IT专业英语UNIT8-Operating-System.ppt

单击此处编辑母版标题样式,UNIT 8,Operating System,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,UNIT8,Operating System,8-1 Technical Part,8-2 Reading Material,8-1 Technical Part,8-1-1 Definition,An operating system is a program designed to run other programs on a computer.A computers operating system is its most important program.It is considered the backbone of a computer,managing both software and hardware resources.Operating systems are responsible for everything from the control and allocation of memory to recognizing input from external devices and transmitting output to computer displays.They also manage files on computer hard drives and control peripherals,like printers and scanners.,1.Process ManagementA process is a program in execution.A process needs certain resources,including CPU time,memory,files,and I/O devices,to accomplish its task.OS responsibilities for process management include:process creation and deletion;process scheduling,suspension,and resumption;process synchronization,inter-process communication.,2.Memory ManagementMemory is a large array of addressable words or bytes or a data repository shared by the CPU and I/O devices.OS responsibility for memory management include:,Allocate and deallocate memory space as requested;,Keep track of which parts of memory are currently being used and by whom;,Efficient utilization when the memory resource is heavily competed.,3.The operating system also handles the organisation and tracking of files and directories(folders)saved or retrieved from a computer disk.The system allows the user to perform such tasks as creating files and directories,renaming files,coping and moving files,and deleting files.The operating system keeps track of where files are located on the hard drive through the type of.The two main types of are table(FAT)or New Technology (NTFS),5.User Interface ManagementThe operating system also manages the user interface,whether graphical or text-based.This function does involve the hardware management component mentioned above,but on a more advanced level.The user interface must respond to the users directions via mouse,keyboard,touch screen or other input device.The part of the operating system that manages this function must translate key presses,mouse clicks and other user actions into the appropriate commands to the other parts of the computer.,6.Priority ManagementThe operating system must prioritize and manage the scheduling of the various applications running on the computer.For instance,if you are downloading a large file,but want to work on a document while it downloads,the operating system slices the processor availability to give priority to your input actions while managing the download in the background.This is sometimes called preemptive scheduling,as anything that the user does takes priority and preempts other less important tasks.This ability to carve up processor time gives what is actually a single-tasking OS the appearance of a multi-tasking OS.,Classification of Operating System,Operating systems can be classified as follows:1.Multi userMulti user operating systems allow two or more users to run programs at the same time.Some operating systems permit hundreds or even thousands of concurrent users.The operating systems of mainframes and minicomputers are multi user system.,3.MultitaskingMultitasking allows more than one program to run concurrently.Multitasking is the ability to execute more than one task at the same time,a task being a program.The terms multitasking and multiprocessing are often used interchangeably,although multiprocessing sometimes implies that more than one CPU is involved.,4.MultithreadingMultithreading allows different parts of a single program to run concurrently.Multithreading is the ability of an operating system to execute different parts of a program called threads,simultaneously.,Several Commonly Used Operating System,Operating systems provide a software platform on top of which other programs,called application programs,can run.It is shown in Figure 8-1.The application programs must be written to run on top of a particular operating system.Your choice of operating system,therefore,determines to a great extent the applications you can run.For PCs,the most popular operating systems are DOS,OS/2,and Windows,but others are available,such as Linux.,Figure 8-1 Position of operating system,1.WindowsWindows,in computer science,is a personal computer operating system sold by Microsoft Corporation that allows users to enter commands with a point-and-click device,such as a mouse,instead of a keyboard.The Windows operating system provides users with a Graphical User Interface(GUI),which allows them to manipulate small pictures,called icons,on the computer screen to issue commands.Windows is the most widely used operating system in the world.It is an extension of and replacement for Microsofts Disk Operating System(MS-DOS).,The Windows GUI is designed to be a