Monitor
System Unit
Keyboard
Floppy Disk
Drive
CD-ROM /
DVD-ROM Drive
Mouse
A computer is an electronic machine that accepts
information (Data), processes it according to specific
instructions, and provides the results as new
information.
Chapter:o1
Computer overview
=> Computer: A computer is an
electronic device that can perform a
different types of operations in
accordance with set of instructions is
called program.
=> Data: Data are raw facts.
=>Information:
Information
is
meaningful data.
=> Input-Process-Output(IPO Cycle) : Certain input
is needed to accomplished a task , a process is
carried out on the input to obtain the output.
Functional
INPUT
UNIT
Components of a computer:
CENTRAL
PROCESSING UNIT
OUTPUT
MAIN MEMORY
In IPO Cycle, First stage is performed in
computer by input unit, Second stage is
performed by its central processing unit and the
Third stage is performed by output unit.
The main memory holds the input and
intermediate output during the processing.
=>INPUT UNIT: The input unit is
performed by the input devices
attached to the computer. Input unit is
responsible for taking input and
converting
it
into
computer
understandable form(the binary code).
EXAMPLES:KEYBOARD,MOUSE
MICR, OMR, OCR, JOYSTICK.
=> Central Processing Unit: The CPU
is the control Centre for a computer .it
guides
,
directs,
governs,
its
performance. It is brain of computer.
=> The CPU divided into two parts:
(a).Arithmetic Logic UNIT(ALU): The ALU
performs all four arithmetical (+, -,*,/) and
some logical operations(<, >,<=,>=,<>).
(B) CONTROL UNIT(CU): The CU control
and guides the interpretation , flow and
manipulation of all data and information.
The CU sends control signals until the
required operation are done properly by
ALU and memory. It also responsible for
execute
the program. The CU gets
program instruction from memory and
executes the one after the other. After
getting the instructions from memory in
CU, the instruction is decoded and
interpreted.
=>OUTPUT UNIT: The output unit is performed by
the output devices attached to the computer. the
output coming from CPU is in the form of electrical
binary signals which needs conversion in some form
which can be easily understood by human beings i.e.
characters, graphical or audio visual.
Examples: Monitor, printer , plotter, speaker.
=> MEMORY: The memory is a device which can
store the data and information.
=> MEMORY CELL: It is a device which can store
a symbol selected from set of symbols.
bit
cell 0
01 1
cell
0
0
0
1
1
0
=> BYTE OR NIBBLE: A group of 8 bits is
called byte and a group of 4 bits is know as
Short Name
Full Name
nibble. Unit
1 Bit
Bit
Binary Digit
8 Bits
1 Byte
Byte
2 10 i.e. 1024 bytes
1 KB
Kilo Byte
2 10 i.e. 1024 KB
1 MB
Mega Byte
2 10 i.e. 1024 MB
1GB
Giga Byte
2 10 i.e. 1024 GB
1TB
Terra Byte
2 10 i.e. 1024 TB
1PB
Peta Byte
2 10 i.e. 1024 PB
1EB
Exa Byte
2 10 i.e. 1024 EB
1ZB
Zetta Byte
2 10 i.e. 1024 ZB
1YB
Yotta Byte
2 10 i.e. 1024 YB
1 BRONTO BYTE
Bronto Byte
2 10 i.e. 1024 Bronto
Bytes
1 GEOP BYTE
Geop Byte
=> There are two types of memory
(a). Primary (Main ) Memory: It is also know
as temporary Memory. Ram and Rom
(b). Secondary Memory: To store the data
and information permanently. CD, Hard disk.
=> Hardware : The physical and tangible
parts of the computer. i.e. The components
that can seen and touched. Monitor ,mouse
etc.
=> peripherals: The peripherals are devices
that surround the system unit. Examples:
keyboard, mouse, speaker, printer, monitor.
=> Software:
The set of program that
Types of Software
There are two types of software
1.System software
2. Application Software
 System software: The software that
controls internal computer operations is
called system software
 system software Divided into two
parts
Operating system
 Language system.
