📚 Core Knowledge Points Review for Year 11 CIE Computer Science | Year 11 CIE 计算机：核心知识点梳理
This article provides a structured revision of the essential topics covered in the Year 11 CIE Computer Science syllabus. Understanding these core areas is critical for success in both Paper 1 (Theory) and Paper 2 (Problem-solving and Programming). We will walk through data representation, hardware, software, networks, and algorithmic thinking, ensuring you have a solid foundation for exam preparation.
本文为 Year 11 CIE 计算机科学教学大纲中的核心知识点提供系统梳理。掌握这些关键领域对于在 Paper 1（理论）和 Paper 2（问题解决与编程）中取得成功至关重要。我们将梳理数据表示、硬件、软件、网络以及算法思维，帮助你在备考中打下坚实基础。
1. Data Representation | 数据表示
All data in a computer is stored as binary digits (bits). Understanding how numbers, text, images and sound are represented is fundamental. Binary is base‑2, using only 0 and 1.
计算机中的所有数据都以二进制数字（比特）存储。理解数字、文本、图像和声音的表示方式是基础。二进制是基数为 2 的进制，仅使用 0 和 1。
Denary (base‑10) integers can be converted to binary by successive division by 2, reading the remainders backwards. Hexadecimal (base‑16) is used as a shorthand for binary, with digits 0‑9 and letters A‑F.
十进制（基数为 10）整数可通过连续除以 2 并反向读取余数转换为二进制。十六进制（基数为 16）用作二进制的简写，使用数字 0‑9 和字母 A‑F。
For text, ASCII uses 7 bits (extended ASCII uses 8 bits) per character, while Unicode supports a much wider range of characters using up to 4 bytes. Images are represented as a grid of pixels, with colour depth determining the number of bits per pixel.
对于文本，ASCII 每个字符使用 7 位（扩展 ASCII 使用 8 位），而 Unicode 最多使用 4 字节来支持更广泛的字符集。图像以像素网格表示，颜色深度决定了每个像素的位数。
Sound is sampled at regular intervals (sample rate) and each measurement is stored as a binary number (sample resolution). Higher sample rate and resolution give better quality but larger file sizes.
声音按固定间隔（采样率）进行采样，每个测量值以二进制数（采样分辨率）存储。采样率和分辨率越高，音质越好，但文件大小也越大。
t × colour depth (bits); sound file size = sample rate × resolution × duration × channels.
文件大小计算：文本文件大小 = 字符数 × 每个字符的位数；图像文件大小 = 宽度 × 高度 × 颜色深度（位）；声音文件大小 = 采样率 × 分辨率 × 时长 × 声道数。
2. Data Transmission | 数据传输
Data can be transmitted serially (one bit at a time) or in parallel (multiple bits simultaneously over separate wires). Serial transmission is more suitable for long distances due to less interference.
数据传输可分为串行（一次传输一位）或并行（通过多条线路同时传输多位）。串行传输因干扰较少而更适用于长距离。
Transmission can be simplex (one‑way), half‑duplex (both ways but not simultaneously), or full‑duplex (both ways at the same time). USB supports half‑duplex or full‑duplex modes.
传输方式可以是单工（单向）、半双工（双向但不同时）或全双工（双向同时）。USB 支持半双工或全双工模式。
Error detection methods include parity checks (even or odd), checksums, and echo checks. A parity bit is added to make the number of 1‑bits even or odd; it detects only an odd number of bit errors.
错误检测方法包括奇偶校验（偶校验或奇校验）、校验和以及回波校验。添加奇偶位使 1 的位数为偶数或奇数；它仅能检测奇数个位错误。
Encryption is used to protect data during transmission. Symmetric encryption uses a single key; asymmetric encryption uses a public key for encryption and a private key for decryption, which is more secure but slower.
加密用于在传输过程中保护数据。对称加密使用单个密钥；非对称加密使用公钥加密和私钥解密，更安全但速度较慢。
3. Hardware | 硬件
The central processing unit (CPU) follows the fetch‑decode‑execute cycle. The control unit (CU) manages the flow of data, the arithmetic logic unit (ALU) performs calculations, and registers hold temporary data.
中央处理器（CPU）遵循取指–译码–执行周期。控制单元（CU）管理数据流动，算术逻辑单元（ALU）执行计算，寄存器存放临时数据。
Key registers include the program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR), and accumulator (ACC). The system clock synchronises operations.
