Computer Awareness for Bank Exams

8/11/2019 Computer Awareness for Bank Exams

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www.BankExamsToday.com

Computer

AwarenessFor SBI, IBPS and other Govt exams

Ramandeep Singh

B.com (PU), MBA (PAU)


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What are computers?

Computers are machines that perform tasks or calculations according to a set of

instructions, or programs. The first fully electronic computers, introduced in the

1940s, were huge machines that required teams of people to operate. Compared to

those early machines, today's computers are amazing. Not only are they thousands

of times faster, they can fit on your desk, on your lap, or even in your pocket.

Computers work through an interaction of hardware and

software. Hardware refers to the parts of a computer that you can see and touch,

including the case and everything inside it. The most important piece of hardware

is a tiny rectangular chip inside your computer called the central processing unit

(CPU), or microprocessor. It's the "brain" of your computerthe part that

translates instructions and performs calculations. Hardware items such as your

monitor, keyboard, mouse, printer, and other components are often

called hardware devices, or devices.

Software refers to the instructions, or programs, that tell the hardware what to do.

A word-processing program that you can use to write letters on your computer is a

type of software. The operating system (OS) is software that manages your

computer and the devices connected to it. Windows is a well-known operating

system.

Types of computers

Computers range in size and capability. At one end of the scale are

supercomputers, very large computers with thousands of linked microprocessors

that perform extremely complex calculations. At the other end are tiny computers

embedded in cars, TVs, stereo systems, calculators, and appliances. These

computers are built to perform a limited number of tasks.


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The personal computer, or PC, is designed to be used by one person at a time.

This section describes the various kinds of personal computers: desktops, laptops,

handheld computers, and Tablet PCs.

Desktop computers

Desktop computers are designed for use at a desk or table. They are typically

larger and more powerful than other types of personal computers. Desktop

computers are made up of separate components. The main component, called

the system unit, is usually a rectangular case that sits on or underneath a desk.

Other components, such as the monitor, mouse, and keyboard, connect to the

system unit.

Desktop computer

Laptops and netbooks

Laptops are lightweight mobile PCs with a thin screen. Laptops can operate on

batteries, so you can take them anywhere. Unlike desktops, laptops combine the

CPU, screen, and keyboard in a single case. The screen folds down onto the

keyboard when not in use.


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Netbooks (also referred to as mini notebooks), are small, affordable laptops that

are designed to perform a limited number of tasks. They're usually less powerful

than laptops, so they're used mainly to browse the web and check e-mail.

A laptop and a netbook

Smartphones

Smartphones are mobile phones that have some of the same capabilities as acomputer. You can use a smartphone to make telephone calls, access the Internet,

organize contact information, send e-mail and text messages, play games, and

take pictures. Smartphones usually have a keyboard and a large screen.

Smartphone

Handheld computers

Handheld computers, also called personal digital assistants (PDAs), are

battery-powered computers small enough to carry almost anywhere. Although not


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as powerful as desktops or laptops, handheld computers are useful for scheduling

appointments, storing addresses and phone numbers, and playing games. Some

have more advanced capabilities, such as making telephone calls or accessing the

Internet. Instead of keyboards, handheld computers have touch screens that you

use with your finger or a stylus (a pen-shaped pointing tool).

Handheld computer

Tablet PCs

Tablet PCs are mobile PCs that combine features of laptops and handheld

computers. Like laptops, they're powerful and have a built-in screen. Like

handheld computers, they allow you to write notes or draw pictures on the screen,

usually with a tablet pen instead of a stylus. They can also convert your

handwriting into typed text. Some Tablet PCs are convertibles with a screen

that swivels and unfolds to reveal a keyboard underneath.

Tablet PC

What can you do with computers?

In the workplace, many people use computers to keep records, analyze data, do

research, and manage projects. At home, you can use computers to find


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information, store pictures and music, track finances, play games, and

communicate with othersand those are just a few of the possibilities.

You can also use your computer to connect to the Internet, a network that links

computers around the world. Internet access is available for a monthly fee in most

urban areas, and increasingly, in less populated areas. With Internet access, you

can communicate with people all over the world and find a vast amount of

information.

Here are some of the most popular things to do with computers:

The web

The World Wide Web (usually called the web, or web) is a gigantic storehouse

of information. The web is the most popular part of the Internet, partly because it

displays most information in a visually appealing format. Headlines, text, and

pictures can be combined on a single webpagemuch like a page in a

magazinealong with sounds and animation. A website is a collection of

interconnected webpages. The web contains millions of websites and billions ofwebpages.

