Explanation Of Major Components Of Operation System Computer Science Essay

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Windows 7 is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops, net books, tablet PCs, and media center PCs. Windows 7 also includes a number of new features, such as advances in touch and handwriting recognition, support for virtual hard disks, improved performance on multi-core processors,[13][14][15][16] improved boot performance, Direct Access, and kernel improvements. Windows 7 adds support for systems using multiple heterogeneous graphics cards from different vendors (Heterogeneous Multi-adapter), a new version of Windows Media Center,[17] a Gadget for Windows Media Center, improved media features, the XPS Essentials Pack and Windows Power Shell being included, and a redesigned Calculator with multiline capabilities including Programmer and Statistics modes along with unit conversion for length, weight, temperature, and several others. Many new items have been added to the Control Panel, including Clear Type Text Tuner, Display Color Calibration Wizard, Gadgets, Recovery, Troubleshooting, Workspaces Center, Location and Other Sensors, Credential Manager, Biometric Devices, System Icons, and Display.[18] Windows Security Center has been renamed to Windows Action Center (Windows Health Center and Windows Solution Center in earlier builds), which encompasses both security and maintenance of the computer. Ready Boost on 32-bit editions now supports up to 256 gigabytes of extra allocation. The default setting for User Account Control in Windows 7 has been criticized for allowing untrusted software to be launched with elevated privileges without a prompt by exploiting a trusted application.[19] Microsoft's Windows kernel engineer Mark Russinovich acknowledged the problem, but noted that malware can also compromise a system when users agree to a prompt.[20] Windows 7 also supports images in RAW image format through the addition of Windows Imaging Component-enabled image decoders, which enables raw image thumbnails, previewing and metadata display in Windows Explorer, plus full-size viewing and slideshows in Windows Photo Viewer and Windows Media Center.[21]

Major components of windows 7ultiamte:

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Component

Description

Introduced

Control Panel

Control Panel

Allows users to view and manipulate basic system settings and controls, such as adding hardware, adding and removing software, controlling user accounts, changing accessibility options, and so on.

Windows 1.0

Device Manager

Allows the user to display and control the hardware attached to the computer, and control what device drivers are used.

Windows 95

Windows Mobility Center

Centralizes the most relevant information related to mobile computing.

Centralizes the most relevant information related to mobile computing.

Windows Action Center

Centralizes and reports on the status of anti-virus, Automatic Updates, Windows Firewall, and other security-related components of the operating system.

Windows XP SP2

Administrative Tools

Microsoft Management Console

Provides system administrators and advanced users with a flexible interface through which they may configure and monitor the system.

Windows NT 4.0 Option Pack

Windows System Assessment Tool

A built-in benchmarking tool that analyzes the different subsystems (graphics, memory, etc.), and uses the results to allow for comparison to other Windows Vista systems, and for software optimizations. It rates the computer's performance using the Windows Experience Index.

Windows Vista

System Restore

Allows for the rolling back of system files, registry keys, installed programs, etc., to a previous state in the event of a system failure.

Windows Me

Windows Disk Defragmenter

Rearranges files stored on a hard disk to occupy contiguous storage locations in order to optimize computer performance.

Windows 95, Windows 2000

Event Viewer

Lets administrators and users view the event logs on a local or remote machine.

Windows NT 3.1

Resource Monitor (or Reliability and Performance Monitor)

Lets administrators view current system reliability and performance trends over time.

Windows Vista

Logical Disk Manager

A logical volume manager developed by Microsoft in conjunction with Veritas Software.

Windows NT 4.0 (as a separate Tool) 2000 (integrated in the Management Console)

Registry Editor

Edits the Windows registry.

Windows 3.1

Software installation and deployment

Windows Update

An online service which provides critical updates, service packs, device drivers, and other updates. A variation called Microsoft Update also provides software updates for several Microsoft products.

Windows 98

Windows Installer

A packaging format and engine for the installation, maintenance, and removal of software. Includes a GUI framework, automatic generation of the uninstallation sequence and deployment capabilities for corporate networks.

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Windows 2000

Click Once

Technology for deploying .NET Framework-based software via web pages, with automatic update capabilities. Intended for per-user only applications.

.NET Framework 2.0

Core components

Component

Acronym

Description

Windows kernel (Windows NT)

Main article: Architecture of the Windows NT operating system line

Ntoskrnl.exe

The Windows kernel image. Provides the kernel and executive layers of the kernel architecture, and is responsible for services such as hardware virtualization, process and memory management, etc.

hal.dll

HAL

Provides and handles the interaction between software and hardware via the Hardware Abstraction Layer.

