1,2Introduction to Computers & Operating System

8/2/2019 1,2Introduction to Computers & Operating System

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Introduction To Computers


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Meaning

A device that computes, especially aprogrammable electronic machine thatperforms high-speed mathematical orlogical operations or that assembles,stores, correlates, or otherwiseprocesses information.

One who computes. Used for performing a mundane task

of adding two no.s as well as complextask of controlling satellites.

Capable of handling things likenumbers, characters, images, audio,video, etc.


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Computer can be defined as anelectronic machine that receives data,process the data & then generates

output. The data is processed based on the

instruction given by the user.


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Components Of Computer

INPUT OUTPUT

CPU

MEMORY

Instructions

+


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Components of Computer

Central Processing Unit. Main Component of Computer.

Consist of ALU & Control Unit. Is a small silicon Chip Called Microprocessor.

Storage : Used for Saving information.

Information is saved as bit ( Binary Digit ). Storage capacity is measured in Byte i.e collection

of 8 bits.

Primary Memory. Made up of Microelectronic semiconductor memory

chips.

Two types : RAM & ROM.


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Secondary Memory. Non volatile.

Used for storage .

E.g. Pen Drive. Magnetic Discs.

Hard Disk.

Metal or Plastic discs Covered with iron oxide

recording material. Data is recorded in the form of Magnetic pits.


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Optical Disk Storage. Portable storage medium.

Plastic discs.

Records data by using laser to bun pits. Pen Drive.

Plug and play device.

It is a Universal Serial Bus flash memory drive.

support upto 8 GB disk space.


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Input/output Devices :Keyboard.

Mouse.

Webcam.Joystick.

Scanner.

Headphone.Monitor.

Computer Ports.


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Printer : Dot Matrix Printer


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Inkjet Printer :


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Laser Printer :


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Types of Computer

Can be classified based on size,speed, technology, cost, mode of use,etc.

Based On size & processing Power: Micro Computers.

Mini Computers.

Mainframes. Super Computers.


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Application of Computers.

Used in Communication, Education,Marketing, Production, research,medicine, etc.

Common people uses it for : Spreadsheet.

E- mailing.

Word Processing. Desktop Publishing ( DTP ).


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Business Org uses : Accounting.

Computer based production technology.

Design & manufacturing.

Control movements of parts using robotsconveyors, driverless carts or other automaticdevices.

Major job is Information processing &storage.

For Performing complicated calculations.Eg : Weather Forecasting.


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Advantage of UsingComputers. Work without getting Tired.

Speed.

Increase work efficiency.

Availability of information in hand,facilitates better service.

Major source of Instruction Medium.


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Operating System.

Is a collection of various programs usedto operate the computer.

It acts as an intermediate between User& the computer.

Designed with following three goals: To manage resources of Computer system

efficiently. Resources include .. To provide convenient Environment to user to

interact with resources. To provide secure environment to users sothat he can share resources & interact withother users of the system or on the network.


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Functionality of Layers in computersystem :

USER

APPLICATION SOFTWARE

SYSTEM SOFTWARE

HARDWARE


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Various Operating Systems

MS-DOS. Unix.

Linux.

MacOS. VMS.

Windows XP.

Windows 2003.

Windows NT.

Novel Netware.


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Functions of OS

Process Management.

Memory & Storage mgt.

Device Mgt.

Communication & Security mgt.

Application Interface.


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Types of Operating System.

Single user , Single tasking. (PDA,Hand Held Computers )

Single User, Multi tasking.(Windows-

Microsoft ) Multi User Operating System. ( Unix )

RTOS used to control machinery,

scientific instruments & industrialsystems.


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Booting Process

Booting process : From power on tillOS is loaded.

1. Power Supply is switched ON-

send power to processor allowingCPU to begin operation.

2. CPU loads the ROM BIOS- BasicInput/Output system Built in

software integrated in ROM chipcontains code required to controlkeyboard, mouse , Monitor screen

etc.


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3. ROM BIOS performs a basic test ofcentral hardware to verify basicfunctionality & searches for adapters

that may need to load their ownROM BIOS routine.

4. The ROM BIOS then checks to see

if this is a cold start or a warmstart .


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5. If this is a cold start, the ROM BIOSexecutes a full power-on self-test(POST) it is a built in diagnostic

program that checks your hardwareto ensure that everything is presentand functioning properly, before the

BIOS begins the actual boot.


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6. The video test initializes the videoadopter , test the video card & videomemory, and displays configuration

information or any errors. The BIOSidentification displays the BIOSversion, manufacturer & date. Thememory test tests the memory chip

& display a running sum of installedmemory. If there are errors the bootprocess stops.


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7. The BIOS then locates and readsthe Configuration information storedin complementary metal-oxidesemiconductor ( CMOS ). CMOS is asmall area of memory ( 64 MB ).Mostimportantly, the ROM BIOS startuproutines CMOS indicates the order

in which drivers should beexamined for operating systemCD ROM first or fixed disc first.


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8. If the first bootable disk is a fixeddisk, the BIOS examines the veryfirst sector of the disk for a masterboot record (MBR ).

9. MBR occupies the very first sectorat cylinder 0, head 0 and sector 1.It is 512 MB in size. If the sector is

found it is loaded. MBR is made upof two parts- the partition table &partition loader code.


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10. The BIOS transfers control of theboot process to the partition loadercode.

11. Partition loader examines thepartition table for a partition markedas active. It then searches the veryfirst sector of the partition for a bootrecord.

12. The boot record is also 512 Bytes andcontains a table that describes thecharacteristics of the partition.(

number of bytes per second/ cluster

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