Example of a

webpage (Microsoft Game Studios)


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Surfing the web means exploring it. You can find information on the web about

almost any topic imaginable. For example, you can read news stories and movie

reviews, check airline schedules, see street maps, get the weather forecast for your

city, or research a health condition. Most companies, agencies, museums, and

libraries have websites with information about their products, services, or

collections. Reference sources, such as dictionaries and encyclopedias, are also

widely available.

The web is also a shopper's delight. You can browse and purchase products

books, music, toys, clothing, electronics, and much moreat the websites of

major retailers. You can also buy and sell used items through websites that use

auction-style bidding.

E-mail

E-mail (short for electronic mail) is a convenient way to communicate with

others. When you send an e-mail message, it arrives almost instantly in the

recipient's e-mail inbox. You can send e-mail to many people simultaneously, and

you can save, print, and forward e-mail to others. You can send almost any type

of file in an e-mail message, including documents, pictures, and music files. And

with e-mail, you don't need a postage stamp!

Instant messaging

Instant messaging is like having a real-time conversation with another person or a

group of people. When you type and send an instant message, the message is

immediately visible to all participants. Unlike e-mail, all participants have to be

online (connected to the Internet) and in front of their computers at the same time.

Communicating by means of instant messaging is called chatting.

Pictures, music, and movies

If you have a digital camera, you can move your pictures from the camera to your

computer. Then you can print them, create slide shows, or share them with others


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by e-mail or by posting them on a website. You can also listen to music on your

computer, either by importing music from audio CDs or by purchasing songs

from a music website. Or, you can tune in to one of the thousands of radio stations

that broadcast over the Internet. If your computer comes with a DVD player, you

can watch movies too.

Gaming

Do you like to play games? Thousands of computer games in every conceivable

category are available to entertain you. Get behind the wheel of a car, battle

frightening creatures in a dungeon, or control civilizations and empires! Many

games allow you to compete with other players around the world through the

Internet.


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Computer Components

A computer can process data, pictures, sound and graphics. They can solve highly

complicated problems quickly and accurately.

A computer as shown in Fig. performs basically five major computer operations

or functions irrespective of their size and make. These are

1) It accepts data or instructions by way of input,

2) It stores data,

3) It can process data as required by the user,

4) It gives results in the form of output, and

5) It controls all operations inside a computer.

We discuss below each of these Computer operations

1. Input: This is the process of entering data and programs in to the computer

system. You should know that computer is an electronic machine like any other

machine which takes as inputs raw data and performs some processing giving out


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processed data. Therefore, the input unit takes data from us to the computer in an

organized manner for processing.

2. Storage: The process of saving data and instructions permanently is known as

storage. Data has to be fed into the system before the actual processing starts. It is

because the processing speed of Central Processing Unit (CPU) is so fast that the

data has to be provided to CPU with the same speed. Therefore the data is first

stored in the storage unit for faster access and processing. This storage unit or the

primary storage of the computer system is designed to do the above functionality.

It provides space for storing data and instructions.

The storage unit performs the following major functions:

All data and instructions are stored here before and after processing.

Intermediate results of processing are also stored here.

3. Processing: The task of performing operations like arithmetic and logical

operations is called processing. The Central Processing Unit (CPU) takes data and

instructions from the storage unit and makes all sorts of calculations based on the

instructions given and the type of data provided. It is then sent back to the storage

unit.

4. Output: This is the process of producing results from the data for getting

useful information. Similarly the output produced by the computer after

processing must also be kept somewhere inside the computer before being given

to you in human readable form. Again the output is also stored inside thecomputer for further processing.

5. Control: The manner how instructions are executed and the above operations

are performed. Controlling of all operations like input, processing and output are

performed by control unit. It takes care of step by step processing of all operations

inside the computer.

FUNCTIONAL UNITS


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In order to carry out the operations mentioned in the previous section the

computer allocates the task between its various functional units. The computer

system is divided into three separate units for its operation. They are

1) arithmetic logical unit

2) control unit.

3) central processing unit.

Arithmetic Logical Unit (ALU) Logical Unit

Logical Unit :After you enter data through the input device it is stored in the

primary storage unit. The actual processing of the data and instruction are

performed by Arithmetic Logical Unit. The major operations performed by the

ALU are addition, subtraction, multiplication, division, logic and comparison.

Data is transferred to ALU from storage unit when required. After processing the

output is returned back to storage unit for further processing or getting stored.