 Operating system(os): An operating system is a
program which acts as an interface between a user
and the hardware(i.e. all computer resources)
Functions of operating system:
(i).It provide the instructions to prepare
user
interface.i.e, way to interact with user whether
through typed commands or through graphical
symbols.
(ii). Loads necessary programs (into the computer
memory) which are required for proper compute
functioning.
(iii). Coordinates how programs work with the CPU ,
keyboard, Mouse, Printer, and other Hardware as
well as with other software
(iv). Manages way information is stored on and
retrieved from disks
A set of software instructions that tells the computer what to
do is called a computer program.
 Major Component of Computer System are:
1.Single Program OS. As the name suggests , this OS is
single user operating system , so only one user program can
be supported and executed by it at any point.
2.MultiProgram OS. It supports multiprogramming.i.e., more
than one user can be supported by it, therefore ,more than
one user programs are loaded and active in the main store at
he same time.
3.Time Sharing OS. This OS uses the time sharing
technique. Each active user program is given a fair share of
CPU time(δ),if the time elapses or an I/O operation is
requested, CPU shifts over to the next jobs waiting and the
previous program.
4.Real Time os: The jobs have fixed deadlines and the jobs
have to be completed within their deadlines. the system
performance is measured by its ability to complete its jobs
within specified deadlines. If a job cannot be complete within
its deadline, its situation is called deadline overrun.
5. Multiprocessing os: The Multiprocessing os is capable of
handling more than one processors as the have to be
executed on more than one processor(CPU)
Examples of operating systems are: Unix,
Windows NT, Windows XP, MS-DOS, Linux, Solaris,
VMS, OS/2 and System
=>Language processors: It is a collection of
program that convert high level language program
into machine level language program.
High-level language: A high-level language consists
of instructions, or statements, that are closer to
English and common mathematical notation.
When programming in a high-level language, you do
not have to concern yourself with the specific machine
language
of the CPU.
.
Assembler: It translates(converts) the assembly
language program into an equivalent machine
language program.
Interpreter: IT Converts a High level Language
program into machine language by converting
and executing it line by line. if there is any error
in any line, it reports it at the same time and
program execution cannot resume until the error
is rectified.
Once a given instruction has been executed, then
it translates and executes the next, and so on.
Compiler: It Translate(convert) the Entire HLL
program into machine language program in one
go, and reports all errors of the program along
with the line numbers.
All instructions are compiled before any are
executed by the CPU.
Application Software: It is a set of programs
necessary to carry out operations for a specified
application.
=> Application software Categories into
two types:
(a). Customized Application software :
This type of software is tailor –made
software
according
to
a
user’s
requirements.
The
software
is
developed to meet all the requirements
specified by the user.
(b). General Application software : This
type of software is developed keeping in
Strength and Weakness of a computer:
=> Computer Strengths:
(i). Speed: Computer are much faster as
compared to human beings. A computer can
perform a task in a minute that may take day if
performed manually.
(ii). High storage Capacity: Computers can
store a large amount of information in very
small space.
(iii). Accuracy: Computer s can perform all tha
calculations and comparisons accurately
provided the hardware does not malfunction.
(iv).
Reliability:
Computers
can
immune(protect) to tiredness and boredom or
fatigue(mental exhaustion) .
(v). Versatility: Computers can perform

Computer Weakness:
(i). Lack of Decision Making Power:
Computer cannot decide on their own.
(ii). IQ Zero: Computers are dumb
machines with zero IQ
=> FIRMWARE: It is prewritten program
that is permanently stored in read only
memory (ROM). It configures the computer
and not easily modifiable by the user.
Example: BIOS(BASIC INPUT OUTPUT
SERVICE)
=> Liveware: The people associated with
and benefited from the computer system.


The origin of computers can be traced
back to inventors who were interested
in
processing
information
and
developing devices to simply tedious
arithmetic calculations.

