Fundamental note New

Computer Fundamental
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Introduction of Computer:
The term of computer word from the Greek word “COMPUTE” which means to calculate.
The term of computer word stands for Common Oriented Machine Popular Used for Trade
Education Research. Actually, computer is an electronic machine which accepts the Input data,
stores a large amount of data in a small place and does the Arithmetical and Logical operations
rapidly and gives the data (Output) in a desired format. In the year 1822 Charles Babbage a
mathematician of Cambridge University developed a new machine known as COMPUTER.So he was
regarded as father of computer.
Now a day’s computers are highly used in various sectors because to save time, Quick
performance, Avoid mistakes and stores data in a small place for longer period.
A computer has basically four components that are keyboard, Mouse, C.P.U., and Monitor.
By those four components are Input Unit, Process Unit and Output Unit. Key Board and Mouse come
under Input Unit. By using two components a user can give any type of data to the computer. Then
comes C.P.U. (Central Processing Unit) it means by using this C.P.U. a computer does all type of
operation likeArithmetic, Logicand control operation and gives the output. Then come Output Unit.
Under this category basically Monitor and Printer is used. By using these two components a
computer displays the output data. So above allthere are four Units make a computer as acomplete
machine.
The activity of processing data using a computer is called data processing. Data processing
consists of three sub activities: capturing input data, manipulating the data and managing the
output results. Data is raw material used as input the data processing and information is the
processed data obtained as the output of data processing.
Parts of a computer system:
A computer is an electronic device that processes data, converting it into information that
is useful to people. A computer systemconsists of four parts hardware, software, one or more user
and data.
Users:
People are the computer operators also known as users.
Data:
Any type of instruction, information or command used by the user is known as data. The
data become various in types like alphabetic data, logical data, and arithmetic data, when a user
uses any type of data in a computer it must be a series of logical steps. Then the computer
understands and does the operation required by the user. A file that the user can open and use is
often called a document.
Needof Computer:
Now a computer is highly used in various sector because to save the time, to avoid mistake,
quickly performance, store data easily in a small place and for better performance.
Feature of Computer:
In this day’s computer is essential part of the life. Now a day’s computers have 8 mini
characteristics. This changes the life style due to the following fracture.
 Speed
 Accuracy
 Memory
 Automation
 Versatility
 Diligence
 No IQ like slave
 No fillings
Speed:

A computer is very fast devices. It can process instruction in fraction. So performance of
computer depends upon in speed. In a few second a computer Can perform the task that a human
being can ‘t does in a year or more. The speed of the computer is divided in 4categories that is as
follow.
1 millisecond =1/1000 sec =10-3
1Micro second =1/106sec =10-6
1Nino second =1/109sec =10-9
1Pico second =1/1012sec =10-12.
Accuracy:
It is a most accurate machine in this world. The accuracy of computer is constantly high it
depends upon the data given by the user. If a user inputs the data accurately as per required.
Memory:
A computer can remember what even we tell it to store. Every piece of data may be store in
a computer memory, as long we desired it. It has large memory power. And the memory of
computer can define as fallows: -
1 or 0 =1 bit
8 bits = 1 Byte
4 Bits = 1 Nibble
1024 Byte =1 kilo Byte
1024 K.B = 1 Mega Byte
1024 M.B = 1 Gaga Byte
1024 G.B = 1 Tara Byte
Automation:
Thought the data a computer can perform all types of task in a few second. Once you input
data computer dose all types of operation automatically to give the output data. It does not require
any types and human help during the operation.
Versatility:
Computer can perform any types of task in every few second. And also it is a multi-tasking
machine. We can do two or three types of works in a single time. But it always needs a prepare data
or the data must be a series of logical steps to perform. So versatility is one most wonderful
character sticks of computer.
Diligence:
Human being generally gets tired after a couple of hours of work, and makes the mistakes.
But computers simply don’t get bored and can perform the same operation repeatedly over any
long of time. Move over the computer will take the since to do the first calculation as the thousand
calculation.
No feeling:
A computer has no felling because it has no life. It is only a machine. We the human being
can choose what is bad of or what is good. But computer never do things this way. When a user
gives wrong data, it takes and when input accurate data if it receives. He never thought what is
perfect or not. So, it has no feeling.
No IQ:
A computer is a magical device but it’ IQ is zero. A computer cannot take its own decision
in this day. It works like a slave. Once you order some things it performs. Otherwise it can’t these
are the character sticks of a computer.

