www.muhammadniaz.blogspot.com computer science xi

7/22/2019 Www.muhammadNiaz.blogspot.com Computer Science XI

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Hardware Software(1)It is the Physical Components of a

Computer System.

(2)Hardware is Manufactured.

(3)It is Physical in Nature.(4)Duplication from the Original is

Not Possible.

(1) It is the very large Computer

Program or It is a set of many

Programs.

(2)It is Developed.

(3)It is Non Physical in Nature.(4)Duplication from the Original is

Possible.

Software

Operating System:-

Software used to manage Hardware and software Resources.Compiler & Interpreter:-It is the software that Translate high-level language into low-

level language.

Linker:-It is software that is used to attach Pre-Defined Translated Code

in a Program to Produced Executables file.

Source Program:-The Code we Type in a Computer Language Program is called

Source Program.

OR

High Level Language Code we Type in an IDE (Integrated

Development Environment)

System Software Applications Software

Operating System

Compiler

Interpreter

Linker

Assembler

MS WORD


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Object Program:-It is the Program with Comes in Machine Language from after

Translation of Source Program.

ORTranslated (Complied) Version of Source Program.

Executable:-The Complied and Library Code Intended Version of program

is Called Executable program.

Input DeviceDevice that are used to take data Input into the Computer

Memory. Example Key Board, Mouse, Toy Stick, Scanner Light Pen Exc.

Mouse:-It is a small Assembly which keep Two, Three button and a

Digital Circuitry to Navigate. Pointer over the Screen Area.

Some Mouse Keep is Roiling Mechanism to Navigate Cursor while

same keep Optical Mechanism.

WorkingWhen the Mouse button is pressed a signal is sent to the Computer for

the Corresponding Screen Position. The Mouse is accepted by the Computer

and the Application to do Corresponding Action.

Mouse Clicking Types(I) Left Click

(II) Right Click(III) Double Click

(I) Left ClickPressing of Left Mouse button is called Left Click.

(II) Right Click

Pressing of Right Mouse button is called Right Click.

(III) Double ClickThe Pressing of Left Mouse Button Twice is a Rapid Succession.

Keyboard:-It is an assembly that continues Number Button (Key)

corresponding to Different types of data and action input into the memory of

a Computer.

Key are Grouped together in a special manner and their Grouping are

as follow.

1.Character Key Pad (A to Z, a to z, Symbol)


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2.Numeric Key Pad (0 to 9)

3.Functions Key Pad (F1 to F12)

4.Screen Navigate Key Pad ( )5.Special Function Key Pad (Tab, Ctrl, Alt)

Working

When a key is pressed it is Corresponding ASCII Code is send in a

Memory Buffer than the contents of Buffer is sent to R.A.M.

Software Development Process/ Life Cycle

System Development:-System is the computerized solution for a set of Problem of an

organization or a group of persons.

Its development is divided mainly into four phases;

A.Analysis

B.Design

C.Coding

D.Testing & Maintenance

(A) Analysis:-

This is the first Phase in which following major tasks are done.

1. Meeting with Client.

2. Finding all existing problems.

3. Selecting subset of problem that can be solved through computer.(B) Design Phase:-

In this phase we deal with following Task are performed here;

1. Designing of Algorithms and flow Charts.

2. Determination of inputs, procedures, filing method and outputs.

(C) Coding:-

It is simply the typing of source program in a Selected IDE.

(D) Testing & Maintenance:-

In testing we check for verification and validation of program.

Verification is the functionality check whether the program is running or not

validation is the achievement of desired level of accuracy and precision. In

Maintenance we perform following tasks;

1. Delivery of system to client.

2. Software/Hardware Changes are made.

3. Training of end users.

4. Away of doing tasks.


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Networking

Networking:--The Interconnection of Hardware resources to Share resources.

Topology:--The art of Physical Connection of Computers to form a Network.

Node:--A Physical Device or Computer on a Network.

Server:--A Computer that services its resources and Application.

Client:--A Computer or Node that request for the Services.

Types of Topology:--1. Bus Topology2. Star Topology3. Ring Topology4. Ring Topology

Bus Topology:--

In Bus on all the Node are connected to the main Bus (Group of Wire)

At ends High Value residences are connected to signal lows.

Working:-

The Communication in the Bus Topology is slow due to a single port.