Abacus(3000BC)
•
•
•

allowed the user to manipulate data
Babylon, 3000 BC
Still in use today
beads on rods to count and calculate
2- The Roman Numerals
I
II
III IV
V
3- The Arabic Numerals
0 1
2
3
4
VI
VII
VIII IX X
7
8
(base 10)
5
6
9
10
► Slide
Rule 1962
► based on Napier’s rules for logarithms
► used until 1970s
► It simplified and used logs to transform
multiplication problem to addition problem and
division to subtraction
1642
The Pascaline is a mechanical calculating(adding)
device invented by the French philosopher and
mathematician Blaise Pascal in 1642. It capable of
addition and subtraction .it worked on clock work
mechanism principle.
1671
The Leibniz Wheel was invented by the famous
mathematician Leibniz in 1671.It perform
(
+ , - , * , / ) . this machine performed
multiplication through repeated addition of
number.
1801
=>Punched Cards were used by the French weaver
Joseph Jacquard in 1801. The cards carried weaving
instructions for the looms, later this idea offered a
great use for storing info.
=>In
1822
Charles
Babbage
(English
mathematician,
philosopher),
sometimes called the
“father
of
computing” built the
Difference Engine.
=>Machine
designed
to
automate the computation
(tabulation) of polynomial
functions (which are known
to be good
approximations
=>Based
on the
“method of finite difference”
of many useful functions)
=>Implements some storage
1822
1852
As designed, it would have
been programmed using
punch-cards and would have
included features such as
sequential control, loops,
conditionals and branching. If
constructed, it would have been
the first “computer” as we think
of them today.
 Difference Engine c.1822
• huge calculator, never finished

Analytical Engine 1833
• could store numbers
• calculating “mill” used punched metal cards for instructions
• powered by steam!
• accurate to six decimal places

The Tabulating Machine
•
•
•
•
•
Herman Hollerith, American inventor, worked at
the Census Bureau & later taught at MIT
A machine which used punch cards and did the
mechanical work of tabulating the population
Won the Census Bureau contest and contract;
selling 56 of his Tabulating Machines
Organized his own company and continued to
produce the machines for the census
Merged with other companies eventually
becoming known as International Business
Machines – IBM
 The
IBM Automatic Sequence Controlled
Calculator (ASCC) Computer was
created by IBM for Harvard University,
which called it the Mark I. First universal
calculator.
 It
used electro magnetic signals
 It was slow machine took 3-5 seconds to
perform a calculation
 It was inflexible
 It could perform basic arithmetic as well
as complex calculations
 Modern
age of computers is divided into
five generations of computers
 First Generation (1949-1955)
 Second Generation (1956-1965)
 Third Generation (1966-1975)
 Fourth Generation (1976-Present)
 Fifth Generation (Present and Beyond)
The First Generation of Computers
The first computers used vacuum tubes for circuitry
and magnetic drums for memory, and were often
enormous, taking up entire rooms. They were
expensive to operate and in addition to using a great
deal of electricity, generated a lot of heat, which was
often the cause of malfunctions. First generation
computers relied on machine language, the lowestlevel programming language understood by
computers, to perform operations, and they could
only solve one problem at a time. Input was based
on punched cards and paper tape, and output was
displayed on printouts. The UNIVAC and ENIAC
computers are examples of first-generation
computing devices. The UNIVAC was the first
commercial computer delivered to a business client,
the U.S. Census Bureau in 1951.




CHARACTERISTICS
First generation computers were based on vacuum
tubes.
The operating systems of the first generation
computers were very slow.
They were very large in size.
Production of the heat was in large amount in first
generation computers.
 Air



conditioning required
Machine language was used for programming.
First generation computers were unreliable.
They were difficult to program and use.
 Frequent
hardware failure
 Applications:
These computers were used for record
keeping and payroll processing
 ENIAC
(Electronic Numerical Integrator
And Calculator)
 Developed by John Presper Eckert (19191995) and John W. Mauchley (1907-1980)
 Developed in 1946
 Space requirement 30 X 50 sq. ft.