Evolution or History of computer:
Necessity is mother of invention so human beings invent computer. At fast computer were
invented because of human being’s search for fast time accurate calculating device.
History of computer is divided into three type that as fallows
Dark Age (before 1500 AD)
Middle Age (1500-1900 AD)
Modern Age (1900 onwards)
Dark Age:
IN this age human beings are living in jungles. They don’t know any things after few years
they do exchange product to purchase and thing. So that ere is known as Dark Ageof human society.
Roman number system was introduced in this age. In this age ABACUS (Abundant beads addition
and Calculation Utility System) was introduce.
Middle Age:
In this generation, lots of things have been developed. A new year has been come through
in this century. In the year 1617 john Napier discovered logarithms. In 1642 Blaise Pascal designs a
first mechanical calculating (adding) machine called Pascaline for addition and substation. In the
year 1671 Baron Gottfried Wilhelm Von Leventiz of Germany developed first calculator machine
to multiplied and divide.
In the year 1822 a leady mathematician known as leady Ada Lovelace of Cambridge
University developed a program to build a machine. In the same year by adapting that program a
mathematician of same University known as Charles Babbage(Father of modern digitalcomputers)
build a machine known as “Deferential machine”. In 1842, Babbage came out with new idea of
Analytical Engine which was intended to be completely automatic.
Modern Age:
Later in the year 1933 again he designed a machine called Analytic Machine known as
complete computer. So, he was regarded father of computer.
Mark-1 computer:
The Mark-1computer was the fastfullyautomatic calculating machine designedby Howard
A. Aiken of Harvard University, in collaboration with IBM (International Business Machines)
Corporation in 1937-44. It was an electro mechanical device, since both mechanical and electronic
components were used in its design.
Atansoff-Berry Computer:
The Atansoff-Berry Computer is an electronic device. It was developed by Dr. John Atansoff
to solve certain mathematical educations in 1939-42. It used 45 vacuum tubes for internal logic and
capacitors for storages.
ENIAC:
In 1943-46 ENIAC (Electronic Numerical Integrator and Calculator) developed computers
which have 18000 vacuum tubes, 70000 resisters, 10000 capacities, 6000switch  took 30 tones 
consumed 15000 square foot  130 Kilo watt current. It was the first all electronic computer. It
was constructed at the Moore School of Engineering of the University of Pennsylvania. It was
design by Professors J. Presper Eckert and John Mauchly.
EDVAC:
The EDVAC (Electronic Discrete VariableAutomatic Computer) was developed in 1946-52 by
John von Neumann. The basic idea behind this concept is that a sequence of instructions, as well
as data, can be stored in the memory of the computer for automatically directing the flow of
operations. It was designed on stored program concept.

EDSAC:
The EDSAC (Electronic Delay Storage Automatic Calculator) was developed in 1047-49 by a
group of scientists, headed by Professor Maurice Wilkes, at the Cambridge University
Mathematical Laboratory.
UNIVAC:
The UNIVAC (Universal Automatic Computer) was introduced in 1951 and was used for 10
years. It was the first digital computer which was not “one of a kind”. In 1952, the International
Business Machine (IBM) Corporation introduced the 701 commercial computers. In 1953, IBM
produced the IBM-650.
Generation of Computer:
“Generation” in computer talks is a step-in technology. It provides a framework for the
growth of the computer industry. Today there are several millions of computers in use. The
evolution of computer has been rapid developments in electronic technology by this reason the
generation of computer has been classified in to six types. That is as fallows.
1st Generation (1942-1955):
In this generation thousands vacuum tubes are used and they were too bulky in size,
requiring large spacefor installation. A vacuum tube was afragileglass device,which used filaments
as a source of electronics and control & amplify electronic signal. Vacuum device was only high
speed electronic switching device. In these computer thousands of individual components had to
assemble manually by hand into functioning circuits. So computer is difficult to programming. In
this generation machine label language (Binary code) was used.
Ex: - ENIAC, EDVAC, EDSAC, UNIVAC, IBM 701
Advantages:
 Vacuum tubes were the only electronic component.
 These computers were the fastest calculating device of their time.
Disadvantages:
 They were too bulky in size.
 It was unreliable.
 They were produces large amount of heat.
 Frequently computer hardware was failure in this generation.
 It requires constant maintenance and Air condition.
 It was non-portable
2nd Generation (1955-1964)
2nd generation computer used transistors in place of vacuum tubes. Transistor is an
electronic switching device, was invented at Bell Laboratories in 1947 by John Bardeen, Willian
Shockley and Water Brattain. It consumed almost one-tenth the power consumed by a tube
Ex: -1BM1400
Advantages:
 It was fastening then 1st generation.
 It was small in size and more reliable.
 It consumed much less power than 1st generation computers.
 It easier to program and use than the first-generation computers.
 They were produces less amount of heat.
Disadvantages:

 It requires maintenance and air conditioning room.
3rd generation: (1964-1975)
3rd generation computer used Integrated Circuit chip(IC). So they are much more powerful
then 2nd generation. It was small in size and less power required. They used storage devices like
magnetic tapes, discs. Integrated Circuit was invented by Jack St. Clair Kilby and Robert Noyce in
1985. This circuit consists of several electronic components like transistor, resisters and capacitors
grown on a single chip of silicon. IC is known as Microelectronics because it contains large number
of circuits in smallsurface of silicon.Initially the IC contained only about ten to twenty components.
This technology was named as Small Scale Integration. Later IC chips became possible to integrate
up to about hundred components on a single chip. This technology was named as Medium Scale
Integration. Also high label language like FORTRAN & COBOL ware used in the 3rd generation.
FORTRAN and COBOL were standardized by the American National Standards Institute (ANSI) in
1966 and 1968 respectively. FORTRAN stands for Formula Translation and COBOL stands for
Common Business Oriented Language.
In this generation, John Kemeny and Thomas Kurtz of Dartmouth College introduced the
concept of Timesharing Operation System. Timesharing Operating System allows a large number
of users to directly access and shares the computing resources in a manner.
The development and introduction of minicomputers took place during 3rd generation
period. The first commercially available minicomputer, PDP-8 (programmed Data Processor) was
introduced in 1965 by DigitalEquipment Corporation (DEC).It could easilyfitin the corner of a room
and did not require the attention of a full time computer operator.
Ex:-IBM360
Advantages:
 They are much more powerful then 2nd generation.
 It was small in size and less power required.
 Even lower heat generated than 2nd generation computer.
 They were more reliable and less prone to hardware failures than 2nd generation
computer.
Disadvantages:
 It requires air conditioning room in many cases.
4th generation (1965-1990):
4th generation machines are used silicon chips. This chip was possible to integrate over
30000 electronic components on a single chip. This technology was named as Large Scale
Integration (LSI). After, this chip was possible to integrate about one million electronic components
on a single chip. This technology was named as Very Large Scale Integration (VLSI). In this
generation, development the electronic chip is known as microprocessor which used for creation
of a microprocessor. A microprocessor contains all the circuits needed to perform arithmetic logic
and control functions on a single chip.
Another significant development during the 4th generation period is known as networking.
It was high speed computer networking, which enabled multiple computers to be connected
together, to enable them to communicate and share data. Local Area Network became popular for
connecting several dozen or hundred computers within organization. Wide area Network became
popular for connecting computers located at larger distance. In this generation, Graphical User
Interface (GUI) was developed. GUI was providing icons and menus, which users can select with a
mouse. During 4th generation period, the UNIX operating system and ‘C’ programming language
became very popular. Operating system was introduced to provide multiprogramming system.
Advantages:

