📚 Components of a Computer System and Modes of Use | 计算机系统组件与使用模式
A computer system is a combination of hardware and software that works together to receive, process, store and output data. Understanding the main components and the different modes of use is essential for Cambridge Computer Science, because it explains how machines operate and how they are selected for real-world tasks.
计算机系统是由硬件和软件共同组成的整体，用于接收、处理、存储和输出数据。理解主要组件以及不同的使用模式是剑桥计算机科学课程的基础，因为它说明了机器如何运行，以及在实际任务中如何选择合适的计算机系统。
1. Hardware and Software | 硬件与软件
Hardware refers to the physical parts of a computer that can be touched, such as the motherboard, processor, memory chips, keyboard and monitor. It provides the physical platform on which all computing activities take place.
硬件是指计算机中可以触摸到的物理部件，例如主板、处理器、内存芯片、键盘和显示器。它为所有计算活动提供了物理平台。
Software is a collection of instructions and data that tells the hardware what to do. It is divided into system software, such as operating systems and utility programs, and application software, such as word processors and web browsers.
软件是指告诉硬件如何工作的一组指令和数据。软件分为系统软件（如操作系统和实用程序）和应用软件（如文字处理器和网络浏览器）。
2. The Central Processing Unit (CPU) | 中央处理器
The CPU is often called the brain of the computer. It carries out the fetch-decode-execute cycle and performs all arithmetic, logical and control operations needed to run programs.
中央处理器常被称为计算机的大脑。它执行取指-译码-执行周期，并完成运行程序所需的全部算术、逻辑和控制操作。
The CPU contains the control unit (CU), the arithmetic logic unit (ALU) and registers. The CU directs data flow, the ALU performs calculations and comparisons, and registers provide extremely fast temporary storage inside the processor.
CPU 包含控制单元 (CU)、算术逻辑单元 (ALU) 和寄存器。控制单元指挥数据流动，ALU 执行计算和比较，寄存器则提供处理器内部极快的临时存储。
3. Main Memory: RAM and ROM | 主存储器：RAM 与 ROM
Main memory, also called primary storage, is directly accessible by the CPU. It includes RAM and ROM, which have different roles in the computer system.
主存储器也称为主存，可由 CPU 直接访问。它包括 RAM 和 ROM，它们在计算机系统中扮演不同的角色。
RAM (Random Access Memory) is volatile memory used to hold programs and data currently in use. When the power is turned off, the contents of RAM are lost. More RAM generally allows more applications to run smoothly at the same time.
RAM（随机存取存储器）是易失性存储器，用于保存当前正在使用的程序和数据。断电后，RAM 中的内容会丢失。通常 RAM 越大，同时运行多个应用程序就越流畅。
ROM (Read Only Memory) is non-volatile memory that stores essential startup instructions such as the BIOS or boot loader. Its contents are kept even when the computer is switched off and are usually fixed during manufacture.
ROM（只读存储器）是非易失性存储器，用于存储基本的启动指令，如 BIOS 或引导加载程序。即使计算机关机，其内容仍然保留，并且通常在制造时就已固定。
4. Secondary Storage | 辅助存储器
Secondary storage provides non-volatile, long-term storage for data and programs. Unlike RAM, it is not directly accessed by the CPU, so data must be loaded into main memory before use.
辅助存储器为数据和程序提供非易失性的长期存储。与 RAM 不同，CPU 不直接访问辅助存储器，因此数据必须先加载到主存中才能使用。
Common types include magnetic storage, such as hard disk drives (HDD), solid-state storage such as solid-state drives (SSD) and USB flash drives, and optical storage such as CDs and DVDs. SSDs are faster and more durable than HDDs because they have no moving parts, but they are usually more expensive per gigabyte.
常见类型包括磁存储器（如硬盘驱动器 HDD）、固态存储器（如固态硬盘 SSD 和 USB 闪存盘）以及光存储器（如 CD 和 DVD）。SSD 比 HDD 更快、更耐用，因为没有移动部件，但每 GB 的价格通常更高。
5. Input Devices | 输入设备
Input devices allow users to enter data and instructions into a computer system. They convert human-readable information into digital signals that the processor can understand.
