Computer Studies

What is Computer ?

A computer is an electronic machine which helps in solving problems quickly and easily. It solves problems according to instructions given to it by the computer user.

Different use of Computer

OFFICE Computers are used to type and print document, letters, etc. Computers helps in keeping records of office employees. Computers help in sending e-mails.

BANK

Computers are used in banks for s to r ing in fo rmat ion about different accounts holders. Computers help in keeping a record of the cash. Computer help in giving all kinds of information regarding any account in the bank.

EDUCATION

Computers are used in school for teaching and distance learning. Computers are used for d i f f e r e n t o n l i n e e x a m i n a t i o n a n d t o announce the result in time.

ENTERTAINMENT Computers are used for playing games, listening to m u s i c , a n d w a t c h i n g movies. Computers are used for making drawings, making c a r t o o n m o v i e s a n d animation films.

RAILWAY STATIONS AND AIRPORTS

Computer help in giving in format ion about t i cket reservations, bookings, arrival and departure timings of trains and aeroplanes. Computers help in keeping records of all the passengers.

HOSPITALS Computers help in keeping records of all the patients in the hospitals. Computers help doctor in controlling operation theatre machines and in doing a number of medical tests.

DEFENCE

Computer help in launching of missiles in defence, constructing weapons and controlling their functions. Computer help in establishing communication links between t h e s o l d i e r s a n d t h e i r commanders through satellites.

Types of computer based on Application

An analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved.

Analog computer

Digital computer

A digital computer is machine that stores data in a numerical format and performs operations on that data using mathematical manipulation.

Hybrid computer Hybrid computers are computers that exhibit features of analogue computers and digital computers. The digital component normally serves as the controller and provides logical operations, while the analogue component normally serves as a solver of differential equations.

Types of computer based on Size

Micro computer

A microcomputer is a small, relatively inexpensive computer with a microprocessor as its central processing unit (CPU).[2] It includes a microprocessor, memory, and input/output (I/O) facilities. Desktop computer, Laptop computer and Palmtop computer are called microcomputers.  

Mini computer

A minicomputer is a type of computer that possesses most of the features and capabilities of a large computer but is smaller in physical size.  

Main Frame Computer

Mainframe computers are computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning and transaction processing.  

Super Computer The fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculations, nuclear energy research, and petroleum exploration.  

Computers Have Two Main Parts 1. Computer Hardware Computer Hardware is the physical part of the computer system, the machinery and equipment.

Parts of the computer “you can see”

2. Computer Software Computer Software are programs that tell the computer what to do.

Computer Hardware

1.System unit - Central Processing Unit (C.P.U.) 2.Input unit - Key Board - Mouse - scanner 3.Output unit - Monitor - Printer

Computer system

CPU: Central Processing Unit ALU: arithmetic logic unit

–  Performs arithmetic and Boolean logical calculations

CU: control unit –  Controls processing of instructions –  Controls movement of data within the CPU

Interface unit –  Moves instructions and data between the

CPU and other hardware components

Memory

In computing, memory refers to the devices used to store information for use in a computer.  

RAM

Random Access Memory (RAM) is a computer storage location that allows information to be stored and accessed quickly from random locations.

Types of RAM

There are two different types of RAM:

DRAM (Dynamic Random Access Memory)

SRAM (Static Random Access Memory).

 

ROM Read-Only Memory is a computer memory on which data has been prerecorded. Once data has been written onto a ROM chip, it cannot be removed and can only be read.

 Types of RAM

PROM (Programmable Read-Only Memory)

EPROM (Electrically Programmable Read-Only Memory)

EEPROM (Electrically Erasable Programmable Read-Only Memory)

EAROM (Electrically Alterable Read-Only Memory)

 

Input Units Key Board

A keyboard is the set of typewriter-like keys that enables you to enter data into a computer. The keys on computer keyboards are often classified as follows: Alphanumeric keys -- letters and numbers

Punctuation keys -- comma, period, semicolon, and so on.

Special keys -- function keys, control keys, arrow keys, Caps Lock key etc  

Mouse A device that controls the movement of the cursor or pointer on a display screen. A mouse is a small object you can roll along a hard, flat surface.  

Scanner scanner or optical scanner is a hardware input device that allows a user to take an image or text and convert it into a digital file, allowing the computer to read or display the scanned object.  

Output Units

Monitor The monitor is the piece of computer hardware that displays the video and graphics information generated by the computer  

Printer A printer is an external hardware device responsible for taking computer data and generating a hard copy of that data. Printers are commonly used to print text, images, and photos.  

Storage device

Storage Devices are the data storage devices that are used in the computers to store the data. Following are the different storage devices:  

Computer Software

1. Operating System

2. Application Software

3. Utility Software

Computer hardware would be useless without software, the lists of instructions which tell the hardware what to do.

Computers require various types of software to make them useful. These can be classified as follows:  

1. Operating System

An operating system is the core software that allows a computer to run as an useful device. It manages the hardware, the user interface and all other software running on the computer.  

Basic Function of OS

Operating System

Device Configuration : Controls peripheral devices connected to the computer  

File Management : Transfer files between main memory and secondary storage. Manages file folders. Allocates the secondary storage space, and provides file protection and recovery.  

Memory Management : allocates the use of random access memory (RAM) to requesting process.  

Interface Platform : Allow the computer to run other application  

2. Application software

An application program is any program designed to perform a specific function directly for the user or, in some cases, for another application program. Application programs use the services of the computer's operating system and other supporting programs. Ex: word processor, database programs, Web browser ,development tools, drawing, paint, and image editing programs, and communication programs.  

