Computer Fundamentals & Programming
Introduction To Computer System
Computer is most important device for this era. The computer technology has almost changed the world in
short times. It becomes very essential tool in
every walk of human life. The word computer is developed from
the Latin word ‘
which means “To
Roughly we can say
the machine which
calculates is called a computer; but it is incomplete, In
a computer is a programmable electronic
calculating machine. It received data through it input devices, process it and produce output as our
requirement with in a second. With help of computer technology a person can communicate to other people
from one p
lace to another place of the world through telephone, telex, fax, e
mail etc within a minute. A
computer accepts data from an input device and processes it into useful information which it displays on its
output device. It operates under the control of a
set of instructions that is stored in its memory unit.
Definition of computer
A computer is an electronic device that accepts data; process it according to a set command and then gives
results. In other words a computer is an electronic machine that is used for data processing to produce
With viewpoints of this defi
is said to
device, Automatic system etc
The computer has following basic system and components devices to process data and gets the outp
Central Processing Unit (CPU)
Monitor and Printer
CPU Consists motherboard, hard disk, floppy disk drive, sound card, power supply, modem, etc.
Basic and optional component device
Capacity & functions
600 MHz, 1200 MHz, 1700 MHz
40 GB, 100 GB, 160
GB, 200 GB, 2000 GB
, 256 MB, 512 MB, 1GB, 2GB
Display /Video Card
64 MB, 128MB, 512 MB, 1 GB
84 keys , 104 Keys, 124 Keys
Hard disk drive
reads, writes on HD
Floppy disk drive
reads, writes on floppy
reads, writes on CD
pointing & clicking device
A complete basic components set of these devices is called a computer. Computer may have optional
Capacity & functions
18 Pg/min, 4
Flat bed type & Handheld type
Reads/writes on DVD
Reads/writes on Zip disk
Reads/writes on Pen drive
(Characteristics of computer)
very important and useful device for everywhere of a
human being of this century. This is due to
features. There are some important features
Computer is an automatic
; any given a job it performs independently without
High processing speed
A computer is a very fast processing device .It can perform in a few seconds, the amount of work that a
human being can do in an entire year. It can perform data processing job very fast usually measure in micro
Computer is working its job very accurate. A computer performs every calculation with the same accuracy.
However the mistake may occur; if any mistake found in it is not due to the mistake of computer but the
programmer. It works consistently and accurately throughout the time.
Individual components of computer have a very high life and degree of reliability. Computer is only a
machine and it does not make errors on its own. So computer is reliable
Diligence (Stay constant)
Computer is a machine .It is free from monotony, tiredness and lack of concentration. It can continuously
work for hours without creating any error and without grumbling
Versatility (Simple to complicated jobs)
Versatile is one of the most wonderful things for a computer. It is capable to performing almost any task if the
task is reduced to the finite series of logical steps .Once moment it is preparing result of an examination next
it is busy to prepare electric
ity bills and in between it help to type a business letter.
Huge storing device
storing capacity. It can store a large number of data in it. The secondary storage device is
used for it. Thousands of books can be store in a small chip.
= 1024 characters/symbol = 10
= 1024x1024 ʺ = 10
= 1024x1024x1024 ʺ
In accordance the computer has huge storage capacity.
World Wide Networking
Computers are connected to word wide. Through internet a person from any place to the other person in any
place of the world
can talk, share picture etc .in a moment, a person get any kind of information through
computer .This is all with the help of computer and its word wide network.
No I.Q. and Feeling
Computer is a machine. It is free from any kind of emotion and feeling
. It is not a magical device also.
Though it perform the task as human being
it has no brain as like a human
Impact of the Computer Technology in the Society
In the world today, computer awareness, use and its impact is
increasing in a very high speed day by day.
Compared to other technologies, it is developing and changing very frequently. It is a multi
technology, which can create a multidimensional effect in the all round development of the person, the
ety and the country. It can help the society providing quality service cost effectively. That is why people
are adapting this technology very fast. At present, we have seen that people from different sectors like
doctors, engineers, managers, teachers, res
earchers, businessmen, industrialists and students etc. are using the
computers. Using this technology, they are increasing their living standards, economic status, and personal
working capacity and so on.
It can bring rapid progress and prosperity in the
country. Singapore, Japan, South Korea, Taiwan and others
are good examples. To develop the country and society, the revolution of agriculture had taken more than
thousand years and the industrial revolution had taken about a century. But the revolution of
taken only about 25 years to change the society and country. It is a very fast changing technology, which can
accelerate the developing speed of the nation. It can bring fast economical revolution to the country. It can
quickly change the l
ife style to bring prosperity. Therefore, it can impact the society in multiple ways.
Advantage and disadvantage of the technology are as follows.
Higher Quality Product
and educational benefit
Aid to handicapped
Better Information retrieval
Personal finance benefits
Benefit of greater personal efficiency.
System Security problem
The privacy issue
The threat to access by the hackers
The threat to the system security, etc.
of Computer in the society
Realizing the above social impact, the people of the world are endeavoring to provide computer education
their children from an early age. Most of the developed countries have made Computer Education compulsory
from grade one to Ph.D. level. They had prepared the curriculums to use it according to the level and
requirements. Most of the countries are inve
sting lots of money on the computer education for better quality
of life and speedy development. Due to the development of computer technology, India, South Korea,
Taiwan, Singapore and Malaysia have upgraded the living standards of their people within the
decades. But Nepal could not develop much compared to what they had done. In fact, Nepal had also started
using this technology since 1970 AD but, because we did not care about the quality Computer Education in
the right time. We have not yet bee
n able to frame proper national policy of IT (Information Technology)
development and human resource development on IT. Anyway, in Nepal also people had started computer
Education from class 3 to the Ph. D. level at present. They are using computers in dif
ferent sectors. There are
good impacts of this technology. At present, people in Nepal are using this technology in the following fields
for the personal and social benefits.