关键寄存器包括程序计数器（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）。系统时钟同步各操作。
Factors affecting CPU performance are clock speed, number of cores, and cache size. Cache memory is faster than RAM but smaller; it stores frequently used instructions to reduce the need to access slower main memory.
影响 CPU 性能的因素包括时钟速度、核心数量和缓存大小。缓存内存的存取速度比 RAM 快但容量较小；它存储常用指令以减少访问较慢主存的次数。
Input devices (keyboard, mouse, sensor) take real‑world data and convert it into digital signals. Output devices (monitor, printer, actuator) present or act on processed data. Storage devices include magnetic (HDD), optical (CD/DVD), and solid state (SSD).
输入设备（键盘、鼠标、传感器）获取真实世界数据并将其转换为数字信号。输出设备（显示器、打印机、执行器）呈现或处理数据。存储设备包括磁性（HDD）、光学（CD/DVD）和固态（SSD）。
4. Software | 软件
System software includes the operating system (OS) and utility programs. The OS manages hardware resources, provides a user interface, handles multitasking, memory management, peripheral management, and security.
系统软件包括操作系统（OS）和实用程序。操作系统管理硬件资源，提供用户界面，处理多任务、内存管理、外设管理和安全。
Application software serves specific user tasks, such as word processors, spreadsheets, and database management systems. It cannot run without the OS providing platform services.
应用软件服务于特定的用户任务，如文字处理软件、电子表格和数据库管理系统。它们必须依赖操作系统提供平台服务才能运行。
High‑level languages (e.g., Python, Java) are easier for humans to read but must be translated into machine code. Translators include compilers (translate whole program once), interpreters (translate and execute line by line), and assemblers (for assembly language).
高级语言（如 Python、Java）便于人类阅读，但必须翻译成机器码。翻译器包括编译器（一次性翻译整个程序）、解释器（逐行翻译并执行）和汇编器（用于汇编语言）。
5. The Internet and Its Uses | 互联网及其用途
The Internet is a global network of interconnected networks. Data is broken into packets and sent using TCP/IP. IP handles addressing and routing, while TCP ensures reliable delivery by reassembling packets and requesting retransmission of lost ones.
互联网是互连网络的全球性系统。数据被拆分为数据包，通过 TCP/IP 协议发送。IP 负责寻址和路由，而 TCP 通过重组数据包并请求重发丢失的数据包来确保可靠传输。
Web technologies include HTTP and HTTPS. HTTPS uses SSL/TLS encryption to secure data. A URL consists of protocol, domain name, and path. The Domain Name System (DNS) converts domain names to IP addresses.
网络技术包括 HTTP 和 HTTPS。HTTPS 使用 SSL/TLS 加密来保护数据。URL 由协议、域名和路径组成。域名系统（DNS）将域名转换为 IP 地址。
Common threats include malware, phishing, denial‑of‑service (DoS) attacks, and SQL injection. Prevention methods involve firewalls, anti‑malware software, strong authentication, and regular updates.
常见的威胁包括恶意软件、网络钓鱼、拒绝服务（DoS）攻击和 SQL 注入。预防措施包括防火墙、反恶意软件、强身份验证和定期更新。
6. Automated and Emerging Technologies | 自动化与新兴技术
Automated systems use sensors, microprocessors, and actuators to perform tasks without human intervention. Examples include traffic light control, greenhouse monitoring, and industrial robots.
自动化系统使用传感器、微处理器和执行器在无人干预下执行任务，例如交通灯控制、温室监控和工业机器人。
Artificial intelligence (AI) enables machines to perform tasks that normally require human intelligence, such as speech recognition and decision‑making. Machine learning is a subset where systems improve from data without being explicitly programmed.
人工智能（AI）使机器能够执行通常需要人类智能的任务，如语音识别和决策。机器学习是其中一个子集，系统无需明确编程即可从数据中学习改进。
Ethical issues arise with AI, including unemployment, bias in algorithms, and privacy concerns. Automated decision‑making must be transparent and accountable.
人工智能带来伦理问题，包括失业、算法偏见和隐私担忧。自动化决策必须透明且可问责。
7. Algorithm Design and Problem‑Solving | 算法设计与问题解决
An algorithm is a step‑by‑step procedure to solve a problem. Key building blocks are sequence, selection (if‑else), and iteration (loop). Algorithms can be expressed using flowcharts or pseudocode.
算法是解决问题的逐步过程。关键构建块包括顺序、选择（if‑else）和迭代（循环）。算法可用流程图或伪代码表示。
Common search algorithms are linear search (checks each element) and binary search (repeatedly divides a sorted list). Binary search is much faster for large, sorted datasets.
