WRITE CD USING NERO SOFTWARE

You can write a CD using Nero software by following simple and easy short steps.
1. Open Nero software.
2. Select what type of CD you want to make.
3. Insert CD.
4. Add files or folder from your computer
5. Click burn.
6. After completing, it will be ready to use

HOW TO FORMAT YOUR COMPUTER

You can format your computer by following these simple steps.

1) All computers have BIOS (Basic input/output system). Here, you can set up how your PC will run. It is a blue colored full screen with different tabs like general, exit, devices and many more. Go to BIOS by simply hitting Del (delete) continuously after restarting your computer.

2) Once in BIOS, look for the booting set up. Listed there are the devices which computer normally boots. ( Hard disk, CD-ROM, Floppy Disk and Network)

3) Place the CD-Rom as the first boot and see to it that the bootable CD of Operating system you want is inserted in the CD-Rom. Then Place hard disk as the second booting device. Third and fourth booting devices are not usually important.

4) Save the changes and Exit. This will restart your computer automatically.

5) When your computer restarts wait until you see a message saying.........
Boot to CD........<----if this showed up hit any key to boot to CD. This will make your computer refer to the CD.

6) They will ask you if you want to delete or to create a new partition. For me just delete the partition and do not create anymore partitions. This will only slows your computer down.

7) After deleting the partitions, they will ask you if you wanted to format you PC. There are 4 choices in there:

a. Quick format (FAT)
b. Format (FAT)
c. Quick format (NTSF)
d. Format (NTSF)

Choose the format either NTSF or FAT. Sometimes quick formatting result to corruption of some files.

8) The computer will copy the contents needed from the CD to your PC and installs it. Windows will appear but i know when you see one you can understand what to do. It will just ask for date and time and user name if you want to.

9) After the installation is complete the computer will automatically restart.

10) Once restarted, set the display in your choice. You can do anything now. Congratulations, you now can reformat PC.

SOFTWARE TESTING

What is testing?

Testing is the process of evaluating a system or its component(s) with the intent to find that whether it satisfies the specified requirements or not. This activity results in the actual, expected and difference between their results. In simple words testing is executing a system in order to identify any gaps, errors or missing requirements in contrary to the actual desire or requirements.
According to ANSI/IEEE 1059 standard, Testing can be defined as A process of analyzing a software item to detect the differences between existing and required conditions (that is defects/errors/bugs) and to evaluate the features of the software item.

Who does testing?

It depends on the process and the associated stakeholders of the project(s). In the IT industry, large companies have a team with responsibilities to evaluate the developed software in the context of the given requirements. Moreover, developers also conduct testing which is called Unit Testing. In most cases, following professionals are involved in testing of a system within their respective capacities:

• Software Tester
• Software Developer
• Project Lead/Manager
• End User

Different companies have difference designations for people who test the software on the basis of their experience and knowledge such as Software Tester, Software Quality Assurance Engineer, and QA Analyst etc.
It is not possible to test the software at any time during its cycle. The next two sections state when testing should be started and when to end it during the SDLC.

When to Start Testing?

An early start to testing reduces the cost, time to rework and error free software that is delivered to the client. However in Software Development Life Cycle (SDLC) testing can be started from the Requirements Gathering phase and lasts till the deployment of the software. However it also depends on the development model that is being used. For example in Water fall model formal testing is conducted in the Testing phase, but in incremental model, testing is performed at the end of every increment/iteration and at the end the whole application is tested.
Testing is done in different forms at every phase of SDLC like during Requirement gathering phase, the analysis and verifications of requirements are also considered testing. Reviewing the design in the design phase with intent to improve the design is also considered as testing. Testing performed by a developer on completion of the code is also categorized as Unit type of testing.

When to Stop Testing?

Unlike when to start testing it is difficult to determine when to stop testing, as testing is a never ending process and no one can say that any software is 100% tested. Following are the aspects which should be considered to stop the testing:

• Testing Deadlines.
• Completion of test case execution.
• Completion of Functional and code coverage to a certain point.
• Bug rate falls below a certain level and no high priority bugs are identified.
• Management decision.