Control Unit (CU)

The next component of computer is the Control Unit, which acts like the

supervisor seeing that things are done in proper fashion. Control Unit is

responsible for co ordinating various operations using time signal. The control

unit determines the sequence in which computer programs and instructions are

executed. Things like processing of programs stored in the main memory,

interpretation of the instructions and issuing of signals for other units of the

computer to execute them. It also acts as a switch board operator when several

users access the computer simultaneously. Thereby it coordinates the activities of

computers peripheral equipment as they perform the input and output.

Central Processing Unit (CPU)

The ALU and the CU of a computer system are jointly known as the central

processing unit. You may call CPU as the brain of any computer system. It is just

like brain that takes all major decisions, makes all sorts of calculations and directs


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different parts of the computer functions by activating and controlling the

operations.

Each generation of computer is characterized by a major technological

development that fundamentally changed the way computers operate, resulting in

increasingly smaller, cheaper, more powerful and more efficient and reliable

devices.

The various generations of computers an listed below :

(i) First Generation (1946-1954) : In 1946 there was no 'best' way of storing

instructions and data in a computer memory. There were four competing

technologies for providing computer memory: electrostatic storage tubes, acoustic

delay lines (mercury or nickel), magnetic drums (and disks?), and magnetic

core storage.

The digital computes using electronic valves (Vacuum tubes) are known as first

generation computers. the first 'computer' to use electronic valves (ie. vacuum

tubes). The high cost of vacuum tubes prevented their use for main memory. They

stored information in the form of propagating sound waves.

The vacuum tube consumes a lot of power. The Vacuum tube was developed by

Lee DeForest in 1908. These computers were large in size and writing programs

on them was difficult. Some of the computers of this generation were:

Mark I : The IBM Automatic Sequence Controlled Calculator (ASCC), called

the Mark I by Harvard University, was an electro-mechanical computer. Mark

I is the first machine to successfully perform a long services ofarithmetic and

logical operation. Mark I is the First Generation Computer. it was the first

operating machine that could execute long computations automatically.Mark

Icomputer which was built as a partnership between Harvard and IBM in 1944.

This was the first programmable digital computer made in the U.S. But it was not

a purely electronic computer. Instead the Mark I was constructed out of switches,


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relays, rotating shafts, and clutches. The machine weighed 5 tons, incorporated

500 miles of wire, was 8 feet tall and 51 feet long, and had a 50 ft rotating shaft

running its length, turned by a 5 horsepower electric motor.

ENIAC: It was the first general-purpose electronic computer built

in 1946 at University of Pennsylvania, USA by John Mauchly and J. Presper

Eckert. The completed machine was announced to the public the evening

ofFebruary 14, 1946. It was namedElectronic Numerical Integrator and

Calculator (ENIAC). ENIAC contained 17,468 vacuum tubes, 7,200 crystal

diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million

hand-soldered joints. It weighed more than 30 short tons (27 t), was roughly 8 by

3 by 100 feet (2.4 m 0.9 m 30 m), took up 1800 square feet (167 m2), and

consumed 150 kW of power. Input was possible from an IBM card reader, and

an IBM card punch was used for output. These cards could be used to produce

printed output offline using an IBM accounting machine, such as the IBM 405.

Today your favorite computer is many times as powerful as ENIAC, still size is

very small.

EDVAC: It stands for Electronic Discrete Variable Automatic Computer and

was developed in 1950.it was to be a vast improvement upon ENIAC, it

was binary rather than decimal, and was a stored program computer. The

concept of storing data and instructions inside the computer was introduced

here. This allowed much faster operation since the computer had rapid access to

both data and instructions. The other advantage of storing instruction was thatcomputer could do logical decision internally.

The EDVAC was a binary serial computer with automatic addition, subtraction,

multiplication, programmed division and automatic checking with an ultrasonic

serial memory. EDVAC's addition time was 864 microseconds and

its multiplication time was 2900microseconds (2.9 milliseconds).


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The computer had almost 6,000 vacuum tubes and 12,000 diodes, and consumed

56 kW of power. It covered 490 ft (45.5 m) of floor space and weighed 17,300

lb (7,850 kg).

