Transcript Chapter 1 Computer Overview

Welcome
Presentation on
Computer
Fundamentals
&
Computer
Presented By:- Sunil Verma,PGT(C.S.)
Objective of the topic To learn the About the history of the computer.
 To develop the knowledge about the basics of the computer.
 To develop the knowledge about the devices.
 To develop the knowledge about the hardware and software.
Contents About Computer
 Data and Information
 Functioning of a computer
Input Unit
CPU Unit
Output Unit
Memory Unit
 Hardware and Software
 Operating system
 Evolution of computers
Contents
• Generations of modern computer
• Types of computers
1. Digital Computers
2. Analog Computers
3. Hybrid Computers
WHAT IS A COMPUTER ?
Def.
A computer is an electronic device that can perform a variety of
operations in accordance with a set of instructions called program.
Computer can access and process data millions of times faster than humans can.
A computer can store data and information in its memory, process them and produce
the desired results.
Computers can do a lot of different tasks such as playing games, railway
reservation, weather forecasting, error detection and controlling the flight of a aircraft
etc.
Computer is used essentially as a data processor.
The difference between data and information is :
Data Vs. Information
Data : Data in computer terminology mean raw facts and figures.
For example,’Mohan’,1977,A . Data are processed to form information.
Information : It means what we get after processing data (meaningful data).
 For example, ’Mohan, whose roll number is 1977, has got grade A’ is an
information as it is conveying some meaning.
 This process of turning data into information is also known as information
processing.
 FUNCTIONING OF A COMPUTER :
 Certain input is needed to accomplish a task, a process is carried out on the
input to obtain the output.
 Every process follows this Input-Process-Output cycle (IPO cycle).
 Functional Components of a Computer :
1. Input Unit :
 It is formed by the input devices attached to the computer.
 Ex. Keyboard, mouse, magnetic ink character reader (MICR), optical mark
reader (OMR), optical character reader (OCR), joystick etc.
 It is responsible for taking input and converting it into computer
understandable form (the binary code).
 Basic Structure of a computer :
INPUT
UNIT
CENTRAL
PROCESSING
UNIT (CPU)
OUTPUT
UNIT
Storage
Devices
MAIN MEMORY
 Computer can understand only two stages ON/OFF or High/Low voltage or the
binary language that uses just two symbols : 1 for ON and 0 for OFF.
2. Central Processing Unit (CPU) :
 It is the control centre for a computer.
 It guides, directs and governs its performance.
 It is the brain of the computer.
 CPU has two components :
(i) CU (Control Unit)
(ii) ALU (Arithmetic Logic Unit)
 Arithmetic Logic Unit : It performs all the four arithmetical (+,-,*,/) and
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some logical (<,>,<=,>=,<>) operations.
When two numbers are required to be added, these numbers are sent from
memory to ALU where addition takes place and the result is put back in the
memory.
For logical operation also same procedure. The result of logical operation is
either TRUE or FALSE.
Control Unit : It controls and guides the interpretation, flow and
manipulation of all data and information.
It sends control signals until the required operations are done properly by
ALU and memory.
Another function of CU is program execution. It gets program instructions
from memory and executes them one after the other.
After getting the instructions from memory in CU, the instruction is
decoded and interpreted. Then the asked operation is carried out.
After the work of this instruction is completed, control unit sends signal to
memory to send the next instruction in sequence to CU.
It also control the flow of data from input devices to memory and from
memory to output devices.
 Output Unit :
 It is formed by the output devices attached to the computer.
 The o/p coming from the CPU is in the form of electronic binary signals which needs
conversion in some form which can be easily understood by human beings. i.e.
characters, graphical or audio visual.
 This function of conversion is performed by output units.
 Example. VDU (Visual Display Unit), printer, plotter, speech synthesizer and coder

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etc.
The Memory :
Def : A memory cell may be defined as a device which can store a symbol selected
from a set of symbols.
Each of these cells is further broken down into smaller parts known as bits.
A bit means a binary digit. i.e., either 0 or 1.
A bit is an element unit of the memory.
0
1
0
0
0
1
1
0
Bit
cell 0
cell 1
 Def. A group of 8 bits is called a byte and a group of 4 bits is called a nibble.
 One byte is the smallest unit which can represent a data item or a character.
 One KB(Kilobyte) -> 2¹º -> 1024 bytes.
 One MB(Megabyte) -> 2¹º KB -> 1024 x 1024 bytes.
 One GB(Gigabyte) -> 2¹º MB -> 1024 x 1024 x 1024 bytes.
 One TB(Terabyte) -> 2¹º GB -> 1024 x 1024 x 1024 x 1024 bytes.
 Two types of memory :
(i) Volatile
- > Primary Memory
(ii) Non Volatile -> Secondary Memory
 Hardware and Software :
 Hardware : It represent the physical and tangible components of the
computer i.e., the components that can be seen and touched.
 The electronic, electrical and mechanical equipment that makes up a
computer is called hardware.
 Example. Input devices, Output Devices, CPU, floppy disk, hard disk, etc.

