chapter5 operating system understanding os

8/8/2019 Chapter5 Operating System Understanding OS

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Operating System


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What is OS? Software that controls a computer

Managehardware

Run applications

Provides an interface for users

Stores, retrieves & manipulates files


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Why OS?

provide consistent environmentfor other software to executecommands.

gives user an interface withcomputer where input can be sent andoutput can be received

middleman between applications &hardware, between the users &hardware, between the users &

applications


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OS Terms & Concepts

Version:

revision of a piece of software i.e MS-DOS

Major revision i.e DOS5.0 to DOS6.0

Minor revision i.e DOS6.21 to DOS6.22

Source:

actual code defines of software works open source user can modify i.e linux

close source cant modify i.e windows xp


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OS Terms & Concept Every OS has 3 main internal

components:

- The shell

- The kernel

-

Configuration data


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OS Terms & Concepts

Shell:

program to issue commands thru set a menu orGUI i.e. microsoft dos shell (menu-driven)

Windows (fully GUI)

Provides a way for the user to do such a things asselect music to burn to a CD, install an applications,or change the wallpaper on the Windows desktop

Made up of several subsystems that all operate inuser mode, means these subsystems have onlylimited access to system information & can accesshardware only thru other OS services


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Kernel: kernel or core of the OS is responsible for

interacting withhardware

More power to communicate withhardware

devices than shell has

Applications operating under the OS cannot get tohardware devices without the shell passing thoserequest to the kernel

2 main components : hardware abstraction layer(HAL) & executive services


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Configuration data :

- Os needs a place to keep hardware &software configuration information, user

preferences & application settings- Windows uses a database called theRegistry for most of this information

- Keeps some data in text files calledinitialization files (.ini or .inf)


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OS Classificationmulti-user :Allows two or more users to runprograms at the same time. Some operating systemspermithundreds or even thousands of concurrent users.multiprocessing : Support running a program on

more than one CPU.multitasking :Allows more than one program to runconcurrently.multithreading :Allows different parts of a single

program to run concurrently.real time: Responds to input instantly. General-purpose operating systems, such as DOS and UNIX, arenot real-time


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OS- MicrosoftWindows successor of MS-DOS and released in 1985 GUI environment easier to navigate, more uniform &user friendlyVersion:

windows 1.x

tile windows, mouse support, menu system,multitasking no icon & few programs only

Boot up screen Notepad program


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OS- MicrosoftWindows windows 2 released in 1987

added icons & windows can overlap each others

Boot up screen Programsoverlapped eachothers


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OS- MicrosoftWindows windows 3

features File Manager & Program Manager,network support, virtual memory & support 386enhanced mode.

windows 3.1 more support on display &multimedia.

Boot up screen Programs manager


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windows 3.1(1992) more support on display &multimedia. windows 3.11(windows for workgroup) 32 bit application

Boot up screen for 3.1 Boot up screen for 3.11


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integrated OS and shell (W95 GUI is part of the OS) support plug n play

Boot up screen Interface of windows 95


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OS- MicrosoftWindows windows 98/ME

few enhancements like hyper help, Live Web Page onbackground, hyper links clickable, graphic can animate

Boot up screen Boot up screen for ME


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OS- MicrosoftWindows windows NT/2000/XP

NT(new technology)- powerful than previous version uses 32-bit code & able to access 4GB RAM Few edition XP home, XP Professional, XP Media Center

Boot up screen Boot up screen for W2000


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OS- MicrosoftWindows Windows Server 2003 (formely known Windows.Net Server)

designed to be backbones for small & large network Features:

Support 64-bit processors(i.e itanium 2)

Datacenter support up to 64 processors support up to 512GB RAM Centralized security management support network services like SQL,IIS & Terminal Server and Streamingmedia

Boot up screen


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OS- MicrosoftWindows Windows Vista (formerly known-longhorn)

released in 5 versions business,enterprise,homepremium, home basic & ultimate. new user interface called aero,IE7,speech & handwriting

recognition and easy access pop-up sidebar& gadgets.

desktop


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Alternative OS Mac OS

run in Macintosh computer. Build by Apple company latest version is Mac OS X (ten) Leopard

Desktop screen

time machine

backup tool

Multiple desktopscalled spaces


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Alternative OS Linux (developed by Linux Torvalds)

based on Unix and open source (free OS) Linux distribution like Mandrake, RedHat, Debian, Slackware,suSE, TurboLinux, Ubuntu

extremely powerful & stable (i.e used in web & email server)

mandrake redhat


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Using Operating System Windows Interface

Common elements in windows regardless of windowsversion:

Desktop

virtual desk which all program & utilities run. default items i.e. Start Menu, Taskbar and few icons Configurable as user like

Screen to change Desktop Properties


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The Taskbar contains 2 major items i.e, Start Menu & System Tray a quick way to access program & to show they are

running

Taskbar

Start Menu System Tray


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Start Menu Central point of focus in windows interface Contains submenu such as Programs, Documents,

Setting, Find,Help and Run

Start Menu


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Using Operating System The Control Panel

A common configuration Utility in windows

Command Prompt screen


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Using Operating System The Command Prompt

designed to have the look and feel like DOS commandline use as tool for configuration and its stable

Command Prompt screen


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Using Operating System

Registry a centralized database that stored Windows configurationinformation editable use Special Registry Editor application i.e.

REGEDIT or REGEDT32(without I). REGEDT32 has extrasetting such as assigning permissions. hives a series of separate areas & divided to 2: usersetting section & computer setting section. Basic hives of registry are:

be careful editingregistry!!!! cant UNDO


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Virtual Memory (swap file/paging file) a hard-drive space which idle pieces of program placed.Means, a program running believe that all info in RAM, butactually its moved to hard-disk. When needed, its swapped

back into RAM XP configures swap file size automatically, but can change. in W2K & XP, swap file is calledPAGEFILE.SYS & its hidden filelocated in the root directory.


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Disk Management Disks are pyhsical storage and need to be managed such as

getting disk ready to store files, back up data, involve inchecking the health of disks & optimizing performance.

getting disk ready to store files1. Partitioning create logical hard drive2. Formatting creating & configuring file allocation table

& root directory. FAT (file allocation table) 2GB max partition size

VFAT(Virtual FAT) 2GB max size(used in win95) FAT32 2048GB max size NTFS(New Technology File System) features like

individual file security & compression, RAID support,disk transaction monitoring, etc.