Result Processing in Schools, 10+2, Colleges and Universitie
School Information System Processing in Ministry of Education.
Students & Teacher's Record Keeping.
As a teaching tool for Science, Health, Geography, etc.
As a learning tool in the practical class of Schools, Colleges and Universities.
keeping, Payroll System and others.
Statistical record keeping, etc.
Patient Record Keeping
Medical Store Inventory Control
Research and Development.
Bank Account Keeping
Electronic Money Transfer
Monthly/Yearly Income & Expenditure Record Keeping
Monthly/Yearly Money Transaction
Research and Development
Front Desk Management System
Store and kitchen Inventory Control System
Hotel Management System
Billing & Ticketing
Spare parts Inventory Control System
Commission Agents’ record keeping
Personnel Management System.
National Agriculture Census
Research and Development
Production Control Management System
Store and Inventory Control System.
National Industrial census
Research and Development
Inventory Control System
Demand and Supply System
Manpower Management System
(viii) Property Management System
Spare parts Inventory Control System.
ional News Collection, Dissemination & Control
National News Collection, Dissemination & control
Dissemination of news, in terms of text, voice and views
Research and Development
Store Inventory Control System
Keeping System, etc.
There are other sector
where the application of computer
Office, Intelligence Machine, Weather Forecasting, Decision Making, Distance Education, Film
recording, Traffic Control, Playing
History And Development Of Computers
A computer is an invention of human beings to enhance their capabilities to accomplish tasks. Modern
computers are developed after a gradual change over a long period of time. In another word,
it was not
developed in one day. Hence it has its own history.
Tribal life in ancient time required man to remember a lot of information, so an early man felt the need to
count the things. Then he started counting using his own fingers. However, the limite
d number of fingers had
made it difficult for him to remember more facts. Thus, he started different methods to count using stones,
sticks, scratches on a rock or wall or knots in a string. As a result, during fifth century Hindu philosophers
were able to
develop a new method of counting using the numbers (digits) 0 to 9. Since there are ten digits,
the Arabic Number System method was called Decimal Number System of counting. Hence, the history of
computer implies the gradual change in the concept over a lo
ng period of time. In the following section, we
will explain the history of computing machines from their early forms to the most modern high
(a) BC 5000 to 2000 Abacus
In early days, people used pebbles or beads on a counting
board to carry out simple calculations. This tool is
called the Abacus. Its exact origin is unknown. It may have originated in China, Egypt and Greece during
5000 B.C. to 2000 B.C. An abacus can be used to add, subtract, multiply and divide. Even today the
used in many parts of the world (e.g. China).
(b) A.D. 1614: Napier’s Bone
In 1614 John Napier, a Scottish Mathematician, first published the first table of logarithms. It was very
helpful in simplifying multiplication of large numbers. In
1614, Napier also developed a numbered rod in
order to multiply, divide and extract roots, known as Napier’s bone. It was called so because it was made up
of strips of bones on which numbers were painted. By the combination of these bones, direct multiplic
could be done.
(c) A.D. 1620: Slide Rule
In 1620, Slide Rule was developed by William Oughtred, UK which is an analog device. It used the principle
of logarithms. It has two graduated scales. One scale slides or slips upon the other. With the proper
of the two scales, it is easy to find the product, quotient or any other function simply by viewing on the
A.D. 1642: Pascal’s adding machine
The first real calculating machine that could add and subtract was a mechanical calculator
Adding Machine or Pascaline, invented by a French scientist Blaise Pascal in 1642. Pascal’s Adding machine
consisted of ten toothed wheels. The addition or subtraction was performed by turning these wheels.
e) A.D. 1694: Leibnitz’s Calc
The first calculator that could perform automatic addition, subtraction as well as multiplication and division
was developed by a German philosopher Gottfried
Von Leibniz. In 16
, Leibnitz modified his
calculator. It was also known as. Step
(f) A.D. 1801: Jacquard’s Loom
At the beginning of the nineteenth century (i.e. A. D. 1801), Joseph Marie Jacquard of France invented a
punched card as an accessory to the loom. The punched card could automate the loom for th
e weaving of
intricate patterns. Thus, he could control the weaving loom through the set of holes in a card, which could
store the instruction for the loom.
(g) A.D. 1822 and 1833: Babbage’s Differential Engine
In 1822, another interesting development t
ook place in the history of computers. Charles Babbage, an English
Mathematician, invented a calculating device called Differential Engine . Babbage wanted to calculate
Polynomial functions using the method of differences.
Babbage, also wanted to design
a bigger machine, called an Analytical Engine. The idea of an Analytical
Engine developed in 1833 AD was considered as a most significant step in the history of computers, because
of his idea only, the dream of modern computer has come true. That is why he
is famous as “Father of
Babbage intended to have his machine to have a mechanism to input data and output the results. He wanted to
input data with the help of punched cards and the output to be printed on copper plates. Babbage’s analytical
gine and modern day computers are similar in their structure. This engine had four major units.
Store: A memory or store which could store data and intermediate results.