 It doesn’t require air condition in must case.
 Hardware failure is negligible and hence minimal maintenance is required.
 Heat generated is negligible in these generations.
 They consumed much less power than the 3rd generation computer.
Disadvantages:
 It requires highly sophisticated technology.
5th generation (1989-2005):
The 5th generation computer is states with Pentium and used microchip technology. The VLSI
technology became ULSI (Ultra Large Scale Integration) technology in the fifth generation. The ULSI
having ten million electronic components. Input & output devices,Programming, internet, CD-ROM,
floppy disk, hard disk and Multiprocessing facilities are developed in this generation.
Advantages:
 Searching for artificial intelligence.
6th generation (2005 onwards): -
In 6thgeneration, the since have been developed much more things in our computer. Now
a day we are using multiprogramming, multitasking, in super computers.
Advantages:
 Significant research.
Classification of computer:
Classy a computer can be classified in to several ways according to the purpose that is
follows.
1. Digital computer
2. Analog computer
3. Hybrid computer
Digital computer:
The digitalcomputer works with digits.In other word a digital computer is a counting device.
All the expressions are coded into digits (0-9). Inside the computer it manipulates them instruct on.
It has low memory power.
Analog computer:
It is unlike a digital computer. It is used to measuring voltage, speed. Also it can use to count
signal&display output continuously when current is flow within it. But the accuracy of this machine
is quite low.
Hybrid computer:
Hybrid computer is one, which combines best feature of analog or digital computer. These
machines are used for scientific & industrial sectors.
Again the computers are divided into 4 categories as per this & purpose.
1. Microcomputer
2. Mini computer
3. Mainframe computer
4. Super computer
Microcomputer:
These are the smallest in size and memory. So they are single user and used as personal
computer in small jobs and it is less efficient, by the introduced of micro chips it became so
powerful.
Ex: -home PC.
Minicomputer:

It is larger the microcomputer with multitasking facility. By involving centralized Processing
systemor in other word user can transform the data during aspecifiedarea likebusiness,education,
and scientific and engineering fields.
Ex: -Air ticket  railway reservation.
Mainframe computer:
These computers are very big in size with a powerful process. High speed, large memory 
accepts in big job. They involved in multitasking by decentralized processing systemor in other word
we can transfer the data universally.
Ex: - Air ticket  railway reservation.
Super computer:
The powerful main frames are called as super computer. They are used in weather
forecasting, nuclear research center, and in military application. It is multi tasking,multi user, multi-
programmable computer with lots of memory power.
On use of computer are again classified into 2types they are,
1 general computer
2. Special computer
Generalpurpose:
A general purpose computer is designed to meets the needs of many different applications.
When one job is over, the instruction for another job can be loaded into the memory. These are
broadly classified as micro -computer, minicomputer, main frame computer and super computer.
Specialpurpose:
A special purpose computer is dedicated as per requirements of a particular set of
application. The computerized programs loaded in the chips.They are used cameras, TVsets,watch,
singing toys etc
About the computer:
A total computer system includes both hardware & software. The computer hardware tells
us the physical equipments necessary for a computer. Software is a set of instruction that directs
the computer (CPU) to perform a particular task into a particular order. It related each other and
can’t function independently. In other word when we studied that language of computers is known
as software. Computer system has two main units that is Hardware and Software.
1. Hardware:
The study of physical components of computer is known as hardware. The physical devices
that make up the computer are calledhardware. A computer’s hardware consists of interconnected
electronic devices that we can use to control the computer’s operation, input and output. It is
combination of mechanical  electrical devices. So it has four types of devices.
1. Input device
2. Output device
3. Processing device
4. Storage device
Input device:
The devices by which enter or input data or instruction into the computer for processing is
called input device. Input devices accept data and instructions from the user. There are many
devices. Some important input devices are keyboard, mouse, joysticks, light pen, optical scanner,
touch screen, microphone for voice as input and trackball.
Keyboard:
Key board is most common input device. It allows data entry into a computer by a input
device. The keyboard is connected to the back side of the CPU. There are alpha numerical keys such
as A to Z, 0 to 9, special character (! , @, # $etc.) and mathematical symbol in the keyboard. There

