Case Study On Windows Prof. Sujata Rizal Unit V: Case . PDF

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Case Study on WindowsProf. Sujata RizalUnit V: Case Study on Windows1. What is Windows Operating System? Windows OS, computer operating system (OS) developed by Microsoft Corporation torun personal computers (PCs). Featuring the first graphical user interface (GUI) for IBMcompatible PCs, the Windows OS soon dominated the PC market. Approximately 90percent of PCs run some version of Windows.The first version of Windows, released in 1985, was simply a GUI offered as an extensionof Microsoft’s existing disk operating system, or MS-DOS. Based in part on licensedconcepts that Apple Inc. had used for its Macintosh System Software, Windows for thefirst time allowed DOS users to visually navigate a virtual desktop, opening graphical“windows” displaying the contents of electronic folders and files with the click ofa mouse button, rather than typing commands and directory paths at a text prompt.Subsequent versions introduced greater functionality, including native Windows FileManager, Program Manager, and Print Manager programs, and a moredynamic interface. Microsoft also developed specialized Windows packages, includingthe networkable Windows for Workgroups and the high-powered Windows NT, aimedat businesses. The 1995 consumer release Windows 95 fully integrated Windows andDOS and offered built-in Internet support, including the World WideWeb browser Internet Explorer.With the 2001 release of Windows XP, Microsoft united its various Windows packagesunder a single banner, offering multiple editions for consumers, businesses, multimediadevelopers, and others. Windows XP abandoned the long-used Windows 95 kernel (coresoftware code) for a more powerful code base and offered a more practical interfaceand improved application and memory management. The highly successful XP standardwas succeeded in late 2006 by Windows Vista, which experienced a troubled rollout andmet with considerable marketplace resistance, quickly acquiring a reputation for being alarge, slow, and resource-consuming system. Responding to Vista’s disappointingadoption rate, Microsoft developed Windows 7, an OS whose interface was similar tothat of Vista but was met with enthusiasm for its noticeable speed improvement and itsmodest system requirements.History of Windows:Microsoft’s Windows operating system was first introduced in 1985.1

Case Study on WindowsProf. Sujata RizalWindows 1This is where it all started for Windows. The original Windows 1 was released in November1985 and was Microsoft’s first true attempt at a graphical user interface in 16-bit.Development was spearheaded by Microsoft founder Bill Gates and ran on top of MS-DOS,which relied on command-line input.Windows 2Two years after the release of Windows 1, Microsoft’s Windows 2 replaced it in December1987. The big innovation for Windows 2 was that windows could overlap each other, and it alsointroduced the ability to minimise or maximise windows instead of “iconising” or “zooming”.The control panel, where various system settings and configuration options were collectedtogether in one place, was introduced in Windows 2 and survives to this day.Microsoft Word and Excel also made their first appearances running on Windows2

Case Study on WindowsProf. Sujata RizalWindows 3The first Windows that required a hard drive launched in 1990. Windows 3 was the first versionto see more widespread success and be considered a challenger to Apple’s Macintosh and theCommodore Amiga graphical user interfaces, coming pre-installed on computers from PCcompatible manufacturers including Zenith Data Systems.Windows 3 introduced the ability to run MS-DOS programmes in windows, which broughtmultitasking to legacy programmes, and supported 256 colors bringing a more modern, colorfullook to the interface.Windows 3.1Windows 3.1 released in 1992 is notable because it introduced TrueType fonts makingWindows a viable publishing platform for the first time.3

Case Study on WindowsProf. Sujata RizalMinesweeper also made its first appearance. Windows 3.1 required 1MB of RAM to run andallowed supported MS-DOS programs to be controlled with a mouse for the first time. Windows3.1 was also the first Windows to be distributed on a CD-ROM, although once installed on ahard drive it only took up 10 to 15MB (a CD can typically store up to 700MB).Windows 95As the name implies, Windows 95 arrived in August 1995 and with it brought the first ever Startbutton and Start menu.Windows 98Released in June 1998, Windows 98 built on Windows 95 and brought with it IE 4, OutlookExpress, Windows Address Book, Microsoft Chat and NetShow Player, which was replaced byWindows Media Player 6.2 in Windows 98 Second Edition in 1999.Windows MEConsidered a low point in the Windows series by many – at least, until they saw Windows Vista– Windows Millennium Edition was the last Windows to be based on MS-DOS, and the last inthe Windows 9x line.Released in September 2000, it was the consumer-aimed operating system twined withWindows 2000 aimed at the enterprise market. It introduced some important concepts toconsumers, including more automated system recovery tools.4