EDSAC: It stands for Electronic Delay Storage Automatic Computer and was

developed by M.V. Wilkes at Cambridge University in 1949. Two groups of

individuals were working at the same time to develop the first stored-program

computer. In the United States, at the University of Pennsylvania the EDVAC

(Electronic Discrete Variable Automatic Computer) was being worked on. In

England at Cambridge, the EDSAC (Electronic Delay Storage Automatic

Computer) was also being developed. The EDSAC won the race as thefirst stored-program computerbeating the United States EDVAC by two

months. The EDSAC performed computations in the three millisecond range. It

performed arithmetic and logical operations without human intervention. The key

to the success was in the stored instructions which it depended upon solely for

its operation. This machine marked the beginning of the computer

age. EDSAC is the first computer is used to store a program

UNIVAC-1: Ecker and Mauchly produced it in 1951 by Universal

Accounting Computer setup. it was the first commercial computer produced in

the United States. It was designed principally by J. Presper Eckert and John

Mauchly, the inventors of the ENIAC.

The machine was 25 feet by 50 feet in length, contained 5,600 tubes, 18,000

crystal diodes, and 300 relays. It utilized serial circuitry, 2.25 MHz bit rate, and

had an internal storage capacity 1,000 words or 12,000 characters.

It utilized a Mercury delay line, magnetic tape, and typewriter output. The

UNIVAC was used for general purpose computing with large amounts of input

and output.

Power consumption was about 120 kva. Its reported processing speed was 0.525

milliseconds for arithmetic functions, 2.15 milliseconds for multiplication and 3.9

Milliseconds for division.


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The UNIVAC was also the first computer to come equipped with a magnetic tape

unit and was the first computer to use buffer memory.

Other Important Computers of First Generation

Some other computers of this time worth mentioning are the Whirlwind,

developed at Massachussets Institute of Technology, and JOHNNIAC, by the

Rand Corporation. The Whirlwind was the first computer to display real time

video and use core memory. The JOHNNIAC was named in honor of Jon Von

Neumann. Computers at this time were usually kept in special locations like

government and university research labs or military compounds.

Limitations of First Generation Computer

Followings are the major drawbacks of First generation computers.

1. They used valves or vacuum tubes as their main electronic component.

2. They were large in size, slow in processing and had less storage capacity.

3. They consumed lots of electricity and produced lots of heat.

4. Their computing capabilities were limited.

5. They were not so accurate and reliable.

6. They used machine level language for programming.

7. They were very expensive.

Example: ENIAC, UNIVAC, IBM 650 etc

(ii) Second Generation (1955-1964) : The second-generation computer

used transistors for CPU components & ferrite cores for main

memory & magnetic disks for secondary memory. They used high-level

languages such as FORTRAN (1956), ALGOL (1960) & COBOL (1960 -

1961). I/O processor was included to control I/O operations.

Around 1955 a device calledTransistor replaced the bulky Vacuum tubes in the

first generation computer. Transistors are smaller than Vacuum tubes and have


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higher operating speed. They have no filament and require no heating.

Manufacturing cost was also very low. Thus the size of the computer got reduced

considerably.

It is in the second generation that the concept of Central Processing Unit (CPU),

memory, programming language and input and output units were developed. The

programming languages such as COBOL, FORTRAN were developed during this

period. Some of the computers of the Second Generation

were

1. IBM 1620: Its size was smaller as compared to First Generation computers and

mostly used for scientific purpose.

2. IBM 1401: Its size was small to medium and used for business applications.

3. CDC 3600: Its size was large and is used for scientific purposes.

Features:

1. Transistors were used instead of Vacuum Tube.

2. Processing speed is faster than First Generation Computers (Micro Second)

3. Smaller in Size (51 square feet)

4. The input and output devices were faster.

Example: IBM 1400 and 7000 Series, Control Data 3600 etc.

(iii) Third Generation (1964-1977) : By the development of a small chip

consisting of the capacity of the 300 transistors. These ICs are popularly known

asChips. A single IC has many transistors, registers and capacitors built on a

single thin slice ofsilicon. So it is quite obvious that the size of the computer got

further reduced. Some of the computers developed during this period were IBM-

360, ICL-1900, IBM-370, and VAX-750. Higher level language such as BASIC

(Beginners All purpose Symbolic Instruction Code) was developed during this

period. Computers of this generation were small in size, low cost, large memory

and processing speed is very high. Very soon ICs Were replaced by LSI (Large


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Scale Integration), which consisted about 100 components. An IC containing

about 100 components is called LSI.

Features:

1. They used Integrated Circuit (IC) chips in place of the transistors.

2. Semi conductor memory devices were used.

3. The size was greatly reduced, the speed of processing was high, they were

more accurate and reliable.

4. Large Scale Integration (LSI) and Very Large Scale Integration (VLSI) were

also developed.

5. The mini computers were introduced in this generation.

6. They used high level language for programming.

Example: IBM 360, IBM 370 etc.

