Introduction to Computer
Computer is an advanced electronic device that takes raw
data as input from the user and processes these data under
the control of set of instructions (called program) and gives
the result (output) and saves output for the future use.
A computer is a combination of hardware and
software resources which integrate together and provides
various functionalities to the user. Hardware are the physical
components of a computer like the processor, memory
devices, monitor, keyboard etc. while software is the set of
programs or instructions that are required by the hardware
resources to perform various operations as per the
requirement of users.
What is Computer?
 A computer is a device that can be instructed to
carryoutsequences
of
arithmetic
or
logical
operations
automatically. Modern computers have the
ability to follow generalized sets of operations,
called programs. These programs enable
computers to perform an extremely wide range
of tasks
Introduction to Computer
What is Data?
Data. Data in a computer
terminology mean raw facts and
figures.
For ex-mohan,1977 etc.
What is Information?
means what we get after processing.
Data Vs. Information?
you should understand that what goes in the
computers is data and what comes out of them
is information.
This process of turning data into information is
also known as information processing cycle.
BASIC COMPUTER
ORGANISATION
COMPONENT OF A COMPUTER SYSTEM
Functional components of a Computer
Input Unit
The input unit consists of input
devices that are attached to the
computer.
These devices take input and convert
it into binary language that the
computer understands.
Some of the common input devices
are keyboard, mouse, joystick,
scanner etc.
Input Unit
Central Processing Unit(CPU)
Once the information is entered
into the computer by the input
device, the processor processes it.
The CPU is called the brain of the
computer because it is the control
centre of the computer.
 As the CPU is located on a small
chip, it is also called the
Microprocessor.
Central Processing Unit(CPU)
• The
CPU
has
three
main
components which are responsible for
different functions –
Arithmetic Logic Unit (ALU)
The ALU, as its name suggests
performs mathematical calculations
and
takes
logical decisions.
Arithmetic
calculations
include
addition, subtraction, multiplication
and division.
Logical decisions involve comparison
of two data items to see which
one is larger or smaller or equal.
Control Unit (CU)
The Control unit coordinates and
controls the data flow in and out
of CPU and also controls all the
operations of ALU, memory registers
and also input/output units.
It is also responsible for carrying out
all the instructions stored in the
program.
Memory Registers
A register is a temporary unit of
memory in the CPU.
These receive data/information and
then this data/information is held in
them as per the requirement.
Output Unit
The output unit consists of output devices that are
attached with the computer.
It converts the binary data coming from CPU to
human understandable from. The
common output devices are monitor, printer,
plotter etc.
Classification of Computers
Micro Computers
These are also known as Personal
Computers. These type of digital
computer uses a microprocessor (a
CPU on a single chip) and include both
desktops and laptops.
Micro Computers
Small portable computers such as
PDAs (Personal Digital Assistants) and
tablets with wireless computing
technology are increasingly becoming
popular.
Micro Computers
Micro Computers
Micro Computers
Mini Computers
These computers can support
multiple users working simultaneously
on the same machine.
These are mainly used in an
organization
where
computers
installed in various departments are
interconnected. These computers are
useful for small business organizations.
Mini Computers
Examples
Honeywell-Bull DPS 6/DPS 6000 series.
IBM midrange computers.
Interdata 7/32 and 8/32.
Varian 620 100 series.
Mainframe Computers
These computers are large and very
powerful computers with very high
memory capacity.
These can process huge databases
such as census at extremely fast rate.
They are suitable for big organizations,
banks, industries etc. and can support
hundreds of users simultaneously on
the network.
Mainframe Computers
History of IBM mainframes, 1952–
presentMarket name700/7000 series
System/360
System/370
IBM 308X
IBM 3090
System/390
zSeries 900, 800, 990, and 890
System z9
System z10
Super Computers
These are fastest and very expensive
computers.
They can execute
instructions per second.
billions
of
Super Computers
These are multiprocessor, parallel
systems suitable for specialized
complex
scientific
applications
involving
huge
amounts
of
mathematical applications such as
weather forecasting.
Super Computers
The main difference between a
supercomputer and a mainframe is
that a supercomputer executes fewer
programs as fast as possible whereas a
mainframe executes many programs
concurrently.
Hardware and Software
Hardware and Software
A computer consists of both hardware and
software and both are equally important for
the working of the computer system.
The electronic components of a computer
system that we can see and touch are called
hardware.
Software is a general term used for
computer programs that control the
operations of the computer.
Hardware and Software
A program is a sequence of instructions
that perform a particular task. A set of
programs form a software.