Case Study on WindowsProf. Sujata RizalWindows 2000The enterprise twin of ME, Windows 2000 was released in February 2000 and was based onMicrosoft’s business-orientated system Windows NT and later became the basis for WindowsXP.Windows XPArguably one of the best Windows versions, Windows XP was released in October 2001 andbrought Microsoft’s enterprise line and consumer line of operating systems under one roof.It was based on Windows NT like Windows 2000, but brought the consumer-friendly elementsfrom Windows ME. The Start menu and task bar got a visual overhaul, bringing the familiargreen Start button, blue task bar and vista wallpaper, along with various shadow and othervisual effects.Windows VistaWindows XP stayed the course for close to six years before being replaced by Windows Vista inJanuary 2007. Vista updated the look and feel of Windows with more focus on transparentelements, search and security. Its development, under the codename “Longhorn”, wastroubled, with ambitious elements abandoned in order to get it into production.Windows 7Considered by many as what Windows Vista should have been, Windows 7 was first released inOctober 2009. It was intended to fix all the problems and criticism faced by Vista, with slighttweaks to its appearance and a concentration on user-friendly features and less “dialogue boxoverload”.Windows 8Released in October 2012, Windows 8 was Microsoft’s most radical overhaul of the Windowsinterface, ditching the Start button and Start menu in favour of a more touch-friendly Startscreen.The new tiled interface saw programme icons and live tiles, which displayed at-a-glanceinformation normally associated with “widgets”, replace the lists of programmes and icons. Adesktop was still included, which resembled Windows 7.5

Case Study on WindowsProf. Sujata RizalWindows 8.1A free point release to Windows 8 introduced in October 2013, Windows 8.1 marked a shifttowards yearly software updates from Microsoft and included the first step in Microsoft’s Uturn around its new visual interface.Windows 10Announced on 30 September 2014, Windows 10 has only been released as a test version forkeen users to try. The “technical preview” is very much still a work in progress.Windows 10 represents another step in Microsoft’s U-turn, bringing back the Start menu andmore balance to traditional desktop computer users.2. Explain operating system structure with diagram.The design of an operating system architecture traditionally follows the separation ofconcerns principle. This principle suggests structuring the operating system into relativelyindependent parts that provide simple individual features, thus keeping the complexity of thedesign manageable.Besides managing complexity, the structure of the operating system can influence key featuressuch as robustness or efficiency: The operating system posesses various privileges that allow it to access otherwiseprotected resources such as physical devices or application memory. When theseprivileges are granted to the individual parts of the operating system that require them,rather than to the operating system as a whole, the potential for both accidental andmalicious privileges misuse is reduced.Breaking the operating system into parts can have adverse effect on efficiency becauseof the overhead associated with communication between the individual parts. Thisoverhead can be exacerbated when coupled with hardware mechanisms used to grantprivileges.6

Case Study on WindowsProf. Sujata Rizal1. Simple StructureIn MS-DOS, applications may bypass the operating system. Operating systems such as MS-DOS and the original UNIX did not have well-definedstructures.There was no CPU Execution Mode (user and kernel), and so errors in applications couldcause the whole system to crash.2. Monolithic Approach Functionality of the OS is invoked with simple function calls within the kernel, which isone large program.Device drivers are loaded into the running kernel and become part of the kernel.A monolithic kernel, such as Linux and other Unix systems.7

Case Study on WindowsProf. Sujata Rizal3. Layered ApproachThis approach breaks up the operating system into different layers. This allows implementers to change the inner workings, and increases modularity.As long as the external interface of the routines don’t change, developers have morefreedom to change the inner workings of the routines.With the layered approach, the bottom layer is the hardware, while the highest layer isthe user interface.o The main advantage is simplicity of construction and debugging.o The main difficulty is defining the various layers.o The main disadvantage is that the OS tends to be less efficient than otherimplementations.The Microsoft Windows NT Operating System. The lowest level is a monolithic kernel, but manyOS components are at a higher level, but still part of the OS.4. MicrokernelsThis structures the operating system by removing all nonessential portions of the kernel andimplementing them as system and user level programs. Generally they provide minimal process and memory management, and acommunications facility.Communication between components of the OS is provided by message passing.The benefits of the microkernel are as follows: Extending the operating system becomes much easier.Any changes to the kernel tend to be fewer, since the kernel is smaller.8