Peripherals :

Def. Peripherals are the devices that surround the system unit. E.g., the
keyboard, mouse, speakers, printers, monitors etc.

A computer consists of five primary hardware components :
(i) input devices
(ii) CPU
(iii) memory
(iv) output devices
(v) storage devices

Software : It represent the set of programs that govern the operation of a
computer system and make the hardware run.

Three types :
(i)
Operating System
(ii)
Language Processor
(iii)
Application Software
(i)
Operating System :
Def. An operating system is a program which acts as an interface between a
user and the hardware.

We pass our orders/requests to operating system and ‘the
Operating System’ does it for us.

OS itself decides : How to do ? ; What to do ? ; When to do ?

The primary goal of an OS is to make the computer system
convenient to use and secondary goal is to use computer hardware
in an efficient manner.

Major components of a computer system are :
1. The Hardware
2. The Operating System
3. The Application Program routines (compilers, linkers, database
management systems, utility programs)
4. The Human ware (users)
The operating systems perform the following functions :
(i)
(ii)
(iii)
(iv)
Provides the instructions to prepare user-interface
Loads necessary programs (into the computer memory) which are
required for proper computer functioning.
Coordinates how programs work with the CPU, keyboard, mouse,
printer and other hardware as well as with other software.
Manages the way information is stored on and retrieved from disks.
CPU
Operating System
Application Software
User
 User
Interacts with
 Application Software
Interacts with
 Operating System
Interacts with
 CPU and Hardware
Types of OSs : single user OS, multiuser OS, batch processing OS, multiprocessing OS
etc.
Language Processors :
-> Programmer’s language is HLL and computer does not understand it.
->So it is require to convert HLL in to machine language. Software which does this is know
as Language Processors.
-> (i) Assembler : It converts the program written in assembly language into machine
language.
-> (ii) Interpreter : It converts a HLL 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 can not resume until the error is rectified.
 Interpreter must always be present in the memory.
 For error debugging, interpreter is very much useful as it reports the error
(s) at the same time.
(iii) Compiler :
 It converts the entire HLL program in one go, and reports all the errors of
the program along with the line numbers.
 After all the errors are removed, the program is recompiled, and after that
the compiler is not needed in the memory as the object program is available.
 Therefore, if we combine interpreter and compiler, it gives the best
combination for HLL program translation into object code.
 Application Software :
 Def. An application software is the set of programs necessary to carry out
operations for a specified application.
 These are the programs written by programmers to enable computer to
perform a specific task such as inventory control, medical accounting,
financial accounting, result preparetion, railway reservation, billing etc.
 Application software can be subdivided into two catergories :
1.
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2.
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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.
Software may not fit in the requirements of the new user.
General Application Software :
This type of software is developed keeping in mind the general
requirements for carrying out a specific task.
Many users can use it simultaneously as it fulfills the general
requirements.
Strengths and Weakness of a Computer :
Strengths :
1.
Speed
2.
High Storage Capacity
3.
Accuracy
4.
Reliability
5.
Versatility

1.
2.
Limitations :
Lack of Decision Making Power
IQ Zero
Firmware :
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Firmware is a prewritten program that is permanently stored in read-only
memory. It configures the computer and is not easily modifiable by the
user.

Example : BIOS ( Basic Input Output Services) instructions.
Live ware :

It is the term used for the people associated with and benefited from the
computer system.
FAQ A data is a collection of-
3.
Raw facts
Processing
Transformations
None of these
Which of the following are software and hardware?
Transistor
FORTON
Compiler
4.
Integrated Circuit
1.
2.
3.
4.
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1.
2.
FAQ Who invented the punched card?
1.
2.
3.
4.
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1.
2.
3.
4.
5.
6.
Charles Babbage
Herman Hollerith
Both 1 and 2
None of these
Define each of the followingNibble
Byte
Kilobyte
Megabyte
Gigabyte
Tetra byte
FAQ Which of the following does not represent an I/O device?
1.
2.
3.
4.