It is the software which gives hardware its
capability.
Hardware is of no use without software
and software cannot be used without
hardware.
Types of Software
Software can
categorized as:
be
System Software
Application Software
Utility Software
broadly
are
Types of Software
System Software
System Software is the software that is directly
related to coordinating computer operations and
performs tasks associated with controlling and
utilizing computer hardware. These programs assist
in running application programs and are designed to
control the operation of a computer system.
System Software
System software directs the computer
what to do, when to do and how to
do. System software can be further
categorized into:Operating System
Language Translators
Operating System
 An Operating system is the most
important system software.
It is a set of programs that control
and supervise the hardware of a
computer and also provide services to
application software, programmers
and users.
Operating System
Some of the popular operating
systems used in personal computers
are DOS, Windows, Unix, Linux,
Solaris, etc.
COMPILERS AND
INTERPRETERS
COMPILER
Its a translator used to convert HLL to MLL and vice
versa.
COMPILER
Its a translator used to convert HLL to MLL and vice
versa.
INTERPRETER
Its a translator used to convert HLL to MLL and vice
versa.
Application Software
An application software is bought by the user to
perform specific applications or tasks.
Say for example making a document or making a
presentation or handling inventory or managing the
employee database.
Application Software
 An application software can be of two types:
General Purpose Application Software
&
Customized Application software.
Application Software - General Purpose
Application Software
 Some of the application software is
made for the common users for day to
day applications and uses.
These are also referred as Office
Tools.
 The users may use them in the
manner they want.
Application Software - General Purpose
Application Software
 Some of the popular types of general
purpose application software are:
Word Processor
Presentation Tools
Spreadsheet Packages
Database Management System
Application Software - Customized
Software
Customized Software is one which is
tailor made as per the user’s
requirement. Such type of software is
customer specific.
 It is made keeping in mind the
individual needs of the user and so are
also referred as Domain Specific Tools
Application Software - Customized
Software
Examples:
Inventory Management System &
Purchasing System
School Management System
Payroll System
Financial Accounting
Hotel Management
Reservation System
Weather Forecasting system
MEMORY CONCEPTS
Memory
Memory is one of the most
important
components
of
a
computer system as it stores data
and instructions.
Every memory chip contains
thousands of memory locations. In
the computer, the data is stored in
the form of bits and bytes.
Memory
A bit is the smallest storage unit of
memory. A nibble is a collection of 4
bits. Eight bits combined together to
form a single byte, which in turn
represents a single character
Memory Units
Types of Memories
The computer memories can be
divided into following categories:
Primary Memory
Cache Memory
Secondary memory
Primary Memory
Primary memory or main
memory is a Metal Oxide
Semiconductor (MOS) memory
used for storing program and
data during the execution of the
program. It is directly accessible
to CPU.
Primary Memory
Broadly primary memory
can be of two types :–
1. RAM (Random Access Memory)
2. ROM (Read only memory).
Random Access Memory (RAM)
the memory can be accessed from
any desired location randomly.
The instructions and data that we
input into the computer are stored in
the RAM of the Computer.
It is a read/write memory, so data
can be both read from and written to
the RAM.
Random Access Memory (RAM)
It is a volatile memory and loses its
contents when the power is switched
off or interrupted.
Nowadays RAMs are available in
gigabytes. The normal memory
access time of a RAM is 20-80 ns.
Random Access Memory (RAM)
RAM can be broadly classified into
two categories:
Dynamic RAM (DRAM) and
 Static RAM (SRAM).
Dynamic RAM (DRAM)
It consists of a transistor and a
capacitor that stores electric charge.
The DRAMs are physically smaller,
cheaper and slower memories. They
are slower because the data stored in
them
needs
to
continuously
refreshed and this consumes lot of
processor time.
Static RAM
This type of RAM is large in physical size but is an
expensive and faster memory.
It is faster because it is made up of flip flops to
store data and these flip flops do not require any
refreshing.
Types of ROM
(i) PROM : It’s programmable ROM. Its
contents are decided by the user. The
user can store permanent programs,
data etc in a PROM. The data is fed
into it using a PROM programs.
Types of ROM
(ii) EPROM : An EPROM is an erasable
PROM. The stored data in EPROM’s
can be erased by exposing it to UV
light for about 20 min. It’s not easy to
erase it because the EPROM IC has to
be removed from the computer and
exposed to UV light. The entire data is
erased and not selected portions by
the user. EPROM’s are cheap and
reliable.
