📚 Types of Software and Interrupts | 软件类型与中断
Software tells a computer system what to do, but not all software works in the same way. In IGCSE Computer Science, you need to distinguish between system software and application software, and you must understand how interrupts allow devices and programs to get the processor’s attention.
软件告诉计算机系统该做什么，但并非所有软件都以相同方式工作。在 IGCSE 计算机科学中，你需要区分系统软件和应用软件，并理解中断如何让设备和程序获得处理器的关注。
1. Software Categories: System and Application | 软件分类：系统软件与应用软件
All software can be placed into two broad groups. System software manages the hardware and provides a platform for running application software; application software performs tasks directly for the user.
所有软件都可以归入两大类。系统软件管理硬件并为运行应用软件提供平台；应用软件直接为用户执行任务。
The distinction is based on purpose, not on how advanced or popular the program is. A game is application software even though it uses complex graphics, because it serves the user rather than managing the machine.
这种区分基于用途，而不是程序有多先进或流行。游戏属于应用软件，即使它使用了复杂的图形，因为它是为用户服务而不是管理机器。
| Category | Purpose | 中文目的 | Examples |
|---|---|---|---|
| System software | Manages hardware and supports applications | 管理硬件并支持应用程序 | Operating system, utilities, device drivers |
| Application software | Performs user tasks | 执行用户任务 | Word processor, browser, game |
2. What Is System Software? | 什么是系统软件？
System software is not usually noticed by the user, but it is essential for the computer to operate. It controls hardware resources, maintains the system and allows other programs to run.
系统软件通常不被用户注意，但它对计算机运行至关重要。它控制硬件资源、维护系统并允许其他程序运行。
- Operating system: manages memory, processor time, files and input/output devices. 操作系统：管理内存、处理器时间、文件和输入/输出设备。
- Device drivers: translate operating system instructions into commands specific to each hardware device. 设备驱动程序：将操作系统指令翻译为每个硬件设备特定的命令。
- Utility software: carries out maintenance tasks such as backup, repair, compression and security scanning. 实用软件：执行备份、修复、压缩和安全扫描等维护任务。
- Language translators: convert high-level programming code into machine code the processor can execute. 语言翻译器：将高级编程代码转换为处理器可以执行的机器代码。
3. What Is Application Software? | 什么是应用软件？
Application software is designed to help the user perform specific tasks. It can be general-purpose, such as word processors and spreadsheets, or special-purpose, such as a payroll system or air traffic control program.
应用软件旨在帮助用户执行特定任务。它可以是通用的，如文字处理器和电子表格，也可以是专用的，如工资系统或空中交通管制程序。
General-purpose application software can be used for many different jobs. Special-purpose software is written for one particular task and is often customised for an organisation.
通用应用软件可用于许多不同的工作。专用软件针对某一特定任务编写，通常为某个组织定制。
- General-purpose: browsers, email clients, presentation software, database management systems. 通用：浏览器、电子邮件客户端、演示软件、数据库管理系统。
- Special-purpose: school timetabling, weather forecasting, hospital patient records, stock control. 专用：学校排课、天气预报、医院病人记录、库存管理。
4. Operating Systems: Purpose and Functions | 操作系统：目的与功能
The operating system is the most important type of system software. It hides the complexity of the hardware from the user and makes efficient use of resources such as memory, storage and processor time.
操作系统是最重要的系统软件类型。它向用户隐藏硬件的复杂性，并高效利用内存、存储和处理器时间等资源。
- Memory management: allocates RAM to processes and prevents one process from corrupting another. 内存管理：为进程分配 RAM，防止一个进程破坏另一个进程。
- Processor scheduling: decides which process runs next and for how long. 处理器调度：决定下一个运行哪个进程以及运行多长时间。
- File management: creates, stores, retrieves and protects files and directories. 文件管理：创建、存储、检索和保护文件及目录。
- User management: controls user accounts, passwords and access rights. 用户管理：控制用户账户、密码和访问权限。
- Input/output control: communicates with peripherals through device drivers. 输入/输出控制：通过设备驱动程序与外围设备通信。
5. Utility Software: Keeping the System Running | 实用软件：保持系统运行
Utility programs are a type of system software that carry out specific maintenance and optimisation tasks. They often run automatically in the background and do not produce work for the user directly.
实用程序是一种系统软件，执行特定的维护和优化任务。它们通常在后台自动运行，不直接为用户产生工作成果。
- Antivirus software: detects, blocks and removes malware. 防病毒软件：检测、阻止和移除恶意软件。
- Backup software: copies data to another location so it can be recovered. 备份软件：将数据复制到另一个位置以便恢复。
- Disk defragmenter: reorganises file fragments on a magnetic disk so files are stored contiguously. 磁盘碎片整理程序：重新组织磁盘上的文件碎片，使文件连续存储。
- Compression tools: reduce file size for storage or transfer. 压缩工具：减小文件大小以便存储或传输。
- Encryption tools: scramble data so that only authorised users can read it. 加密工具：打乱数据，使只有授权用户才能读取。
6. What Is an Interrupt? | 什么是中断？
An interrupt is a signal sent to the processor to tell it that an event needs immediate attention. Without interrupts, the processor would have to constantly poll devices to see if they need service, which wastes processor time.
中断是发送给处理器的信号，告诉它某个事件需要立即处理。没有中断，处理器就必须不断轮询设备看它们是否需要服务，这会浪费处理器时间。
When an interrupt arrives, the processor suspends the current program, runs a small routine called the interrupt service routine, then returns to the suspended program.
当中断到来时，处理器暂停当前程序，运行称为中断服务程序的小例程，然后返回被暂停的程序。
Normal program → Interrupt received → Save state → Run ISR → Restore state → Resume program
This sequence allows the computer to respond to events while still returning correctly to the original task.
这个顺序使计算机既能响应事件，又能正确地返回原始任务。
7. Hardware and Software Interrupts | 硬件中断与软件中断
Hardware interrupts are generated by physical devices. Software interrupts are generated within the processor by program instructions or by errors such as division by zero.
硬件中断由物理设备产生。软件中断由处理器内部的程序指令或错误产生，例如除以零。
| Feature | Hardware interrupt | Software interrupt |
|---|---|---|
| Source | Physical device | Program instruction or error |
| 中文来源 | 物理设备 | 程序指令或错误 |
| Example | Key press, printer out of paper | Division by zero, system call |
| 中文示例 | 按键、打印机缺纸 | 除以零、系统调用 |
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