Computer
Computer is an electronic machine used to solve different problems according to a set
of instructions given to it. A computer can accept data, process data into useful information
and store it for later use.
History of Computer
(i) Abacus
Abacus was the first computing device. It was developed 5000 years ago. It was used
to perform simple addition and subtraction.
(ii) John Napier’s Bone
John Napier was a Scottish mathematician. He created logarithm tables to facilitate
calculations. He also created a device known as Napier’s Bones.
(iii) Blaise Pascal
Blaise Pascal was a French mathematician. He invented a mechanical adding
machine in 1642 known as Pascaline calculator.
(iv) Von Leibnitz
Von Leibniz was a German scientist. He developed a calculation machine in 1694. It
was the first calculator that could multiply and divide also. It was similar to Pascal’s
calculator but it was more reliable and accurate.
(v) Charles Xavier
A French scientist Charles Xavier developed a machine that could perform addition,
subtraction, multiplication and division.
(vi) Punched Board
A French engineer Joseph developed the punchboard system for power looms. It was
used to create specific weaving patterns on cloths. Later on, the system was used in
computing devices.
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(vii) Charles Babbage (1791–1871)
In 1822, a mathematician Charles Babbage invented a difference engine for
mathematical calculations. In 1842, he developed the Analytical Engine that was automatic.
Charles Babbage known as Father of Computer.
(viii) Herman Hollerith
In 1889, Herman applied the idea of punchboards in computers. He used punch cards
in computers for input and output.
(ix) Atanasoff
Atanasoff was a professor at Lowa University. He invented an electronic computer.
He applied Boolean algebra to computer circuitry. Berry was co-founder. Also known as
ABC (Atanasoff and Berry Computer).
(x) George Boole
George Boole simplified binary system of algebra. His rule states that any
mathematical equation can be stated simply as either true or false.
Early Computer Age
The Mark 1 Computer (1937–44)
It is also known as Automatic Sequence Controlled calculator. It was first fully
automatic calculating machine. It was designed by Howard A. Aiken of Harvard University.
It was very reliable but huge in size.
Generation of Computers
(i) First Generation Computers (Vacuum tube) 1946–1959
(ii) Second Generation Computers (Transistor) 1959–1965
(iii) Third Generation Computers (Integrated Circuits) 1965–1971
(iv) Fourth Generation Computers (Microprocessor) 1971–1980
(v) Fifth Generation Computers (Artificial intelligence) 1980–Present
(i) First Generation Computers
Duration: 1946–1959
Technology: Vacuum Tubes
→ ENIAC and UNIVAC were computers of first generation
(ii) Second Generation Computer
Period: 1959–65
Technology: Transistors
Inventor of transistor John Bardeen
→ Transistors was developed by Bell Laboratories in 1947.
→ Computer are IBM 7094 series, IBM 1400, CDC 164.
(iii) Second Generation Computer
Period: 1965–1971
Technology: Integrated Circuits
→ IBM 370, IBM 360.
(iv) Fourth Generation Computer
Period: 1971–1980
Technology: Microprocessor
LSI: Large Scale Integration
VLSI: Very Large Scale Integration
→ IBM PC and Apple Macintosh
(v) Fifth Generation Computer
Period: 1980–Present
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Technology: Artificial Intelligence
ULSI (Ultra Large Scale Integration)
Different Types of Computers
Analog Computer
Digital Computer
Hybrid Computer
Analog Computer (1930)
Analog Computer, any of a class of devices in which continuously variable physical
quantities such as voltage pressure, speed etc. (1930) Father: Mihailo Petrovic Alas
Digital Computer
Digital Computer use (on) and (off) and (on) means (1) and (off) mean 0.
Examples: IBM, Apple Macintosh are Digital Computers.
Hybrid Computer
Combination of both analog and Digital Computer these computers are used in
Robotics and Laborites.
Classification of Computers
(i). Super Computer
(ii). Mainframe Computer
(iii). Minicomputer
(iv). Microcomputer or Personal Computer
Super Computer
→ Most Powerful Computer
→ Most Fastest Computer
- Used for Tanks, Weather forecasting and Atomic research.
Examples:
- Roadrunner • Blue Gene
- Cray T90 • ASCI White
Mainframe Computer
- Also very big
- Powerful than Micro and Mini
→ Used in institutions, Ranks and Research institutions. Air companies control ticket
system by the help of mainframe computers.
