📚 IB Edexcel Computer Science: End-of-Term Revision Guide | IB Edexcel 计算机：期末复习提纲
This revision outline brings together the essential topics for IB and Edexcel Computer Science end-of-term assessments. It serves as a structured checklist, covering number systems, data representation, computer architecture, logic, programming fundamentals, algorithms, data structures, databases, networking, cybersecurity, system software, and the wider ethical implications of computing. Use this guide to test your understanding of key definitions, processes, and problem-solving techniques that frequently appear in exam scenarios.
这份复习提纲整合了 IB 和 Edexcel 计算机科学期末考试的核心主题。它作为一份结构化的检查清单，涵盖了数制、数据表示、计算机体系结构、逻辑、编程基础、算法、数据结构、数据库、网络、网络安全、系统软件以及更广泛的计算伦理影响。使用本指南来检验你对关键定义、过程和常见考试题型的掌握程度。
1. Number Systems and Conversions | 数制及其转换
All digital systems operate on binary, but humans prefer decimal and hexadecimal. You must be able to convert between binary (base 2), denary (base 10), and hexadecimal (base 16) fluently. Understand the place values: for an 8-bit binary number the columns are 128, 64, 32, 16, 8, 4, 2, 1. Hexadecimal uses digits 0–9 and letters A (10) to F (15).
所有数字系统都基于二进制，但人类更习惯十进制和十六进制。你必须在二进制（底数为2）、十进制（底数为10）和十六进制（底数为16）之间熟练转换。理解位权：对于 8 位二进制数，位权依次为 128, 64, 32, 16, 8, 4, 2, 1。十六进制使用数字 0–9 和字母 A（10）到 F（15）。
Binary addition and subtraction, including the use of two’s complement to represent negative integers, is required. The range of an 8-bit two’s complement value goes from –128 to +127. Overflow occurs when a calculation exceeds the representable range.
二进制加减法，以及使用补码表示负整数，是必需的。8 位补码整数的范围从 –128 到 +127。当运算超出可表示范围时，会产生溢出。
- Quick check: Convert 10110110₂ to denary and hexadecimal.
- 快速自测：将 10110110₂ 转换为十进制和十六进制。
2. Data Representation | 数据表示
Computers store text, images, and sound as binary patterns. Characters are encoded using ASCII (7-bit, extended 8-bit) or Unicode. An ASCII string ‘A’ is 65 (01000001), but Unicode allows representation of global scripts with multi-byte code points. String length can be measured in bytes depending on the encoding.
计算机将文本、图像和声音存储为二进制模式。字符使用 ASCII（7 位，扩展 8 位）或 Unicode 进行编码。ASCII 字符 ‘A’ 是 65（01000001），而 Unicode 允许使用多字节代码点表示全球文字。字符串长度取决于编码，以字节为单位。
Bitmap images are grids of pixels, each assigned a colour via its colour depth (bits per pixel). The image file size (in bytes) = width × height × colour depth / 8. Metadata stores dimensions and palette. Vector graphics represent images with mathematical shapes and are resolution-independent.
位图是像素网格，每个像素通过色深（每像素位数）指定颜色。图像文件大小（字节）= 宽度 × 高度 × 色深 / 8。元数据存储尺寸和调色板。矢量图形使用数学形状表示图像，与分辨率无关。
Sound is sampled at a rate (Hz) and bit depth. Higher sample rate and bit depth improve quality but increase file size. File size (uncompressed) = sample rate × bit depth × duration in seconds × number of channels. MIDI stores performance instructions rather than raw audio.
声音以采样率（Hz）和位深度进行采样。更高的采样率和位深度能提升质量，但会增加文件大小。文件大小（未压缩）= 采样率 × 位深度 × 时长（秒）× 声道数。MIDI 存储的是演奏指令而非原始音频。
3. Computer Architecture | 计算机体系结构
The Von Neumann architecture describes a system with a CPU, memory, input/output, and a stored program concept. The CPU consists of the Control Unit (CU), Arithmetic Logic Unit (ALU), and registers such as the Program Counter (PC), Memory Address Register (MAR), Memory Data Register (MDR), Current Instruction Register (CIR), and Accumulator (ACC). Buses (data, address, control) carry signals between units.