Types of ROM
(iii) EEPROM (Electrically Erasable
PROM) : The chip can be erased &
reprogrammed on the board easily
byte by byte. It can be erased with in
a few milliseconds. There is a limit on
the number of times the EEPROM’s
can be reprogrammed, i.e.; usually
around 10,000 times.
Cache Memory
 Cache memory is a special high
speed memory made up of high speed
static RAMs.
It is used to hold frequently
accessed data and instructions.
We know that the processing speed
of CPU is much more than the main
memory access time of the computer.
Secondary Memory
Secondary Memory
The major limitation of primary
memory is that it has limited storage
capacity and is volatile.
To overcome this limitation we have
secondary memory storage devices.
This type of memory is also called
external memory. For example Floppy
disk, hard disk, USB drives, CD/DVDs
Hard disk
A hard disk consists of one or more
circular disks called platters which are
mounted on a common spindle. Each
surface of a platter is coated with a
magnetic material. Both surfaces of
each disk are capable of storing data
except the top and bottom disk where
only the inner surface is used.
Hard disk
The information is recorded on the
surface of the rotating disk by magnetic
read/write heads. These heads are
joined to a common arm known as
access arm. This arm moves over the
surface of the rotating disk as shown in
the figure (next slide)
Rotating Arm of Hard disk
OPTICAL DISKS
OPTICAL DISKS
An optical disk is primarily used as a portable
and secondary storage device. It can store more data
than the previous generation of magnetic storage
media, and has a relatively longer lifespan. Compact
disks (CD), digital versatile/video disks (DVD) and Bluray disks are currently the most commonly used
forms of optical disks. These disks are generally used
to:
Distribute software to customers.
Store large amounts of data such as music, images
and videos.
Transfer data to different computers or devices.
Back up data from a local machine.
EVOLUTION OF COMPUTING DEVICE
First Generation (1940-56):
The first generation computers used vacuum
tubes & machine language was used for giving the
instructions. These computers were large in size & their
programming was difficult task.The electricity consumption
was very high. Some computers of this generation are
ENIAC, EDVAC, EDSAC & UNIVAC-1.
In this generation, mainly batch processing
operating system was used. Punch cards, paper tape,
and magnetic tape was used as input and output
devices. The computers in this generation used machine
code as the programming language.
Second Generation (1956-63):
In 2nd generation computers, vacuum tubes were replaced by
transistors. They required only1/10 of power required by
tubes. This generation computers generated less heat & were
reliable. The first operating system developed in this
generation. IBM 1620, IBM 7094, CDC 1604 are the examples
of this generations computers.
In 2nd generation, magnetic cores were used
as the primary memory and magnetic tape and magnetic disks
as secondary storage devices.
In this generation, assembly language and high-level
programming languages like FORTRAN, COBOL were used. The
computers used batch processing and multiprogramming
operating system.
Third Generation (1964-71):
The 3rd generation computers replaced transistors with
Integrated circuit known as chip. From Small scale integrated
circuits which had 10 transistors per chip, technology
developed to MSI circuits with 100 transistors per chip. These
computers were smaller, faster & more reliable. High level
languages invented in this generation.
The IC was invented by Jack Kilby. This
development made computers smaller in size, reliable, and
efficient. In this generation remote processing, time-sharing,
multiprogramming operating system were used. High-level
languages (FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC,
ALGOL-68 etc.) were used during this generation. IBM-360
series, Honeywell-6000 are some examples of computers in 3rd
generation. .
Fourth Generation (1972- 1980):
LSI & VLSI were used in this generation. As a result
microprocessors came into existence. The computers using this
technology known to be Micro Computer. High capacity hard
disk were invented. There is great development in data
communication.
Fourth generation computers became
more powerful, compact, reliable, and affordable. As a result, it
gave rise to Personal Computer(PC) revolution. In this
generation, time sharing, real time networks, distributed
operating system were used. All the high-level languages like
C, C++, DBASE etc., were used in this generation.
Fifth Generation (1980-Present & Beyond):
Fifth generation computing devices, based on artificial
intelligence, are still in development, though there are some
applications, such as voice recognition, that are being used
today. The use of parallel processing and superconductors is
helping to make artificial intelligence a reality. Quantum
computation and molecular and nanotechnology will radically
change the face of computers in years to come.
Some computer types of this generation are −
Desktop
Laptop
Note Book
Ultra Book
MEMORY UNITS: Memory is used to store the data for later
reference. The smallest unit is bit, which mean either 0 or 1.