Core processes (Windows NT)

System idle process

SIP

A counter which measures how much idle capacity the CPU has at any given time. The process runs in the background and monitors processing bandwidth, occupied memory and the Windows virtual paging file.

Session Manager Subsystem

SMSS

Performs several critical boot-time operations, such as the creation of environment variables, starting CSRSS, and performing file-copy operations that were queued up from before the system was booted (pending file rename operations). During system operation, it handles Windows File Protection and the creation of logon sessions via Winlogon.

Client/Server Runtime Subsystem

CSRSS

User-mode side of the Win32 subsystem. Provides the capability for applications to use the Windows API.

Local Security Authority Subsystem Service

LSASS

Responsible for enforcing the security policy on the system. Verifies users logging on to the computer and creates security tokens.

Winlogon

Responsible for handling the secure attention key, loading the user profile on logon, and optionally locking the computer when a screensaver is running. On Windows NT systems prior to Windows Vista, Winlogon is also responsible for loading GINA libraries which are responsible collecting logon credentials from the user.

Svchost.exe

A generic host process name for services that run from dynamic-link libraries (DLLs). Several Svchost processes are typically present on a Windows machine, each running in a different security context, depending on what privileges the contained services require.

Windows on Windows and WOW64

WoW

An abstraction layer that allows legacy code to operate on more modern versions of Windows; typically this means running 16-bit Windows applications on 32-bit Windows, and 32-bit applications on 64-bit Windows.

Virtual DOS machine

NTVDM

Allows MS-DOS programs to run on Intel 80386 or higher computers when there is already another operating system running and controlling the hardware. Introduced in Windows 2.1; not available in any 64-bit edition of Windows.

System startup (Windows NT)

Main articles: Windows NT Startup Process and Windows Vista Startup Process

Recovery Console

Provides the means for administrators to perform a limited range of tasks using a command line interface, primarily to aid in recovering from situations where Windows does not boot successfully.

ntdetect.com

Used during the boot process to detect basic hardware components that may be required during the boot process.

NTLDR, IA64ldr, Winload

The boot loader; performs basic system initialization options such as loading the hardware abstraction layer and boot-time device drivers, prior to passing control to the Windows kernel. In versions prior to Vista, NTLDR and IA64ldr also display menus to the user if multiple operating systems are defined in boot.ini, or if F8 is pressed.

Windows Boot Manager

In Windows Vista and later operating systems, displays boot menus to the user if multiple operating systems are configured in the system's Boot Configuration Data.

Graphical subsystem

Desktop Window Manager

DWM

The compositing manager introduced in Windows Vista that handles compositing and manages special effects on screen objects in a graphical user interface.

Graphics Device Interface

GDI/GDI+

The kernel graphics component for representing graphical objects and transmitting them to output devices such as monitors and printers.

Windows USER

The Windows USER component provides core user interface, messaging and visual elements.

Windows Server components

Component

Acronym

Description

Supported by

Windows Server domain

A logical group of computers that share a central directory and user database.

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All Windows NT-based versions

Active Directory

AD

A set of technologies introduced with Windows 2000 that allows administrators to assign enterprise-wide policies, deploy programs to many computers, and apply critical updates to an entire organization. Active Directory stores information and settings relating to an organization in a central, organized, accessible database. Networks can vary from a small installation with a few objects, to global-scale directories with millions of objects.

   Related topics: Active Directory Service Interfaces, Flexible single master operation, IntelliMirror, Active Directory Application Mode

Windows 2000, Windows Server 2003

Domain controller

DC, PDC, BDC

A server that responds to security authentication requests (logging in, checking permissions, etc.) within a Windows Server domain. Prior to Windows 2000, a domain controller was either a Primary Domain Controller (PDC), of which there could only be one with this role; or a Backup Domain Controller (BDC). In Windows 2000 and later the concept of primary and secondary domain controllers were eliminated, partially to emphasize the multi-master replication technology available in Windows.

All Windows NT-based versions

Group Policy

GP, GPO

Provides centralized management of user and computer settings in an Active Directory environment. Group policy can control a target object's registry, NTFS security, audit and security policy, software installation, logon/logoff scripts, folder redirection, and Internet Explorer settings. Policy settings are stored in Group Policy Objects (GPOs), and may be linked to one or more sites, domains or organizational units.