At a time only two Node can either Transfer or received data. No either

Transmition can take Place during a Communication Return two Nodes.

Advantages:-

1. Easy to build.2. Suitable for work group.

3. Low building cost.

Disadvantages:-

1. It is very slow Topology for Network Communication.

2. If a main Bus is Broken or a Node Expire, the whole Network Collapse.

3. To add new node, the network has to be stop.


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Star Topology:--

In Star Topology All the Nodes are connected to a Central Node

(HUB/Switch). It is sample to construct but it is costly. Hub can be Active or

Passive. The Active Hub Required a Power supply so that it can regenerate

in coming signal. Passive Hub do not required a Power supply.Working:-The Data from a Node is first sent to Central Node then it is routed.

Advantages:-

1. It is easy to build.

2. New user can be entering without stopping whole Network.

3. If any single Node Expire the networks remain operating.

Disadvantages:-

1. It is costly Topology.

2. If a Central Node expired the whole Network Collapse.

Ring Topology:--

In Ring Topology, Every Node is connected physically to its two

neighboring Node to from a circular Pattern called Ring. In Electronic

privilege called Token.

Working:-The Token Circulator in either Clock-wise, Anti Clock-wise Direction.

Node attaches massage to the token with Destination I.D and other


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information. The Token is then passed to the Neighboring Node the

Neighbor checks the massage in the token and it accept or reject the take it.

It can also attach a new massage the token and the distributions of data take

place due to circulating token or tokens.

Advantages:-

1. It is easy to build.

2. It is low in cost.

3. It is easy to maintain.

Disadvantages:-

1. It a single Node Expire the whole Network Collapse.

2. The Network has to be stop for enter a new user/Node.

3. It the Number of Node increase the Network be come slow.

Mesh Topology:--

In this Topology every Node is individually connected to every other

on the Network. It is a costly Network but Reliable. Data Communicationcan be Perform through more than one Route.

Advantages:-

1. There is no chance of data collision.

2. Most Reliable Network Topology.

Disadvantages:-

1. It is very costly.

2. It is time Consuming to build and Difficult maintains.


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Types of etworkThe Network is categorized basically into 4 types.

1. Local Area Network (LAN)

2. Wild Area Network (WAN)3. Metropolitan Area Network (MAN)

4. Global Area Network (GAP)

(1) Local Area Network (LAN):-It is a Network that is confine within geographical area of one squire

Kilometer.

Example:-

A Computer Network in a building or group of buildingextra

It is the faster Communication Network that is owned by a person or a

group of person.It is easy to minuteness and incorporate few Networking devices.

(2) Wild Area Network (WAN):-This Network is extended geographically ever more than 1KM

distance. It can cover many buildings and mach area of the city It user both

Networking and internetworking devices. It cant be Owen by a person it is

10 time Slower than Local Area Network. Many Protocols are used and so

the gateway is used to form Wild Area Network.

(3) Metropolitan Area Network (MAN):-This Network is extended across entire city. It is much bigger than

WAN and it used Telephone line as well and Telephone exchange service

for building communication link.

(4) Global Area Network (GAP):-This Network is extended across the entire global and it covered all

sold devices, topology, Links and services to from global Area Network.

There much is single topology so that information can uniformally beexchange ever the world.

Example:-

Internet uses

Transportation control protocol /Internet Protocol (TCO/IP).


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Networking:--Networking Devices are used for two purposes

1. To build a Network.2. To extend the Network.

These exude LAN Card, Switches, Hub, repeater, cables and Bridge.

Inter networking:--Inter Networking Devices are used to link to deformfan

Types of Inter Networking Devices these are Router, Booster, Gateway,

CSU, DSC extra

( )

Network Operating System:--An Operating System that manages the resources of every Node on the

Network is called Network Operating System.Example:-

UNIX, Linux, Windows NT (New Technology)

The server Computer is the Real Place for NOS.

Protocol:--Protocols are the rule and resolution to convey information from one

Computer to another. Some protocols are routable and same are not.

Protocols are installing as standard for information exchange on every Node

on the Network. There are install on client side and on sever side.Example:--

NA, NET, BUE, IE, TCP/IP Groper FTP extraMedia:--

There are two types of media

(1)wires media(2)Wireless

Wires Media:--

In wires media we used toasted cable, to estate cable, coaxial cable and

optical fibber.Wireless Media:--

In wireless media we used redo value microbes and seta light System.