Example:
IBM system =10
Minicomputer
- Minicomputer are smaller than Mainframe.
Example:
HP 3000
Microcomputer or personal computer
- Microcomputer also called personal computer.
- IBM introduced 1st Microcomputer in 1981 that was IBM–PC.
Types
- Desktop
- Laptop
- Handhold
Father of personal
Computer is Henry
Edward Roberts
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What is Program?
A set of instructions that given to computer for perform a task.
Programming Languages
(i) High Level Languages
(ii) Law Level Languages
High Level Languages
A type of language that is close to human language and far from computer is called
high level language.
Example:
(i).FORTRAN (ii). COBOL (iii). BASIC (iv). PASCAL
(v). JAVA (vi). C/C++ (vii). Python
FORTRAN
FORTRAN Stands for Formula Translation. Introduced in 1957.
BASIC
BASIC Stands for Beginners All Purpose Symbolic Instructions Code.
COBOL
COBOL Stands for Common Business Oriented Language. Introduced in 1959
JAVA
JAVA was created at Sun Microsystems in 1995. JAVA Founder is James Gosling.
C/C++
- C language invented by Dennis Ritchie at Bell Laboratories in 1972.
- C Language is called mother of all programming language.
C++
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C++ invented by Bjarne Stroustrup in 1880s.
Python
Python invented by Guido Van Rossum in 1989.
LISP (High Level Languages)
LISP stands for list processing. Developed in 1950.
Visual Basic
Designed by Microsoft.
Low Level Language
Near to computer and Far From human Languages.
Types
(i) Machine Language (0,1, Binary)
(ii) Assembly Language (Ne–Monics)
Language Translators
Language translator is a type of system software that are used to convert high level
language into low level language or assembly programs into machine code.
(i) Assembler
(ii) Compiler
(iii) Interpreter
Assembler
Assembler is a program that is used to convert Assembly program into machine
language.
Compiler
Compiler is a program that is used to convert high level program into machine
language as a whole.
Interpreter
Interpreter is a program that is used to translate source program into, machine
language line by line.
What is source code?
A code written in high level language is called source code.
What is object code?
A code written in low level language is called object code.
Keyboard
Inventor: Christopher Latham Sholes
Input Device–QWERTY
101–105 Keys
Function Keys
F1–F12
ESC Key
ESC Key is used to terminate a command or current task.
Tab Key
Tab Key is used to move the cursor to next tab stop.
Backspace Key
Backspace key is used to delete single character on the left of the cursor.
Enter Key
Enter Key is used to move the cursor to the beginning of the next line.
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Numeric Keys
Numeric keys are located on the right side of most keyboards. If Num Lock is on the
Keys are used to enter numeric data (+,-,*,/) if Num Lock key is off, the numeric key perform
such operations:
End
It is used to move the cursor to the right corner of screen.
Page Down
It is used to move the cursor one page down on the screen.
↓(Down Arrow)
It moves the cursor down one line.
← (Left Arrow)
It moves the cursor one character to the left.
→ (Right Arrow)
It moves the cursor one character to the right.
Home
It is used to move the cursor to the top of the screen.
↑(Up Arrow)
It moves the cursor one line up.
Page Up
It is used to move the cursor one page up on the screen.
Ins or Insert Key
It is used to switch between Insert Mode and Overtype Mode. It is a toggle Key.
Del
It deletes characters to the right of cursor. It is also used to delete files.
Pointing Devices
- Mouse • Trackball • Pointing Stick • Joystick
- Touch Pad • Touch Screen • Light Pen
Mouse
Inventor Douglas Engelhard
Scanning Devices
1) Bar Code Reader
2) Mark Character Recognition Devices
(i) MICR
(ii) OMR
(iii)OCR
Barcode Reader
Barcode reader uses laser bean to read bar codes.
UPC→ Universal Product Code
MICR
MICR Stands for Magnetic-Ink character Recognition-used to read cheques.
OCR
OCR Stands for Optical Character Recognition. Used to scan documents or images.
OMR
OMR Stands for Optical Mark Reader: SAT, GRE etc.
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Output Devices
It deletes characters to the right of cursor. It is also used to delete files.
- Monitors • Printers
- Plotters • Speakers
Input Devices
- Keyboard • Mouse
- Scanner • Microphones
Video Display Adapters
A display screen must have a video display adapter attached with the computer to
display graphics. It is also called video graphics card.