Mill: An arithmetic unit which was called a ‘Mill’. It could perform calculati
His machine had mechanism having gears and shafts by which data and results were transferred between
the store and the mill which is similar to the control unit of today’s computer.
Input and Output devices
(h) A.D. 1848 Lady
In 1848 AD, a British mathematician Lady Agusta wrote a first program to run an analytical engine made by
Prof. Charles Babbage. Hence she is called a first programmer.
(i) A.D. 1850 George Boole
George Boole, a British mathematician, introduced mathema
tics of logic known as Boolean algebra. It laid
the foundation of digital computers. Boolean considered two
valued binary notation (i.e. 0 and 1) to represent
any form of data.
(j) A.D. 1890: Dr. Herman Hollerith
The first card machine which was electri
cally activated was used by Dr. Herman Hollerith to compute the
statistics of the 1890 AD United States population census. Hollerith was an American mechanical engineer
and statistician, working for the Census Bureau. He used the punched cards to store dat
a, with the holes
representing data values. He developed an electromechanical tabulating machine for punched cards. Because
of his sincere efforts, the population census of 1890 could be processed in one
third of the time allotted.
(k) A.D 1937: Electrom
In the early part of the twentieth century, tabulating machines were growing rapidly. In 1937, next important
event occurred in history. The first electromechanical computer with the development of MARK I was
invented by Howard
Aiken and other was constructed MARK I at Harvard University under the sponsorship
of IBM (International Business Machine).The MARK
also known as the Automatic Sequence Controlled
Calculator. It was 50ft. long and 8 ft. high. It used electronic tubes an
d electrical relays. MARK I took 4½
seconds to multiply two 23
digit numbers. It was able to produce
tables that were used in
connection with Second World War. The input device used was the punched paper tape.
(l) A.D. 1939: Electronic Comput
The age of electronic computer began when vacuum tubes were introduced. Such tubes were thousands of
times faster than the earlier electromechanical devices. The first electronic digital computer was developed in
1939 AD by John V. Atan
asoft and his student Clifford Berry It was called Atanasoft
Berry Computer (ABC
(m) A.D 1940: ENIAC (Electronic Numerical Integrator And Computer)
In the true sense, the first electronic computer was developed by John W. Mauchly and John Presp
It was developed at the university of Pennsylvania and called ENIAC (Electronic Numerical Integrator And
Computer), based Decimal Number System.
ENIAC used high
speed vacuum tubes (switching devices). The high speed operation of the computer in
world was first experienced with ENIAC. It could add two numbers in 200 microseconds and multiply two
numbers in 2800 microseconds. Number of vacuum tubes used was 19,000. It occupied an area of 150 square
meters and was 1,000 times faster than Mark
(n) A.D. 1949: EDSAC (Electronic Delay Storage Automated Computer)
In 1945, a noticeable improvement in the development of the computer took place when John Von Neumann,
the Hungarian mathematician genius developed the idea of Stored Program Concept, whi
ch was a very
important technique to design today's Computer. According Neumann, it would use Binary Number system
instead of Decimal Number System used in ENIAC. Then Prof. Maurie Wilkes used the I.V Neumann’s
stored program concept to design the computer
called EDSAC (Electronic Delay Storage Automatic
Computer). EDSAC was called the first stored program electronic computer developed completely in 1949.
(o) A.D. 1951: UNIVAC (Universal Automatic Computer)
After developing ENIAC, Mauchly and Eckert formed
their own company in 1946. This company built a new
computer called UNIVAC
I (Universal Automatic Computer
I) in 1951. UNIVAC was delivered to the
Census Bureau. Business organizations too started using UNIVAC. Hence, it was called the first
used electronic computer in the world.
(p) A.D. 1970: Microprocessor
The first Microprocessor was built at Intel Co
operation, USA in 1970. It was used to build minicomputer and
micro computer at the beginning.
(q) A.D 1972: Minicomputer
The first minicomputer was developed by Digital Equipment Corporation (DEC) in 1972 A.D. Within 1977
AD different computers started developing varieties of Minicomputers.
(r) A.D. 1974: Microcomputer
The first microcomputer called ALT AIR 8800 was
manufactured in 1974. It used an 8
microprocessor. The Apple personal computer and IBM pc was first introduced in 1976 and 1981 AD
(s) A.D. 1994: Pentium Series
IBM Company launched PCXT (Extended Technology) and PCAT (Advanced Tec
were developed first time in 1983 and 1984 AD respectively. Then in 1994 AD Pentium series of
Microprocessor Chips were launched.
In the same year, US vice President Mr. Algor announced about “Internet for all”. Then most of the
veloped and developing countries tried to use Information Technology (IT), where people could use
Internet, Intranet, extranet and email. With the help of this technology they also started using Website, Digital
nd Telemedicine, etc.
(t) AD 1995: Multimedia Technology (MMX)
Pentium I with Multimedia Technology (MMX) computer was built and released. In the same year, Windows
95 and Graphical User Interface (GUI) were launched by Microsoft.
(u) A.D.1996: Linux Ope
This year different individual software developers developed Linux Operating System.
(v) A.D. 1997: MS
Microsoft Company Launched MS
Office 97 (Office Application) for Windows 95. Similarly in the same
year private individuals also
designed and sold a special type of Operating System named LINUX in the
(w) A.D. 1998: Windows 98
Microsoft Company released advanced Windows 98 Operating System, which was the corrected and
advanced version of Windows 95 and windows 97.
x) AD: 2000: Windows 2000
Microsoft Company again developed and released advanced version of windows 2000 Operating System,
which are being used worldwide even today.
