Computer Hardware and Network

By – MaiTreya PaTniScholars 2 DSubodh Public School

Computer HardwareAll the elements that go together to make up a PC fall into one of

two categories, hardware or software. This section is about hardware, the stuff upon which software runs. Everything you can see and touch in your PC is hardware. Motherboard Some Hardware are :-

Hard Disk Drive (HDD)

Floppy Disk Drive (FDD)

Compact Disk Drive (CDD)

Digital Video Disk drive (DVD)

Monitors (CRT and LCD)

Keyboard

Mouse

Audio

Cables & Wires

Input DevicesInput Devices:

devices that input information into the computer such as a keyboard, mouse, scanner, and digital camera.

Output DevicesOutput: devices that

output information from the computer such as a printer and monitor.

Central Processing UnitCPU (Central Processing Unit) also called the

Microprocessor or “The Brain” of the Computer.Processor speed: The speed at which a

microprocessor executes instructions. This is usually measured in megahertz (MHz).

Brands of Processors include: PentiumCeleronMACAMD Cyrix

Hard DiskThe hard-drive is a

mechanical storage device typically located internally. Fast recording and recovery

of dataLarge storage capacityMagneticPrimary storage device for

data and programsSpeed is measured in

R.P.M.’s

Computer MemoryRAM (random access

memory) stores data that is processing. This type of memory is erased when the computer is turned off.

ROM (read only memory) contains special instructions for the computer to operate.

Cache memory increases the speed of the processor by recording and anticipating instructions.

Graphic User Interface (GUI)GUI (Graphic User Interface) is a set of

images and icons seen on the desktop used to operate a program. The GUI makes the programs loaded

on the computer easier to access and use. Basic Windows GUI

Icons are small pictures that represent files, commands, or windows.

Windows is a GUI operating system unlike UNIX, which uses text commands.

Video CardsVideo cards plug into the

motherboard and are used to display video.

VRAM is video memory that enhances the refreshment rate of the image.

Video cards have chipsets that can increase the speed of video display.

Ports and PeripheralsPorts are an interface between the computer and

another peripheral device such as a disk drive, mouse, printer, modem, monitor, camera, FLASH drive or keyboard.Examples:

Serial Parallelhot-wire USB

Ports and PeripheralsPeripherals are devices

that plug into a computer and are not housed internally.Examples:

PrintersScannersCameras

Computer NetworkA network

consists of two or more computers that are linked in order to: share resources

(such as printers and CD-ROMs),

exchange files, or allow electronic

communications

How are they linked?Computers on a

network may be linked through: cables, telephone lines, radio waves,

satellites or wireless

technologies

The two basic types of networks include:

Local Area Networks (LAN)

Wide Area Networks (WAN)

LAN

WAN

Local area networksLANs are confined to a relatively

small area such as a school or a building

LANs usually have one computer designated as the file server

Other computers are connected to the network by cables connecting network interface cards in each computer

Wide Area Networks

WANs connect larger areas, such as whole states, or even the world.

Transoceanic cables and satellites are used to connect WANs

ProtocolA protocol is a set of

rules that governs the communications between computers on a network

These rules include guidelines that regulate the method of access, types of cabling and speed of data transfer

PROTOCOL =

SET OF RULES ABOUT

COMMUNICATIONS BETWEEN NETWORKS!

The most common protocols are:EthernetLocal TalkToken RingFDDIATM

Protocol = a formal description of a set of rules and conventions that govern how devices on a network exchange information

Did you ever wonder what HTTP in web addresses was about? It stands for HyperText Transfer Protocol

EthernetMost widely usedUses an access

method called CSMA/CD (Carrier Sense Multiple Access/Collision Detection

Local TalkLocal Talk is a network

protocol that was developed by Apple for Macintosh computers

Local Talk uses the CSMA/CA method (Carrier Sense Multiple Access with Collision Avoidance) which works in a similar way to CSMA/CD

It is a lot slower than Ethernet (only 230 Kbps)

Token RingToken ring

protocol involves ‘token-passing’.

It is not as popular as Ethernet protocol

A single electronic ‘token’ moves around the ring from

one computer to the next. If a computer wishes to transit

and receives an empty token, it attaches data to the token which then proceeds around the ring until it comes to the computer the data is meant

for.

FDDIStands for Fiber

Distributed Data Interface

Is used mainly to connect two or more LANs, often over large distances

Can operate over fiber optic cable at 100 Mbps

ATMStands for Asynchronous

Transfer ModeTransmit data at a speed

of 155 Mbps and higherWorks by transmitting all

data in small packets of fixed size (other protocols transfer variable size packets)

Like FDDI , is most often used to connect two or more LANs