Parts of Computer

Parts of a Computer

Monitor
CPU
Keyboard
Mouse
Memory


Monitor-shows the pictures as we see on the television.
Keyboard-works for computer and helps writing characters.
Mouse-points on the monitor as your teacher points on the blackboard with a finger.
CPU-brain of the computer as we have.
Memory-to store figures on memory chip.
Monitor(screen)-
It is also known as Visual Display Unit.
It can be black and White or Colored.
It comes in various sizes.

Keyboard-
It looks like a typewriter.
It is used to type alphabets,numbers and symbols.
There are special keys for special functions.
Summary
Computer has 4 main parts-Monitor,CPU,Memory and Keyboard.
CPU is known as the brain of the computer.
What we do on the computer can be seen on the monitor.
Keyboard has many keys which are used to type alphabets,numbers and other special characters.

Some More parts of a computer

Mouse
It is also called a pointing device.
It has 2 or more buttons.
Clicking it,selects an item on the screen.
It helps us to draw pictures on the screen.
When mouse is moved on the desk,the pointer on the screen moves in the same direction.
A mouse has cord to connect to the CPU and cordless as well.

Printer
It is used to print letters and drawing on the paper.
Popular printers are Dot matrix,Deskjet and Laser Printers.

Floppy
It stores data/information as we write in our notebook for future use.
It is placed in a floppy disk drive.
It stores less amount of information.

Floppy Disk Drive
It is used to read and write the data to a floppy as we use our eyes while reading or writing.


Hard Disk Drive
It can store a large amount of data.
It is fixed inside the cabinet of computer.
It comes in various storage capacities.

CD ROM
CD stands for Compact Disk.
It can contain Games,Music,Movies and Programs.
It has shiny surface.

CD ROM Drive
It reads data from the CD ROM.

Joystick
It is used to play games,on the computer as we play video games.
It is an input device.

Speakers
Speakers are used for listening to music and other sounds.

Microphone
We can record our voice using a microphone.

Scanner
It scans text/image and puts it into computer as we see any picture and store it in the memory.

Summary
Mouse is used to move the mouse pointer on the screen in the desired direction.
Printer is used to print the output on the paper.
CD ROM is used to store movies,songs and other data.
Floppy is also used to store information but has lessor capacity in comparison to CD ROM.
Joystick is used to play games.
Scanner copies images to the computer.
We can listen to music with the help of speakers.

Computers-MS Excel

MS Excel
MS Excel is a powerful spreadsheet program that allows you to organize data,complete calculations,make decisions,graph data.
Excel allows you to organize data in rows and columns.These rows and columns collectively are called a worksheet.In electronic worksheet data is organized in same manner as manual worksheet.As like MS Word,spreadsheet has basic features to help create,edit and format worksheets.
Starting Excel
Click start.
Click All Programs.
Click MS Office.
Click MS Excel.

On opening Excel program,a blank workbook is displayed called Book1.

Title bar shows name of the displayed document.

File Tab help manage file information to save,open,print information for the document.

Quick Access Toolbar displays quick access buttons to save,undo and redo commands.

Program Window Controls buttons are used to minimize the program window,restore the window to full size or close the window.

The workbook contains sheets,called worksheets.A new workbook contains three worksheets.Each sheet has a name displayed on a sheet tab at the bottom of the workbook.

A cell is called the intersection of each column and row in a worksheet.A cell is the basic unit of a worksheet into which data is entered.

Each worksheet in a workbook has 16384 columns and 1048576 rows.

A cell is referred by its unique address or cell reference.To identify a cell,specify column letter first,followed by the row number,eg B8.

Formulas and Functions

Formulae are expressions which help you to calculate and analyse data in your worksheet.A formula in the worksheet always begins with an equal sign.
In maths,when you write a formula,you write out the values and the operators,followed by an equal sign(=).as 2+2=.
But in Excel,formulas begin with an equal sign(=),as =2+2.

Cell Referencing

Every cell in a worksheet has a unique address,also called a cell reference.

Cell Range

A group of related cells in a worksheet is called a range.Cell ranges are identified by their anchor points,upper left corner and lower right corner.The range reference includes both anchor points separated by a colon,eg A1:A3 includes A1,A2,A3.

Using Average,Max,Min Functions

If you want to calculate the average,highest,lowest sale of few persons in January,February,March from a range you can use functions like Average,Max,Min.
Excel,by default,includes formula called functions to help in computing the data.A function takes a value,performs an operation and returns a result to the cell,eg,=AVERAGE(G5:G14).