 30 ton weight and 18000 vacuum tubes
 70000 registers, 10000 capacitors
 6000 switches and 150,000 watts
electicity
 cosr $ 400000
 When
ENIAC completed calculations it
inform the users by turning on a
sequence of lights
 It was used until 1955
 Only one system of ENIAC was
developed
 When operated the lights of near by area
were dimmed
 EDVAC
(Electronic Discrete Variable
Automatic Calculator)
 Developed by John Von Neuman (19031957)
 It contain a memory to store data and
programs as well
EDSAC
(Electronic Delay Storage
Automatic Calculator)
 Developed
in 1949 by Britishes
Prop.M.V.Wilkes .
 IT uses mercury delay lines for storage.
 UNIVAC
(UNIVersal Automatic
Computer)
 Developed by John Presper Eckert, Jr.,
and John Mauchly
 Developed in 1951
 First commercial computer
 Could manipulate numeric as well as
textual data
SECOND GENERATION
TIME PERIOD : 1956s- 1965s
TECHNOLOGY USED : Transistors
SIZE AND SPEED :Lesser size and increased speed
LANGUAGE USED : Assembly language and
languages like
COBOL and FORTRAN
COST : Cost decreased
TRANSISITORS
UNIVAC
1108
OTHER FEATURES : More efficient and reliable.
Though the transistors still generated a great deal of
heat that subjected the computer to damage, it was a
vast improvement over the vacuum tube.
Second-generation computers still relied on punched
cards for input and printouts for output.
EXAMPLE
: UNIVAC 1108, IBM 1401, CDC 1604
IBM 1401
THIRD GENERATION
TIME PERIOD
: late 1966s-1975's
TECHNOLOGY USED : Integrated Circuit
IBM
360/50
SIZE AND SPEED
: Size Lesser and speed further increased
LANGUAGE USED
: Operating System was developed.
COST
: Cost decreased further
OTHER FEATURES
: Instead of punched cards and printouts, users
interacted with third generation computers through keyboards and
monitors and interfaced with an operating system, which allowed the
device to run many different applications at one time with a central
program that monitored the memory.
Computers for the first time became accessible to a mass audience
because they were smaller and cheaper than their predecessors.
EXAMPLE
Honeywell – 6000
: IBM-360 series, Honeywell Model 316,
series, CDC – 1700.
FOURTH GENERATION
TIME PERIOD
: 1976s-today
TECHNOLOGY USED
: Microprocessor
SIZE AND SPEED
: Reduced size and
tremendous speed
LANGUAGE USED
: High Level Languages
like PASCAL,
•
COBOL, C, C++, JAVA
COST
: Reduced Cost
OTHER FEATURES
: Microprocessors also moved
out of the realm of desktop computers and into many areas
of life as more and more everyday products began to use
microprocessors.
•As these small computers became more powerful, they
could be linked together to form networks, which
eventually led to the development of the Internet.
•Fourth generation computers also saw the development of
GUIs, the mouse and handheld devices.
EXAMPLE
The Macintosh 128K,
the first Macintosh,
was the first
commercially
successful personal
computer to use
images, rather than
text, to communicate.
: Intel 4004, Apple Macintosh
Intel 4004D
microprocessor
FIFTH GENERATION
TIME PERIOD
: today--beyond
TECHNOLOGY USED : Microprocessor
SIZE AND SPEED
: Reduced size and tremendous speed
LANGUAGE USED
: Based on Artificial intelligence
COST
: Reduced Cost
OTHER FEATURES
: 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 goal of fifth-generation computing is to develop devices that
respond to natural language input and are capable of learning and selforganization. The use of parallel processing and superconductors is
helping to make artificial intelligence a reality.
The goal of fifth-generation computing is to develop devices that
respond to natural language input and are capable of learning and
self-organization.
EXAMPLE
: Parallel Inference Machine
Note: Artificial Intelligence is the branch of computer science concerned
with making computers behave like humans.
•Voice Recognition is the field of computer science that deals with
designing computer systems that can recognize spoken words.