   Related topics: Administrative Templates

Windows 2000 and later

Internet Information Services

IIS

Web server

Windows NT family

3) Explanation of unique features of the Operating Systems.

The top 10 Microsoft Windows7 unique features.

1. Speed

Even aside from incompatibilities and other issues that many people had with Vista, one of the most straightforward was speed - it just felt too sluggish compared to XP, even on pumped up hardware. Windows 7 brings a more responsive and sprightly feel and Microsoft has spent a lot of time and effort getting the Start Menu response just right.

Microsoft has also recognised the need for improved desktop responsiveness, which gives the impression that the computer is responding to the user and that they are in control - something that was often lacking with Vista.

You can also expect faster boot times. And the boot sequence is now not only prettier than it was with Vista, but it's speedier too.

2. Compatibility

In simple terms, compatibility on Windows 7 will be far better than it was with Vista. Many programs that individuals and companies used on Windows XP did not work immediately and required updates, but with Windows 7 almost all applications that work on Vista should still run.

In essence, Windows Vista has done most of the hard work for Windows 7 in this respect.

3. Lower hardware requirements

Vista gained a reputation for making even the beefiest hardware look rather ordinary. Windows 7, however, will run well on lower end hardware, making the transition from Window XP less painful.

Microsoft is even pushing Windows 7 for netbooks. This could provide a modern replacement for Windows XP, which has found a new lease of life as the OS of choice on netbooks, supplanting Linux. The downside is that Windows 7 Starter Edition, as it will be called, will be limited to only three applications running at the same time.

4. Search and organisation

One of the best things about Windows 7 is the improved search tool, which now rivals Mac OS X's Spotlight to be able to find what you need quickly and easily. For example, typing 'mouse' will bring up the mouse option within the control panel or typing a word will display it and split it up neatly into files, folders and applications.

Also introduced is the concept of Libraries, which takes the 'My Documents' concept a stage further. The various Libraries, such as Documents and Pictures, will watch multiple locations which you can add yourself, so you don't have to keep everything in one place.

5. TaskBar/Start menu

At first glance, the task bar looks like nothing has much has changed since Vista. In fact, that's not the case and it's a lot more powerful. Microsoft is now making best use of its aero technology. By default, taskbar icons are now larger and items are grouped together and are not labelled with clumsy text.

If you have multiple Word documents or Windows Explorer windows open then you'll see a stack appear on the task bar. Hover the mouse over the app and each Window will be visible in a thumbnail. Hover over each thumbnail and it will become visible, while all other open windows temporarily disappear, save for their outlines. You can close each document or Window down from the thumbnail directly or click on it to bring it to the front.

Even better, this works with individual tabs in Internet Explorer 8, though unfortunately not Firefox.

Right clicking gives a 'Jump menu ', giving you speedily access to recent documents and you can pin apps of your choice directly to the taskbar.

In the Start menu, a small arrow to the right of applications such as Word now expands to give a list of recent documents and any can be pinned so you can keep one permanently on the list.

6. Aero-shake

Our favourite new visual feature is called 'Aero Shake'. If you have a multitude of Windows open but want to focus on just the one you can all you have to do is grab it by the title bar (at the top) and shake with the mouse. This minimises all the other Windows leaving just the one you've grabbed on the desktop.

7. Stacking

Another great touch is Stacking. You simply drag a Window to the sides of your screen and it will stick automatically to the side filling half the screen, making it quick and easy to view documents side by side. Move to the top and it will maximise to the whole screen.

8. Peace from UAC

Vista's User Account Control (UAC) was one of the headline annoyances in Windows Vista. In a reaction to malware problems, the Windows designers introduced the UAC, a dialogue box that popped up every time you made any changes to Windows when installing apps. It proved quite annoying, especially to power users who tended to turn it off straight away, thereby negating any benefit it might have.

In Windows 7, a slider has been added, enabling users to tone down its nagging factor, making you less likely to turn it off completely. It works too and one or two notches down should be enough for most. In this state it actually gives more confidence that your OS is looking after you.

9. Gamma curve

The display properties now boast a useful gamma curve feature enabling you to calibrate your display. Set aside 10 minutes to go through it carefully and you can really give your monitor image a boost, which will pay dividends when you're sitting in front of a screen all day. Think of it as a free monitor upgrade.