❑ 1 bit = 0 or 1
❑ 1 Byte = 8 bits
❑ 1 Nibble = 4 bits
❑ 1 Kilo Byte = 1024 Byte= 210 Byte
❑ 1 Mega Byte = 1024 KB= 210 KB
❑ 1 Giga Byte = 1024 MB= 210 MB
❑ 1 Tera Byte = 1024 GB= 210 GB
❑ 1 Peta Byte =1024 TB= 210 TB
❑ 1 Exa Byte =1024 PB= 210 PB
❑ 1 Zetta Byte = 1024 EB= 210 EB
❑ 1 Yotta Byte = 1024 ZB= 210 ZB
CONCERNS OF COMPUTER SECURITY
Computer Security is concerned with four main areas:
1. Confidentiality:- Only authorized users can access the data resources
and information.
2. Integrity:- Only authorized users should be able to modify the data
when needed.
3. Availability:- Data should be available to users when needed.
4. Authentication:- are you really communicating with whom you think
you are communicating with
OPERATING SYSTEM ARCHITECTURE
TYPES OF OPERATING SYSTEM
SINGLE USER OS:
As the name implies, this operating
system is designed to manage the computer so that one user can
effectively do one thing at a time.
MULTI USER OS: A multi-user operating system (OS) is a
computer system that allows multiple users that are on different
computers to access a single system's OS resources
simultaneously.
MULTI TASKING OS: Multitasking, is an operating system,
that
allows a user to perform more than one
computer task (such as the multiple operation of an application
program) at a time. The operating system is able to keep track
of where you are in these tasks and go from one to the other
without losing information.
MULTI PROCESSING OS:
sometimes
used
to
refer
to
Multiprocessing is
the
execution
of multiple concurrent processes in a system. A program in
execution is called process.
EMBEDDED OS:
Embedded Operating System is an
Embedded System’s Operating System. Embedded Systems
are a specially designed computer system that essentially
contains software and hardware for performing specific
tasks. Mobile Phones, Laptops, Cameras, Washing Machines,
ATMS, and Hair Straightener etc are examples of embedded
operating sytem.
UTILITY SOFTWARE
Utility software is designed to aid in analyzing, optimizing,
configuring and maintaining a computer system. It supports
the computer infrastructure. This software focuses on how an
OS functions and then accordingly it decides its trajectory to
smoothen the functioning of the system. Software’s like
antiviruses, disk cleanup & management tools, compression
tools, defragmenters, etc are all utility tools. Some examples of
utility tools are:
K7 Antivirus, WinRAR, WinZip etc.
Data
Representation
In general term computer represent information in different types of
data forms i.e. number , character ,picture ,audio , video etc.
Computers are made of a series of switches/ gates. Each switch
has two states: ON(1) or OFF(0).That's why computer works on
the basis of binary number system(0/1).But for different
purpose different number systems are used in computer world
to represent information. E.g. Octal, Decimal, Hexadecimal.
Decimal Number System
Characteristics
Positional
Binary Number System
Characteristics
Positional
Most (digital) computers use the binary number system Why?
Computers are made of a series of switches/ gates. Each switch has two
states: ON(1) or OFF(0).That's why computer works on the basis of
binary number system(0/1).
Decimal-Binary Equivalence
Binary – Decimal Conversion
Using positional notation
Decimal-Binary Conversion
Using the Division Method:
Divide decimal number by 2 until you reach zero, and then collect the
remainders in reverse.
Hexadecimal Number System
Characteristics
Positional
Computer programmers often use the hexadecimal number
system,Why?
Computers only work on the binary number system.
The hexadecimal number system is commonly used
to describe locations in computer memory. They are
also used in assembly language instructions.
Hexadecimal to decimal
• Decimal to hexadecimal
• Read from bottom to top: 2516
Binary - hexadecimal
Binary to hexadecimal
Convert 1101001102 to hex
Starting at the right end, split into groups of 4:
(pad empty digits with 0)
Hexadecimal to Binary
Convert
3D916 to binary
Convert each hex digit to 4 bits:
(can remove
leading zeros)
Octal to decimal
positional powers of 8:
decimal positional value:
Octal number:
Decimal to octal
Using the Division Method:
Example 1:
Representing Unsigned Integers
Mathematics
Computer programming
Representing Unsigned Integers
Adding Unsigned Integers
Start at right column
Proceed leftward Carry 1
when necessary
String representation
String is
any finite
sequence
of
characters.Any string includes letters,
numerals,
symbols
and
punctuation
marks.
Computers are designed to work internally with
numbers. In order to handle characters, we need to
choose a number for each character. There are
many ways to do this
String representation
Following are some form of character set
• ASCII
• UNICODE
• ISCII
ASCII
String representation
It is most common coding system (Pronounced ass-key).