History and Development of Computer in Nepal:
Although the first electronic digital computer was built in mid 1940’s, computer was introduced in Nepal in
the year 1972 only. It was introduced by Government for the population census of 1972 (2028 B.S). This was
the second generation computer of IBM Com
pany called IBM 1401. The Government had paid Rs One lakh
twenty five thousand per month as rent for this computer.
The Census Department at Thapathali Kathmandu had used IBM 1401 computer for the first time to process 1
corer 12.5 lakhs population census
taking 1 year, 7 months and 15 days. Later, it became essential to operate
the computer for day and night, for this reason a separate branch office called Yantric Sarinikaran Kendra
(Electronic Data Processing Centre), was established in 1974 (15th Paush 2
031 B.S.), which, after six years,
was converted to National Computer Centre (NCC).
For the population census of 1981 (B.S. 2038), a British computer ICL 2950/10 (International Computer
Limited 2900 Series) which had 64 terminals was added from the aid of
UNDP and UNFPA at two million
American dollar from the British ICL Company. By the help of this fourth generation computer, the 1981
population census was completed within one year and 3 months.
Microcomputer such as Apple, Vector and Sirus were introduced
in Kathmandu for the first time in 1982
(B.S. 2039). New companies such as Computer consultancy (CC), Management Information Processing
System (MIPS) and Data System International (DSI) were established.
Since 1983 (BS. 2040) National Computer Center, on
the other hand, also started giving training on
programming, data entry, data processing, and development of software packages. As a result, many people
from various sectors started showing their interest in the field of computers.
Since 1977 (B.S. 2034)
His Majesty’s Government employed IBM 1401 computer in tourist statistical data
processing, industrial data processing, statistical and loan account keeping of Agricultural Development
Bank, Provident fund, SLC result processing and TU result processing, e
tc. After a few years, new computer
ICL 2950/10 was brought in use, which was more efficient for data processing in some other corporations
such as Telecommunication, Electricity Authority, Janakpur Cigarette factory, Hetauda Cement Factory,
ersity, etc. Many others like travel agencies, hotels, factories, printing presses also started
using computer for better & faster work. At present, not only Kathmandu is using microcomputers but also
Lalitpur, Bhaktapur, Pokhara, Nepalgunj, Bhairhawa, But
wal, Hetauda, Birgunj, Biratnagar, Janakpur, Jhapa
etc. are using computer for different purposes. Nowadays, computers have been used in different areas like,
travel agencies, hotels, Airlines, Government offices, Banks, Colleges, Schools, Hospitals, etc.
People are using computer even at home for day
day use for their personal convenience.
Now there are more than 1000 private computer
training centers all over Nepal. About 50 software
development centers are working in the Nepali market. At p
resent, in Nepal more than 1250 schools, 107
higher secondary schools, 50 general colleges, 42 IT related colleges and 4 Universities are teaching and
using computer technology. More than one hundred thousand computers are busy in Nepal. More than 28
te Internet Service Provider (ISP) are providing services in the Nepali market. Nepal had started using e
mail, Internet, e
Banking and Websites since 1996 AD.
The purpose of using the computers is for word processing, keeping accounts, keeping the record
s and details
of employees, inventory control, etc. A few software houses are involved in software development and in
exporting the software to the international market (i.e. in Japan, Germany, USA, UK etc) also. Some of the
private institutes and companie
s are involved in computer assembling, selling and distributing like in other
developed countries. The scope of computer in our country is increasing rapidly day by day. In May 2000
AD, Ministry of Science and Technology, HMG had announced the national pol
icy on IT. Similarly, HMG
had announced the Cyber Law and copyright Law in Sept 2004 etc.
The "Generations of computer" refers to the development step of technology of computer. It provides a
framework for growth of computer industry. Initially it was classified according to the use various hardware
technologies but it has now been extended to
include both hardware and software. Up to now there are five
computer generations. They are classified with their hardware and software technologies, characteristics and
working speed which are shown by the following table.
Bulky in size
use and costly
Difficult to use
n 1955 to
Faster, smaller, more
reliable and easier to
production was still
difficult and costly
ICs with SSI and
magnetic disks and
family of computer
Faster, smaller, more
reliable, easier and
cheaper to produce
easier to use, and
easier to upgrade
ICs with VLSI
hard disks as in
magnetic tapes and
floppy disks as
systems for PCs;
windows on a
reliable, and easy to
More powerful and
systems and super
Easier to produce
Easier to upgrade
based on parallel
spread of high
1990 to now
ICs with ULSI
main memory hard
disk with RAID
Ooptical disks as
MPI and PVM
reliable, and easier
to use desktop
High uptime due to
Easier to produce
IBM SP/2, SGI
Types of computer
There are various Types of computer they are classified as follows
, Mini, Micro computer, Laptop,
Digital, Analog, Hydride
Branded and Assembled
CPU, ALU,CU, Memory
The computer architecture means the
functional design of computer. This
means the design of
any part of the computer system or of an entire system including
hardware and software.
operation of computer system
The process of entering data and instruction to the computer system is inputting.
Saving data and instruction to the computer to make them readily
available for initial or
additional processing whenever required is storing
add, subtract, multiply, divide, etc.) or logical operation
to, less than, greater then, etc
data to conve
rt them into useful information is
The process of producing useful information or result user such a printed report or visual
Directing the manner and sequence in which all of the above operation
are perform is
To perform above function there are corresponding functional unit.