常见搜索算法有线性搜索（逐一检查元素）和二分搜索（反复对半分割有序列表）。二分搜索对于大型有序数据集要快得多。
Sorting algorithms include bubble sort (repeatedly swapping adjacent elements) and insertion sort (building sorted portion one element at a time). Understanding their efficiency and the number of comparisons is essential.
排序算法包括冒泡排序（反复交换相邻元素）和插入排序（每次插入一个元素到已排序部分）。理解其效率及比较次数至关重要。
Standard pseudocode uses INPUT, OUTPUT, variables, IF … THEN … ELSE, FOR … TO … NEXT, WHILE … DO … ENDWHILE, REPEAT … UNTIL, and procedures/functions.
标准伪代码使用 INPUT、OUTPUT、变量、IF … THEN … ELSE、FOR … TO … NEXT、WHILE … DO … ENDWHILE、REPEAT … UNTIL 以及过程/函数。
8. Programming | 编程
Programming involves writing code in a high‑level language. Variables store data of different types: integer, real, char, string, and Boolean. Constants hold values that do not change.
编程涉及用高级语言编写代码。变量存储不同数据类型：整型、实型、字符、字符串和布尔型。常量保存不变的值。
Sequence, selection, and iteration structures are implemented with specific syntax. Count‑controlled loops (FOR) execute a set number of times; condition‑controlled loops (WHILE, REPEAT) depend on a Boolean expression.
顺序、选择和迭代结构通过特定语法实现。计数控制循环（FOR）执行固定次数；条件控制循环（WHILE、REPEAT）依据布尔表达式执行。
Arrays are data structures that hold multiple items of the same type under one name, accessed by index. One‑dimensional arrays are easy to traverse; two‑dimensional arrays use row and column indices for tables.
数组是使用一个名称存放多个同类型元素的数据结构，通过索引访问。一维数组易于遍历；二维数组使用行和列索引来处理表格数据。
Modular programming breaks a problem into sub‑tasks using procedures (which return no value) and functions (which return a value). Parameters can be passed by value or by reference.
模块化编程使用过程（无返回值）和函数（有返回值）将问题分解为子任务。参数可以按值传递或按引用传递。
9. Databases | 数据库
A database is an organised collection of data. Relational databases store data in tables with rows (records) and columns (fields). Each table has a primary key to uniquely identify each record.
数据库是有组织的数据集合。关系数据库以表形式存储数据，表包含行（记录）和列（字段）。每个表有一个主键来唯一标识每条记录。
Foreign keys link tables together to reduce data redundancy. Structured Query Language (SQL) is used to manage and query data. Basic SQL commands: SELECT … FROM … WHERE, ORDER BY, and INSERT INTO.
外键将表连接在一起以减少数据冗余。结构化查询语言（SQL）用于管理和查询数据。基本 SQL 命令：SELECT … FROM … WHERE、ORDER BY 和 INSERT INTO。
Flat‑file databases store all data in a single table, which can lead to duplication. Relational databases solve this through normalisation, which organises fields to minimise redundancy.
平面文件数据库将所有数据存储于单一表中，可能导致数据重复。关系数据库通过规范化来解决这个问题，规范化组织字段以最大限度减少冗余。
10. Boolean Logic | 布尔逻辑
Boolean algebra uses binary variables that can only be TRUE (1) or FALSE (0). Basic logic gates are NOT, AND, OR, NAND, NOR, and XOR. Each gate corresponds to a truth table and a Boolean expression.
布尔代数使用只能为 TRUE（1）或 FALSE（0）的二进制变量。基本逻辑门包括 NOT、AND、OR、NAND、NOR 和 XOR。每种门都有对应的真值表和布尔表达式。
n, e.g., Q = (A AND B) OR (NOT C). Simplifying such expressions using laws (like De Morgan's) can reduce the number of gates needed.
逻辑电路由门组合而成。它可以用逻辑表达式描述，例如 Q = (A AND B) OR (NOT C)。使用定律（如德摩根定律）简化这些表达式可以减少所需门的数量。
A half adder adds two bits and produces a sum and carry. A full adder adds two bits plus a carry‑in to produce sum and carry‑out. Both are built from combinations of logic gates.
半加器将两个位相加，产生和位与进位。全加器将两个位连同进位输入相加，产生和位与进位输出。两者均由逻辑门组合构建。
Published by TutorHao | Computer Science Revision Series | aleveler.com
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