ASCII =American National
Standard
Code for
Information Interchange
It is Defined in ANSI document X3.4-1977.
It is a 7-bit code. Its 8th bit is unused (or used for a
parity bit)
String representation
ASCII
“Hello, world” Example
UNICODE
It is a
worldwide character-encoding
standard .Its main objective is to enable a
single, unique character set that is
capable of supporting all characters from
all scripts, as well as symbols, that are
commonly
utilized
for
computer processing throughout the
world.
ISCII
ISCII
stands
for
Indian
Script
Code
for
Information Interchange for Indian languages. It is an 8bits code to represent Indian scripts.
The Department of Electronics (DOE) has established
standard and standard are in action from 1983.
These codes are used for 10 Indian scriptsDevanagri, Punjabi, Gujrati, Udia, Bengali, Asami,
Telgu,
Kannad, Malayalam
and
Tamil.
C-DAC
(established in August- September, 1988) developed
standard for font coding in 1990 is called ISFOC
(Indian Standards for Font Coding).
Data
Representation
In general term computer represent information in different types of
data forms i.e. number , character ,picture ,audio , video etc.
Computers are made of a series of switches/ gates. Each switch
has two states: ON(1) or OFF(0).That's why computer works on
the basis of binary number system(0/1).But for different
purpose different number systems are used in computer world
to represent information. E.g. Octal, Decimal, Hexadecimal.
Decimal Number System
Characteristics
Positional
Binary Number System
Characteristics
Positional
Most (digital) computers use the binary number system Why?
Computers are made of a series of switches/ gates. Each switch has two
states: ON(1) or OFF(0).That's why computer works on the basis of
binary number system(0/1).
Decimal-Binary Equivalence
Binary – Decimal Conversion
Using positional notation
Decimal-Binary Conversion
Using the Division Method:
Divide decimal number by 2 until you reach zero, and then collect the
remainders in reverse.
Hexadecimal Number System
Characteristics
Positional
Computer programmers often use the hexadecimal number
system,Why?
Computers only work on the binary number system.
The hexadecimal number system is commonly used
to describe locations in computer memory. They are
also used in assembly language instructions.
Decimal-Hexadecimal Equivalence
Hexadecimal to decimal
• Decimal to hexadecimal
• Read from bottom to top: 2516
Binary - hexadecimal
Binary to hexadecimal
Convert 1101001102 to hex
Starting at the right end, split into groups of 4:
(pad empty digits with 0)
Hexadecimal to Binary
Convert
3D916 to binary
Convert each hex digit to 4 bits:
(can remove
leading zeros)
Octal to decimal
positional powers of 8:
decimal positional value:
Octal number:
Decimal to octal
Using the Division Method:
Example 1:
Representing Unsigned Integers
Mathematics
Computer programming
Representing Unsigned Integers
Adding Unsigned Integers
Start at right column
Proceed leftward Carry 1
when necessary
String representation
String is
any finite
sequence
of
characters.Any string includes letters,
numerals,
symbols
and
punctuation
marks.
Computers are designed to work internally with
numbers. In order to handle characters, we need to
choose a number for each character. There are
many ways to do this
String representation
Following are some form of character set
• ASCII
• UNICODE
• ISCII
ASCII
String representation
It is most common coding system (Pronounced ass-key).
ASCII =
American National
Standard
Code
for Information Interchange
It
is
Defined
in
ANSI document X3.41977. It
is
a
7-bit code.Its 8th bit is unused
(or used for a parity bit)
Two general types of codes:
95 are “Graphic” codes (displayable on a console) 33
are “Control” codes (control features of the console or
communications channel)
String representation
ASCII CHART
LSB
String representation
ASCII
“Hello, world” Example
UNICODE
It is a
worldwide character-encoding
standard .Its main objective is to enable a
single, unique character set that is
capable of supporting all characters from
all scripts, as well as symbols, that are
commonly
utilized
for
computer processing throughout the
world.
ISCII
ISCII
stands
for
Indian
Script
Code
for
Information Interchange for Indian languages. It is an 8bits code to represent Indian scripts.
The Department of Electronics (DOE) has established
standard and standard are in action from 1983.
These codes are used for 10 Indian scriptsDevanagri, Punjabi, Gujrati, Udia, Bengali, Asami,
Telgu,
Kannad, Malayalam
and
Tamil.
C-DAC
(established in August- September, 1988) developed
standard for font coding in 1990 is called ISFOC
(Indian Standards for Font Coding).