Overview Of The Operating System Computer Science Essay

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An Operating System is a set of programs that schedule tasks, allocates storage and presents a default interface to the user between application. Many of the first operating system were device-dependent and properties.

An Operating System is a set of program that coordinates all the activities among computer hardware devices.

An Operating System is a set of basic programming instruction to computer hardware, forming a layer of programming code on which most other functions of the computer are built.

An Operating System is very important, computers cannot be used or started without an operating system.

Functions of Operating System

Starting the computer

Warm boot (restarting a computer)

Cold boot (starting a computer)

Providing a user interface

To start an application program

To manage disks and files such as formatting, copying and renaming

To shut down the computer safely by following the correct procedures

Managing & Data and programs

When we start an application, the CPU loads the application from storage into memory.

Managing Memory

Monitoring the contents of memory

Optimizing the use of random access memory (RAM)

Configuring devices

Handling input and output, as well as enabling communication with input and output devices.

Key features include:

Plug and play capability with hardware and peripheral devices

Completely customizable task bar

Jump lists

Homegroup networking

Low memory footprint

The computer system can be divided roughly into four components:

The hardware

The operating system

The application software

The Users


The enhancements to windows 7

A new look and feel to the user interface

Increased reliability and security

Increased performance to run programs faster

The ability to create multiple user accounts and easily switch between accounts

A redesigned start menu and control panel

A more comprehensive Help and Support system

Increased emphasis on the use of digital media

An easy-to-install home or small office network

New versions of windows media player, movie maker, internet explorer and windows messenger

Operating System Services

User interface

Program execution

File-system manipulation


Error detection

Resource allocation


Protection and security

Control Panel

Microsoft Windows graphical user interface

Allows user to view and manipulate basic system settings and controls

Two views : class view and category view

Allow users to uninstall and change existing software packages

Allow users to manually install software from a CD-ROM or Pendrive

Task Manager

Set process priorities, processor affinity, forcibly terminate a few processes, and shutdown , restart, hibernate or log off from Windows.

Shutdown menu is also present that allows access to Standby, Hibernate, Turn off, Restart, Log off and Switch User.

To view and manage your computer's currently running programs and process.

To stop a program, which may be necessary, for instance.

If a program is not responding and you want to quit the program.

Device Manager

Provide enough information about the hardware so that you can manually install the device driver.

A fairly simple opening screen

A good first feeling for the hardware installed and recognized


Direct3D 11.0, Direct3D 10.1/10.0, DXGI 1.0/1.1, Direct2D 1.0, DirectWrite, Windows Imaging Component (WIC) APIs

Kernel mode


Provides basic Operating System services, such as memory management, process and thread management, and security


Provides low-level Operating System functions, such as thread scheduling

Device drivers

Translates user input and output requests into specific hardware input and output requests

Only the kernel mode can communicate directly with hardware through the hardware abstraction layer

Hardware abstraction layer (HAL)

Insulates the kernel and device drivers from the intricacies of hardware

Only the hardware abstraction layer interfaces with the Hardware layer

Hardware requirements


1 GHz (32-bit or 64bits processor)


1GB memory for 32bit

2GB memory for 64 bit

Hard disk

16GB for 32-bit

32GB for 64-bit

Video adapter

Direct X 9 graphics with 128MB

DVD-R/W drive

Network interface card

Windows firewall

Packets that are in response to something you sent out

Packets that are sent to a specific program that you put on Windows Firewall's Exceptions list.

Packets set to specific addresses- call ports - that you tell Windows Firewall to ignore.

Windows Installer

Responsible for installing, removing, and updating software by asking the Windows Installer Service Package for instructions on how the application should be installed, removed, modified, or repaired.

Use an application programming interface (API) to communicate with Windows Installer Service about how a package should be modified after an application is installed.

Internet Explorer Add-on Manager

Install them while running an executable, but add-ons can also be installed unnoticed while viewing Web pages.

When Internet Explorer crashes occur due to an add-on, Internet Explorer will prompt the user to disable the add-on.

Peer-to-peer Network

A network with all the nodes acting as both servers and clients.

A PC can access files located on another PC and can also provide files to other PCs.

All computers in the peer-to-peer network has equal responsibilities and capabilities to use the resources available on the network.