(iv) Fourth Generation : An IC containing about 100 components is called

LSI (Large Scale Integration) and the one, which has more than 1000 such

components, is called as VLSI (Very Large Scale Integration). It uses large

scale Integrated Circuits (LSIC) built on a single silicon chip called

microprocessors. Due to the development of microprocessor it is possible to place

computers central processing unit(CPU) on single chip. These computers are

called microcomputers. Later very large scale Integrated Circuits (VLSIC)

replaced LSICs. Thus the computer which was occupying a very large room in

earlier days can now be placed on a table. The personal computer (PC) that you

see in your school is a Fourth Generation Computer Main memory used fast

semiconductors chips up to 4 M bits size. Hard disks were used as secondary

memory. Keyboards, dot matrix printers etc. were developed. OS-such as MS-

DOS, UNIX, Apples Macintosh were available. Object oriented language, C++

etc were developed.

Features:

1. They used Microprocessor (VLSI) as their main switching element.


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2. They are also called as micro computers or personal computers.

3. Their size varies from desktop to laptop or palmtop.

4. They have very high speed of processing; they are 100% accurate, reliable,

diligent and versatile.

5. They have very large storage capacity.

Example: IBM PC, Apple-Macintosh etc.

(v) Fifth Generation (1991- continued) : 5th generation computers use ULSI

(Ultra-Large Scale Integration) chips. Millions of transistors are placed in a single

IC in ULSI chips. 64 bit microprocessors have been developed during this period.

Data flow & EPIC architecture of these processors have been developed. RISC &

CISC, both types of designs are used in modern processors. Memory chips and

flash memory up to 1 GB, hard disks up to 600 GB & optical disks up to 50 GB

have been developed. fifth generation digital computer will be Artificial

intelligence.


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Parts of a Computer

If you use a desktop computer, you might already know that there isn't any singlepart called the "computer." A computer is really a system of many parts working

together. The physical parts, which you can see and touch, are collectively called

hardware. (Software, on the other hand, refers to the instructions, or programs,

that tell the hardware what to do.)

The following illustration shows the most common hardware in a desktop

computer system. Your system might look a little different, but it probably has

most of these parts. A laptop computer has similar parts but combines them into a

single, notebook-sized package.

Desktop

computer system

Let's take a look at each of these parts.

System unit


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The system unit is the core of a computer system. Usually it's a rectangular box

placed on or underneath your desk. Inside this box are many electronic

components that process information. The most important of these components is

the central processing unit (CPU), or microprocessor, which acts as the "brain"

of your computer. Another component is random access memory (RAM), which

temporarily stores information that the CPU uses while the computer is on. The

information stored in RAM is erased when the computer is turned off.

Almost every other part of your computer connects to the system unit using

cables. The cables plug into specific ports(openings), typically on the back of the

system unit. Hardware that is not part of the system unit is sometimes called a

peripheral device or device.

System unit

Storage

Your computer has one or more disk drivesdevices that store information on a

metal or plastic disk. The disk preserves the information even when your

computer is turned off.

Hard disk drive


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Your computer's hard disk drive stores information on a hard diska rigid

platter or stack of platters with a magnetic surface. Because hard disks can hold

massive amounts of information, they usually serve as your computer's primary

means of storage, holding almost all of your programs and files. The hard disk

drive is normally located inside the system unit.

Hard disk drive

CD and DVD drives

Nearly all computers today come equipped with a CD or DVD drive, usually

located on the front of the system unit. CD drives use lasers to read (retrieve) data

from a CD; many CD drives can also write (record) data onto CDs. If you have a

recordable disk drive, you can store copies of your files on blank CDs. You can

also use a CD drive to play music CDs on your computer.

CD


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DVD drives can do everything that CD drives can, plus read DVDs. If you have a

DVD drive, you can watch movies on your computer. Many DVD drives can

record data onto blank DVDs.

Tip

If you have a recordable CD or DVD drive, periodically back up (copy)

your important files to CDs or DVDs. That way, if your hard disk ever

fails, you won't lose your data.

Floppy disk drive

Floppy disk drives store information on floppy disks, also

called floppies or diskettes. Compared to CDs and DVDs, floppy disks can store

only a small amount of data. They also retrieve information more slowly and are

more prone to damage. For these reasons, floppy disk drives are less popular than

they used to be, although some computers still include them.

Floppy disk

Why are these disks called "floppy" disks? The outside is made of hard plastic,

but that's just the sleeve. The disk inside is made of a thin, flexible vinyl material.