Testing, Quality Assurance and Quality Control

Most people are confused with the concepts and difference between Quality Assurance, Quality Control and Testing. Although they are interrelated and at some level they can be considered as the same activities, but there is indeed a difference between them. Mentioned below are the definitions and differences between them:

S.N.	Quality Assurance	Quality Control	Testing
1	Activities which ensure the implementation of processes, procedures and standards in context to verification of developed software and intended requirements.	Activities which ensure the verification of developed software with respect to documented (or not in some cases) requirements.	Activities which ensure the identification of bugs/error/defects in the Software.
2	Focuses on processes and procedures rather then conducting actual testing on the system.	Focuses on actual testing by executing Software with intend to identify bug/defect through implementation of procedures and process.	Focuses on actual testing.
3	Process oriented activities.	Product oriented activities.	Product oriented activities.
4	Preventive activities.	It is a corrective process.	It is a corrective process.
5	It is a subset of Software Test Life Cycle (STLC).	QC can be considered as the subset of Quality Assurance.	Testing is the subset of Quality Control.

Testing and Debugging

Testing:

It involves the identification of bug/error/defect in the software without correcting it. Normally professionals with a Quality Assurance background are involved in the identification of bugs. Testing is performed in the testing phase.

Debugging:

It involves identifying, isolating and fixing the problems/bug. Developers who code the software conduct debugging upon encountering an error in the code. Debugging is the part of White box or Unit Testing. Debugging can be performed in the development phase while conducting Unit Testing or in phases while fixing the reported bugs.

COMPARISON BETWEEN INTERNET & INTRANET

Internet

• Internet is a world-wide/global system of interconnected computer networks.
• Internet uses the standard Internet Protocol (TCP/IP)
• Every computer in internet is identified by a unique IP address.
• IP Address is a unique set of numbers (such as 110.22.33.114) which identifies a computer location.
• A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name.
• For example, a DNS server will resolve a name http://www.tutorialspoint.com to a particular IP address to uniquely identify the computer on which this website is hosted.
• Internet is accessible to every user all over the world.

Intranet

• Intranet is system in which multiple PCs are networked to be connected to each other.
• PCs in intranet are not available to the world outside of the intranet.
• Usually each company or organization has their own Intranet network and members/employees of that company can access the computers in their intranet.
• Each computer in Intranet is also identified by a IP Address, which is unique among the computers in that Intranet.

Similarities in Internet & Intranet

• Intranet uses the internet protocols such as TCP/IP and FTP.
• Intranet sites are accessible via web browser in similar way as websites in internet. But only members of Intranet network can access intranet hosted sites.
• In Intranet, own instant messengers can be used as similar to yahoo messenger/gtalk over the internet.

Differences in Internet & Intranet

• Internet is general to PCs all over the world where Intranet is specific to few PCs.
• Internet is wider access and provides a better access to websites to large population whereas Intranet is restricted.
• Internet is not as safe as Intranet as Intranet can be safely privatized as per the need.

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Macs And PCs

Personal computers come in two main "styles": PC and Mac. Both styles are fully functional, but they do have a different look and feel, and many people prefer one or the other.

A PC

A Mac

• PC: This type of computer began with the original IBM PC that was introduced in 1981. Other companies began to create similar computers, which were called IBM PC Compatible (often shortened to PC). Today, this is the most common type of personal computer, and it typically includes the Microsoft Windows operating system.
• Mac: The Macintosh computer was introduced in 1984, and it was the first widely sold personal computer with a Graphical User Interface, or GUI (pronounced gooey). All Macs are made by one company, Apple Inc., and they almost always use the Mac OS X operating system.

Although PC can refer to an IBM PC Compatible, the term can also be used to refer to any personal computer, including Macs.

INTRODUCTION OF COMPUTER

What Is Computer?

Computer is an advanced electronic device that takes raw data as input from the user and processes these data under the control of set of instructions (called program) and gives the result (output) and saves output for the future use.

Functions Of a Computer.

Any digital computer carries out five functions in gross terms:

• Takes data as input.
• Stores the data/instructions in its memory and can use them when required.
• Processes the data and converts it into useful information.
• Outputs the information.
• Controls all the above four steps.
  
  
  

  Advantages

  Following list demonstrates the advantages of Computers in today's arena.
  

  High Speed

• Computer is a very fast device.
• It is capable of performing addition of very big data.
• The computer has units of speed in microsecond, nanosecond and even the picosecond.
• It can perform millions of calculations in a few seconds as compared to man, who can spend many months for doing the same task.

Accuracy

• In addition to being very fast, computers are very accurate.
• The computer has performed calculations 100% error-free.
• Computers perform all jobs with 100% accuracy.

Storage Capability

• Memory is a very important characteristic of computers.
• The computer has much more storage capacity than human beings.
• It can store large amount of data.
• It can store any type of data such as images, videos, text, audio and any other type.