3. Utility software

Utility program is a type of system software that allows a user to perform maintenance type tasks  

System tools command   Utility for

managing files  

Utility for removing unwanted files  

Utility for defragmenting disks  

Utility for restoring backed up files  

Thumbnail

A file manager is a utility that performs function related to file management. !  Displaying a list of files ! Organizing files in folders !  Copying, renaming, deleting,

moving and sorting files and folders.

!  Creating shortcuts  

A search utility is a program that attempts to locate a file on your computer based on criteria you specify  

Type  here  a  word  you  want  to  search    

An image viewer allows user to display, copy, and print the contents of a graphic file.  

An Uninstaller removes a program, as well as any associated entries in the system files  

A disk cleanup utility searches for and removes unnecessary files. "  Downloaded program files "  Temporary internet files "  Deleted files "  Unused program files  

A disk defragmenter reorganizes the files and unused space on computer's hard disk so that the operating system accesses more quickly and programs run faster  

Files before defragmenting  

Files after defragmenting  

A backup utility allows user to copy files to another storage medium. A restore utility reverses the process and returns backed up files to their original form.  

A screen saver causes a display device's screen to show a moving image or blank screen if no activity occurs for a specified time.  

A personal firewall detects and protects a personal computer from unauthorized instructions.  

A virus describes a potentially damaging computer program that affects a computer negatively

A virus cannot be spread without a human action, (such as running an infected program) to keep it going.  

Antivirus program protects a computer against viruses  

Worms spread from computer to computer and, unlike a virus, have the ability to travel without any help from a person  

Spyware is a program placed on a computer without the user's knowledge that secretly collects information about users. A spyware remover detects and deletes spyware and other similar programs  

Trojan horses do not reproduce by infecting other files nor do they self-replicate. At first glance they will appear to be useful software but will actually do damage once installed or run on your computer.  

Filters are programs that remove or block certain items from being dilplayed  

A file compression utility shrinks the size of a files. Compressing files frees up space on the storage media and they can be uncompressed too. Compressed files sometimes called as zipped files  

Computer Network

A computer network or data network is a telecommunications network which allows computers to exchange data.

In computer networks, networked computing devices pass data to each other along data connections.

The best-known computer network is the Internet.  

Uses of Computer Networks SHARING RESOURCES In  a  computer  network,  resources  such  as,  printers,  scanners,  fax  machines  and  modems  can  be  shared  among  different  users.  

COMMUNICATION People  can  communicate  at  very  low  cost  in  all  over  world  via  e-­‐mail,  cha@ng,  telephone,  video  telephone,  video  conferencing,  groupware,  and  SMS  services  etc.  

SHARING SOFTWARE In a computer network, usually application programs and other software are stored on the central computer.  

DATA SHARING In a network environment, any authorized user can access data stored on other computers on the network.  

Network Topology

"  Point-to-Point

"  Bus Topology

"  Star Topology

"  Ring Topology

"  Mesh Topology

"  Tree Topology

"  Daisy Chain

"  Hybrid Topology

A Network Topology is the arrangement with which computer systems or network devices are connected to each other.  

POINT-TO-POINT

Point-to-point networks contains exactly two hosts such as computer, switches or routers, servers connected back to back using a single piece of cable. Often, the receiving end of one host is connected to sending end of the other and vice-versa.

 

BUS TOPOLOGY

All devices share single communication line or cable. Both ends of the shared channel have line terminator. The data is sent in only one direction and as soon as it reaches the extreme end, the terminator removes the data from the line.

 

STAR TOPOLOGY

All hosts in Star topology are connected to a central device, known as hub device, using a point-to-point connection.

 

RING TOPOLOGY

In ring topology, each host machine connects to exactly two other machines, creating a circular network structure.

 

MESH TOPOLOGY

In this type of topology, a host is connected to one or multiple hosts.

TREE TOPOLOGY

Also known as Hierarchical Topology, this is the most common form of network topology in use presently.

 

DAISY CHAIN

This topology connects all the hosts in a linear fashion. Similar to Ring topology, all hosts are connected to two hosts only, except the end hosts.

 

HYBRID TOPOLOGY

A network structure whose design contains more than one topology is said to be hybrid topology.

 

Local area network (LAN)

A LAN is a computer network that interconnects computers within a limited area such as a home, school, computer laboratory, or office building, using network media  

Wide area network (WAN)

A WAN is a network that covers a broad area. Business and government entities use WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations.  

Metropolitan area network (MAN)

A MAN is a computer network larger than a local area network, covering an area of a few city blocks to the area of an entire city, possibly also including the surrounding areas.  

Introduction of Internet

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to link several billion devices worldwide.  

The most widely used part of the Internet is the World Wide Web (often abbreviated "WWW" or called "the Web").

Using the Web, you have access to billions of pages of information. Web browsing is done with a Web browser, the most popular of which are Chrome, Firefox, Safari and Internet Explorer.

 

Additional hardware required for internet are:

Modem Router Network Card

Transmission media

Types of Transmission Media

Transmission media is broadly classified into two groups.

1. Wired Transmission Media

2. Wireless Transmission Media

Transmission media is a pathway that carries the information from sender to receiver. We use different types of cables or waves to transmit data. Data is transmitted normally through electrical or electromagnetic signals.  

Wired Transmission Media are the cables that have physical existence and are limited by the physical geography. Popular wired transmission media in use are:  

TWISTED PAIR CABLE

 

CO-AXIAL CABLE  

FIBER OPTICAL CABLE  

SATELITE TRANSMISSION WI-FI TRANSMISSION

Wireless Transmission Media are the ways of transmitting data without using any cables. These media are not bounded by physical geography.