are ctrl, shift, alt which are used combined with some other function key. There are function key
such as f1 to f12, four cursor movement keys and special keys such as page down, page up, home,
end, insert and delete are used in case of running different types of program. The back space key is
used to erase the left side text of the cursor position. The Del or delete key is used to erase the right
side text of the cursor position. The caps lock key will be type in upper case letter.
Mouse:
It is an input device. It is an electro-mechanical, hand-held device. It is a point and device. It
is held in one hand and moved across a flat surface. The mouse pointer moves on the screen the
direction of the mouse movement. The mouse point is also known as graphics corner. There are
used in every function of the any time. There are three bottoms such as left and right bottom and
round bottom. A mouse is used replace hard to remember key combinations with easier point and
click actions. There are two types of mouse. They are optical mouse and mechanical mouse. An
optical mouse has no moving part. It is used with a special pad covered with a grid of vertical and
horizontal lines. A mechanical mouse detects the direction in which the ball is rolling and moves the
screen pointer accordingly.
Joystick:
It is also a pointing device which work on the same way us a track ball. We make movement
of the mouse pointer there is a stick on the top of the stick and there is a small in the top. Joysticks
are used in case of video game.
Light pen:
There is pen like device used to draw directly on the monitor. This is called light pen. A light
pen is similar to a mouse, except that with a light pen we can move the pointer and select objects
on the display screen by directly pointing to the objects with the pen.
Touch screen:
The VDU screens are designed such that the touch of a particular point of the screen with
our fingers is recognized by the system. These are very useful when menu driven programs are run.
The menu is displayed in the screen and the user just touch the item to be selected with fingers.
Scanner:
Scanners are used to scan picture and scripts and store them in computer. If a picture has
to be stored in computer, the picture can be scanned by using scanner. While scanning the picture
is held below the scanner. Immediately the scanner digitizes the picture and stores it in the
computer. We could immediately see the picture in the computer screen. There are several
types of scanner. The color scanners are capable of scanning color pictures with high resolution.
The hand scanners are used in DTP centers to scan signatures and logos.
Track ball:
It is the most important of input devices. It moves much similar to the mechanical mouse.
In case of track ball is placed on the right side of the keyboard to move the mouse pointer rolled
the ball with the finger. There are usually one to three buttons next to the ball which you see just
like mouse button.
Optical character reader (O.C.R):
It is an input device which can be use the printed character directly and understand them.
For this purpose each character can be printed standard shape, which is standardized by ANSI
(American national standardized institute). This device is not hundred percent successful because
it is very difficult to write a character in a particular cell.
The advantage of OCR is that no internet device is needed during the preparation of data.
The disadvantage of this device that the equipments are very expensive and any small variation in
the character shape, we need to incorrect result.
Optical mark reader (O.M.R):

These input device are capable of accepting a predefine type of mark made by pencil or pen.
It is mostly used in correcting multiple choice questions in competitive examinations.
Optical bar reader (O.B.R):
The data codes in the form of small lines are known as bar code data. The bar code
represented as alpha numerical data by combination of vertical lines. This type of scanner is used
in super market and department.
Magnetic ink character reader (M.I.C.R):
It is similarly to O.C.R. It is used by banking industry for vary fast and large volume of checks.
The bank which is used a specify type of ink which is called magnetic ink for writing checks number
bank identification number and account number.
Output device:
Output devices are used to show the information stored in a computer or the result of any
processing done by the computer to the outside of world. The output unit of the computer presents
the result of calculation. The V.D.U. screen or monitor, printers and plotters are some popular
output devices. Some output units are card punch, paper tape, punch m magnetic tape and
magnetic disk.
Visual Display Unit (V.D.U):
It is most commonly use in output devices. Generally monitor is considered as visual display
unit which is like a television screen. The result is displayed on the screen the VDU screen act as an
effective man machine interface in the fieldof information technology. There are monochrome soft
white screen and color screen. Now-a-days color screens are widely used almost all computers. A
VDU normally consists of 20 rows and 80 columns, the screen is represented by an array of dots are
called pixels. It has 200 pixels from top to button and 640 pixels left t0 right.
There are basically 6 types of technology used for constructing display screen.
1. Cathode Ray Tubes (CRT)
2. Liquid Crystal Display (LCD)
3. Light Emitting Diodes (LED)
4. Plasma Display Panels (PDP)
5. Vacuum Florescent Display (VFD)
6. Electric Luminescent Display (ELD)
Printer:
Printers are the most popular output devices. They produce printed output of results
programs and data. Printers are the mostly used output devices today for producing hard-copy
output. There are different types of printers depending upon the printing mechanism, speed and
quality of printing.
Impact printer:
The printer that can be used to produce multiple copies of a document in a single printing
by using carbon paper is known as impact printer.
Dot-Matrix printers:
Dot-Matrix printers are character printers which print one character at atime. It is anoutput
device. A dot matrix printer has aprint head, which can move horizontally across the paper. It allows
the printer to print many special characters, different sizes of print and the ability to print graphics
such as charts and graphs. It is impact printer. Inkjet printer can be used to produce multiple copies
by using carbon paper. It is slow and speed usually ranging between 30 and 600 characters per
second.
Drum printers:

Drum printers are line printers, which print one line at a time. It consists of a solid cylindrical
drum with characters embossed on its surface in the form of circular bands. Each band consists of
all the printing characters supported by the printer in its character set and the total number of
bands is equal to the maximum number of characters that can be printed on a line.The drum rotates
at a high speed.
A drum printer with 132 characters per line and supporting a character set of 96 characters.
It is an output device. It is impact printers. The drum printers are print by hammering the paper and
the inked ribbon against the characters embossed on the drum. The drum of drum printer is can’t
be changed. Typical speeds of drum printers are in the range of 300 to 2000 lines per minutes.
Chain printers:
It is a line printer, which print one lineat a time. The chain printer consists of ametallic chain
or band on which all the characters of the character set supported by the printer are embossed.
Chain printers are impact printers becausethey print by hammering the paper and the inked ribbon
againstthe characters embossed on the chain. They canbe used to produce multiple copies by using
carbon paper or equivalent. Typical speed of chain printers re in the range of 400 to 3000 lines per
minutes.
Non Impact printer:
The printer that can’t be used to produce multiple copies of a document in a single printing
by using spraying ink on the paper is known as impact printer.
Inkjet printers:
Inkjet printers are character printers, which form characters and all kinds of images by
spraying small drops ink onto the paper. It is an output device. It is a non-impact printer. They are
print by spraying ink on the paper. Inkjet printers cannot be used to produce multiple copies
document in a singleprinting. Inkjet printers are slower than dot-matrix printers with speeds usually
ranging from 40 to 300 characters per second.
Laser printer:
Laser printers are page printers which print one page at a time. The main components of a
laserprinter are a laserbeamsource, amulti sided mirror, a photoconductive drum and toner. Laser
printers produce very high quality output, because they form characters by vey tiny ink particles.
Laser printers are non impact printers, because they do not have hammers striking on an inked
ribbon or paper. Laser printers cannot be used to produce multiple copies of a document in a single
printing.
Processing device:
The procedure that transforms raw input data into useful information for output is called
processing. The device which are used for process to the user data or instruction for result is called
processing device.
Ex- CPU
Central processing unit (CPU):
The procedure that transforms raw input data into useful information for output is called
processing. To perform this transformation, the computer uses central processing unit. The CPU or
processor is the “brain” of the computer. All major calculations and comparisons performed by a
computer are carried out inside its CPU. The CPU is responsible for activating and controlling the
operations of other units of the computer system. The CPU has three basic parts they are
1. Control unit (CU)
2. Arithmetic logic unit (ALU)
3. Register
Control unit:

The control unit manages all the computer resources and coordinates all the computer
activities it contain the basic instruction for execution of programs. So any type of data can operate
or perform in CPU in other word it is the brain of computer. A list of all the operations execute by
user it performs on CPU. The control unit can thought and direct to the CPU by using all data.
Arithmetic logic unit:
When control unit check the data an instruction that involves mathematically calculation
decision means arithmetic operation (add, subtract, multiply, divide) or a logical operation (<,>,=)
it passes the control to the second component the ALU. It does any types of mathematical
operation. Microprocessor is a single tiny silicon chip.
Register:
The register is smallest high storage area in the CPU. When we put some data through
keyboard or mouse the data must have represented in this resister before it can process. It does
not store the data. The length of register equals the number of bits it can store. Hence a register
can store 8 bits normally. Now CPU has 32-bits or 64 bits registers. There are different types of
registers such as:
Memory Address registers (MAR): it holds the address of the active memory location. It is
located from the program control register when an instruction is read from memory.
Memory Buffer Register (MBR): It holds the contents of the memory word read from or written
in memory. A word to be stored in a memory location must first be transferred to the MBR, from
where it is written in memory.
Program Control Register (PCR): It holds the address of the next instruction to be executed.
Accumulator register (AR): It holds the data to be operated upon the intermediate results and
the results of processing. It is used during the execution of most instructions.
Instruction Register (IR): It holds the current instruction, which is being executed. As soon as the
instruction is stored in this register, the operation part and the address part of the instruction
are separated. The address part of the instruction is sent to the MAR and the operation part is
sent to control unit.
Input/output Register: it is used to communicate with the input/output devices. All information
such as instruction and data are transferred to this register by an input device.
Storage device:
The devices which are used for store the data or information for feature reference is called
storage device. There are two type of storage device such as primary and secondary storage device.
Storage Evaluation criteria
Any storage unit of a computer system is characterized and evaluated based on some
properties such as:
Storagecapacity:itis the amount of datawhich canbe stored in the storageunit. A largecapacity
is desired. As compared to secondary storage units, primary storage units have less storage
capacity.
Access time: it is the time required to locate and retrieve stored in the storage unit, in response
to a program instruction. As compared to secondary storage units, primary storage units have
faster access time.
Cost per bit of storage: it refers to the cost of a storage unit for a given storage capacity. As
compared to secondary storage units, primary storage units have higher cost per bit of storage.
Volatile: if the storage unit can retain the data stored in it, even when the power is turned off or
interrupted, it is called non-volatile memory. If the data stored are lost, when the power is
turned off or interrupted, it is called volatile memory. In all computer system, the primary
storage units are volatile and secondary storage units are non-volatile.