1.
2.
3.
4.
Speaker which beeps
Plotter
Joystick
ALU
Storage of 1 KB means the following number of bytes1000
964
1024
1064
 EVOLUTION OF COMPUTERS :
Abacus :
 Around 3000 years before the birth of Jesus Christ, the Mesopotamians
quite unknowingly laid the foundation of the computer era.
They discovered the earliest form of a bead-and-wire
counting machine, which subsequently came to be known
as abacus.
 An abacus consists of beads divided into two parts which are movable on the
rods of the two parts. Addition and multiplication etc. of numbers is
done by using the place value of the digits of the numbers and position of
beads in the abacus.
Napier’s ‘Logs’ and ‘Bones’ :
 John Napier (1550-1617) developed the idea of Logarithm. He used ‘logs’ to
transform multiplication problem to addition problem.
Pascal’s Adding Machine :
 Blaise Pascal, a French mathematician, invented a machine in 1642 made up of
gears which was used for adding numbers quickly. This machine was named as
Adding Machine ( Pascaline ) and was capable of addition and subtraction.
The adding machine
consisted of numbered
toothed wheels having
unique position values. The
rotation of wheels
controlled the addition and
subtraction operations.
 Leibnitz’s Calculator :
Gottfried Leibnitz, a German Mathematician,
improved an adding machine and
constructed a new machine in 1671 that was
able to perform multiplication and division
as well. This machine performed
multiplication through repeated addition of
numbers.
 Leibnitz’z machine used stepped cylinder each with nine teeth of varying
lengths instead of wheels as was used by Pascal.
 Jacquard’s Loom :
 Joseph Jacquard manufactured punched cards at the end of American
revolution and used them to control looms in 1801. Thus the entire control
weaving process was automatic.
 The entire operation was under a program’s control.
 Babbage’s Difference Engine :
Charles Babbage. A professor of
mathematics, developed a machine called
Difference Engine in the year 1822.
This machine was expected to calculate
logarithmic tables to a high degree of
precision. It was made to calculate various
mathematical functions.
 Babbage’s Analytical Engine :
 This engine was capable of performing all four arithmetic operations as well
as comparison.
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He included the concept of central processor,
storage area, memory and input - output
devices in his design.
The two revolutionary innovations
incorporated in Anaytical Engine were
comparisons and modification of stored
information.
Charles Babbage known as the ‘Father of Modern Computers’.
Hollerith’s Machine :
In 1887,an American named Herman Hollerith
fabricated the first electromechanical punched
card tabu lator that used punched cards for
input, output and instructions.
This machine was used by American
Department of Census to compile their 1880
census data and were able to complete compilation
in 3 years which earlier used to take around 10 years.
 Mark-I :

Prof. Howard Aiken in U.S.A.
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constructed in 1943 an electromechanical

computer named Mark-I which could
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multiply two 10-digit number in 5 seconds.
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It was the first machine which could
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perform according to pre programmed