natural,or intuitive,work environment for the user.With Windows,the user can move a cursor around on the computer screen with a mouse.By pointing the cursor at icons and clicking buttons on the mouse,the user can issue commands to the computer to perform an action,such as starting a program,accessing a data file,or copying a data file.Other commands can be reached through pull-down or click-on menu items.The computer displays the active area in which the user is working as a window on the computer screen.The currently active window may overlap with other previously active windows that remain open on the screen.This type of GUI is said to include WIMP features:windows,icons,menus,and pointing device(such as a mouse).,2.UNIXUNIX,in computer science,is a multiuser,multitasking operating system originally developed by Ken Thompson and Dennis Ritchie at AT among these are versions developed at the University of California at Berkeley(known as BSD releases)and versions released by AT&T,the most recent being AT&T System V.,Its popularity is due in large part to the growth of the interconnected computer network known as the Internet,the software for which initially was designed for computers that ran UNIX.Variations of UNIX include SunOS(distributed by SUN Microsystems Inc.),Xenix(distributed by Microsoft Corporation),and Linux.UNIX and its clones support multitasking and multiple users.Its provides a simple means of organizing disk files and lets users protect their files from other users.The commands in UNIX are not intuitive,however,and mastering the system is difficult.,Figure 8-2 Unix System Interface,3.LinuxLinux(/5links/)is a UNIX-like computer operating system assembled under the model of free and open source software development and distribution(See Figure 8-3).The defining component of Linux is the Linux kernel,an operating system kernel first released 5 October 1991 by Linus Torvalds.,Figure 8-3 Graphical login interface of Red Flag Linux,The development of Linux is one of the most prominent examples of free and open source software collaboration:the underlying source code may be used,modified,and distributedcommercially or non-commerciallyby anyone under licenses such as the GNU General Public License.Typically Linux is packaged in a format known as a Linux distribution for desktop and server use.Some popular mainstream Linux distributions include Debian(and its derivatives such as Ubuntu),Fedora and openSUSE.Linux distributions include the Linux kernel,supporting utilities and libraries and usually a large amount of application software to fulfill the distributions intended use.,VxWorks has some similarities to UNIX and includes a shell,debugging functions,memory management,performance monitoring and support for multiprocessing.The OS includes a kernel for preemptive multitasking,interrupt response,interprocess communication and a.Programming in VxWorks can be difficult for novices because the programmer must write the code on an as-needed basis.However,the fact that there is minimal content to save and restore means that VxWorks uses less processing power than UNIX,so it can run faster.VxWorks is a trademark of Wind River Systems,a company specializing in software optimization and based in Alameda,California,USA.,Figure 8-4 Development tool interface of VxWorks,8-1-3 Application Case or Example,Windows 7 Operating System,Windows 7 is the current release of Microsoft Windows,a series of operating systems produced by Microsoft for use on personal computers,including home and business desktops,laptops,netbooks,tablet PCs,and media center PCs.Windows 7 was released to manufacturing on July 22,2009,and reached general retail availability worldwide on October 22,2009,less than three years after the release of its predecessor,Windows Vista.Windows 7s server counterpart,Windows Server 2008 R2,was released at the same time.,Unlike Windows Vista,which introduced a large number of new features,Windows 7 was intended to be a more focused,incremental upgrade to the Windows line,with the goal of being compatible with applications and hardware with which Windows Vista was already compatible.Presentations given by Microsoft in 2008 focused on multi-touch support,a redesigned Windows shell with a new taskbar,referred to as the Superbar,a home networking system called HomeGroup,and performance improvements.,Some standard applications that have been included with prior releases of Microsoft Windows,including Windows Calendar,Windows Mail,Windows Movie Maker,and Windows Photo Gallery,are not included in Windows 7;most are instead offered separately at no charge as part of the Windows Live Essentials suite.Only several functions of Windows 7 are shown below.,1.Windows 7 Taskbar,You can do so much more from the Windows 7 taskbar(See Figure 8-5).Windows 7s taskbar is greatly improved in two ways.First,you can pin programs to it indefinitely for easy quick launch.Second,on a crowded desktop covered with windows,using the new