The computer hardware that
accept or r
data and instruction from the
performs following function
Accepts (or reads) instruction and data
from the user
Converts these instruction data in computer acceptable form
Supplies the converted instruction an
d data to the computer system for further processing
Keyboard and mouse are the examples of input device
The hardware of the computer
system which display or give result which is generated by
processing of data. It performs following functio
Accept the results produce by the internal devices and software, which are in coded form and hence,
cannot be easily
Convert these coded results to human
Supplies the converted results to the user.
and printer are the examples of output device.
The hardware of the computer system which holds(or stores) the following:
Data and instructions required for processing time which are received from input device.
Final result processing, before they are released to an output device.
memory is also known as main
Use to hold running program
Used to hold data ,intermediate results ,and result of ongoing processing of job(s)
Fast in operation
Volatile (looses data on power dissipation)
Use to hold stored program instructions.
Used to hol
and information of stored jobs
Slower than primary storage
Lot cheaper than primary storage
retains data even without
They are additional storage locations to store data during processing time. They appear
in between ALU and CU of CPU
Character storage locations numbers in the main memory like a mail box numbers.
Location numbers remains the same but the contents changes continuously.
The device inside CPU Box which performs Arithmetical & log
ical calculations. It is the place
where the actual execution of
Control Unit (CU):
The control unit of a computer system manages and coordinates the operation of all
other component of the computer sy
stem. It is
like a nerves system of the body; the whole system sending
signal of data program and tells
to process data and to store in the right place.
Central Processing Unit (CPU):
The CU and ALU together constitute a processing
is like brain
f a computer
is responsible for controlling the operation of all other units
of a computer system. It
called micro processor.
It is a brain of the computer system
It is responsible for controlling the operation of
all other units of a computer system
A system has following three characteristics
It has more than one element
All element of a system are logically related
All elements of a system are controlled in a manner to achieve the system goal
A computer is a
system as it comprises of integrated components (input unit, output unit, storage unit,
work together to perform the steps called for in the executing program.
The architecture of CPUs with the small instruction set, fixed length instruction and reduce references to
memory to retrieve operands is known as RISC. It is called
reduce instruction set computer.
The architecture of CPUs with the large instruction set,
variable length instruction and a variety of addressing
mode is known as CISC. It
complex instruction set computer
The architecture of CPUs with
the emerging technology which includes three key features, explicit
parallelism, prediction and sp
is known as
. It is
Units Of The
speed of a computer means the speed
CU and ALU perform operation at
incredible speed. The
by the built
clock (known as system
clock) that emits
millions of regularly spa
ced electric pulse per second (known as clock cycles). It is
measured in hertz .Hertz means one cycle per
second. Normally, several clock
and execute single program
which an instruction is
in clock speed
which is the number of pulse produce per second.
in mega hertz, giga
hertz. Some examples are
Approx year (1970
5 MHz, 8 MHz and 10 MHz
4.77 MHz and 8MHz
8 MHz, 10 MHz and 12 MHz
INTEL 20386 DX
16 MHz, 20MHz and 25 MHz, 33
INTEL 20386 SX/SL
16 MHz, 20MHz and 25 MHz,
25 MHz, 33 MHz and 50 MHz
INTEL 20486 DX2
33 MHz and 66 MHz
60 MHz to 200 MHz
166 200,233 MHz and 266 MHz
166 and higher
INTEL PENTIUM II
233 MHz to
INTEL PENTIUM III
500 MHz, 750 MHz
More than 1.1 GHz up to 2.0
INTEL Dual Core
INTEL Core 2 Duo
A device or a media that can accept data holds them and deliver as per demand at a later time is called
memory. Every computer has a temporary storage built into the computer hardware. It stores instruction and
data of a program mainly when the program is
being executed by the CPU.The
storage memory is
known as main memory or primary memory or simply memory.
of some chips either on
the motherboard or on the small circuit board
the mother board of a
is volatile and
random access property.
Types of main memory:
Random Access Memory
The memory in which time to retrieve stored information is independent of
the address where it is stored. It is
and random access memory.
Types of RAM
Very commonly used RAM. They are refreshed thousa
nd times per sec. They are used
everywhere like in printer.
Special RAM. They are less often refreshed. They are costly than dynamic RAM.
(Computer writes on COMPASS offer
Read Only Memory (
It is non volatile memories chips in which data are stored permanently, and
by programmers .It holds
small amount data and displays it
during to start computer.
A program strong empty memory chip. Once stored a program, it is permanent. Therefore
PROM is non
EPROM (Erasable PROM)
A chip, where the program can be erased by exposing it to ultraviolet
EEPROM (Electrically Erasable PROM
that is Electrically Erasable
PROM. It is a chip in which stored information
using high voltage of electrical pulse .it is also
Auxiliary or Secondary Storage Device
devices that store data supplements main memory of a computer are called auxiliary or secondary
memory. It is
non volatile memory and
used in computer to overcome the limitations of primary
storage memory. The operating speed in it is very slow a
nd cost of per
bit of storage very low than that of the
memory. There are two types of secondary storage device
Types of Auxiliary Storage Device:
It is a device where the data con only be
in the same sequence
in which it is stored. The access time
varies accorting to the storage location of the information being accessed. The example of this type of device
Tape (Sequential Type)
The storage device in
stored information is direct, and
approximately equal access time is required for accessing any information irrespective of its location.
Magnetic, Optical and Magneto Optical disks are the the typical examples of
such a storage device.