Diligence

• Unlike human beings, a computer is free from monotony, tiredness and lack of concentration.
• It can work continuously without creating any error and boredom.
• It can do repeated work with same speed and accuracy.

Versatility

• A computer is a very versatile machine.
• A computer is very flexible in performing the jobs to be done.
• This machine can be used to solve the problems relating to various different fields.
• At one instant, it may be solving a complex scientific problem and the very next moment it may be playing a card game.

Reliability

• A computer is a reliable machine.
• Modern electronic components have failure-free long lives.
• Computers are designed to make maintenance easy.

Automation

• Computer is an automatic machine.
• Automation means ability to perform the task automatically.
• Once a program is given to computer, i.e., stored in computer memory, the program and instructions can control the program execution without human interaction.

Reduction in Paper Work

• The use of computers for data processing in an organization leads to reduction in paper work and speeds up the process.
• As data in electronic files can be retrieved as and when required, the problem of maintenance of large number of files gets reduced.

Reduction in Cost

• Though the initial investment for installing a computer is high but it substantially reduces the cost of each of its transaction.

Disadvantages

Following list demonstrates the disadvantages of Computers in today's arena.

No IQ

• A computer is a machine and has no intelligence of its own to perform any task.
• Each and every instruction has to be given to the computer.
• A computer can not take any decision on its own.

Dependency

• It can perform function as instructed by user, so it is fully dependent on human being.

Environment

• The operating environment of computer should be dust-free and suitable to it.

No Feeling

• Computer has no feeling or emotions.
• It cannot make judgement based on feeling, taste, experience and knowledge unlike a human being.

COMPUTER OPERATING SYSTEM

• An operating system is a program that acts as an interface between the software and the computer hardware.
• It is an integration set of specialised programs that are used to manage overall resources and operations of the computer.
• It is a specialised software that controls and monitors the execution of all other programs that reside in the computer, including application programs and other system software.

Objectives of Operating System

• Making a computer system convenient to use in an efficient manner.
• To hide the details of the hardware resources from the users.
• To provide users a convenient interface to use the computer system.
• To act as an intermediary between the hardware and its users and making it easier for the users to access and use other resources.
• Manage the resources of a computer system.
• Keep track of who is using which resource, granting resource requests, according for resource using and mediating conflicting requests from different programs and users.
• The efficient and fair sharing of resources among users and programs.

Characteristics of Operating System

• Memory Management -- It keeps track of primary memory, i.e., what parts of it are in use by whom, what parts are not in use, etc. Allocates the memory when the process or program requests it.
• Processor Management -- Allocates the processor (CPU) to a process. Deallocate processor when processor is no longer required.
• Device Management -- Keeps tracks of all devices. This is also called I/O controller. Decides which process gets the device when and for how much time.
• File Management -- Allocates the resources. Deallocates the resource. Decides who gets the resources.
• Security -- By means of passwords & similar other techniques, preventing unauthorized access to programs & data.
• Job accounting -- Keeping track of time & resources used by various jobs and/or users.
• Control over system performance -- Recording delays between requests for a service & from the system.
• Interaction with the operators -- The interaction may take place via the console of the computer in the form of instructions. Operating System acknowledges the same, do the corresponding action and inform the operation by a display screen.
• Error-detecting aids -- Production of dumps, traces, error messages and other debugging and error-detecting methods.
• Coordination between other software and users -- Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems

COMPUTER NETWORKING

What is a Computer Network?

A computer network is a system in which multiple computers are connected to each other to share information and resources.

Characteristics

• Share Resources from one computer to another
• Create files and store them in one computer, access those files from the other computer(s) connected over the network
• Connect a printer, scanner or a fax machine to one computer within the network and let other computers of the network use the machines available over network.

Following is the list of hardwares required to set up a computer network:

• Network Cables
• Distributors
• Router
• Internal Network Cards
• External Network Cards

Network Cables

• Network cables are used to connect computers. The most commonly used cable are Category 5 cable RJ-45.

Distributors

• Each and every computer can be connected to another one via a serial port, but if we need to connect many computers to produce a network, this serial connection will not work. The solution is to use a central body to which other computers, printers, scanners, etc., can be connected and then this body will manage or distribute network traffic.

Router

• A router is a type of device, which acts as the central point among computers and other devices that are part of a network.
• A router is equipped with holes called ports.
• Computers and other devices are connected to a router using network cables.
• Nowadays, router comes in wireless modes using which computers can be connected without any physical cable.