10. Touch

The most whizz-bang visual feature to come to Windows 7 is its touch capability. This of course will only be available to those with a touch enabled PC, such as HP's Touch Smart range, but for those suitably equipped it will provide a new way of interacting with their PC.

The video will let you open apps from the taskbar, scroll up and down by flicking, and zoom and rotate pictures by holding and turning. Tap and holding reveals 'right-click' context menus. At present, it's mainly used for kitchen based media centres but it could add a whole new wow factor to corporate presentations - at least until the novelty wears off.

1) Antivirus: AVG Anti-virus

Pros: Only a handful of antivirus software products perform so well.

Cons: Excellent support is available by live chat or email, but if you simply must use the telephone, it is not an option.

2) Image Editing Software: Adobe Photoshop

Pros:

Manipulation of color

Vector capabilities

Filter capabilities/effects

Fonts/graphics

Pre press capabilities

Can find affordable plug-ins

Multiple platforms/cross platforms

Inexpensive

Cons:

Plug-ins are essential

Doesn't support production

3) Internet Brower: Google Chrome

Pros:

Start up speed

Page speed load times

Javascript execution speeds

Works better for Google products

Built in search engine into the URL bar

Cons:

Unable to not save all data automatically (no cookies, history, downloads, etc (small issue))

Unable to control sessions  (no longer an issue, extension came out)

Limited right click menu, no "copy email address", no "properties for images" etc.

Runs multiple processes in the task manager all labeled "Chrome", it would be nice if they were labels something more useful, like "Chrome: NYTimes.com" which would be the name of the tab.

4) Word processing: Mircosoft Word

Microsoft Word is undoubtedly a great tool. Here are ten pros of Microsoft Word:

- Typing is faster than ever

- It is easy to correct mistakes by just hitting the backspace or delete button

- Spelling and grammatical mistakes are pointed out instantly

- Bullets and numbers are done automatically

- Aligning text, whether at the center, right or left margins, or justified takes just one click

- Images and figures can be attached and laid out easily

- Copying documents is fast and easy

- One can use the thesaurus feature when one's words run out

- There are templates for just about any type of document

- There is always an option to ask for help

While Microsoft is indeed wonderful, it is not devoid of any quirks. Here are ten cons of Microsoft Word.

Typing is impossible when there is a black out or laptops run out of batteries

- People tend to become careless because they know they can easily correct mistakes

- The spelling and grammar checker cannot spot all mistakes and people can become dependent on them

- Bullets and numbering sometimes have a mind of their own

- The auto-format tool can be annoyingly inflexible at times

- Images and figures can be quite stubborn and hard to position well

- Plagiarism is easy to do because it is very easy to just copy and paste

- The thesaurus has very limited vocabulary

- People use the same templates over and over; documents just become clones of each other

- The help option sometimes provides vague answersat times

Text descriptions on the buttons are gone, in favor of big icons. The icons can-finally-be rearranged; no longer will restarting an application put all your taskbar icons in the wrong order. The navigation between windows is now two-level; mousing over an icon shows a set of window thumbnails, and clicking the thumbnail switches windows.

Right clicking the icons shows a new UI device that Microsoft calls "Jump Lists."

http://origin.arstechnica.com/images/windows7/Windows%20Media%20Player%20JumpList.png

They're also found on the Start Menu:

Windows 7 Screenshots

Jump lists provide quick access to application features. Applications that use the system API for their Most Recently Used list (the list of recently-used filenames that many apps have in their File menus) will automatically acquire a Jump List containing their most recently used files. There's also an API to allow applications to add custom entries; Media Player, for example, includes special options to control playback.

This automatic support for new features is a result of deliberate effort on Microsoft's part. The company wants existing applications to benefit from as many of the 7 features as they can without any developer effort. New applications can extend this automatic support through new APIs to further enrich the user experience. The taskbar thumbnails are another example of this approach. All applications get thumbnails, but applications with explicit support for 7 will be able to add thumbnails on a finer-grained basis. IE8, for instance, has a thumbnail per tab (rather than per window).

Window management has also undergone changes. In recognition of the fact that people tend only to use one or two windows concurrently, 7 makes organizing windows quicker and easier. Dragging a window to the top of the screen maximizes it automatically; dragging it off the top of the screen restores it. Dragging a window to the left or right edge of the screen resizes the window so that it takes 50% of the screen. With this, a pair of windows can be quickly docked to each screen edge to facilitate interaction between them.