冯·诺依曼体系结构描述了具有 CPU、内存、输入/输出和存储程序概念的系统。CPU 由控制单元（CU）、算术逻辑单元（ALU）和寄存器组成，如程序计数器（PC）、内存地址寄存器（MAR）、内存数据寄存器（MDR）、当前指令寄存器（CIR）和累加器（ACC）。总线（数据、地址、控制）在部件之间传递信号。
The fetch-decode-execute cycle moves data from main memory into the CPU and carries out instructions. Factors affecting performance include clock speed (cycles per second), number of cores, and cache size. Embedded systems are specialised computers built into larger devices, often running real-time control tasks.
取指-译码-执行周期将数据从主存移入 CPU 并执行指令。影响性能的因素包括时钟速度（每秒周期数）、内核数量和缓存大小。嵌入式系统是内置于大型设备中的专用计算机，通常运行实时控制任务。
| Register | Function |
| PC | Holds address of next instruction |
| MAR | Holds address of memory to be read/written |
| MDR | Holds data or instruction just read from memory |
| CIR | Stores the current instruction being executed |
4. Logic Gates and Boolean Algebra | 逻辑门与布尔代数
Logic gates implement Boolean functions. The fundamental gates are NOT (inverter), AND (output 1 only if all inputs 1), OR (output 1 if at least one input 1), NAND, NOR, XOR (exclusive OR), and XNOR. Truth tables exhaustively list output for all input combinations.
逻辑门实现布尔函数。基本门包括 NOT（反相器）、AND（仅所有输入为 1 时输出 1）、OR（至少一个输入为 1 时输出 1）、与非（NAND）、或非（NOR）、异或（XOR）和同或（XNOR）。真值表详细列出所有输入组合下的输出。
Boolean expressions can be simplified using Boolean laws (De Morgan’s laws, distributive, absorption) or Karnaugh maps (up to 4 variables). Logic circuits are built from gate combinations; always write the expression for intermediate points and reduce where possible.
布尔表达式可以使用布尔定律（德摩根律、分配律、吸收律）或卡诺图（最多 4 个变量）进行化简。逻辑电路由门的组合构成；务必写出中间点的表达式并在可能时化简。
De Morgan: ¬(A ∧ B) = ¬A ∨ ¬B and ¬(A ∨ B) = ¬A ∧ ¬B
5. Programming Concepts | 编程概念
Programming involves writing sequences of instructions in a high-level language (e.g., Python, Java) or low-level assembly. Key constructs are sequence, selection (if/else, switch), and iteration (for, while loops). Variables store data; their data types include integer, float, character, string, and Boolean.
编程涉及使用高级语言（如 Python、Java）或低级汇编语言编写指令序列。关键结构包括顺序、选择（if/else, switch）和迭代（for, while 循环）。变量存储数据；其数据类型包括整数、浮点数、字符、字符串和布尔值。
Subprograms (functions/procedures) aid modularity. Parameters can be passed by value (a copy) or by reference (the original). Recursion is a technique where a function calls itself; it must have a base case to prevent infinite calls. Scope determines where a variable is accessible (local/global).
子程序（函数/过程）有助于模块化。参数可以通过传值（副本）或传引用（原变量）传递。递归是函数调用自身的技术；必须有一个基线条件防止无限调用。作用域决定了变量的可访问范围（局部/全局）。
Basic string manipulation, array processing, and file handling operations (open, read, write, close) are often tested. Know how to trace code to predict output or identify errors.
基本的字符串操作、数组处理和文件操作（打开、读取、写入、关闭）常被考查。要懂得如何跟踪代码以预测输出或识别错误。
6. Algorithms and Flowcharts | 算法与流程图
An algorithm is a step-by-step procedure to solve a problem. Common searching algorithms are linear search (O(n)) and binary search (O(log n), requires sorted data). Sorting algorithms include bubble sort, insertion sort, and merge sort. Quicksort is also common in more advanced syllabi.