Random access: If the time taken to access a piece of data from the storage unit is independent
of the location of the data in the storage unit, it is calledrandom access storageor random access
memory.
The execution of an instruction by the CPU, during program execution, normally involves
fallowing steps:
1. The CU takes the address of the next program instruction to be executed from the program
control register,and reads the instruction from the corresponding memory address,into the
instruction register of the control unit.
2. The CU then sends the operation part and the address part of instruction, to the decoder
and the memory address register, respectively.
3. The decoder interprets the instruction and accordingly the CU sends signals to the
appropriate unit, which needs to be involved in carrying out the task specified in the
instruction.
Ex: if it is an arithmetic or logical operation, the signal is sent to the ALU. In this case,
the CU also ensures that the data corresponding to the address part of the instruction is
loaded in a suitableregister in the ALU, before the signals senttothe ALU. The ALU performs
the necessary operation on the data and signals the CU as soon as it has finished.
4. As each instruction is executed, the address of the next instruction to be executed is
automatically loaded into the program control register, and step 1to 4 repeated.
Primary memory
Every computer has such a storage space which is known as primary memory or main
memory or simply memory. It is a temporary storage area which is built into the computer
hardware. Physically, this memory consists of some chips either on the motherboard or on a small
circuit board attached to the motherboard of a computer system. The primary memory is 100 times
faster than from a high speed secondary storage like disk.
In a computer the memory has been divided in two types like RAM  ROM is known as
temporary memory of computer or volatile memory of computer. Again ROM is known as
permanent memory of computer. All types of data must be given a file name before store in to it.
RAM activateROM. RAM does allthe work. The primary memory consists two types of memory that
is
1. Random Access Memory
2. Read Only Memory
RAM
The CPU have not sufficient storage space to execute the program so the control unit store
the data and instruction receive from input devices into primary memory called RAM. RAM can
store data indefinitely. RAM holds information only while the computer is on.
When the computer is turn off or restart the information disappears unless it has been store
into it. RAM is known as volatile memory or temporary of computer. Again the RAM has divided
into 3 types
1. Dynamic RAM (DRAM)
2. Static RAM (SRAM)
3. Synchronous Dynamic RAM (SDRAM)
ROM
Some data and instruction remain permanently stored into memory which can’t be changed.
This memory is called read only memory. ROM contains a set of instruction that check to see
whether the rest of memory is functioning properly. It is CPUs permanent storage device. So it can’t
be change or lost. Thus it is known as non-volatile memory. Again it is divided into three categories
like
1. Programmable ROM (PROM)

a. Manufacturer PROM
b. User PROM
2. Erasable PROM (EPROM)
a. Ultra Voilet EPROM
b. Electrically EPROM
Programmable ROM:
It is non volatile storage i.e. the stored information remains intact even if power is witched
off. It is possible to read the stored information. ROM is known as PROM, because a user can
program it. PROMare programmed to record information using a specialdevice,is known as PROM-
programmer.
Manufacturer PROM:
Manufacturer PROM chips are supplied by the manufacturers of electronic equipment. It is
not possible for user to modify the programs or data stored inside the ROM chips.
User PROM:
User PROM is one in which the user can load and store read only programs and data. It is
possible for a user to customize a system by converting his own programs to micro programs and
storing them in a user programmed micro chip.
Erasable PROM:
It is possible to erase information stored in an EPROM chip and the chip can be
reprogrammed to store new information.
Ultra Voilet EPROM:
The stored information is erased by exposing the chip for some time to ultraviolet light that
is known as Ultra Voilet EPROM.
Electrically EPROM:
The stored information is erased by using high voltage electric pulse that is known as Ultra
Voilet EPROM. It is alsoknown as flashmemory.Flash memory is used in many new I/Oand Storage
devices.
Cache memory:
When using to main memory, the memory processor speed mismatch with which the CPU
can process instructions because there is a 1 to 10 speed mismatch between the processor and
main memory. Hence many situations the performance of processors gets limited due to the slow
speed of main memory. Obviously, the overall performance of processors can be greatly improved
by minimizing the memory-processors speed mismatch. Cache memory is used for minimizing the
memory processor speed mismatch. It is an externally fast, small between CPU and main memory.
It acts as a high speed buffer between CPU and main memory and is used to temporarily store very
active data and instructions during processing. It is faster than main memory.
Secondary storage devices:
To store large amount of data for longer period we use the secondary storage device. It is
non-volatile memory. We can transfer data from one place to another place by using this secondary
storage device. It is like floppy disk, hard disk, magnetic tape, pan device, CD, DVD etc. these
components are external storage devices of computer.
There are two types of secondary storage device such as:
1. Sequential access device
a. Magnetic tape
2. Direct access device
a. Magnetic disk
i. Floppy disk

