）。
The CPU executes instructions continuously through the fetch-decode-execute cycle. The Program Counter (PC) holds the address of the next instruction, the Memory Address Register (MAR) holds the address being accessed, and the Memory Data Register (MDR) holds the data or instruction.
CPU 通过取指-解码-执行周期不断执行指令。程序计数器（PC）保存下一条指令的地址，内存地址寄存器（MAR）保存被访问的地址，内存数据寄存器（MDR）保存数据或指令。
Clock speed (Hz), number of cores, and cache size directly affect CPU performance. A faster clock, more cores and larger cache generally improve processing speed.
时钟频率（赫兹）、内核数量和缓存大小直接影响 CPU 性能。更高的时钟频率、更多的内核和更大的缓存通常能提高处理速度。
Embedded systems are dedicated computers built into larger devices (e.g., washing machines, cars). They have specific tasks, limited resources, and often use firmware.
嵌入式系统是内置于大型设备（如洗衣机、汽车）中的专用计算机。它们具有特定任务、有限资源，并且通常使用固件。
5. Memory and Storage | 内存与存储
Primary memory includes RAM and ROM. RAM (Random Access Memory) is volatile and holds currently running programs and data. ROM (Read-Only Memory) is non-volatile and stores the boot-up instructions (BIOS).
主存储器包括 RAM 和 ROM。RAM（随机存取存储器）是易失性的，保存当前运行的程序和数据。ROM（只读存储器）是非易失性的，存储启动指令（BIOS）。
Virtual memory uses a portion of secondary storage as if it were RAM when the physical RAM is full. This allows larger applications to run but is slower than physical RAM.
虚拟内存使用一部分辅助存储作为 RAM 来用，当物理 RAM 不足时。这允许运行更大的应用程序，但比物理 RAM 慢。
Secondary storage is non-volatile and comes in three main types: magnetic (hard disk drives), optical (CDs, DVDs), and solid-state (SSDs, USB flash drives). They are compared by capacity, speed, durability, portability and cost.
辅助存储是非易失性的，主要有三种类型：磁性（硬盘驱动器）、光学（光碟）和固态（固态硬盘、USB 闪存驱动器）。它们通过容量、速度、耐用性、便携性和成本进行比较。
6. Computer Networks | 计算机网络
A LAN (Local Area Network) covers a small geographical area like a school or office, while a WAN (Wide Area Network) connects LANs across cities or countries. The Internet is the largest WAN.
局域网（LAN）覆盖像学校或办公室这样的小地理区域，而广域网（WAN）连接跨越城市或国家的局域网。互联网是最大的广域网。
Networks can operate in client-server or peer-to-peer (P2P) models. In client-server, a central server provides resources and services. In P2P, all devices share resources equally.
网络可以采用客户-服务器或对等（P2P）模型运行。在客户-服务器模型中，中央服务器提供资源和服务。在 P2P 中，所有设备平等共享资源。
Protocols are rules for data transmission. Common ones include HTTP/HTTPS (web), FTP (file transfer), SMTP/POP3/IMAP (email), TCP/IP (transmission control / internet protocol). TCP ensures reliable delivery; IP routes packets across networks.
协议是数据传输的规则。常见的有 HTTP/HTTPS（网页）、FTP（文件传输）、SMTP/POP3/IMAP（电子邮件）、TCP/IP（传输控制/互联网协议）。TCP 确保可靠交付；IP 在网络上路由数据包。
The TCP/IP 4-layer model simplifies network communication: Application layer (HTTP, FTP, SMTP), Transport layer (TCP, UDP), Internet layer (IP), and Network Access layer (Ethernet, Wi-Fi).
TCP/IP 四层模型简化了网络通信：应用层（HTTP、FTP、SMTP）、传输层（TCP、UDP）、互联网层（IP）和网络接入层（以太网、Wi-Fi）。
7. Cybersecurity | 网络安全
Malware is malicious software including viruses (self-replicating, attaching to files), worms (self-spreading across networks), Trojans (disguised as legitimate software), spyware and ransomware.
恶意软件是恶意软件，包括病毒（自我复制，附着于文件）、蠕虫（通过网络自我传播）、木马（伪装成合法软件）、间谍软件和勒索软件。
Social engineering attacks manipulate people into revealing confidential information. Examples include phishing (fake emails seeking personal data), blagging/pretexting (pretending to be someone else), and shoulder surfing.
