Operating systems and utility software · 操作系统与实用软件
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| operating system/ˈɒpəreɪtɪŋ ˈsɪstəm/ | 操作系统 | cāo zuò xì tǒng |
| utility programs/juːˈtɪlɪti ˈprəʊɡræmz/ | 实用程序 | shí yòng chéng xù |
| device driver/dɪˈvaɪs ˈdraɪvə/ | 设备驱动 | shè bèi qū dòng |
| memory management/ˈmeməri ˈmænɪdʒmənt/ | 内存管理 | nèi cún guǎn lǐ |
| memory protection/ˈmeməri prəˈtekʃn/ | 内存保护 | nèi cún bǎo hù |
| virtual memory/ˈvɜːtʃuːəl ˈmeməri/ | 虚拟内存 | xū nǐ nèi cún |
| paging/ˈpeɪdʒɪŋ/ | 分页 | fēn yè |
| process/ˈprəʊses/ | 进程 | jìn chéng |
| process management/ˈprəʊses ˈmænɪdʒmənt/ | 进程管理 | jìn chéng guǎn lǐ |
| scheduling/ˈʃedjuːlɪŋ/ | 调度 | diào dù |
| time slice/taɪm slaɪs/ | 时间片 | shí jiān piàn |
| hardware interrupt/ˈhɑːdweə ˈɪntərʌpt/ | 硬件中断 | yìng jiàn zhōng duàn |
| software interrupt/ˈsɒftweə ˈɪntərʌpt/ | 软件中断 | ruǎn jiàn zhōng duàn |
| interrupt handler/ˈɪntərʌpt ˈhændlə/ | 中断处理程序 | zhōng duàn chǔ lǐ chéng xù |
| directory/daɪˈrektəri/ | 目录 | mù lù |
| access rights/ˈækses raɪts/ | 访问权限 | fǎng wèn quán xiàn |
| signatures/ˈsɪɡnɪtʃəz/ | 签名 | qiān míng |
| incremental backups/ˌɪŋkrɪˈmentl ˈbækʌps/ | 增量备份 | zēng liàng bèi fèn |
| fragmented/fræɡˈmentɪd/ | 碎片化 | suì piàn huà |
1202 alarm
- Three minutes before the first Moon landing, the Apollo 11 guidance computer flashed a code the crew had never seen in training: 1202. A misconfigured radar was flooding it with work it could not finish.
- The computer's tiny operating system 操作系统 did what an operating system is for. It ranked every job by priority, dropped the ones that did not matter, and kept the descent calculations running. The landing continued.
- Without that scheduler, the computer would have frozen and the landing been aborted. Every phone and laptop today makes the same decisions thousands of times a second.
- This lesson is why a computer needs an OS, the five management tasks the syllabus names, and the utility programs bundled with it.
1202 警报
- 第一次登月前三分钟,阿波罗 11 号的制导计算机闪出一个乘员在训练中从未见过的代码:1202。一台配置错误的雷达正用它做不完的工作淹没它。
- 这台计算机微小的操作系统(operating system)做了操作系统该做的事。它按优先级给每项任务排序,丢掉不重要的,让下降计算继续运行。着陆继续。
- 没有那个调度器,计算机会冻结,着陆会被中止。今天每部手机和笔记本每秒做着同样的决定几千次。
- 这一课讲计算机为什么需要 OS、大纲点名的五项管理任务,以及随它捆绑的实用程序。
Why a computer needs an operating system
- Hardware alone can only fetch and execute instructions. It knows nothing about files, programs, networks or users.
- The OS provides an interface between the user and the hardware, and hides the complexity of the hardware from the user and from application programs.
- It manages the hardware resources, processor time, memory, storage and input/output, and shares them between programs; it loads application software into memory and runs it; and it provides security and utilities.
- Without one, every program would need its own device drivers and only one program could safely run at a time.