Floppy (Random Access Type)
Zip Disk, Super Disk
Jaz Disk (A cartridge)
Super Disk (A cartridge)
Optical Disk (
R , CD
1GB) (About 700
3,000,000 page texts)
It creates CD
ROM or Audio CDs to
It needs a CD
R software package.
It can read CD
R and play Audio CDs.
Writable CD. (Many times
It is like a floppy disk of high storage
looks same as
ROM but has capacity
of 4.7 or 8.5 GB
It is also two types DVD
R and DVD
It is a special type of disk drive.
It can read and write MO
It stores 200 MB faster than CD
It is a compact device of the size of a
plugs into a USB(Universal
Port of the
8 MB to 8 GB
Key Board, Mouse
101 keys, Alphanumeric key, Punctuation keys, Special keys, Arrow keys, etc.
Curser or Pointer controller, developed in 1963 USA.
Track Balls, Joystick
Pointer mover by your palm, or thumb press.
Pointer mover leaver with two buttons (Triggers).
It can read text and pictures to convert it into digitals form and store to print them. It can print
600 dots per inch quality text or Images. There is single color or multiple colored sca
nners. There are half or
full page scanner.
It can manipulate, save, delete, and rotate the images. It sends as digitals input files to the
OCR, Bar Code Reader
Optical Mark Reader (OMR):
OMR is also called mark sensing, which is a technology. It can sense the
presence or absence of the pencil mark. OMR is used in the aptitude texts.
Optical character Reader (OCR)
It reads the page of text and converts images into ASC II codes to store
into the computer. In the future it can print ditto for the user. All OCR system includes an optical scanner. It
enables to take a book and save into a computer file.
Bar code Reader
Bar code reader is a photoelectric scanner that reads the bar code (Vertical Zebra
Striped marks,) printed on the product. In the supermarket, you can find bar codes in ever items.
Magnetic ink character Reader (MICR)
MICR is direct entry method used in the banks. It is a special
type of input device used in ATM.
Speech Input Devices
It is a type of device that allow a person to input data to a computer system by
speaking to it.
Touch Screen, Touch Pad
It is a type of display screen that has the touch sensitive transparent panel covering the
screen. As a mouse
pointer, you can use your finger on screen.
On a portable PC you can find a small touch pad where you can u
se your finger along the
Light Pen, Digitizing tablet
It is special pen, which uses light sensitive defector too select object on the screen display.
This pen is also similar to
It is an electronic tablet. A
stylus pen is used here to draw pictures and to
operate computer. They are called touch tablet
There are two types of output device
copy Output and Hard
copy Output device. Monitor and printer
copy and hard
copy output device.
Monitor and Its Type
The classification of monitor is as follows:
(a) Color wise
(i) colored monitor
(ii) Monochrome monitor
(b) Signal wise
(i) Digital monitor
(i) Box type monitor
(ii) Flat type
monitors (LCD): Liquid Crystal Display
Characteristics, Size, Bandwidth of a Monitor:
14", 15", 17", 24"
densely pixels are packed?
= 640x480 pixels = 300,000 pixels
= 1024x 768 pixels = 800,000 pixels
= 24 bits per pixels = 16 million color
High and monitor
= 1600x1200 pixels = 2,000,000 pixels
and its Types:
common output device for producing hard
output is a printer
. They can also classified as
: uses letter headed hammer, ink ribbon, paper :
Dot matrix & Line printer,
jet, Laser, LCD printer, Thermal printer
Ink jet printer
Ionized ink spray, qualify print, diff. fonts.
Utilizes a laser beam to produce image on the drum. 1200
2400 dpi quality.
& Led printer
Uses liquid crystal to produce im
age. Uses light emitting diodes produce image.
It is a high speed printer 3000 lines/min. It can print only font. No pictures.
Produces images by trashing electrically heated pins against special paper.
only pictures using pen with continuous lines. Multi color plotters use different colored
pens. They are used in the engineering applications.
Sound cards & speakers
Sound card is compulsory in the modem computers where speakers are used.
Sound card e
nables the computer to output sound, to record input from a microphone connected to the
computer and manipulate sound stored on a disk. Sound card translate digital data into analog sounds.
Software is the computer program. A program is the set of logical instructions given to a computer to
perform a certain task. All the logical components and the programs are called the software. So software is an
instruction that given to the computer. Co
mputer software means instructions or data, which are electronically
stored on the storage device. Software is mainly classified into two types.
The software required executing users program is known as system software. It
helps to impro
ve the interface between the user and the computer. It includes operating system and utilities
software that enables computer to functions. Computer cannot be operated without system software. The
system software includes;
rocessors (assemblers, compilers, debugged) and
The software, which is used to perform specific job, is called application
software. This software is available for applications, which are common to many users and organizations. It
includes programs, which do real job for the user. An application progra
m is a computer program which
installed on computers to give users ability to do specific task. For examples word processing, spreadsheet,
DBMS and other end user made programs. There various types of application software/program.
is a must to run a computer. OS performs basic tasks like
recognizing impact from keyboard, sending output to display screen, keeping tracks o files and directories on
the disk. Most commonly used OS are MS
Windows, DOS, XENIX, Mac OS, OS/2, UNIX
, MVS etc. There
are single user and multi
user operating systems.
the program translated by the language processor is understood by the
hardware of the computer. It translates the program written in a programming language into an executable
program. These are
is a program which converts source code into object code after looking whole part of
the source code all at a time
Interpreter is a program which converts source code into object code line by line. The
advantage of the interpreters is
that they can execute a program immediately.