Case Study on Windows Prof. Sujata RizalThe microkernel also provides more security and reliability.Main disadvantage is poor performance due to increased system overhead from messagepassing.A Microkernel architecture.3. Write a note on memory management.Every Windows administrator has to field user complaints about client performance. Clientsystem performance can be affected by factors such as memory, CPU, disk and the network. Ofthese factors, the most confusing is memory management, which admins need to understandfor making informed decisions and troubleshooting. Users typically equate adding memory toresolving performance bottlenecks, and it's relatively cheap and easy to add memory.9

Case Study on WindowsProf. Sujata RizalFigure 1Figure 1 shows the memory component of the Windows XP and Windows 7 Task Manager.Note that there are fundamental differences between Windows XP, Vista and Windows 7 TaskManager versions.It's important to know the difference between physical and virtual memory. Physical memory isthe amount of physical RAM available in the computer. Physical memory can be visualized as atable shown in Figure 2, where data is stored. Each cell shown in the table is a unique "address"where data is stored.Figure 210

Case Study on WindowsProf. Sujata RizalVirtual memory essentially allows each process -- applications, dynamic link libraries (DLLs), etc.-- to operate in a protected environment where it thinks it has its own private addressspace. Figure 1 shows the virtual memory table for a process on a computer with 2 GB of RAM.The CPU translates or maps the virtual addresses into physical addresses in RAM using pagetable entries (PTEs).Virtual memory limitsThe virtual address space for 32-bit architecture has a physical limit of about 4 GB, regardless ofthe amount of RAM in the computer. Windows divides this into two sections, as shownin Figure 2: user space and kernel space. The addresses in the kernel space are reservedfor system processes. Only those in the user space are accessible for applications. So, eachapplication has a virtual memory limit of 2 GB. Again, this is regardless of physical RAM. Thatmeans that no process can ever address more than 2 GB of virtual address space by default.Exceeding this limit produces an "out of virtual memory" error and can occur even when plentyof physical memory is available.Note that, as shown in Figure 2, the use of virtual memory allows the three applications, eachwith 2 GB of virtual address space, to share the 2 GB RAM in the computer. This isaccomplished by paging infrequently used data to disk, then paging it back to RAM whenneeded.Figure 311

Case Study on WindowsProf. Sujata RizalProcesses will run faster if they reside in memory as opposed to requiring the memory managerpage data in from the disk and put it back in memory. Thus, more memory in the system allowsmore processes to reside in memory and reduces paging from disk.4. Explain physical memory management. Windows reports how much physical memory is currently installed on your computer alongwith how much memory is available to the operating system and the hardware reservedmemory. Windows may show that the usable memory may be less than the installed memory (RAM).The indicative Usable memory is a calculated amount of the total physical memory minus“hardware reserved” memory.Physical MemoryOne of the most fundamental resources on a computer is physical memory. Windows’ memorymanager is responsible with populating memory with the code and data of active processes,device drivers, and the operating system itself. Because most systems access more code anddata than can fit in physical memory as they run, physical memory is in essence a window intothe code and data used over time. The amount of memory can therefore affect performance,because when data or code a process or the operating system needs is not present, thememory manager must bring it in from disk.Besides affecting performance, the amount of physical memory impacts other resource limits.For example, the amount of non-paged pool, operating system buffers backed by physicalmemory, is obviously constrained by physical memory. Physical memory also contributes to thesystem virtual memory limit, which is the sum of roughly the size of physical memory plus themaximum configured size of any paging files. Physical memory also can indirectly limit themaximum number of processes, which I’ll talk about in a future post on

The Microsoft Windows NT Operating System. The lowest level is a monolithic kernel, but many OS components are at a higher level, but still part of the OS. 4. Microkernels This structures the operating system by removing all nonessential portions of the kernel and implementing them as system and user level programs.