Network Card

• Network card is a necessary component of a computer without which a computer cannot be connected over a network.
• Also known as network adapter or Network Interface Card (NIC).
• Most of branded computers have network card pre-installed.
• Network cards are of two types: Internal and External Network Cards

Internal Network Cards

• Motherboard has a slot for internal network card where it is to be inserted.
• Internal network cards are of two types:
• First type uses Peripheral Component Interconnect (PCI) connection.
• Second type uses Industry Standard Architecture (ISA).
• Network cables are required to provide network access.

External Network Cards

• Comes in two flavors: Wireless and USB based.
• Wireless network card needs to be inserted into the motherboard but no network cable is required to connect to network.

• USB cards are easy to use and connect via USB port.
• Computer automatically detects USB card and can install the drivers required to support the USB network card automatically.

COMPUTER PORTS

What is a Port?

• A computer port is a physical docking point using which an external device can be connected to the computer.
• A computer port can also be programmatic docking point through which information flows from a program to computer or over the internet.

Characteristics

• External devices are connected to a computer using cables and ports.
• Ports are slots on the motherboard into which a cable of external device is plugged in.
• Examples of external devices attached via ports are mouse, keyboard, monitor, microphone , speakers, etc.

Following are few important types of ports:

Serial Port

• Used for external modems and older computer mouse.
• Two versions: 9 pin, 25 pin model.
• Data travels at 115 kilobits per second.

Parallel Port

• Used for scanners and printers
• Also called printer port.
• 25 pin model.
• Also known as IEEE 1284-compliant Centronics port.

PS/2 Port

• Used for old computer keyboard and mouse
• Also called mouse port.
• Most of the old computers provide two PS/2 ports, each for mouse and keyboard.
• Also known as IEEE 1284-compliant Centronics port.

Universal Serial Bus (or USB) Port

• Can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard, etc.
• Introduced in 1997.
• Most of the computers provide two USB ports as minimum.
• Data travels at 12 megabits per second.
• USB compliant devices can get power from a USB port.

VGA Port

• Connects monitor to a computer's video card.
• Has 15 holes.
• Similar to serial port connector but serial port connector has pins, it has holes.

Power Connector

• Three-pronged plug
• Connects to the computer's power cable that plugs into a power bar or wall socket.

Firewire Port

• Transfer large amounts of data at very fast speed.
• Connects camcorders and video equipments to the computer
• Data travels at 400 to 800 megabits per second.
• Invented by Apple
• Three variants: 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector and 9-Pin FireWire 800 connector

Modem

• Connects a PC's modem to the telephone network.

Ethernet Port

• Connects to a network and high speed Internet.
• Connects network cable to a computer.
• This port resides on an Ethernet Card.
• Data travels at 10 megabits to 1000 megabits per second depending upon the network bandwidth.

Game Port

• Connect a PC to a joystick.
• Now replaced by USB.

Digital Video Interface, DVI port

• Connects a Flat panel LCD monitor to the computer's high-end video graphic cards.
• Very popular among video card manufacturers.

Sockets

• Connect microphone, speakers to sound card of the computer

COMPUTER MOTHER BOARD

The motherboard serves as a single platform to connect all of the parts of a computer together. A motherboard connects CPU, memory, hard drives, optical drives, video card, sound card and other ports and expansion cards directly or via cables. It can be considered as the backbone of a computer.

Features

• Motherboard varies greatly in supporting various types of components.
• Normally, a motherboard supports a single type of CPU and few types of memories.
• Video Cards, Hard disks, Sound Cards have to be compatible with motherboard to function properly.
• Motherboards, cases and power supplies must be compatible to work properly together.

Popular Manufacturers

• Intel
• ASUS
• AOpen
• ABIT
• Biostar
• Gigabyte
• MSI

Description:

The motherboard is mounted inside the case and is securely attached via small screws through pre-drilled holes.
Motherboard contains ports to connect all of the internal components. It provides a single socket for CPU. For memory, normally one or more slots are available. Motherboards provide ports to attach floppy drive, hard drive and optical drives via ribbon cables. Motherboard carries fans and a special port designed for power supply.
There are peripheral card slots on front of the motherboard using which video cards, sound cards and other expansion cards can be connected to motherboard.
On left side, motherboard carries a number of ports. These ports connect monitor, printer, mouse, keyboard, speaker, network cables and all to the motherboard. Motherboards also provide USB ports, which allow compatible devices to be connected in plug-in/plug-out fashion. For example, pen drive, digital cameras, etc.