ii. Hard disk
1. Zip disk
2. Disk pack
3. Winchester disk
b. Optical disk
i. CD-ROM
ii. WORM disk
Floppy disk:
It is a magnetic storage media using flat circular platter. Floppy disk are primarily used on
PCs. Information on a floppy disk is recorded in the magnetized states of particles of iron oxides
evenly placed upon concentric circles known as tracks, tracks are further divided into sectors.
Physical size and storage capability of disks vary.
Type size capacity
Double density 5.25” 360KB
High density 5.25” 1.2MB
Double density 3.5” 720KB
High density 3.5” 1.44MB
Very high density 3.5” 2.88MB
Hard disk:
It is non-removable enclosed magnetic disk included in most PCs. A hard disk holds much
more information than a floppy disk is used to store relatively large amount of data. The physical
size and storage capabilities of a hard disk vary. For PCs the storage capacities vary from 1GB to
about 8-10 GB.
Zip disks:
In this type, a single hard disk platter is encased in a plastic cartridge. A commonly used to
Zip disk is having a storage capacity of about 100 MB, depending on the formatting style used by a
particular computer system.
Disk pack: A disk pack consists of multiple hard disk platters mounted on a single central shaft.
Winchester disks:
A Winchester disk also consists of multiple hard disk platters mounted on a single central
shaft.
Magnetic tape:
Magnetic tape is the most popular storage medium for large data which are sequential
access media and process which means to get to a particular point on the tape. The magnetic tape
mainly used for taking backup of hard disk. In contrast disks are random access media because a
disk drive can access ay point at random without passing through intervening points. So the
magnetic tapes can’t be practically used for data that we need often.
Optical disk:
The need for ever greater storage capacities has driven hardware many- factures to use optical
storage technology as the main alternative to magnetic storage.
The two most popular types of optical disks are CDROM and WROM disk.
CDROM:
CDROM stands for compact disk read only memory. It is most popular optical storage
medium. CDROM uses the same technology that is used in music CDs. One can’t write data to a
CDROMbut can always read it. A single CD can hold up to 650 MB of data. Larger CDs can store up
to 20GB.
WROM:

WROM stands for write once, read many. This disk allows the users to create their own CD-
ROM disk by using a CD-Recordable drive which can be attached to a computer as a regular
peripheral device.
Structure of computer
Software:
A computer cannot do anything on its own. Computers always need proper instructions to
tell them what to do, how to do  when to do. A set of instruction written in a sequence which is
on processing gives out the information as desire by the user is known as program. Software is a set
of instructions that makes the computer perform tasks.
A large program which helps the user in doing the task in a complete way is known as
software.
Relationship between hardware and software:
 Both hardware and software are necessary for a computer to do useful job.
 Both hardware and software are complementary to each other.
 The same hardware can be loaded with different software to make a computer system
perform different types of jobs, just as different songs canbe played using the samecassette
player.
 Hardware is normally a onetime expense whereas software is a continuing expense.
Basically there are two kinds of software like
1. System software
2. Application software
System software:
The software, which requirement for booting process of computer i.e. system switch of or
switch on is known as systemsoftware. System software is a setof one or more programs, designed
to control the operation and extend the processing capability of a computer system. Hence system
software makes the operation of a computer system more efficiently. It helps the hardware
components work together. It provides execution of application. The programs included in a system
software package are called system software.
Ex-DOS, Windows 98/XP, UNIX, LINUX, VISTA
SECONDARY MEMORY
PRIMARY MEMORY
REGISTER
ALU CU
RAM ROM
INPUT UNIT OUTPUT UNIT
Key board,
mouse,
magnetic tap,
floppy disk,
CD, DVD, pen
drive ,
scanner , joy
stick , light
pen
Monitor, printer,
speaker
ALU: Arithmetic Logic Unit
CU: Control Unit
ROM: Read Only Memory
RAM: Random Access Memory

Types of system software:
Depending on its used, the system software is two types such as:-
I. Operating system
II. Utility software
Operating System:
An operating system is a set of program use to control the operation of computer system.
The operating system can’t perform any application or does not give us any type of result. We can
only make a print out of those particulars. An operating system is system software which acts an
interface the user and hardware.
Duties of an operating system:
Every operating system has got four important duties such as
 Processor management
 Memory management
 Device management
 Input output management
Types of an operating system:
Depending on number of uses that can work on the operating system, there are two type of
operating system such as: -
 Single user operating system
 Multi user operating system
Depending on weather the operating system supports networks, there are two types such
as: -
 Network operating system
 Non network operating system
Structure of operating system
Logically an operating system is divided into two parts such as kernel and shell.
Kernel:
It is a collection of one or more files which interact with the hardware to carry out a specific
type of task. It is linear layer of an operating system. It received valid data or instruction from the
shell. It is common interpreter. It closes with the hardware. It executes the command.
Shell:
It is a collection of one or more files which interact with the user. It is outer layer of an
operating system. It received command i.e. data or instruction from the user. Then it verifies that
weather the command is valid or not. If the command is invalid, it displays on error message. If the
command is valid then request the kernel on behalf the user to execute the command. It is also
known as execution. It closes with the hardware. It verifies to the command.
Booting:
It is a process of loading of operating systemfrom the external device to the main memory.
Depending on wane booting is done the booting is two types such as: -
1. Cool or cold or soft booting
2. Warm or hot or hard booting
Cool booting: When the computer is switch on then booting which occurs at this time is called as
cool booting.
Hot booting: When the computer is booted the pressing control, alt, delete or key combination or
by pressing the restart button then that type of booting is called as hot booting.
Utility operating system:

The system software which interfaces between the operating system and the hardware is
called as utility software.
Application software:
The software, which not requirement for booting process of computer i.e. systemswitch of
or switch on is known as Application software. Application software is a setof one or more program,
designed to solve a specific problem or do a specific task. Similarly, a program written by a user to
solve a particular research problem is also known as application software. The programs included
in an application software package are called application software.
Ex. - MS Word, MS Excel, Photoshop, Type tutor etc.
Programming Language:
A communication between two parties always needs a common language to
communication each other. So the language is used to communicate between the computers  the
user is known as programming language. They are two types such as Low level language and High
level language.
Low level language:
In the first generation low level languages are used communicate with computer  user.
Again the low level language was divided into two types
1. Machine language
2. Assembly language
Machine language:
The binary code (0, 1) is the only method of communication with a computer. A user must
be convert normal language to binary language before feed into a computer is known as machine
level language. It is used in 1st generation.
Assembly language:
This is a low level language which user general statement to generate machine code. This
language is also called as second generation language. The user must be adopting programming
language after machine code. A program written in assembly language must be translated into
machine languagebefore the program is executed. The translation canbe donning by aprogrammer
known as assembler.
High level language:
In third generation high level language were introduced. It is a programming language that
uses grammatical or mathematical or those language used by us. That is known as high level
language. But every language must be a series of logical stapes or in a sequence. Again this high
level language is divided into two categories
1. Interpreter language
2. Compiler language
Interpreter
An interpreter first reads each line to the program and converts them from unsolved
problem to solved problem. If it finds the line, error – free, it executes and thus the process
continues till the end of program.
Compiler:
A compiler is a program written in machine level language whose function is to translate the
high level program into the machine level program. A compiler usually compiles the whole program
from first to last line before attempting to solve the program.

Number system
Introduction:
A computer systemdoesn’t understand our language. When data is typed into a computer,
the keyboard converts each keystrokes into a binary character codes and vice versa.
Binary:
A computer can store and process the data in two state devices. It can be either ON or OFF.
So two symbols numerically used are 0 and 1.
Definition:
Number are written in a systematically way or sequential way is called number system.
Type of number system:
Depending on the position of the number, number systems are two types:
1. Non-positional number system
2. Positional number system
Non-positional number system:
In early days, human beings counted on fingers. When ten fingers were not adequate,
stones, pebbles or sticks were used to indicate values, this method of counting is called non-
positional number system. In this system, we have symbols, such as I for 1, II for 2, III for 3, etc. each
symbol represents the same value, regardless of its position in the number and the symbols are
simply added find out the value of a particular number.
Positional number system:
In a positional number system, there are only a few symbols called digit and these symbols
represent different values,depending on the position, they occupy in the number. The value of each
digit in such a number is determined by three considerations:
 The digit itself.
 The position of the digit in the number.
 The base of the number system.
Depending on base of the number, positional number systems are 4 types:
I. Binary number system
II. Decimal number system
III. Octal number system
IV. Hexadecimal number system
Binary number system:
In this number system, the base is 2. Hence there are only two symbols and digits 0 or 1.
Latest single digit is 1.
Example: (1101)2
In this number system we are fallow three rules:
 In addition
1+1=10, 1+0=1, 0+1=1, 0+0=0
 In subtraction

1-1=0, 1-0=1, 0-1=-1, 0-0=0
 In multiplication
1x1=1, 1x0=0, 0x1=0, 0x0=0
Some example:
Q1. (11011)2 + (111)2 = (?)2
11011
+ 111
100010
Q2. (110001)2 - (101)2 = (?)2
110001
- 101
101100
Q3. (111)2 x (11)2= (?)2
111 x 11
111
111
10101
Decimal number system:
The number system used almost universally by human is called decimal number system. In
this number system, the base is 10. Hence there are only ten digits or symbols: 0, 1… 9. The latest
single digit is 9.
Example: (986)10
Octal number system:
In this number system, the base is 8.hence there are only 8 digits or symbols: 0 to 7. The
latest single digit is 7.
Example: (123)8
Hexadecimal number system:
In this number system, the base is 16. hence there are only 16 digits or symbols:0 to
9,A,B,C,D,E,F
Where A=10, B=11, C=12, D=13, E=14, F=15.
Example: (BCA)16, (3EF)16, (123)16.
Converting to decimal from another base:
 Multiply to every digit of the given number by determine the column value of each digit.
 Sum of products calculated in step-1.
 The total is the equivalent value in decimal.
Some basic example:
Q1. (234)8 = (?)10
234 = 2 X 82 +3 x 81 + 4 x 80
= 2 x 64 +3x 8 +4x1
= 128+24+4
= 156
Q2. (111001)2 = (?)10
111001 = 1x25+1x24+1x23+0x22+0x21+1x20
= 32+16+8+0+0+1

= 57
Q3. (BCA)16= (?)10
BCA=Bx162+Cx161+Ax160
=11x256+12x16+10x1
=2816+192+10
= 3018
 Converting from decimal to another base:
 Divided the number by the base of required value.
 Write the reminder as rightmost digit of the new quotient number.
 We are continuing this process until quotient is equal to zero.
 Write reminder value down to up this number is equivalent value of required Value.
Q1. (546)10= ( )2
2 546
2 273 0
2 136 1
2 68 0
2 34 0
2 17 0
2 8 1
2 4 0
2 2 0
2 1 0
0 1
(546)10= (1000100010)2
Q2. (270)10= ( )16
16 270
16 16 14 E
16 1 0
0 1
(270)10= (10E)16
Q3. (98)10= ( )8
8 98
8 12 2
8 1 4
0 1
(98)10= (142)8
 Converting from base other than 1o to base other than 10 :
 Convert the original number to a decimal number system.
 Convert the decimal number to a required number system.
Q1. (234)8 = (?)2
234 = 2 X 82 +3 x 81 + 4 x 80 = 2 x 64 +3x 8 +4x1 = 128+24+8 = 156
(234)8 = (156)10
2 156

2 78 0
2 39 0
2 19 1
2 9 1
2 4 1
2 2 0
1 0
(156)10= (10011100)2
(234)8 = (10011100)2

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