instructions automatically without any

manual interference.
 This was the first operational general purpose computer.
 GENERATIONS OF MODERN COMPUTER :
 First Generation Computers(1949-55) :
 It used thermionic valves (vacuum tubes) and machine language was used
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for giving instructions.
It used the concept of stored program.
Large in size
Programming was difficult task.
Examples :
1. ENIAC : (Electronic Numerical Integrator And Calculator)
 First electronic computer developed in 1946 by a team lead by Prof.Eckert
and Mauchly at the University of Pennsylvania in U.S.A.
 Used high speed vacuum tube switching devices
 Very small memory
 Used for calculating the trajectories of missiles.
 Took 200 micro sec for addition and 2800 micro sec for multiplication.
 30x50 feet long, 30 tons weight, 18000 vacuum tubes, 70000 resistors, 10000
capacitors, 6000 switches, used 150000 watts of electricity and cost $400000.
2. EDVAC : (Electronic Discrete Variable Automatic Computer)
 Binary arithmetic was used in construction
 Completed in 1950
 Concept of stored program was used
 Operation became faster since the computer could rapidly access both the
program and data.
3. EDSAC : (Electronic Delay Storage Automatic Computer)
 Developed by Prof. M. V. Wilkes at Cambridge University in 1949
 Used mercury delayed lines for storage
 Concept of stored program used
 This allowed easy implementation of program loops.
4. UNIVEC – I : (Universal Automatic Computer – I)
 Commercial production of stored program electronic computers
 Built by Univac division of Remington Rand and delivered in 1951.
 Limitations of First Gen. Computers :
 Slow operating Speed
 Restricted computing capacity
 High power consumption
 Short mean time between failures
 Very large space requirements
 Limited programming capabilities
 Second Generation Computers (1956-65)
 Invention of transistors in 1946, which were highly reliable
compared to vacuum tubes, less space and required only 1/10 of
the power required by tubes.
 Took 1/10 time (switching from 0 to 1 and 1 to 0) needed by tubes
and were ten times cheaper than those using tubes
 Invention of magnetic cores which were used to construct large
random access memories.
 These are tiny ferrite rings (0.02 inch dia.) that can be magnetised
in either clockwise or anti-clock wise direction. The two
directions represent 0 and 1.
 Used transistors in place of vacuum tubes and development of
magnetic disk storage devices made these computers more
reliable
 HLL like FORTRAN, COBOL, Algol and Snobol etc. developed
 Operating Systems came in to existence
 Commercial applications rapidly developed
Some second generation computers :
Model
Size
Area of Applicatio
IBM 1401
Small to Medium
Business
IBM 1620
Small
Scientific
IBM 7094
Large
Scientific & Business
CDC 1604
Medium to Large
Scientific
CDC 3600
Large
Scientific
RCA 501
Medium
Business
UNIVAC 1108
Large
Scientific & Business
Third Generation Computers (1966-1975)
Replaced transistors with Integrated Circuits which was inverted
by Jack Kilby at Texas Instruments in 1958.
A single I.C. has many transistors, resistors and capacitors
along with the associated circuitry encapsulated in a small
package with many leads.
 In Small Scale Integrated (SSI) circuits about 10 transistors per
chip used
 Medium Scale Integrated (MSI) circuits developed with 100
transistors per chip
 Size of main memories reached about 4 MB.
 Highly reliable
 Relatively inexpensive
 Faster
 Examples : IBM-360 Series, ICL-1900 series, IBM-370/168, ICL2900, Honeywell Model 316, Honeywell-6000 series.
 Fourth Generation Computers (1976- present)
 Development of Large and Very Large Scale Integrated(VLSI)
circuits packing about 50000 transistors in a chip.
 Semiconductor memories replaced magnetic core memories
 Emergence of the microprocessor (CPU on a single chip) led to the
emergence of extremely powerful personal computers.
 Costs of computers came down rapidly
 Speed of microprocessors, size of memory and Hard Disk
increased
 Use of RISC (Reduced Instruction Set Computers)
 For larger disks RAID technology (Redundant Array of
Inexpensive Disks) used
 CDROMs becoming popular, which can store info. Upto 650
MBs.
 Fifth Generation Computers (Coming Generation)
 Based on artificial intellegence, are still in development
 Voice recognition is being used today
 Parallel processing and semiconductors are used in fifth gen.
computers.
 The goal of fifth generation computing is to develop devices that
respond to natural language input and are capable of learning
and self organization.
 Characteristic : Ability to apply previously gained knowledge,
draw conclusion and then execute a task.
 Computers will have to be able to classify information, search
large database rapidly, plan, apply the rules which humans regard
as clear thinking, make decision and learn from their mistakes.
 It also include speech and visual recognition as input devices.
 Applications for Fifth Generation Computers :
 Intelligent robots
 Intelligent system that could control the route of a missile and
defense systems that could fend off attacks
 Word processors that could be controlled by means of speech
recognition
 Programs that could translate documents from one language to
another.
 TYPES OF COMPUTERS
The computers have been classified into three categories.
1. Digital Computers 2. Analog Computers 3. Hybrid Computers
COMPUTERS
Digital
Purpose-Wise
Analog
Hybrid
Size and Performance Wise
Special Purpose General Purpose Embedded Micro Mini Mainframes Super
Programmable
Laptop
Workstations
 Digital Computers :
 The digital computers work upon discontinuous data. They
convert the data into digits (0 and 1) and all operations are carried
out on these digits at extremely fast rates.
 Digital computers are much faster than analog computers and far
more accurate.
 Used for business and scientific applications
 Classification of Digital computers in two ways :
(i) Purpose wise Digital Computers : Classified in to two ways
1. Special-purpose Computer : It is designed to perform a specific
task.
-> The instructions to carry out task are permanently stored in the
machine.
-> Computers are not versatile.
2. General Purpose Computer : It can work on different types of
programs input to it and so used in countless applications.
-> Programs are not permanentaly stored but are input at the time
of execution.
-> Computers are versatile.
(ii) Size and performance wise Digital Computers :Classified in to
following types
1. Embedded Computers : Exist in a wide range of sizes and power.
-> The smallest are embedded within the circuitry of appliances,
such as televisions, washing machines and wrist watches.
-> Programmed for a specific task.
2. Microcomputers : It is a computer whose CPU is a
microprocessor.
-> Microprocessor is a processor whose all components are on a
single integrated – circuit chip.
-> Normally used in offices, homes, schools, shops, stores etc.
Three categories of Microcomputers :
Three categories of microcomputers :
(i)
PDAs (Personal Digital Assistants) :
Programmable computers
Vary in their power, speed, memory, and physical size.
Smallest of these computers can be held in one hand.
Used as notepads, scheduling systems, and address books
They can connect to worldwide computer networks if equipped
with a cellular phone.
(ii) Laptop (Notebook) Computers and Desktop Personal
Computers (PCs) :
Used in business and at home to communicate on computer
networks,
for word processing to track finances,
play games
Large amounts of internal memory
Equipped with kb, mouse, track ball, monitor or LCD