Mouse

A mouse is a small device used to point to and select items on your computer

screen. Although mice come in many shapes, the typical mouse does look a bit

like an actual mouse. It's small, oblong, and connected to the system unit by a

long wire that resembles a tail. Some newer mice are wireless.


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Mouse

A mouse usually has two buttons: A primary button (usually the left button) and a

secondary button. Many mice also have a wheel between the two buttons, which

allows you to scroll smoothly through screens of information.

Mouse pointers

When you move the mouse with your hand, a pointer on your screen moves in the

same direction. (The pointer's appearance might change depending on where it's

positioned on your screen.) When you want to select an item, you point to the

item and then click (press and release) the primary button. Pointing and clicking

with your mouse is the main way to interact with your computer. For more

information, see

Keyboard

A keyboard is used mainly for typing text into your computer. Like the keyboard

on a typewriter, it has keys for letters and numbers, but it also has special keys:

The function keys, found on the top row, perform different functions

depending on where they are used.

The numeric keypad, located on the right side of most keyboards, allows

you to enter numbers quickly.

The navigation keys, such as the arrow keys, allow you to move your

position within a document or webpage.


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Keyboard

You can also use your keyboard to perform many of the same tasks you can

perform with a mouse.

Monitor

A monitor displays information in visual form, using text and graphics. The

portion of the monitor that displays the information is called the screen. Like a

television screen, a computer screen can show still or moving pictures.

There are two basic types of monitors: CRT (cathode ray tube) monitors and thenewer LCD (liquid crystal display) monitors. Both types produce sharp images,

but LCD monitors have the advantage of being much thinner and lighter.

LCD monitor (left);

CRT monitor (right)

Printer


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A printer transfers data from a computer onto paper. You don't need a printer to

use your computer, but having one allows you to print e-mail, cards, invitations,

announcements, and other material. Many people also like being able to print their

own photos at home.

The two main types of printers are inkjet printers and laser printers. Inkjet

printers are the most popular printers for the home. They can print in black and

white or in full color and can produce high-quality photographs when used with

special paper. Laser printers are faster and generally better able to handle heavy

use.

Inkjet printer

(left); laser printer (right)

Speakers

Speakers are used to play sound. They can be built into the system unit or

connected with cables. Speakers allow you to listen to music and hear sound

effects from your computer.


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Computer speakers

Modem

To connect your computer to the Internet, you need a modem. A modem is adevice that sends and receives computer information over a telephone line or

high-speed cable. Modems are sometimes built into the system unit, but higher-

speed modems are usually separate components.

Cable modem

The Motherboard

The motherboard is the main circuit board of a computer. It contains the central

processing unit (CPU), the Basic Input/Output System (BIOS), memory, mass

storage interfaces, serial and parallel ports, expansion slots, and all the controllers

for standard peripheral devices like the keyboard, disk drive and display screen.

The chipset and other motherboard circuitry are the "smarts" of the motherboard.

Their job is to direct traffic and control the flow of information inside the

computer.


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ROM: Read Only Memory

ROM is nonvolatile. ROM chips contain permanently written data, called

firmware (your BIOS lives here).

ROM contains the programs that direct the computer to load the operating

system and related files when the computer is powered on.

ROM chips are usually recorded when they are manufactured.

PROM -Programmable Read Only memory chip cannot be changed to update or

revise the program inside

EPROM Erasable Programmable Read Only memory Data can be erased and

chip can be reused Can be erased by shining high intensity UV light through the

window

EEPROM Electrical Erasable Programmable Read Only memory under high

voltage

FROM -Flash ROM is reprogrammable memory using normal voltage inside the

PC- You can upgrade the logic capabilities by simply downloading new software.

This saves the expense of replacing circuit boards and chips.

Processing Devices


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Cache

Pronounced cash.

It is a small, high-speed memory area that is placed between the processor and the

system memory.

The value of the cache is that it is much faster than normal system memory.

The most frequently used instructions are kept in cache memory so that the CPU

can look in there first - allows the CPU to run faster because it doesn't have to

take time to swap instructions in and out of main memory.


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Large, complex programs such as complex spreadsheets or database management

programs benefit the most from having a cache memory available. Pentium II

processors generally come with at least 512 KB of cache memory.

Random Access Memory (RAM)

RAM is Primary Storage, also called internal storage.

Serves as computers workspace, storing all or part of the program that is

being executed, as well as data being used by the program.

RAM provides instructions and data to the CPU.

These instructions/data are coded in bytes.

Each byte is placed in a precise location in memory, called an address.

To access data or instructions in memory, the computer references the

addresses containing the bytes.