Some time compiler and interpreters are called language translator programs.
Debugged is a program which helps to find the error/mistake to the program
the software that provides additional facilities to the user is called utility program. It
performs very specific tasks, usually related to managing disk drives, printers and other devices, sorting or
margin is done. A call up programs by OS. Transferring
data from one I/O devices to another. Disk repair,
data copy, data move, virus scan etc are utility program
Some examples of
Creating, editing, formatting, previewing coloring line text, designing, tabula
saving, deleting and coping line text. Users do disk top publishing using it.
Creating, editing, formatting line mathematical tables in rows and columns. Using
arithmetical, algebraically, statistical, logical and graphical text documen
ts. Users are the facilities here.
Database Management System (DBMS
It is a collection of record programs. Inserting, deleting,
copying, updating and saving the records are the facilities here.
It is a set of programs, which performs graphical pictures and animations. It has
different facilities like enlarging rotating, coloring, zooming and many more.
Engineering Designing Software
CAL, CAI, CAD, et
. Computer Aided Designing (CAD) is a set
programs, which performs engineering calculations, picture designs, simulations and others.
It helps to solve the problems of the accountant. It is use to account keeping
properly having many facilities. Accounting package, Repacka
ge and Tally are the examples of the
It is a collection of programs which performs the statistical activities. It is a kind of
powerful statistical tool. SPSS and microstate are the good examples.
tailor made software
Locally made any type of software for any type of local institutes.
To run above computer hardware and software and the whole computer system in the big organization, the
different types of the technical personals are
needed. Their types and post names are as given below. It is
called human ware.
Data Entry Operator
Computer System Engineer
Operating System is the base program on a computer.
It tells the computer how to work or operate.
operating system also
allows us to load other programs that do specialized tasks on to our computer. It is
an organized set of programs that control the overall operation of the computer system. It can interact
between the computer hardware and software, and the user. The opera
ting system is the core software
component of our computer. It performs many functions and is, in very basic term, and interface
between computer and the outside world. In the section about hardware, a computer is described as
consisting of several compone
nt parts including monitor, keyboard, mouse, and other parts. The
operating system provides an interface to these parts using what is referred to as “drivers”. This is why
sometimes when you install a new printer or other piece of hardware, your system wil
l ask you to install
more software called a driver.
What does a driver do?
A driver is a specially written program which understands the operation of the device it interfaces to, such as
printer, video card sound card or CD ROM drive. It translates
commands from the operating system or user
into commands understood by the component computer part it interfaces with. It also translates responses
from the component computer part back to responses that can be understood by the operating system,
on program, or user. The below diagram gives a graphical depiction of the interfaces between the
operating system and the computer component;
Functions Of The OS
To keep processing jobs in sequence, determining main memory, secondary storage
capability and their timing.
Any big jobs are classified and grouped in some order, Batch wise they can be
processed. For example number wise or alphabetical
wise or VDC wise or district wise, etc.
Data can be edited, updated and saved in any storage device. It can be retrieved and
stored at any time any data.
Some OS have a feature called virtual storage. Such OS can increa
se the capacity of
the main memory without increasing its size, during processing time, when it is necessary.
For the smooth input data flow to the CPU and output data flow from the CPU, it can
manage. In the big computer system also OS ca
n handle very carefully and accurately. It can stop to handle
the data to the unauthorized persons, so it can save data from the less.
Classification of the OS:
Classifications of the OS are as follows
Any OS, at the same time if more than user can use the OS that is called multi user OS.
Some OS permits hundreds or thousands o your to use concurrently. The OS called MVS for the main frame
and UNIX for the minicomputer are the multi user OS.
Multi processing OS permits many users to use different programs at the same time.
MVS and UNIX are two examples used as multi processing OS. Multi processing OS is more complicated
than single process systems. Multi processing also refers to the
utilizing of multiple CPU in a single computer
system called parallel processing.
Multi tasking permits more than one program to run currently. In multi tasking, only one
CPU is involved, but it switches from one program to another so th
at it gives the appearance. Executing all
the programs concurrently. There are two types of multi tasking
CPU time slices to each program.
Each program controls CPU as needed.
If the program is not using CPU, however, it c
an allow another program to us it temporally. OS/2, Windows
95, Windows NT, Amiga and UNIX use preemptive multi tasking. But
Windows 3.x and the Multi Finder use co
Multi threading allows different parts of a single program to run currently. If is a
ability of an operating system to execute different parts of a program called threads simultaneously, without
interfering with each other.
Real time syste
m is an interactive processing system with severe time limitation. Several
stations (PC's) can operate a database at the same time. The central input file are updated each time and
inquires are answered correctly. Hotel reservation, Air lines ticket reserv
ation and Car rental are the examples
of real time system. But DOS and UNIX is not the examples real time system.
The language which is used to
expressed algorithm in computer understandable form or to make
computer is called programming
language. In brief Programming language means a computer
broad classifications of programming languages are Machine
Language, Assembly Language,
language which is written as strings of binary 1s and 0s.It understood by
the computer without
using a translator. This is basically
based at binary system like (On/OF), (Yes/No),
(True/False), (Right/ wrong) and (1,0) etc. About 50/60 years back, the comp
uters like ENIAC had used the
language only by many switches ON/OFF. There were about 6000 switches for a single program. For the
next program the switches had to reset. A process that might take weeks. Thus the programming were like
11110101, 11010011 000
This was very tedious s
uch language is called machine language.