社会工程攻击通过操纵人员来泄露机密信息。例如网络钓鱼（骗取个人数据的虚假邮件）、骗取/套话（冒充他人）和肩窥。
Other threats include brute-force attacks (trying all possible passwords), denial-of-service (DoS) attacks (flooding a server to make it unavailable), SQL injection (inserting malicious SQL statements) and data interception.
其他威胁包括暴力破解（尝试所有可能的密码）、拒绝服务攻击（DoS）（使服务器不堪重负而无法使用）、SQL 注入（插入恶意 SQL 语句）和数据拦截。
Security measures involve penetration testing, anti-malware software, firewalls, encryption, user access levels, physical security and staff training. Strong password policies and regular updates are essential.
安全措施包括渗透测试、反恶意软件、防火墙、加密、用户访问级别、物理安全和员工培训。强密码策略和定期更新至关重要。
8. Databases and SQL | 数据库与SQL
A relational database organises data into tables linked by keys. Each table has a primary key (a unique identifier for each record). Foreign keys create relationships between tables.
关系数据库将数据组织成由键连接的表。每个表都有一个主键（每条记录的唯一标识符）。外键在表之间创建关系。
Structured Query Language (SQL) is used to manage data. Key commands include SELECT (to retrieve data), INSERT INTO (to add new records), UPDATE (to modify existing records) and DELETE (to remove records).
结构化查询语言（SQL）用于管理数据。关键命令包括 SELECT（检索数据）、INSERT INTO（添加新记录）、UPDATE（修改现有记录）和 DELETE（删除记录）。
Example: SELECT name, grade FROM students WHERE grade > 'B'; retrieves specified columns from the students table with a condition. Wildcards like * (all columns) and placeholders such as % (any sequence of characters) are used with LIKE.
示例：SELECT name, grade FROM students WHERE grade > 'B'; 从 students 表中检索符合条件的指定列。通配符如 *（所有列）和占位符如 %（任意字符序列）与 LIKE 一起使用。
9. Software Development Lifecycle | 软件开发周期
The software development lifecycle (SDLC) includes stages: analysis (defining requirements), design (creating algorithms, interface mock-ups), implementation (writing code), testing (checking for errors) and evaluation (reviewing against requirements).
软件开发生命周期（SDLC）包括各个阶段：分析（定义需求）、设计（创建算法、界面模型）、实施（编写代码）、测试（检查错误）和评价（根据需求进行审查）。
Testing can be iterative (during development) and final/terminal testing. Test plans use normal, boundary and erroneous data to ensure robustness. Logic errors (unintended outcomes) and syntax errors (rule violations) must be identified and fixed.
测试可以是迭代的（开发期间）和最终/终端测试。测试计划使用正常、边界和错误数据来确保健壮性。必须识别并修正逻辑错误（非预期结果）和语法错误（违反语言规则）。
Maintenance is an ongoing process: corrective (fixing bugs), adaptive (adjusting to new environments) and perfective (improving performance or usability).
维护是一个持续的过程：纠正性维护（修复错误）、适应性维护（适应新环境）和完善性维护（提高性能或可用性）。
10. Legal, Ethical and Environmental Impacts | 法律、伦理与环境影响
Relevant legislation includes the Data Protection Act 2018 / GDPR (governing personal data collection, storage and rights), the Computer Misuse Act 1990 (unauthorised access and hacking offences), and the Copyright, Designs and Patents Act 1988 (protecting intellectual property).
相关立法包括《2018 年数据保护法》/ GDPR（规范个人数据的收集、存储和权利）、《1990 年计算机滥用法》（针对未经授权访问和黑客犯罪）以及《1988 年版权、设计和专利法》（保护知识产权）。
Ethical concerns involve privacy (monitoring, data profiling), censorship, and the digital divide. The use of artificial intelligence raises further ethical questions about bias and accountability.
伦理问题涉及隐私（监控、用户画像）、审查以及数字鸿沟。人工智能的使用引发了关于偏见和问责的更深层次伦理问题。
Environmental issues cover e-waste disposal, energy consumption of data centres, and the sustainability of manufacturing devices. The technology lifecycle must consider resource extraction, use, and recycling.
环境问题涵盖电子垃圾处理、数据中心的能耗以及设备制造的可持续性。技术生命周期必须考虑资源开采、使用和回收。
Open source software allows users to access and modify source code freely, while proprietary software restricts access. Each has implications for security, support and innovation.
开源软件允许用户自由访问和修改源代码，而专有软件则限制访问。每种模式都对安全、支持和创新产生影响。
Published by TutorHao | Computer Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图