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OSI Model:-- (open system interconnection)

It is a model proposed by a comate to define the standard to establish

and manage a Computer Network.It defines protocols for every single tastes and group, than protocol in the

form of layers every layer is categorized difficultly due to its nature of work.

Following are the OSI layers

1. Physical Layer

2. Data link Layer

3. Network Layer

4. Transport Layer

5. Session Layer

6. Presentation Layer7. Application Layer

1. Physical Layer:--This Layer due all the physical issues of the Network Topology Cable,

Represent of Data encoding, decoding, Number of pens in a connector and

Network Devices are the men issues solve.

2. Data link Layer:--This Layer is Responsible for establishing a single link between to

Node it manages and Inlay terminates that link. The Data is broken in to

small Data picket and CRCO is imposed.3. Network Layer:--

This Layer is responsible for managing all links between source and

destination Computer. It is responsible for making correct routing decision.

4. Transport Layer:--This Layer is responsible for transporting Data packets across different

types of Network in a reliable and error-free manner.

5. Session Layer:--This Layer is responsible for building a session (A Communication

Channels) between two Applications running on different Nodes on a

Network. It establishes the session and transported after the communication

ends.

6. Presentation Layer:--This Layer is responsible for transforming the transportable form of

Data in to use able form and wise ware.


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7. Application Layer:--This Layer is used to serve services to Network like email services,

file transport services, chatting services, video confessing services.

Networking Devices:--Devices that are used to create and extend a single Network are called

Networking Devices.

Example:--

HUB, switch, repeater, bridge and ether Net card /LAN Card

1. LAN Card :--( Network Adapter/ether Net Card)

This is Hardware card install client side and it Casper UNIX IP

address. This makes the Node dusting disable on a Network for

communication.

2. HUB/Switch:--

It is a central Node of a Network that provides connective among all

Node It may be Active (Requiring a Power Supply) or It may be passive(Does not Requiring compare supply) which is similar to HUB but is farmer

indigent as it can take write design for the Network.

Data Communication Modal:--

Source:--A Point where the Data is first originated

Modulator:--A device that mixes the low frequency data with the carrier high

frequency during sending of data


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Transmitter:--A device that increases the gain of modulated signal so that it can be

transmitted to long distances

Transmission Media:--It is an entity that carries the data signal from source to destination.

Point:--It is divided into two types

(A)Wires Media (Twisted pair, curial cable, Optical fiber )(B)Wireless Media (Radio waves, microwaves, FM Satellite)

Receiver:--

A cirevit that catches the weak incoming signal and amplitude ofsignal is amplified.

Demodulator:--A device that separate the low frequency signal from the high

frequency carrier wave

Destination:--A point where the data is to be reached finally

Types of Data(A)Analog Data (Continuous(point) wave from signal element)(B)Digital Data (Discrete(whole (number) wave from signal element)

Encoding:--Transformation of one form of signal into another form of signal

Types of Encoding:--

(A)Digital to Digital Encoding(B)Digital to Analog Encoding(C)Analog to Analog Encoding(D)Analog to Digital Encoding


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Digital to Digital Encoding:--In this type of encoding the input Digital signal is transformed into

another form of Digital signal.

Digital to Analog Encoding:--

In this type of encoding the input Digital signal is transformed intoanother form of Analog signal.

Analog to Analog Encoding:--Here input signals an analog wave form while the output signal is also

an Analog Signal.

Example are ASK, FSK, and PSK modulation.

Analog to digital Encoding:--

Here input signals an analog wave form while the output signal is alsoa Digital Signal.

Examples are Pulse Code, Delta Modulation.

Wires MediaMedia:--

Entities that convey energy from one place to another wires media

include mainly three types of wires;1. Twisted Pair2. Coaxial Cable3. Optical Fiber1.Twisted Pair wire:--

It is a group of two insulated wires that are twisted together to cancel

the effect of inductions in the wires conveying data signal. They are covered

by an outer covering for strength and protection.


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2.Coaxial Cable:--

Here two wires runs side by side in such a way that the main inner

conductor is in the center (axial) and the second outer Conductor is around

the axial and absorbing any leak radiation from both in and outside of

conductor. It is used for high frequency transmission.