Note: Machine language is also kwon as 1
language that using alph
anumeric mnemonic codes instead of numeric
codes for the instructions in the instruction set e.g using ADD instead of 1110(binary) or 14(decimal) for
instruction to add.
o reduce programming complexity and provide some standardization, assembly
is known as
assembly or symbolic
language use abbreviation or
210(8, 13), O2B (4, 7)
When we provide such assembly language command to
the compute, it converts into machine language then it performs the
Assembly language is also kwon as 2
Machine language and assembly language are known as low
to broken English language
ent to the machine language
Level language. In this language the programmer need not know anything about the internal
structure of computer on which high
level language program will be execute.
written in high
using English words and familiar mathematical symbol and expression.
, C, C
are some examples
of high level language.
High level language
are classified as
generation computer language
generation computer language
generation computer language
uage like BASIC, PASCAL, COBOL
FOTRAN are called procedural
oriented language. They are designed to express the logic and procedure of the
problem. All of them are called high level programming language or third generation language.
dvantages of the procedural oriented language
Program statements are very similarly to English language
Very easy to write program.
Less time consuming to write program.
Easier to understand and edit.
The programming languages are machine independents.
long time to execute.
The programming language does not look active.
Problem oriented language:
The fourth generation languages are called
problem oriented language
They are high level language, which are used designed to solve specific problems like
management system package program, etc.
The fourth generation languages also are used to
application tools as fo
Personal computer application software
Query language and report generator
Design support systems and financial planning language
computer application software
It means word processor, spreadsheet, DBMS, graphics, integrated packages,
owerPoint and other tailor
Query language an
d report generator:
It means query language allows people who are non programmer to search database using certain selection
xample, Airlines ticket reservation, Room booking in hostel, MIS, School information system etc.
Report generators are designed for people needing to prepare their reports easily, e.g.
QBE, SQL, HAL,
Answer/Database, Data retrieve etc.
support systems a
nd financial planning language:
Decision support system (DSS) is made for managers or chief Execution officers to take decisions. Financial
also a kind of decision support system, that are employed or mathematical
Macro Stat, SPSS, Accounting packages, Metaphor, STRATAGEM, etc.
Application generators are a collection of set of program modules, preprogrammed for different jobs. A
uses this required report. Example the user inters his pass word and unique account code numbers,
presenters as in ATM machine to get money.
There are other examples of application generators as: FOCUS, FUSION, SAS, SYSTEM, LINE II,
Fourth generation language
Use by programmer.
Use by non
Requires specification of how to perform
Requires specification of what task is to be performs.
alternatives must be specified
Default alternatives are built in.
Requires large number of procedural
Requires few instructions.
Code is difficult to read, understand and
Code is easy to understand because of English
Language for batch operation.
Language developed for on
Difficult to learn.
Easy to learn.
Difficult to debug.
Easy to debug.
Typically file oriented.
Typically database oriented.
still in developing stage. They will be using in AI and expert systems.
They have two characteristics.
More human like speaking
More smarter with remembering capacity.
There popular natural
LISP and PROLOG.
A computer program that translates an assembly language program to its machine language equivalent is
High level programming language to work on the computer it must be translated
into machine language.
There are two types of translators like.
A translator program (software package) that translates a high
level language program into its
equivalent machine language program is called
compiler. In brief it reads whole program
and converts it
into machine language.
Complier translates the whole program into machine language all at a time.
The translation processor is called
program is called
ut its machine language code is called
A language processor that translates a statement of high
level language, and immediately
executes it before translating the next source language statement is called interpreter. In brief it
and converts into machine language; one statement at a time.
Interpreters translate each program statement
into machine code just before the program statement is to be executed. This process continues till whole
process completes. But compile
r language is better than interpreted language as they can be executed later.
Complier is used in COBOL, C, C++ and FORTRAN. On the other hand interpreter language in BASIC
programming. Interpreter do not need object code and so usually easier to develop.
(i.e. to code &test).
Thus, there are code complier, C compiler and BASIC Interpreter.
that is used to properly combine all objects program files (modules) of a software,
and to convert them
into software’s final executable form is called linker.
The Compilation Process:
Source files are complied into object files, then through linkers object files using routine libraries it produces
executable programs. Thus object codes pass through
linkers. The linker combines modules and gives real values
to all symbolic address.
Hence, the linker translates object files into executables program files.
General Software Features &Trends:
We know the series of instructions that
performs a particular task in the computer is called a program. There
are two categories of programs like system software and application software.
A system software means combination of operating system, control program, database management
tion software. An application, software means any program that processes the data for the
user. In short, the software tells hardware how to process the data.
At present, in the world software projects are becoming more and more complex in size,
ation, and technologies used. Now most software products manage to millions of users in different
shape and size. For example word processors, ERP packages and SCM tools, which run mainframes and
client server systems; different versions of web browsers fo
r the PC and MAC; we have DBMS that run on
MVS, UNIX, Windows NT, Linux and so on. The competition and the advancements in technology are
Now computer and communication are becoming integral part of our lives. The driving force behind
ll these advancement is the computer software. They are becoming more and more complex. For example,
the software is being used in controlling satellites, operating. Intercontinental
Ballistic Missiles, running
banks, hospitals, airlines, hostels, etc, in
cluding door locking system and robotics.
Software may communicate via internet, using e
mail or videoconferencing technologies. Thus its
development is in advance and changing very fast. Now the general software features are given below.
Presently, most of the software companies are producing more and more user’s friendly, software's.