COMPUTER DATA AND INFORMATION

What is Data?

Data can be defined as a representation of facts, concepts or instructions in a formalized manner, which should be suitable for communication, interpretation or processing by human or electronic machine.
Data is represented with the help of characters like alphabets (A-Z, a-z), digits (0-9) or special characters(+,-,/,*,<,>,=, etc.).

What is Information?

Information is organised or classified data so that it has some meaningful values to the receiver.
Information is the processed data on which decisions and actions are based.
For the decision to be meaningful, the processed data must qualify the following characteristics:

• Timely - Information should be available when required.
• Accuracy - Information should be accurate.
• Completeness - Information should be complete.

Data Processing Cycle

Data processing is the re-structuring or re-ordering of data by people or machine to increase their usefulness & add values for particular purpose.
Data processing consists of basic steps input, processing and output. These three steps constitute the data processing cycle.

• Input - In this step, the input data are prepared in some convenient form for processing. The form will depend on the processing machine. For example, when electronic computers are used, the input data could be recorded on any one of several types of input mediums, such as magnetic disks, tapes and so on.
• Processing - In this step, input data are changed to produce data in a more useful form. For example, pay-checks may be calculated from the time cards or a summary of sales for the month may be calculated from the sales orders.
• Output -Here, the results of the proceeding processing step are collected. The particular form of the output data depends on the use of the data. For example, output data may be pay-checks for employees.

COMPUTER SOFTWARE

Software is a set of programs, which are designed to perform a well-defined function. A program is a sequence of instructions written to solve a particular problem.
There are two types of softwares:

• System Software
• Application Software

System Software

The system software is a collection of programs designed to operate, control and extend the processing capabilities of the computer itself. System software are generally prepared by computer manufacturers.
These softwares comprise of programs written in low level languages which interact with the hardware at a very basic level. System software serves as the interface between hardware and the end users.
Some examples of system software are Operating System, Compilers, Interpreter, Assemblers, etc.
Features of System Software are the following:

• Close to system.
• Fast in speed.
• Difficult to design.
• Difficult to understand.
• Less interactive.
• Smaller in size.
• Difficult to manipulate.
• Generally written in low-level language.

Application Software

Application softwares are the softwares that are designed to satisfy a particular need of a particular environment. All softwares prepared by us in the computer lab can come under the category of Application Software.
Application software may consist of a single program, such as a Microsoft's notepad for writing and editing simple text. It may also consist of a collection of programs, often called a software package, which work together to accomplish a task, such as a spreadsheet package.
Examples of Application softwares are the following:

• Payroll Software
• Student Record Software
• Inventory Management Software
• Income Tax Software
• Railways Reservation Software
• Microsoft Office Suite Software
• Microsoft Word
• Microsoft Excel
• Microsoft Powerpoint

Features of Application Software are the following:

• It is close to user.
• It is easy to design.
• More interactive.
• Slow in speed.
• Generally written in high-level language.
• Easy to understand.
• Easy to manipulate and use.
• Bigger in size and requires large storage space.

COMPUTER HARDWARE

Hardware represents the physical and tangible components of the computer, i.e., the components that can be seen and touched.
Examples of Hardware are following:

• Input devices -- keyboard, mouse, etc.
• Output devices -- printer, monitor, etc.
• Secondary storage devices -- Hard disk, CD, DVD, etc.
• Internal components -- CPU, motherboard, RAM, etc.

Relationship between Hardware and Software

• Mutually dependent. Both of them must work together to make computer produce a useful output.
• Software cannot be utilized without supporting hardware.
• Hardware without set of programs to operate upon cannot be utilized and is useless.
• To get a particular job done on the computer, relevant software should be loaded into the hardware.
• Hardware is a one time expense.
• Software development is very expensive and is a continuing expense.
• Different softwares can be loaded on a hardware to run different jobs.
• A software acts as an interface between the user and the hardware.
• If hardware is the 'heart' of a computer system, then software is its 'soul'. Both are complimentary to each other.

COMPUTER ROM

ROM stands for Read Only Memory. The memory from which we can only read but cannot write on it. This type of memory is non-volatile. The information is stored permanently in such memories during manufacture.
A ROM stores such instructions as are required to start computer when electricity is first turned on, this operation is referred to as bootstrap. ROM chip are not only used in the computer but also in other electronic items like washing machine and microwave oven.
Following are the various types of ROM:

MROM (Masked ROM)

The very first ROMs were hard-wired devices that contained a pre-programmed set of data or instructions. These kinds of ROMs are known as masked ROMs. It is inexpensive ROM.