Laptop have similar h/w and s/w as PCs, but they are more
compact and have flat, lightweight LCDs instead of video
display monitors.
 Laptop computers are so called as they can sit on a Lap and
Desktop computers are so called as they can sit on a desk.
(iii) Workstations :
 Similar to PCs but have greater memory and more extensive
mathematical abilities
 Connected to other workstations t or PC to exchange data.
 Found in scientific, industrial and business environments that
require high levels of computational abilities.
3. Minicomputers :
 Also called mid range servers
 More powerful than micro computers in terms of processing
power and capabilities.
 Multiuser system (Multi users can work simultaneously)
Greater storage capacity and larger memories comparedto micro
comp.
Capable of handling more i/p and o/p devices.
Examples : PDP-11, VAX, 7500 MAGNUM etc.
4. Mainframe Computers :
Designed to handle huge volumes of data and information.
Can support more than 100 users at same time
Large and expensive
Great processing speeds and very large storage capacity and
memory as compared to mini comp.
Possess and work with more than one processor at the same time
Very sophisticated operating systems are needed to control and
supervise their operations.
Examples : ICL 39, CDC 6600, VAX 8842, IBM 3090/600, IBM 4381
5. Super Computers :
Most powerful among the digital computers
Consist of several processors running together, so very powerful
and faster
Capable of handling huge amounts of calculations
It can perform billions of instructions per second
Today’s some super computers have the computing capability
equal to that of 40,000 micro computers
These computers cost in 15-20 million dollar range.
Used for weather forecasting, nuclear science research,
aerodynamic modelling, seismology, metrology etc.
Examples : CRAY X-MP-14, CDC-205, ETA GF-10, FUJITSU VP400, NEC SX-2, PARAM, PACE
 Fro general purpose applications, supercomputers do not make
the ideal choice.
It can process information of only a certain kind.
 Its power measured in flops (floating point operations per
second)
 Analog Computers :
As input continuous quantities are used
Computations are carried out with physical quantities such as
voltage, length, current, temperature etc.
Operate by measuring rather than counting
All calculations take place in parallel and hence are faster
Accuracy is poor as compared to digital comp.
Mostly used in engg. And sci. applications.
Example : An electronic weighing scale
 Hybrid Computers :
Utilize the best qualities of both the digital and analog comp.
Some calculations take place in analog manner and rest of them
take place in digital manner
Best used in Hospitals, also used for weather forecasting
FAQ One mega byte is equivalent to?
1.
2.
3.
4.

1.
2.
3.
4.
5.
210 bytes
220 bytes
230 bytes
None of these
Which of the following are parts of the CPU?
ALU
Memory
CU
Input device
Main Memory
FAQ Which of the following is not hardware?
1.
2.
3.
4.
5.
6.

1.
2.
3.
4.
5.
Hard Disk
Printer
Keyboard
CPU
Assembler
Program to print table of 13
Which of the following are parts of the CPU?
ALU
Memory
CU
Input device
Main Memory
FAQ The modern age of data processing began with the competition of the
1.
2.
3.
4.

1.
2.
3.
4.
computer?
Analytical Engine
ENIAC
MARK 1
UNIVAC I
A Micro processor is
A solid state device
Capable of performing Arithmetic operations
Capable of performing Logical operations
All the above
FAQ In computer science ,by information we mean
1.
2.
3.
4.

1.
2.
3.
4.
Any output coming out from computer
Processed data put out from computer
A report printed by computer
Plural of data
The CPU
Is operated from the control panel
Is controlled by the input data entering the system
Controls the storage unit
Controls all input , output, processing
Thanks