Another common task that 7 improves is "peeking" at windows; switching to a window briefly just to read something within the window but not actually interact with the window. To make this easier, scrubbing the mouse over the taskbar thumbnails will turn every window except the one being pointed at into a glass outline; moving the mouse away will reinstate all the glass windows. As well as being used for peeking at windows, you can also peek at the desktop:

Windows 7 Screenshots

Windows 7 Screenshots

Peeking at the desktop is particularly significant, because the desktop is now where gadgets live. Because people are increasingly using laptops, taking up a big chunk of space for the sidebar isn't really viable; Microsoft has responded by scrapping the sidebar and putting the gadgets onto the desktop itself. Gadgets are supposed to provide at-a-glance information; peeking at the desktop, therefore, becomes essential for using gadgets.

Windows 7 Screenshots

The taskbar's system tray has also been improved. A common complaint about the tray is that it fills with useless icons and annoying notifications. With 7, the tray is now owned entirely by the user. By default, new tray icons are hidden and invisible; the icons are only displayed if explicitly enabled. The icons themselves have also been streamlined to make common tasks (such as switching wireless networks) easier and faster.

Windows 7 Screenshots

The other significant part of the Windows UI is Explorer. Windows 7 introduces a new concept named Libraries. Libraries provide a view onto arbitrary parts of the file system with organization optimized for different kinds of files. In use, Libraries feel like a kind of WinFS-lite; they don't have the complex database system underneath, but they do retain the idea of a custom view of your files that's independent of where the files are.

Windows 7 Screenshots

These UI changes represent a brave move by the company. The new UI takes the concepts that Windows users have been using for the last 13 years and extends them in new and exciting ways. Windows 7 may not change much under the hood, but the extent of these interface changes makes it clear that this is very much a major release

1. Lower system requirements

Unlike Windows Vista, which required significantly more memory and processing speed to power its graphical user interface, Windows 7 isn't a system resource hog. As such, the same machines you now having running Vista should easily be able to accommodate the new OS, which in many cases loads programs and boots or shuts down faster. Less money spent on hardware upgrades translates into immediate cost savings, while a decrease in downtime twiddling your thumbs waiting for software to load provides a corresponding productivity boost. Furthermore, even a relatively slow 1GHz PC with 1GB of memory can run Windows 7 (though 2GB of RAM is recommended and 4GB for the 64-bit edition), making it suitable for installation on low-end netbook computers on up to high-end desktops.

2. Simpler navigation

A trio of improvements to the user front-end makes Windows 7 easier to navigate and multitask within than its predecessors. To begin with, using Aero Peek features, Windows 7 users can more easily view desktop contents by turning all open windows transparent. With Aero Shake, you also have the option to simply grab an active window and physically shake the mouse to minimize other panes cluttering up one's monitor. Last, but not least, Aero Snap functions automatically resize windows to take up half the screen when they're dragged to either side of your display.

3. Better multitasking

Borrowing a trick from Apple's Snow Leopard operating system, Windows 7 now offers a more aesthetically pleasing, icon-based taskbar that lets you permanently pin and organize favorite programs on it. You can additionally point to icons to get thumbnail previews of open files and windows associated with each program, all accessible with a click. Everything's displayed in as minimally intrusive a way possible as well, helping cut down on clutter and making it possible to keep track of everything that's happening on your desktop. Jump lists for each piece of software, available when you right-click on the respective program, even let you immediately pull up recently opened files and documents--a major time-saver.

4. Greater stability

Unlike Windows Vista, most hardware and software is readily compatible with Windows 7 and will work right out of the box, with no need to download and install additional drivers. Happily, in instances where necessary, locating and adding these updates to your PC proves a relatively painless procedure.

5. Enhanced security

Instead of making you play watchdog and constantly click to approve program access, Windows 7 does away with the vast majority of Windows Vista's nagging pop-ups. Users can now control the relative amount of prompts regarding system security they receive using an intuitive slider bar control, with alert messages minimized to avoid becoming a nuisance. In addition, the Internet Explorer 8 web browser is better-guarded against external threats. Purchase the Ultimate Edition ($219.99 upgrade), and you can further encrypt drives and data using BitLocker technology to protect sensitive files and even portable USB keys from unauthorized intrusion.

6. Multi-touch capabilities

If you have a compatible touch-screen PC or laptop, multi-touch physical gestures can now be used to navigate the operating system and pull up documents and data with a flick of a finger.