输入设备使用户能够将数据和指令输入计算机系统。它们将人类可读的信息转换成处理器能够理解的数字信号。
Examples include keyboards, mice, touchscreens, microphones, scanners, barcode readers and sensors. Some input devices are manual, such as a mouse, while others are automatic, such as a temperature sensor that continuously captures readings.
常见的输入设备包括键盘、鼠标、触摸屏、麦克风、扫描仪、条形码阅读器和传感器。有些输入设备是手动的，例如鼠标；有些则是自动的，例如连续采集读数温度传感器。
6. Output Devices | 输出设备
Output devices communicate the results of processing back to the user or to another system. They convert digital information into a human-readable or machine-usable form.
输出设备将处理结果返回给用户或另一个系统。它们将数字信息转换成人类可读或机器可用的形式。
Examples include monitors, printers, speakers, projectors and actuators. Visual output is usually displayed on a screen, while printed output is produced by inkjet or laser printers; actuators can produce physical movement in control systems.
常见输出设备包括显示器、打印机、扬声器、投影仪和执行器。视觉输出通常显示在屏幕上，打印输出由喷墨或激光打印机产生；执行器可以在控制系统中产生物理运动。
7. System Software and Application Software | 系统软件与应用软件
System software manages and controls the computer hardware so that application software can run. The most important piece of system software is the operating system, which handles memory management, process scheduling, file management, input/output control and user interfaces.
系统软件管理和控制计算机硬件，使应用软件能够运行。最重要的系统软件是操作系统，它负责内存管理、进程调度、文件管理、输入/输出控制和用户界面。
Utility programs are also system software that perform maintenance tasks, such as antivirus scanning, disk defragmentation, backup and file compression.
实用程序也属于系统软件，用于执行维护任务，例如病毒扫描、磁盘碎片整理、备份和文件压缩。
Application software allows users to perform specific tasks. Examples include spreadsheets, database management systems, photo editors, web browsers and computer games. The same hardware can support many different applications, which makes a general-purpose computer flexible.
应用软件允许用户执行特定任务。例如电子表格、数据库管理系统、照片编辑器、网络浏览器和电脑游戏。同一硬件可以支持许多不同的应用程序，这使通用计算机具有灵活性。
8. Modes of Use: Batch, Real-time, Online, Offline | 使用模式：批处理、实时、在线、离线
A mode of use describes the way a computer system processes data and interacts with users or other systems. Choosing the correct mode is important for efficiency, safety and user experience.
使用模式描述了计算机系统处理数据以及与用户或其他系统交互的方式。选择正确的模式对于效率、安全性和用户体验非常重要。
Batch processing collects data over a period of time and processes it all at once without user interaction. It is suitable for tasks such as payroll systems, billing and large-scale file updates, where a delay between input and output is acceptable.
批处理在一段时间内收集数据，并在没有用户交互的情况下一次性处理所有数据。它适用于工资系统、账单和大型文件更新等任务，这些任务允许输入与输出之间存在延迟。
Real-time processing processes data immediately as it arrives, so the output is produced fast enough to influence the ongoing process. It is essential in air traffic control, heart-rate monitoring, anti-lock braking systems and online booking systems.
实时处理在数据到达时立即进行处理，因此输出速度足以影响正在进行的进程。它在空中交通管制、心率监测、防抱死制动系统和在线订票系统中至关重要。
Online mode means the computer is connected to a network or the internet and can communicate with other systems in real time. Offline mode means the computer is not connected to a network, although it can still process local data and run local programs.
在线模式意味着计算机连接到网络或互联网，可以与其他系统实时通信。离线模式意味着计算机未连接到网络，但它仍然可以处理本地数据并运行本地程序。
9. Single-user and Multi-user Systems | 单用户与多用户系统
A single-user system is designed to be used by one person at a time. Most personal computers, laptops, tablets and smartphones are single-user systems, even though they may run multiple applications at once.