One layer between every program and the hardware
计算机为什么需要操作系统
- 硬件本身只能取指令和执行指令。它对文件、程序、网络或用户一无所知。
- OS 提供用户与硬件之间的接口,并向用户和应用程序隐藏硬件的复杂性。
- 它管理硬件资源——处理器时间、内存、存储和输入/输出——并在程序之间共享它们;它把应用软件加载到内存并运行;它还提供安全和实用程序。
- 没有它,每个程序都需要自己的设备驱动,而且一次只能安全地运行一个程序。
每个程序与硬件之间的一个层
Where the operating system sits · 操作系统位于何处
Tap each layer. The OS is the middle layer — it sits between your applications and the hardware, sharing the machine safely so programs never touch the hardware directly. · 点击每一层。操作系统是中间层——它位于你的应用和硬件之间,安全地共享机器,所以程序从不直接接触硬件。
Which is a core job of an operating system? · 哪个是一个操作系统的核心工作?
The OS manages hardware and provides services and a UI, letting multiple programs run safely on shared hardware. · 操作系统管理硬件并提供服务和一个 UI,让多个程序在共享的硬件上安全地运行。
The operating system lets several programs share the same hardware safely, so they don't interfere with each other. · 操作系统让几个程序安全地共享同一个硬件,所以它们不互相干扰。
Sharing the CPU, memory and devices safely between many programs is exactly what the OS is for. · 在许多程序之间安全地共享 CPU、内存和设备正是操作系统的用途。
Which are purposes of an operating system? Select all · 所有 that apply. · 哪些是操作系统的目的?选出所有适用的。
Interface, hiding complexity, managing and sharing resources are the OS's jobs. Translation is a compiler's or interpreter's. · 接口、隐藏复杂性、管理和共享资源是 OS 的工作。翻译是编译器或解释器的工作。
Memory management
- Memory management 内存管理 allocates memory to each program when it is loaded and frees it when the program ends.
- It keeps every program's memory separate, memory protection 内存保护, so one program cannot overwrite another's data.
- It swaps pages between RAM and disk, virtual memory 虚拟内存 through paging 分页, so more programs can be open than physical memory allows.
Each process gets its own fenced block
内存管理
- 内存管理(memory management)在程序加载时给它分配内存,在程序结束时释放。
- 它让每个程序的内存彼此分开——内存保护(memory protection)——所以一个程序不能覆盖另一个的数据。
- 它在 RAM 和磁盘之间交换页面——通过分页(paging)实现的虚拟内存(virtual memory)——所以能打开的程序比物理内存允许的更多。
每个进程有自己围起来的一块
Virtual memory (paging) lets the OS: · 虚拟内存(分页)让操作系统:
Paging moves blocks between RAM and disk so programs can use more memory than is physically installed. · 分页在 RAM 和磁盘之间移动块,所以程序能使用比物理安装的更多的内存。
Process management
- A running program is a process 进程. Process management 进程管理 creates and ends processes.
- It decides which process gets the CPU next, scheduling 调度, and for how long, a time slice 时间片, then saves the process's state and switches to the next.
- It resolves conflicts when two processes want the same resource, and can end one that stops responding.
进程管理
- 正在运行的程序是一个进程(process)。进程管理(process management)创建和结束进程。
- 它决定哪个进程下一个获得 CPU——调度(scheduling)——以及用多长时间——一个时间片(time slice)——然后保存该进程的状态并切换到下一个。
- 它解决两个进程要同一资源时的冲突,并能结束停止响应的进程。
A running program is called a: · 一个运行中的程序被称为一个:
Process management loads, schedules and switches between processes (running programs). · 进程管理加载、调度运行中的程序(进程)并在它们之间切换。
Worked example: how the OS makes multitasking possible
- Explain how memory management and process management allow several programs to run at the same time. [4]
- Memory management loads several programs into memory at once, each in its own protected area, and keeps track of which addresses belong to which program.
- Process management shares the processor between them: each process runs for a time slice, the OS saves its state and switches to the next.
- The switching is so fast that all the programs appear to run at the same time, though the processor executes only one at any instant.
例题:OS 怎样实现多任务
- 解释内存管理和进程管理怎样让几个程序同时运行。[4]
- 内存管理把几个程序同时加载到内存,各在自己受保护的区域,并记录哪些地址属于哪个程序。
- 进程管理在它们之间共享处理器:每个进程运行一个时间片,OS 保存它的状态并切换到下一个。
- 切换快到所有程序看起来在同时运行,尽管处理器在任一瞬间只执行一个。
Put the steps that let several programs appear to run at once in order. · 把让几个程序看似同时运行的步骤按顺序排列。
Memory management does the first step; process management does the rest. · 内存管理做第一步;进程管理做其余的。
Hardware management and interrupts
- The OS talks to each device through its device driver 设备驱动, queues and buffers data going to slow devices such as a printer, and shares one device between several programs.