7. Simpler file organization

Libraries, which serve as all-purpose containers, allow you to conveniently catalogue photos, music, video and files in single locations, no matter where they live on your hard drive. Because of this, it's a breeze to keep all materials related to the same work project organized in one readily retrievable location.

8. Optimized network setup

Brisk, painless network setup via new HomeGroup features makes it simple to share devices, documents and printers between other PCs running Windows 7 on a password-protected home network. Entrepreneurs who need to access a larger companywide network may need to upgrade to the Professional Edition ($199.99), which allows connectivity with more complex workplace servers.

9. Less clutter

Don't like all the so-called "bloatware"--useless applications that traditionally come installed on any new operating system or PC? You'll be right at home here, as programs like Windows Mail, Windows Calendar, Movie Maker and Photo Gallery aren't even included with installation except in cases where they're pre-bundled by certain PC manufacturers. Instead, you choose to optionally download them for free from Microsoft. While some may balk at these typically preinstalled apps' omission, for others, it'll be seen as an effective way to cut down on unused programs that needlessly waste hard drive space and system memory.

10. Overall performance

Given its suite of welcome upgrades, Windows 7 is sure to inspire more third-party developer support than Windows Vista, and enjoy a larger business software library that takes advantage of its built-in features. As the system's improvements significantly enhance users' everyday work and online experience, it's inevitable that your enterprise will want to take advantage of programs which natively support these updates. Even those who opt for just the basic Home Premium edition ($119.99 upgrade) and never buy another application will be able to appreciate extras like faster and more reliable desktop search functions and simpler document retrieval. Making it infinitely simpler to organize, store and navigate both your desktop and supported applications, more than a few entrepreneurs will find that Windows 7 has been well worth the wait.

Conclusion

OneTouch Ptd. Ltd. is a graphic design company. As it often use a high-tech hardware to support and enhance efficiency of their works. I do recommend a Windows 7 Ultimate to this company because this window provides high speed compared with others. It also supported to others hardware using in the graphic design company for example the graphic into a picture shows more attractive and real life. Also, it allows work browser to be open up faster and more tasks can be performed simultaneously. Windows 7 Ultimate is the best window compares to others.

Part B - Marks (25 marks)

You are provided with following set of processes, with the length of the CPU burst given in

milliseconds:

Process

Burst Time

Priority

P1

19

3

P2

4

1

P3

10

2

P4

8

4

P5

22

2

Schedule the processes using First Come First Serve (FCFS), Shortest Job First (SJF),

Priority Scheduling and Round Robin. (Time quantum: 5ms)

1. Use a Gantt Chart to visualize your answer for each algorithm.

2. Calculate the average waiting time.

A1) First Come First Serve (FCFS)

Suppose the arrival order for the processes is

P1 , P2 , P3 , P4 , P5

Waiting time

P1 = 0;

P2 = 19;

P3 = 23;

P4 = 33;

P5 = 41;

A2) Average waiting time =

B1) Shortest Job First (SJF)

Process

Burst Time

P1

19

P2

4

P3

10

P4

8

P5

22

Suppose the arrival order for the processes is

P2 , P4 , P3 , P1 , P5

Waiting time

P2 = 0;

P4 = 4;

P3 = 12;

P1 = 22;

P5 = 41;

B2) Average waiting time =

C1) Priority Scheduling

Process

Burst Time

Priority

P1

19

3

P2

4

1

P3

10

2

P4

8

4

P5

22

2

Suppose the arrival order for the processes is

P2 , P3 , P5 , P1 , P4

Waiting time

P2 = 0;

P3 = 4;

P5 = 14;

P1 = 36;

P4 = 55;

C2) Average waiting time =

D1) Priority Scheduling (cont)

Suppose the arrival order for the processes is

P2 , P5 , P3 , P1 , P4

Waiting time

P2 = 0;

P5 = 4;

P3 = 26;

P1 = 36;

P4 = 55;

D2) Average waiting time =

Conclusion : C2 is the best for priority scheduling . because C2 take shorten time than D2 .

E1) Round Robin

P1

P2

P3

P4

P5

P1

P3

P4

P5

P1

P5

P1

P5

P5

0 5 9 14 19 24 29 34 37 42 47 52 56 61 63

P1 = (24-5) + (42-29) +(52-47) =37

P2 = 5

P3 = 9+(29-14) = 24

P4 = 14+(34-19) =29

P5 = 19+(37-24)+(47-42)+(56-52)+(61-56) = 46

E2) Average Turnaround time =