单用户系统设计为一次仅供一个人使用。大多数个人计算机、笔记本电脑、平板电脑和智能手机都是单用户系统，尽管它们可以同时运行多个应用程序。
A multi-user system allows several users to access the same computer and share its resources at the same time. The operating system must manage user accounts, file permissions, security and fairness of resource allocation.
多用户系统允许多个用户同时访问同一台计算机并共享其资源。操作系统必须管理用户账户、文件权限、安全性以及资源分配的公平性。
Typical examples include mainframe computers used by banks, university servers and cloud-based systems accessed by many clients through terminals or web browsers.
典型例子包括银行使用的大型机、大学服务器以及许多客户端通过终端或网络浏览器访问的云系统。
10. Multitasking and Multiprogramming | 多任务与多道程序
Multitasking allows a single processor to give the appearance of running several tasks at the same time. The CPU switches rapidly between processes, so the user can listen to music while editing a document and downloading a file.
多任务使单个处理器看起来像是在同时运行多个任务。CPU 在进程之间快速切换，因此用户可以一边听音乐，一边编辑文档，同时下载文件。
Multiprogramming is a related idea in which several programs are loaded into memory at once. When one program waits for input/output, the CPU can execute another program instead of remaining idle. This increases processor utilisation.
多道程序是一个相关概念，即多个程序同时加载到内存中。当一个程序等待输入/输出时，CPU 可以转而执行另一个程序，而不是空闲等待。这提高了处理器利用率。
Modern operating systems combine multitasking, multiprogramming and multiple user accounts in a controlled environment managed by the scheduler.
现代操作系统在调度程序管理的受控环境中结合了多任务、多道程序和多用户账户。
11. Embedded Systems and General-purpose Systems | 嵌入式系统与通用系统
An embedded system is a computer system built into a larger device to perform a dedicated function. It usually has limited memory, storage and processing power, and runs firmware stored in ROM.
嵌入式系统是内置在更大设备中、用于执行专用功能的计算机系统。它通常具有有限的内存、存储和处理能力，并运行存储在 ROM 中的固件。
Examples include washing machine controllers, digital cameras, traffic lights, engine management units in cars and smart thermostats. Embedded systems are often chosen because they are small, reliable, power-efficient and cost-effective for a specific task.
例如洗衣机控制器、数码相机、交通信号灯、汽车发动机管理单元和智能恒温器。嵌入式系统通常因为体积小、可靠性高、功耗低以及对特定任务具有成本效益而被选用。
A general-purpose system, such as a desktop PC or a server, can run many different applications and be reconfigured by the user. It is more flexible but usually larger, more expensive and more complex than an embedded system.
通用系统（如台式机或服务器）可以运行许多不同的应用程序，并可由用户重新配置。它更灵活，但通常比嵌入式系统更大、更昂贵、更复杂。
12. Choosing the Right Mode of Use | 选择合适的使用模式
Different tasks require different modes of use. A payroll system may use batch processing because it deals with large volumes of similar data and does not need instant output, while an anti-lock braking system must use real-time processing because any delay could be dangerous.
不同的任务需要不同的使用模式。工资系统可以采用批处理，因为它处理大量相似数据且不需要即时输出；而防抱死制动系统必须使用实时处理，因为任何延迟都可能造成危险。
The choice also depends on hardware constraints, cost, user interaction and connectivity. For example, a school computer lab may use multi-user servers with online access for shared files, while a scientific sensor in a remote field station may collect data offline and upload it later in batch mode.
选择还取决于硬件限制、成本、用户交互和连接性。例如，学校计算机实验室可以使用多用户服务器并在线访问共享文件，而偏远野外站的科学传感器可以离线收集数据，稍后以批处理模式上传。
Understanding components and modes of use therefore helps designers select the most suitable computer system for each real-world situation.
因此，理解计算机系统组件与使用模式有助于设计者为每种实际情况选择最合适的计算机系统。
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