Creating a Chart

A chart can be created to compare data and view patterns and trends easily.After creating a chart,chart tools on the ribbons can be used to fine tune the chart to display and explain the data.

Select the range of data that you want on chart.
Click on Insert tab on the Ribbon.
Click on chart type from the Charts group.
Excel immediately creates a chart,places it on the worksheet.
Excel displays three chart tabs(Design,Layout,Format)for working with the chart.

Let us know Computer Networkings that are behind the Internet(an update)

Computer network means a collection of autonomous computers interconnected by a single technology.
The internet is a network of networks & the web is a distributed system that runs on top of the internet.

Examples of Networks-
1.Communication
2.Transportation
3.Social
4.Biological
5.Utilities

Components of a network-

• Server                           

1.Dedicated Server
2.Non Dedicated Server

Dedicated Server
We cannot use dedicated servers as a workstation & they are entirely dedicated to their connected workstations. Users access shared directories & resources on dedicated server.Eg. Novel NetWare.

Non dedicated Server
The machine used as a server can also operate as a workstation.

• Workstation

When a computer is connected to a network, it becomes a node on the network & is called a workstation or client.

• Network Interface Card(NIC)

Each computer attached to a network requires a network interface card(NIC) that supports a specific networking scheme such as Ethernet, ArcNet or Token Ring.

• Cabling System

Shared Resources & Peripherals

Network Fundamentals

1.

Local Area Network(LAN)

LAN

a)single building LAN

b)Multiple building LAN

LAN are privately owned networks within a single building or campus of up to a few kilometers in size.

LANs are distinguished from other kinds of networks by 3 characteristics

1)their size

2)their transmission technology

3)their topology

1.LANs are restricted size,which means that the worst-case transmission time is bounded.

2.LANs may use a transmission technology consisting of a cable to which all the machines are attached like the telephone company. Traditional LANs run at speed of 10 Mbps to 100 Mbps,have low delay(microseconds or nanoseconds) & make very few errors.Newer LANs operate at up to 10 Gbps.

3.Topologies for broadcast LANs are bus and ring.

Bus network

In a bus network, at any instant at most 1 machine is the master & is allowed to transmit. All other machines are required to refrain from sending. An arbitration mechanism is needed to resolve conflicts when 2 or more machines want to transmit simultaneously.

IEEE 802.3,popularly called Ethernet is a bus based broadcast network with decentralized control, usually operating at 10Mbps to 10Gbps.


Advantages of bus n/w

1)Short cable length & simple wiring layout because there is a single common data path connecting all nodes.

2)Resilient Architecture
Simplicity in architecture that makes it very reliable from a h/w point of view.

3)Easy to Extend
Additional node can be connected at any point along its length.

Disadvantage
1)Fault diagnosis is difficult
Control of n/w is not centralized. This means that detection of a fault may be performed from many points in the n/w.

2)Fault isolation is difficult
In case where the fault is in the n/w medium itself,an entire segment of the bus must be disconnected.

3)Repeater configuration
When a bus n/w has its backbone extended using repeaters,reconfiguration may be necessary.


Ring

In a ring n/w (loop n/w),several devices or computers are connected to each other in a closed loop by a single communication cable. Here data must travel around the ring to each station in turn until they arrive at the station.A ring can be unidirectional or bidirectional.

    Broadcast n/w can be further divided into static & dynamic, depending on how the channel is allocated.

   Static allocation uses round robin algorithm, allowing each machine to broadcast only when its time slot comes up.

Dynamic allocation method for a common channel are either centralized-there is eg. a bus arbitration unit,which determines who goes next or decentralized -there is no central entity, each machine must decide for itself whether to transmit.

Advantages of Ring n/w

1)Short cable length-A ring topology, is comparable to that of bus & is small relative to that of star.Less connection will be needed,which will in turn increase n/w reliability.

2)No wiring closet space required:since there is only 1 cable connecting each node.

3)Suitable for optical fibre:because traffic on a ring travel in 1 direction.


Disadvantage of Ring n/w

1)Node failure causes n/w failure. If 1node fails to pass through itself,entire n/w has failed & no traffic can flow until the defective node has been removed from the ring.

2)Difficult to diagnose fault:The fault if 1 node will affect all others.

3)N/w reconfiguration is difficult: For a very big ring n/w it is not possible to shut down a small section of a ring.Reconfiguration will have to be done.


Continued on Page 2 - MAN