Peer-to-peer network, no server is needed, each computer in the network called a peer.

Process Management

Control access to shared resources like file, memory, input and output, CPU

Control execution of applications

Create, execute and delete a process

Cancel or resume a process

Schedule a process

Synchronization, communication and deadlock handling for process

Memory Management

Allocate memory

Free memory

Keep track of memory usage

Re-allocate memory to a program when a used block is freed

File Management

Provide access to files

Create and delete files

Keep back-up of files

Secure files

Allocate space for files

Device Management

Open, close and write device drives

Communicate, control and monitor the device driver

Other unique features

Domain membership

Dynamic disks

Encrypting file system

Internet information services

Multilanguage support

Multiprocessor support

Offline files

Remote Desktop

Roaming user profiles

User management

Shell Object Watcher

A new class in Windows API Code Pack that provides notifications on all elements in the shell, including: files, folders, virtual folders (libraries, search results, network items), etc.

Using this class you can get notifications on: Create, Delete, Rename, Share, Drive Added, etc.

Preview Handler APIs

One type of shell extension. It allows you to customize the preview window in Windows Explorer for a specific file extension.

Thumbnail Handler APIs

Thumbnail handler is another type of shell extension. It allows you to customize the thumbnail of a file extension in Windows Explorer.

Microsoft Word

Microsoft Word's spelling and grammar checker is adjustable and catches a wide variety of mistakes.

It has many features

Word is widely used and supports a number of file types

It has a simple layout, the same as all Microsoft programs



This writing enhancement software does not offer writing tutorials, and it fails to identify some advanced grammar issues.

It can crash


Microsoft Excel


Easy to use

Flexible output

Some integrated statistical functions


No transaction log

Limited number of analytical options

Limited data capacity

AVG Antivirus


Virus detection

More support

Security extras

Antivirus protection



Support and updates

Resource usage

Adobe Photoshop


Color change image

Image rotation

Image slicing

Quick search options

Resizing image

Cropping of images

Color change of image parts


Not an easy task


Some do not support the RAW formats of latest cameras

Difficulty in importing, exporting and sharing the image

Mozilla Firefox


Fairly secure


Most customizable browser

Zillion different add-ons


A little bit slow, especially if you're in a hurry

Attractive to virus writers

Disk defragmenter


Protects a computer against viruses by identifying and removing any computer viruses found in a memory or storage media or incoming files

Performs functions related to files and disk management

Help managing a computer easier

Computers can still be used or started without system utilities

Performs maintenance- type tasks

Usually related to managing a computer

Computer still can run without system utilities


Attractive targets for hackers


Could get cut off from the services which they are paying

Network Trouble-shooters


Not expensive

Easy to use interface


Unable to capture packets at wire speed

No expert mode

Does not support Windows NT3.51 and prior

Does not include decodes applications such as database servers

Graphical User Interface (GUI)

Menu-driven user interface


CPU : xeon e3-1240 v2

Mother board : Z77 Chipset

RAM : 8GB~32GB Ram

Graphic Card : Nvidia GTX680 4GB for CUDA acceleration

Storage : 120GB SSD as Boot Drive,240GB as scratch drive & 1TB as local storage

Intel i3 or i5

Processor : 2 GHz x86-64 processor (64-bit)


Windows 7 is not using a lot of RAM or CPU memory.

Easier to use than other Operating System.

The quicker startup, better performance and a new simplified visual appearance.

Windows 7 has shortcut keys, Sticky Notes, Snipping tool.

Microsoft paint is much better.

Internet Explorer 9 is better than Internet explorer 8

Increased security -User Account Control ( UAC) , Firewall

Windows 7 is hardly half-baked

Automatically installed device drivers

Windows 7 look like, unlike the boring-as-vanilla UI of Windows XP

Windows 7 has Aero desktop effect

Graphic card is nicer and better

One click way to enlarge all type and graphics, with crisp, easier to see results

Easy to upgrade path

Part B

First Come First Serve (FCFS)






0 19 23 33 41 63

Shortest Job First (SJF)






0 4 12 22 41 63

Priority Scheduling






0 4 14 36 55 63






0 4 26 36 55 63

Therefore , 21.8 is less average waiting time

Round Robin (Time quantum: 5ms)


































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

P1 = 0+(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)= 41