- A hardware interrupt 硬件中断 comes from a device: a key pressed, a printer out of paper, a disk transfer finished, a power failure. A software interrupt 软件中断 comes from a program: division by zero, an invalid instruction, a request for an OS service.
- The interrupt handler 中断处理程序 saves the state of the current process, deals with the interrupt, then restores the process and continues.
硬件管理与中断
- OS 通过每个设备的设备驱动(device driver)与之通信,为打印机这样的慢设备排队和缓冲数据,并让几个程序共享一个设备。
- 硬件中断(hardware interrupt)来自设备:按键、打印机缺纸、磁盘传输完成、断电。软件中断(software interrupt)来自程序:除以零、无效指令、请求 OS 服务。
- 中断处理程序(interrupt handler)保存当前进程的状态,处理中断,然后恢复进程并继续。
A printer runs out of paper and signals the processor. This is: · 打印机缺纸并向处理器发出信号。这是:
It comes from a device. A software interrupt comes from a program, such as a division by zero. · 它来自设备。软件中断来自程序,比如除以零。
File management and security management
- File management: creates, names, copies, moves and deletes files and folders; keeps the directory 目录 structure and a record of where each file sits on the disk; allocates disk space; enforces access rights 访问权限 for each user.
- Security management: user accounts and passwords, access rights, encryption of stored data, a firewall, automatic security updates, and a log of who did what.
- A "describe" question wants what the OS actually does under each heading, one action per mark.
文件管理与安全管理
- 文件管理:创建、命名、复制、移动和删除文件和文件夹;维护目录(directory)结构和每个文件在磁盘上位置的记录;分配磁盘空间;为每个用户执行访问权限(access rights)。
- 安全管理:用户账户和密码、访问权限、存储数据的加密、防火墙、自动安全更新,以及谁做了什么的日志。
- "描述"题要的是 OS 在每个标题下实际做什么,一个动作一分。
Match each OS management task to what it does. · 把每个操作系统管理任务与它做的事配对。
The OS juggles four core resources — the CPU (processes), RAM (memory), storage (files) and peripherals (devices). · 操作系统兼顾四个核心资源——CPU(进程)、RAM(内存)、存储(文件)和外设(设备)。
Utility software
- Utility programs 实用程序 are system software that maintain, repair or optimise the computer rather than doing a user's task.
- Disk formatter: prepares a disk for use by setting up its file system, deleting any existing data. Virus checker: compares files against a database of known signatures 签名, watches behaviour, quarantines what it finds; must be updated.
- Defragmentation software: gathers the scattered blocks of each file together. Disk contents analysis and repair: shows what uses the space; finds and fixes bad sectors and file-system errors.
- File compression: shrinks files for storage and transfer. Back-up software: copies files to another medium on a schedule; a full copy, then incremental backups 增量备份 of what changed.
Each one does a single maintenance job
实用软件
- 实用程序(utility programs)是维护、修复或优化计算机的系统软件,而不是完成用户任务的软件。
- 磁盘格式化程序:通过建立文件系统让磁盘可用,删除已有数据。病毒检查程序:把文件与已知特征(signatures)库比对,监视行为,隔离发现的东西;必须更新。
- 碎片整理软件:把每个文件散落的块聚在一起。磁盘内容分析与修复:显示什么占用了空间;找到并修复坏扇区和文件系统错误。
- 文件压缩:缩小文件以便存储和传输。备份软件:按计划把文件复制到另一介质;先一次完整副本,再对改动做增量备份(incremental backups)。
每一个只做一项维护工作
System-maintenance programs such as antivirus, backup and defragmenter are called ______ software. · 诸如杀毒、备份和碎片整理程序这样的系统维护程序被称为______软件。
Utility software maintains the system; word processors and browsers are application software. · 实用软件维护系统;文字处理器和浏览器是应用软件。
Worked example: how defragmentation improves performance
- Explain how defragmentation can improve the performance of a computer. [3]
- A hard disk stores a file in whatever free blocks it finds, so over time a file becomes fragmented 碎片化, scattered across the platter, and reading it needs many movements of the read/write head.
- The defragmenter moves the blocks of each file next to each other, so it is stored contiguously, and gathers the free space into one region.