The amount of memory available is therefore measured in bytes

RAM chips consist of millions of switches that are sensitive to changes in

electric current.

RAM chips are typically packaged on small circuit boards called memory

modules, which are inserted into special slots on the motherboard.

RAM is Volatile storage: Power goes, data goes!


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Data/instructions are copied into memory as needed.

Not enough memory or corruption of data/instructions in memory can

cause crash.

On booting, operating system files are loaded from a storage device (the

hard disk, usually) into RAM, and they remain there as long as your

computer is running.

RAM contents changes as programs are executed.

RAM chips consist of millions of switches that are sensitive to changes inelectric current.

RAM chips are typically packaged on small circuit boards called memory

modules, which are inserted into special slots on the motherboard.

On booting, operating system files are loaded from a storage device (the

hard disk, usually) into RAM, and they remain there as long as your

computer is running.

RAM contents changes as programs are executed.

The amount of RAM needed depends on the types of applications you

intend to run on the computer. S/w indicate the minimum amount of RAM

required to run.

Two basic types of RAM are Dynamic RAM (DRAM), and Static RAM (SRAM).

Most computers today use DRAM, which are also of two types:

SDRAM Synchronous Dynamic RAM runs at the same pace as the system

clock runs

DDR SDRAM DDR stands for Double Data Rate - runs at double the pace

the system clock runs - available in speeds from 266 MHZ upto 600MHZ


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DDR2 SDRAM runs at four times the pace the system clock runs -

available in speeds from 400 MHZ upto 800MHZ

Most desktops and notebooks use one of the three most popular types of

synchronous dynamic random access memory (SDRAM) for the main system

memory. Single data rate (SDR) SDRAM is the older type of memory, commonly

used in computers prior to 2002. Double data rate (DDR) SDRAM hit the

mainstream computer market around 2002, and DDR2-based systems hit the

market in mid-2004.

DDR SDRAM is a straightforward evolution from SDR SDRAM. The big

difference between DDR SDRAM and SDR SDRAM is that DDR reads data on

both the rising and falling edges of the clock signal, so the DDR module can

transfer data twice as fast as SDR SDRAM.

While DDR has a limited clock rate, the evolutionary changes to DDR

architecture enable DDR2 to achieve speeds beyond of DDR, delivering

bandwidth of 5.3 GB per second and beyond! Because DDR2 is able to operate

with faster bus speeds, your memory doesn't hold back the performance of your

processor.

Generally speaking, motherboards are built to support only one type of memory.

You cannot mix and match SDRAM, DDR, or DDR2 memory on the same

motherboard in any system. They will not function and will not even fit in the

same.

Why is RAM so important?

Aside from the processor, the two most important factors affecting a PC's

performance are RAM and hard disk capacity.

Hard disks are typically huge, so the primary limiting factor is the amount of

installed RAM.


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Without enough RAM, the operating system must swap out storage space with the

hard disk. The OS creates a Paging File (swap file) to supplement RAM

(workspace). This is Virtual Memory.

Virtual memory is inherently slow! RAM speed can typically be 120,000 times

FASTER than the hard disk so the less you must rely on virtual memory

(swapping files between RAM and hard disk), the faster your system will

perform.

Microprocessor

Heart and brain of the PC

One electrical circuit in control of another

Successive generation of processors

80286,80386,80486 -32 bit interface

Pentium family P1, P2, P3, P4 64 bit interface

Dual-core technology is like having two processors - A dual core

processor is a CPU with two separate cores residing on the same chip


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DBMS - Overview

Database is collection of data which is related by some aspect. Data is collection

of facts and figures which can be processed to produce information. Name of a

student, age, class and her subjects can be counted as data for recording purposes.

Mostly data represents recordable facts. Data aids in producing information which

is based on facts. For example, if we have data about marks obtained by all

students, we can then conclude about toppers and average marks etc.

A database management system stores data, in such a way which is easier to

retrieve, manipulate and helps to produce information.

Characteristics

Traditionally data was organized in file formats. DBMS was all new concepts

then and all the research was done to make it to overcome all the deficiencies in

traditional style of data management. Modern DBMS has the following

characteristics:

Real-world entity: Modern DBMS are more realistic and uses real world

entities to design its architecture. It uses the behavior and attributes too.

For example, a school database may use student as entity and their age as

their attribute.

Relation-based tables: DBMS allows entities and relations among them

to form as tables. This eases the concept of data saving. A user can

understand the architecture of database just by looking at table names etc.