算法是解决问题的逐步过程。常见的搜索算法是线性搜索（O(n)）和二分搜索（O(log n)，要求数据有序）。排序算法包括冒泡排序、插入排序和归并排序。快速排序在更高级的课程中也常见。
Flowcharts visually represent algorithms: ovals for start/end, rectangles for processes, diamonds for decisions, parallelograms for I/O. Tracing a flowchart involves following the flow with sample data. Pseudocode must be precise, using keyword syntax similar to the reference language.
流程图以可视化方式表示算法：椭圆形表示开始/结束，矩形表示处理步骤，菱形表示决策，平行四边形表示输入/输出。跟踪流程图需要使用样例数据跟随流程。伪代码必须精确，使用与参考语言类似的关键字语法。
- Compare the number of comparisons for linear vs binary search on a list of 1024 elements.
- 比较在 1024 个元素的列表上，线性搜索和二分搜索的对比次数。
7. Data Structures | 数据结构
Arrays store a fixed-size collection of elements of the same type, accessed by index. Two-dimensional arrays model tables/matrices. Stacks (LIFO) use push and pop operations; a stack pointer points to the top. Queues (FIFO) support enqueue and dequeue; a circular array implementation uses front and rear pointers.
数组存储固定大小的同类型元素集合，通过索引访问。二维数组可用于建模表格/矩阵。栈（后进先出）使用压入和弹出操作；栈指针指向栈顶。队列（先进先出）支持入队和出队；循环数组实现使用前指针和后指针。
Records (structs) combine fields of different types to represent an entity. For databases, flat files and relational tables are used. Linked lists consist of nodes, each containing data and a pointer to the next node; dynamic memory allocation avoids fixed limits.
记录（结构体）组合不同类型的字段以表示一个实体。在数据库方面，使用平面文件和关系表。链表由节点组成，每个节点包含数据和指向下一节点的指针；动态内存分配避免了固定大小的限制。
8. Databases | 数据库
A relational database organises data into tables (relations) that are linked by primary keys and foreign keys. Each entity becomes a table, attributes become fields. Normalisation reduces data redundancy; you should be able to take an unnormalised dataset to first normal form (1NF) by removing repeating groups, then to 2NF (no partial dependencies) and 3NF (no transitive dependencies).
关系数据库将数据组织成通过主键和外键链接的表（关系）。每个实体成为一个表，属性成为字段。规范化减少数据冗余；你应该能够通过移除重复组将未规范化的数据集转换为第一范式（1NF），然后到 2NF（无部分依赖）和 3NF（无传递依赖）。
SQL (Structured Query Language) uses SELECT, FROM, WHERE, ORDER BY, GROUP BY, and JOIN. You must be able to construct queries that retrieve specific information. Data definition commands (CREATE, ALTER, DROP) change the schema. DBMS systems provide security, integrity, and concurrent access.
SQL（结构化查询语言）使用 SELECT、FROM、WHERE、ORDER BY、GROUP BY 和 JOIN。你必须能够构建检索特定信息的查询。数据定义命令（CREATE、ALTER、DROP）更改模式。数据库管理系统（DBMS）提供安全性、完整性和并发访问。
9. Networks | 网络
Computer networks can be classified by scale: LAN (local, small area), WAN (wide area, across cities/countries), PAN, and MAN. Network topologies include star, bus, ring, and mesh. The star topology uses a central switch; bus topology was common in Ethernet. IP addressing (IPv4 and IPv6) identifies devices, while MAC addresses are hardware identifiers.
计算机网络按规模分类：LAN（局域网，小范围）、WAN（广域网，跨城市/国家）、PAN 和 MAN。网络拓扑包括星型、总线型、环形和网状。星型拓扑使用中央交换机；总线型拓扑曾常用于以太网。IP 地址（IPv4 和 IPv6）标识设备，而 MAC 地址是硬件标识符。
The TCP/IP stack consists of Application, Transport, Internet, and Network Access layers. Protocols such as HTTP/HTTPS, FTP, SMTP, POP3, IMAP, and DNS provide standardised communication. Packet switching breaks messages into packets that may travel different routes. Routers, switches, and gateways direct traffic.