- Files are then read with fewer head movements, so they load faster, and new files can be written into one continuous space. An SSD has no moving head, so it gains nothing.
例题:碎片整理怎样提升性能
- 解释碎片整理怎样提升计算机的性能。[3]
- 硬盘把文件存到它找到的任何空闲块里,所以随着时间文件变得碎片化(fragmented),散落在盘片各处,读取它需要读写头多次移动。
- 碎片整理程序把每个文件的块移到一起,让它连续存储,并把空闲空间聚成一片。
- 之后文件用更少的磁头移动读出,所以加载更快,新文件也能写进一块连续空间。SSD 没有移动的磁头,所以毫无收益。
A disk defragmenter is useful on a hard disk but NOT on an SSD because: · 一个磁盘碎片整理程序在硬盘上有用,但在 SSD 上没用,因为:
Defragmenting reduces head-movement (seek) time on a spinning disk; an SSD has no heads, so it gains nothing (and the extra writes wear it). · 碎片整理减少旋转磁盘上的磁头移动(寻道)时间;一个 SSD 没有磁头,所以它得不到好处(而且额外的写入磨损它)。
Worked example: one line from each utility to its purpose
| Utility | Purpose |
|---|---|
| defragmentation | files load faster because their blocks are together |
| disk repair | a disk with bad sectors or file-system errors works again |
| disk contents analysis | space is freed by finding large, duplicate and temporary files |
| file compression | more data fits on the disk and transfers faster |
| virus checker | malware is found and quarantined |
| back-up software | data is restored after loss, corruption or ransomware |
- Performance on the left half, security on the right. Each utility pairs with exactly one purpose.
例题:每个实用程序连一条线到它的用途
| 实用程序 | 用途 |
|---|---|
| 碎片整理 | 文件的块在一起,加载更快 |
| 磁盘修复 | 有坏扇区或文件系统错误的磁盘重新可用 |
| 磁盘内容分析 | 找出大文件、重复文件和临时文件,释放空间 |
| 文件压缩 | 磁盘装更多数据,传输更快 |
| 病毒检查 | 发现并隔离恶意软件 |
| 备份软件 | 丢失、损坏或勒索软件之后恢复数据 |
- 左半是性能,右半是安全。每个实用程序恰好对应一个用途。
Match each utility to its purpose. · 把每个实用程序与它的用途配对。
One utility, one purpose. The examiner's line-drawing questions are marked exactly this way. · 一个实用程序,一个用途。考官的连线题正是这样评分的。
Marks that slip away
- "Manages memory" is the heading, not the answer. Say what it does: allocates, protects, frees, pages to disk.
- A utility is not the OS and not an application. It performs one maintenance task.
- Defragmentation helps a hard disk; it does nothing for an SSD.
- A virus checker is only as good as its last update; a backup is the only recovery from ransomware.
容易丢掉的分
- "管理内存"是标题,不是答案。要说它做什么:分配、保护、释放、分页到磁盘。
- 实用程序不是 OS,也不是应用程序。它执行一项维护任务。
- 碎片整理帮助的是硬盘;对 SSD 毫无作用。
- 病毒检查程序只和它最近一次更新一样好;备份是勒索软件之后唯一的恢复手段。
You've got it
- the OS is the interface between user and hardware: it hides complexity, manages and shares the processor, memory, storage and I/O, and loads and runs programs
- five management tasks: memory (allocate, protect, page), process (schedule by time slice, switch), hardware (drivers, buffers, interrupts), file (directory, space, access rights), security (accounts, encryption, firewall, logs)
- multitasking = protected memory areas + time-sliced switching fast enough to look simultaneous
- utilities: formatter, virus checker, defragmenter, disk analysis and repair, compression, backup, each with one purpose
你掌握了
- OS 是用户与硬件之间的接口:它隐藏复杂性,管理并共享处理器、内存、存储和 I/O,加载并运行程序
- 五项管理任务:内存(分配、保护、分页)、进程(按时间片调度、切换)、硬件(驱动、缓冲、中断)、文件(目录、空间、访问权限)、安全(账户、加密、防火墙、日志)
- 多任务 = 受保护的内存区域 + 快到看似同时的时间片切换
- 实用程序:格式化、病毒检查、碎片整理、磁盘分析与修复、压缩、备份,各有一个用途