Isolation of data and application: A database system is entirely different

than its data. Where database is said to active entity, data is said to be

passive one on which the database works and organizes. DBMS also stores

metadata which is data about data, to ease its own process.


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Less redundancy: DBMS follows rules of normalization, which splits a

relation when any of its attributes is having redundancy in values.

Following normalization, which itself is a mathematically rich and

scientific process, make the entire database to contain as less redundancy

as possible.

Consistency: DBMS always enjoy the state on consistency where the

previous form of data storing applications like file processing does not

guarantee this. Consistency is a state where every relation in database

remains consistent. There exist methods and techniques, which can detect

attempt of leaving database in inconsistent state.

Query Language: DBMS is equipped with query language, which makes

it more efficient to retrieve and manipulate data. A user can apply as many

and different filtering options, as he or she wants. Traditionally it was not

possible where file-processing system was used.

ACID Properties: DBMS follows the concepts for ACID properties,

which stands for Atomicity, Consistency, Isolation and Durability. These

concepts are applied on transactions, which manipulate data in database.

ACID properties maintains database in healthy state in multi-transactional

environment and in case of failure.

Multiuser and Concurrent Access: DBMS support multi-user

environment and allows them to access and manipulate data in parallel.

Though there are restrictions on transactions when they attempt to handlesame data item, but users are always unaware of them.

Multiple views: DBMS offers multiples views for different users. A user

who is in sales department will have a different view of database than a

person working in production department. This enables user to have a

concentrate view of database according to their requirements.


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Security: Features like multiple views offers security at some extent

where users are unable to access data of other users and departments.

DBMS offers methods to impose constraints while entering data into

database and retrieving data at later stage. DBMS offers many different

levels of security features, which enables multiple users to have different

view with different features. For example, a user in sales department

cannot see data of purchase department is one thing, additionally how

much data of sales department he can see, can also be managed. Because

DBMS is not saved on disk as traditional file system it is very hard for a

thief to break the code.

Users

DBMS is used by various users for various purposes. Some may involve in

retrieving data and some may involve in backing it up. Some of them are

described as follows:

[Image: DBMS Users]

Administrators: A bunch of users maintain the DBMS and are

responsible for administrating the database. They are responsible to look

after its usage and by whom it should be used. They create users access

and apply limitation to maintain isolation and force security.

Administrators also look after DBMS resources like system license,


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software application and tools required and other hardware related

maintenance.

Designer: This is the group of people who actually works on designing

part of database. The actual database is started with requirement analysis

followed by a good designing process. They people keep a close watch on

what data should be kept and in what format. They identify and design the

whole set of entities, relations, constraints and views.

End Users: This group contains the persons who actually take advantage

of database system. End users can be just viewers who pay attention to the

logs or market rates or end users can be as sophisticated as business

analysts who takes the most of it.

DBMS - Architecture

The design of a Database Management System highly depends on its architecture.

It can be centralized or decentralized or hierarchical. DBMS architecture can be

seen as single tier or multi tier. n-tier architecture divides the whole system intorelated but independent n modules, which can be independently modified, altered,

changed or replaced.

In 1-tier architecture, DBMS is the only entity where user directly sits on DBMS

and uses it. Any changes done here will directly be done on DBMS itself. It does

not provide handy tools for end users and preferably database designer and

programmers use single tier architecture.

If the architecture of DBMS is 2-tier then must have some application, which uses

the DBMS. Programmers use 2-tier architecture where they access DBMS by

means of application. Here application tier is entirely independent of database in

term of operation, design and programming.

3-tier architecture


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Most widely used architecture is 3-tier architecture. 3-tier architecture separates it

tier from each other on basis of users. It is described as follows:

[Image: 3-tier DBMS architecture]

Database (Data) Tier: At this tier, only database resides. Database alongwith its query processing languages sits in layer-3 of 3-tier architecture. It

also contains all relations and their constraints.

Application (Middle) Tier: At this tier the application server and

program, which access database, resides. For a user this application tier

works as abstracted view of database. Users are unaware of any existence

of database beyond application. For database-tier, application tier is the


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user of it. Database tier is not aware of any other user beyond application

tier. This tier works as mediator between the two.

User (Presentation) Tier: An end user sits on this tier. From a users

aspect this tier is everything. He/she doesn't know about any existence or

form of database beyond this layer. At this layer multiple views of

database can be provided by the application. All views are generated by

applications, which resides in application tier.

Multiple tier database architecture is highly modifiable as almost all its

components are independent and can be changed independently.

Computer Awareness for Bank Exams

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