Aero Peek feature,you can preview individual windows from grouped taskbar applications,and even close documents from the thumbnails themselves.,Hold your mouse over the thumbnail to see an even larger view of the file.You can also rearrange and organize buttons on the taskbar,including pinned programs and running programs that arent pinned,so they appear in the order you prefer.To rearrange the order of buttons on the taskbar,drag a button from its current position to a different position on the taskbar&as often as you like.,Figure 8-5 Windows 7 Taskbar,2.Show Desktop Show desktop on far right corner,but you dont need to click,just put your mouse over it.If you want to keep the desktop&minimize the files,just click it(See Figure 8-6).,Figure 8-6 Windows 7 Show Desktop,3.Start Menu In Windows 7,you have much more control over the programs and files that appear on the Start menu(See Figure 8-7).The Start menu is essentially a blank slate that you can organize and customize to suit your preferences.Find a program you want to add&right mouse click&choose add to start menu.,Click on the Start button on left bottom corner.,Figure 8-7 Windows 7 Start Menu,The Start Menu List(See Figure 8-8)will appear&if you hold your mouse over the program you will see a list of recently opened files used by that program on the right.This also shows the location that saved to.,Figure 8-8 Windows 7 Start Menu List,4.Shake Shake one window to make the others disappear.You can instantly snap your windows to size,and clear the desktop in one motion.As widescreen monitors become more common,easier side-by-side window management and Windows 7 has it built in.The new Aero Shake feature lets you clear the desktop of all background windows by grabbing the top bar of the active window and moving it back and forth quickly.,5.Pin Pin your favorite programs right to your taskbar.Pinning programs to the taskbar complements pinning programs to the Start Menu,like in earlier versions of Windows.When you pin a favorite program to the taskbar,you can always see it there and easily access it with a single click.Windows 7 also includes Jump Lists,so that in addition to launching a program from the taskbar,you can now launch favorite and recent items from that program,just by clicking the same button(See Figure 8-9).You can also move these around to be in the order you want.,Figure 8-9 Windows 7 Pin,6.Jump Lists Jump Lists are lists of recently or frequently opened items,such as files,folders,tasks,or websites,organized by the program that you use to open them(See Figure 8-10).In addition to being able to open recent items using a Jump List,you can also pin favorite items to a Jump List so you can quickly get to the items that you use every day.,On the taskbar,Jump Lists appear for programs that youve pinned to the taskbar and programs that are currently running.You can view the Jump List for a program by right-clicking the taskbar button,or by dragging the button toward the desktop.You open items from the Jump List by clicking on them.,Figure 8-10 Windows 7 Jump Lists,8-2 Reading Material,8-2-1 Reading comprehension,iPhone Operating System,iOS(previously iPhone OS)is a mobile operating system developed and distributed by Apple Inc.Originally released in 2007 for the iPhone and iPod Touch,it has been extended to support other Apple devices such as the iPad and Apple TV.Unlike Microsofts Windows CE(Windows Phone)and Googles Android,Apple does not license iOS for installation on non-Apple hardware.,As of June 12,2012(2012-06-12),Apples App Store contained more than 650,000 iOS applications,which have collectively been downloaded more than 30billion times.It had a 23%share of the smart-phone operating system units sold in the first quarter of 2012,behind only Googles Android.In June 2012,it accounted for 65%of mobile web data consumption(including use on both the iPod Touch and the iPad).At the half of 2012,there were 410 million devices activated.,The user interface of iOS is based on the concept of direct manipulation,using multi-touch gestures.Interface control elements consist of sliders,switches,and buttons.The response to user input is immediate and provides a fluid interface.Interaction with the OS includes gestures such as swipe,tap,pinch,and reverse pinch,all of which have specific definitions within the context of the iOS operating system and its multi-touch interface.Internal accelerometers are used by some applications to respond to shaking the device(one common result is the undo commanD.or rotating it in three dimensions(one common result is switching from portrait to landscape mode).,iOS is derived from OS X,with which it shares the Darwin foundation,and is therefore a Unix operating system.In iOS,there are four abstraction layers:the Core OS layer,the Core Services layer,the Media layer,and the Cocoa Touch layer.The current version of the operating system(iOS 5.1.1)dedicates 1-1.5 GB of the devices flash memory for the system partition,