TCP/IP 协议栈包含应用层、传输层、互联网层和网络接入层。HTTP/HTTPS、FTP、SMTP、POP3、IMAP 和 DNS 等协议提供标准化通信。分组交换将消息分割为可能走不同路径的数据包。路由器、交换机和网关负责引导流量。
10. Cybersecurity | 网络安全
Threats include malware (virus, worm, Trojan, ransomware), phishing, brute-force attacks, denial of service (DoS/DDoS), and SQL injection. Social engineering relies on tricking users. Authentication methods involve passwords, biometrics, two-factor authentication, and digital certificates.
威胁包括恶意软件（病毒、蠕虫、特洛伊木马、勒索软件）、网络钓鱼、暴力攻击、拒绝服务（DoS/DDoS）和 SQL 注入。社会工程学依赖欺骗用户。认证方法涉及密码、生物识别、双因素认证和数字证书。
Encryption protects data: symmetric (same key) and asymmetric (public/private key pair). Caesar cipher and simple substitution are classic examples, while AES and RSA are modern standards. Firewalls filter traffic; penetration testing probes for vulnerabilities. A well-defined security policy includes access rights and backup regimes.
加密保护数据：对称加密（相同密钥）和非对称加密（公钥/私钥对）。凯撒密码和简单代换是经典示例，而 AES 和 RSA 是现代标准。防火墙过滤流量；渗透测试排查漏洞。定义完善的安全策略包括访问权限和备份制度。
11. System Software and Operating Systems | 系统软件与操作系统
Operating systems manage hardware and provide a platform for applications. Functions include memory management (paging, segmentation), process scheduling (round-robin, priority), file management, and handling I/O. Interrupts allow the CPU to respond to events; the interrupt service routine (ISR) executes and then returns to the original task.
操作系统管理硬件并为应用程序提供平台。功能包括内存管理（分页、分段）、进程调度（轮转、优先级）、文件管理和处理 I/O。中断允许 CPU 响应事件；中断服务程序（ISR）执行后返回原任务。
Utility software includes disk defragmenters, backup tools, compression software, and anti-virus programs. Compilers translate high-level language into machine code as a single unit (static translation), while interpreters execute code line by line. Assemblers convert assembly language mnemonics into machine code. Linkers combine object files into executable programs.
实用工具软件包括磁盘碎片整理、备份工具、压缩软件和防病毒程序。编译器将高级语言一次性翻译为机器码（静态翻译），解释器则逐行执行代码。汇编器将汇编助记符转换为机器码。链接器将目标文件合并为可执行程序。
12. Ethical, Legal, and Environmental Issues | 伦理、法律与环境问题
Computing raises issues around privacy, surveillance, and data protection. Legislation such as the UK Data Protection Act (DPA 2018) and GDPR regulates how personal data is collected, stored, and processed. Copyright and software licensing determine how software can be used (proprietary, open-source, freeware). The Computer Misuse Act addresses unauthorised access.
计算技术引发了隐私、监控和数据保护等问题。英国的《数据保护法》（DPA 2018）和 GDPR 等法律规范了个人数据的收集、存储和处理方式。版权和软件许可决定了软件的使用方式（专有、开源、免费软件）。《计算机滥用法》涉及未经授权的访问。
Environmental concerns include energy consumption of data centres, e-waste disposal, and the lifecycle of devices. The digital divide widens inequality in access to technology. Responsible computing includes designing inclusive interfaces and considering the social impact of automation and AI.
环境问题包括数据中心能耗、电子垃圾处理和设备生命周期。数字鸿沟加剧了技术获得的不平等。负责任的计算包括设计包容性界面，并考虑自动化和人工智能的社会影响。
Published by TutorHao | Computer Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导Cancel reply