Classification of Computers of On the basis of
How It Functions
The current classifications of
computers place them into
Three categories:
Analog Computer
Digital Computer
Hybrid Computers
Classification of Computers of On the basis of
How It Functions
Digital Computers
Analog
Computers
Digital
Computers
• Operate on continuous data, like
measuring temp. changes
• Faster
• Accuracy of an analog computer
is restricted to the accuracy with
which physical quantities can be
sensed and displayed.
• Specific Purpose computers
• Digital computers work on
discrete data.
• digital computer can process
data with greater accuracy
• We generally use digital
computers for business and
scientific data processing.
Hybrid Computers
• Hybrid computers are computers
that comprise features of analog
computers and digital computers.
• The digital component normally
serves as the controller and provides
logical operations, while the analog
component normally serves as a
solver of differential equations.
Digital Computer classified into two types
(i). Purpose –wise
(ii). Size and Performance wise
 (i). Purpose –wise digital computer are
classified into two types.
 (a). Special-purpose computer: It is designed
to performed a specific task. the instructions
to carry out the task are permanently stored in
the machine.
 (b). General-purpose computer: it can work
on different types of programs input to it and
be used in countless applications. The
program are not permanently stored .
Size and Speed Based Classification of digital
Computer Systems
The current classifications of computers place them into five
categories:
Embedded computer,
,Microcomputers (Personal Computers)
Minicomputers,
Mainframes,
Super Computers,
=> Embedded computers: These computers
are typically preprogrammed for a specific
task, such as tuning to a particular television
frequency. Examples: television, washing
machine.etc.
PERSONAL COMPUTER
The term microcomputer, also known as
personal computer (PC), or a computer that
depends on a microprocessor.
A microcomputer contains a central processing
unit (CPU) on a microchip (the microprocessor), a
memory system (read-only memory and random
access memory), placed on a motherboard.
Example: desktop, notebook, laptop, handheld
devices.
Charcteristics:
developed in 1980
designed for single user
not very powerful or expensive
found in homes
Micro computer also divided into three
types
 PDA(Personal digital assistants)
 Laptops and desktop personal
computer.
Workstations:
• Between minicomputer and
microcomputer- in terms of processing
power.
• Looks like PC and used by one person.
MINICOMPUTER
Another term rarely used anymore, minicomputers fall
in between microcomputers (PCs) and mainframes
(enterprise servers).
Minicomputers are normally referred to as mid-range
servers now.
Characteristics:
Smaller than mainframe
Can do several jobs at once
Can be used by many people at one time
Used by small companies
MAINFRAME
In the early days of computing, mainframes were huge computers
that could fill an entire room or even a whole floor.
As the size of computers has decreased while the power has
increased, the term mainframe has fallen out of use in favor of
enterprise server. You'll still hear the term used, particularly in large
companies to describe the huge machines processing millions of
transactions every day.
Characteristics:
Expensive
Powerful and fast
Is not limited to one job
Used by business and small government
organizations
The main difference between a supercomputer and a
mainframe is that a supercomputer channels all its power
into executing a few programs as fast as possible,
whereas a mainframe uses its power to execute many
programs simultaneously.
SUPER COMPUTER
The fastest type of computer.
Supercomputers are very expensive and are employed for
specialized applications that require immense amounts of
mathematical calculations.
For example, weather forecasting requires a
supercomputer.
Other uses of supercomputers include animated graphics, ,
nuclear energy research, and petroleum exploration.
Characteristics
Powerful
Expensive
Dedicated to one purpose - weather, satellites, military
Used by large governments or very large companies
Can be used by thousands of people at the same time
Very large - fill rooms
Sixteen racks of IBM's Blue Gene/L supercomputer can
perform 70.7 trillion calculations per second, making it the
fastest machine known so far.
First
Generation
Technology Vacuum
Tubes
Size
Second
Gen.
Transistors
Filled Whole Filled half a
Buildings
room
Third
Gen.
Integrated
Circuits
(multiple
transistors)
Smaller
Fourth Gen.
Microchips
(millions of
transistors)
Tiny - Palm
Pilot is as
powerful as
old building
sized
computer