3.Optical Fiber:--

It is a fiber of light conducting material its inner central region is of

high density and the outer region is of low density. Light travels in denser

median and remain travels in it due to total internal reflection signal of very

high frequency is transmitted through optical fiber.

Multiplexing Playing:--It is the division of time allocated for sending more than one types of

signal throws a signal channel of frequency. The devices that performMultiplexing are called Multiplayer.

Modulation:--It is a process of mixing low Data frequency with the high carrier

frequency to from modulated signal.

Demodulation:--It is a process in which the signal is separated from the carrier

frequency.

Time sharing:--It is the distribution of time allocated for different tasks.


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Register:--It is a digital sharked that storages a single instruction at a time. It size

me be 8 bit, 16 bit, 32 bit, 64 bit extra. They are located in site micro

processor and are the fasted memory aliasing.

Some of the common registers are

1.

Program Counter2. Memory Address Register3. Intrusion Register4. Accumulator Register5. Buffer Register6. Stack Register7. Flag Register

1. Program Counter:--

This register generates the count this count is actually the address of

memory where over program is storage the address is send to the memory

address Register.

2. Memory Address Register

This register gets the count is address a loads the contents on that

memory address. It then protect for super wise what is being brought in to

the memory and what is being taking out from the memory.

3. Intrusion Register:--

This register holds a complete single instruction. It sends command

part to controller unit and address to MAR.

4. Accumulator Register:--

This register is used to holds the accumulator is filled with data.

B-Register

This register holds the second next value after the accumulator is

filled with data.

Out register

This register supplies the data to the outside world or accepts the data

form.

6. Stack Register:--

This register holds the data item in last in first out principle. It I used

to store paused state of programs that can lather recondite.


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7. Flag register:--

This register is used to indicate and storage the current status of all

register and operations during program execution every operation is

educated by a single bit .etc

Fetch OperationStep 1

Program counter generates the count (Address of 1stinstruction of a

program) and send the count to memory address register.

Step 2

MAR enable the contents of given address to be taken from thememory.

Step 3

The loaded content of memory is brought into instruction register.

Fetch Decode Operation

Decode Operation:--In this operation, the command is interpreted into series of sub

infraction trough controller unit.

Execute Operation:--

Application of sub-instructions to all units from the controller unit is

called execution.

VirusVirus:--

A Computer program that is designed specifically to perform illegal

tasks.

Types of Virus:--


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Following are some main categories into which virus are divided.

1. Worms2. Trojans3. Time Booms4. File Infectors5. Boot Sector virus

WORM:--This virus is designed to duplicate is self to accomay maximum

memory space. They can special form network ant another input/output

resources and can slow down processing of computer.

Trojans:--They are the programs that do not horn computer operations during

there accept ion Next time went the Computer is run they gates intooperation and perform illegal tasks.

Time booms:--These viruses are design to perform illegal operations on a carting

date and time for example; Michelangelo virus activate on March 6.

File Infectors:--These virus spreads automatically injure them self in a file that latter

on Ram in affectedly.

Boot Sector virus:--This virus reside it salve in hard drive on the boot sector and prevent

the booting operations of the system.

Data ProtectionsMethod of data protection:--

We have two resources that need to protect. Following are the ways

mentioned.

1. Use of Anti-virus2. Use of password and domain3. Use of proxy server and firewall4. Use of Data back-up5. Use of Audile Software


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6. Use of Alternate Power supply7. Use of SCSI port and devices8. Use of Physical protection methods9. Use of copyright Law10.Use of Anti-Hacking and Anti-spying Software

1. Use of anti-virus:--The Antivirus software is used to scan hard drive and its contents,detect the virus organize a strategy to remove or isolate the virus the

scanning is centralled by the user or it can automatically be set. The Anti-

virus software has to be updated download latest virus definitions.

Example; AVG, Norton, Avast and ESET NOD32

2.Use of password and domain:--On the Network we use a policy to share resources. We define and

grant privileges to the user in a group of a domain hence only authorized

user can effectively and safely use resources. Password is a digital lock for ausers account if the password is correctly typed, then the user can use

domain privileges. Bio metrically set password can also be applied.

Name: Muhammad Niaz

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