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Introduction of Operating System
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The operating system controls the microprocessor—just at a slightly higher level than that control unit directs activities within the microprocessor. Every cycle of a computer's microprocessor is a resource for accomplishing tasks. Many activities compete for attention of your computer's microprocessor. Commands are arriving from programs that you're using, while input is arriving from the keyboard and mouse. At the same time, data must be sent to the display device or printer, and Web pages are arriving from your Internet connection. To manage all of these competing processes, your computer's operating system must ensure that each one receives its share of microprocessor cycles. Ideally, the operating system should be able to help the microprocessor switch tasks, so that, from the user's vantage point, everything seems to be happening at the same time.
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A microprocessor works with data and executes instructions that are stored in RAM—one of your computer's most important resources. When you want to run more than one program at a time, the operating system has to allocate specific areas of memory for each program. Whilemultiple programs are running, the OS must ensure that instructions and data from one area of memory don't"leak"into an area allocated to another program. If an OS falls down on the job and fails to protect each program's memory area, data can get corrupted, programs can"crash", and your computer will display error messages, such as"General Protection Fault".
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Every device that's connected to a computer is regarded as a resource. Your computer's operating system communicates with device driver software so that data can travel smoothly between the computer and these peripheral resources. If a peripheral device or driver is not performing correctly, the operating system makes a decision about what to do—usually it displays an on-screen message to warn you of the problem.
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A user interface can be defined as the combination of hardware and software that helps people and computers communicate with each other. Your computer's user interface includes the mouse and keyboard that accept your input and carry out your commands, as well as the display device that provides cues to help you use software, and displays error messages that alert you to problems. An operating system typically provides user interface tools, such as menus and toolbar buttons, which define the"look and feel"for all of its compatible software. Most computers today feature a graphical user interface. Sometimes abbreviated"GUI"and referred to as a"gooey", a graphical user interface provides a way to point and click a mouse to select menu options and manipulate graphical objects that are displayed on the screen.
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与微处理器中控制元件的管理活动相比，操作系统只是在稍微高一级的级别上控制着微处理器。计算机微处理器的每个活动周期都是完成任务的一个资源。许多活动都要争夺处理器的关照。当通过键盘和鼠标进行输入的时候，命令也不断从你运行的程序中到达。与此同时，数据必须送到显示设备或打印机，Web页也不断从互联网中到达。为管理所有这些竞争者的进程，计算机操作系统必须保证每一个进程能够分享微处理器的周期。理想的是，操作系统应该能够帮助微处理器转换任务，因而，从用户获取利益的角度来看，所有事情就好像在同一时刻发生一样。
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微处理器要处理和执行存放在RAM——计算机中最重要的资源之一中的数据和指令。当要同时运行一个以上的程序时，操作系统必须为每个程序分配指定的内存区域。当多个程序运行时，操作系统必须保证一个内存区域中的指令和数据不能"泄漏"到已分配给另一个程序的区域中去。如果操作系统在某个任务中失败而不能保护每个程序的内存区域的话，数据就会遭到破坏，程序就会"崩溃"，计算机就会显示诸如"一般性保护错误"的出错信息。
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与计算机相连接的每一个设备都被认为是一个资源。计算机操作系统与设备驱动软件的交互使得数据在计算机和这些外部资源之间顺畅地流动。如果一个外部设备或驱动程序没有正确地工作，操作系统就会做出如何处理的决定。通常，它是在显示器上显示一个信息，以警告你出现的问题。
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用户界面可以定义为软件和硬件的结合，它帮助人与计算机进行交互。计算机用户界面包括能接收输入并执行命令的鼠标和键盘，也包括能提示如何使用软件和出现问题时提示出错信息的显示设备。操作系统一般会提供用户界面工具，如菜单和工具栏按钮等，它们为其所有兼容软件定义了"模样和感觉"。目前许多计算机都具有图形用户界面的特征。图形用户界面有时缩写为"GUI"，并被称为"大众情人"，它提供了鼠标的操作方式：用鼠标指向和单击鼠标来选择屏幕上的菜单选项和对屏幕上的图形对象进行操作。
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