PROM (Programmable Read only Memory)

PROM is read-only memory that can be modified only once by a user. The user buys a blank PROM and enters the desired contents using a PROM programmer. Inside the PROM chip, there are small fuses, which are burnt open during programming. It can be programmed only once and is not erasable.

EPROM (Erasable and Programmable Read Only Memory)

The EPROM can be erased by exposing it to ultra-violet light for a duration of up to 40 minutes. Usually, an EPROM eraser achieves this function. During programming, an electrical charge is trapped in an insulated gate region. The charge is retained for more than ten years because the charge has no leakage path. For erasing this charge, ultra-violet light is passed through a quartz crystal window (lid). This exposure to ultra-violet light dissipates the charge. During normal use the quartz lid is sealed with a sticker.

EEPROM (Electrically Erasable and Programmable Read Only Memory)

The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. Both erasing and programming take about 4 to 10 ms (milli second). In EEPROM, any location can be selectively erased and programmed. EEPROMs can be erased one byte at a time, rather than erasing the entire chip. Hence, the process of re-programming is flexible but slow.

Advantages of ROM

• Non-volatile in nature
• These can not be accidentally changed
• Cheaper than RAMs
• Easy to test
• More Reliable than RAMs
• These are static and do not require refreshing
• Its contents are always known and can be verified

COMPUTER RAM

A RAM constitutes the internal memory of the CPU for storing data, program and program result. It is read/write memory. It is called random access memory (RAM).
Since access time in RAM is independent of the address to the word that is, each storage location inside the memory is as easy to reach as other location & takes the same amount of time. We can reach into the memory at random & extremely fast but can also be quite expensive.
RAM is volatile, i.e., data stored in it is lost when we switch off the computer or if there is a power failure. Hence, a backup uninterruptible power system (UPS) is often used with computers. RAM is small, both in terms of its physical size and in the amount of data it can hold.
RAM is of two types:

• Static RAM (SRAM)
• Dynamic RAM (DRAM)

Static RAM (SRAM)

The word static indicates that the memory retains its contents as long as power remains applied. However, data is lost when the power gets down due to volatile nature. SRAM chips use a matrix of 6-transistors and no capacitors. Transistors do not require power to prevent leakage, so SRAM need not have to be refreshed on a regular basis.
Because of the extra space in the matrix, SRAM uses more chips than DRAM for the same amount of storage space, thus making the manufacturing costs higher.
Static RAM is used as cache memory needs to be very fast and small.
Characteristics of the Static RAM:

• It has long data lifetime
• There is no need to refresh
• Faster
• Used as cache memory
• Large size
• Expensive
• High power consumption
  
  
  
  
  

  Dynamic RAM (DRAM)

  DRAM, unlike SRAM, must be continually refreshed in order for it to maintain the data. This is done by placing the memory on a refresh circuit that rewrites the data several hundred times per second. DRAM is used for most system memory because it is cheap and small. All DRAMs are made up of memory cells. These cells are composed of one capacitor and one transistor.
  Characteristics of the Dynamic RAM:
  
• It has short data lifetime
• Need to refresh continuously
• Slower as compared to SRAM
• Used as RAM
• Lesser in size
• Less expensive
• Less power consumption

ROLE OF COMPUTER IN BUSINESS ORGANIZATIONS

Business

The computer's characteristic as high speed of calculation, diligence, accuracy, reliability, or versatility has made it an integrated part in all business organisations.
Computer is used in business organisation for:

• Payroll Calculations
• Budgeting
• Sales Analysis
• Financial forecasting
• Managing employees database
• Maintenance of stocks, etc.

Banking

Today Banking is almost totally dependent on computer.
Banks provide following facilities:

• Banks on-line accounting facility, which includes current balances, deposits, overdrafts, interest charges, shares and trustee records.
• ATM machines are making it even easier for customers to deal with banks.

Insurance

Insurance companies are keeping all records up-to-date with the help of computers. The Insurance Companies, Finance houses and Stock broking firms are widely using computers for their concerns.
Insurance Companies are maintaining a database of all clients with information showing:

• how to continue with policies
• starting date of the policies
• next due instalment of a policy
• maturity date
• interests due
• survival benefits
• bonus