Different types of Graphics Cards
(i) VGA
VGA Stands for video Graphics Array. It Supports 16 to 256 colors. 4 bit
(ii) SVGA
SVGA Stands for Super Video Graphics Array. 8bit
(iii) XGA
XGA Stands for Extended Graphics Array. 24 bit
Types of Display Screens
1) CRT (Cathode Ray Tube)
2) Flat Panel Display
(i) LCD (Liquid Crystal Display)
(ii) ELD (Electro Luminescent Display)
(iii) Gas Plasma Display
What is Printer?
A printer is an output device that prints characters, Symbols and Graphics on paper.
Types of Printers
Impact Printer
An impact printer works like a typewriter. Different types of impact printer. DDL
- Dot Matrix Printer
- Daisy Wheel Printer
- Line Printer
Non-Impact Printer
An non-impact printer prints characters and graphics on paper without striking paper
different types of non-impact. LTI
- Laser Printer
- Inkjet Printer
- Thermal Printer
→ Resolution of printer is measured in dots per inch (DPI).
→ Speed of Dot Matrix Printer is measured in characters per second (CPS).
→ Speed of Lin Printer is measured in Lines per minuet (LPM)
→ LASER → Light Amplification by Stimulated Emission of Radiation.
→ Laser Printer also known as page printer.
→ The speed of LASER Printer is measure din Pages per Minute (PPM).
What is Plotter?
A plotter is an output device that is used to produce high quality graphics in a variety
of colors. Plotters are used to create maps, architectural drawings, graphs and charts.
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Types of Plotters
Flatbed Plotter
Drum Plotter
Basic Units of Data Storage
(i) Bit
Computer works with Binary Digits. These digits are in the form of 0 and 1. A binary
digit is called bit. One bit takes one storage location in memory. It is the smallest unit
for data storage.
(ii) Byte
A collection of 8 bits is called byte. It is used to store single character. The capacity of
the memory or the storage is expressed in terms of bytes.
(iii) Kilobyte (KB)
A kilobyte consists of 1024 bytes. It is denoted by KB.
(iv) Megabyte (MB)
A megabyte consists of 1024 kilobytes. It is denoted by MB.
(v) Gigabyte
A Gigabyte consists of 1024 megabytes. It is denoted by GB.
(vi) Terabyte (TB)
A terabyte consists of 1024 Gigabytes. It is denoted by TB.
→ One Nibble Contains 4 bits.
Bit 0 and 1
Nibble 4 bits
Byte 8 bits
KB 1024 bits
MB 1024 bytes
GB 1024 KB
TB 1024 GB
SDLC
SDLC stands for software Development life cycle.
STORAGE DEVICES
Floppy Disk
Floppy disk is also called diskette. It consists of a thin plastic disk coated with
magnetic material. It was introduced by IBM in early 1970s. The standard size of floppy
disk is 3 ½ inch. Capacity 1.44 MB.
Hard Disk
Hard disk is a type of magnetic disk. A hard disk consists of several circular disks
called platters. The platters are used to store data. A platter in a hard disk is coated with a
magnetic material. Hard disk provides large storage capacity. 1500 GB or more. It is much
faster than floppy disk.
CD–ROM
CD–ROM Stands for Compact disk-Read-only Memory. It can store about 700MB of
Data.
Computer Based Training (CBT)
Primary Storage Devices Secondary Storage Devices
It refers to the main memory such as RAM &
ROM
It refers to auxiliary memory, external
memory or secondary memory.
It holds data or instructions that are currently
in use.
It is used to store and retrieve data or
information on a long term basis.
It is a volatile memory. It is not volatile memory.
Data is directly accessed by the CPU. Data is not directly accessed by the CPU.
Common examples or primary storage
include RAM, ROM and cache memory.
Common examples of secondary storage
include HDD, CD, DVD, Floppy Disk, Flash
Drives etc.
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Organizations to define network standards
ANSI = American National Standard Institute
IEEE = Institute of Electrical and Electronics Engineers
ISO = International Standard Organization
ITU = International Telecommunication Union
EIA = The Electronic Industries Association
Network Topology
The physical layout or arrangement of connected devices in a network is called
network topology.
Different Topologies
(i). Bus Topology (ii). Ring Topology (iii). Star Topology
(iv). Tree Topology (v). Mesh Topology
Devices used to connect networks of computers
(i). Router (ii). Gateway (iii). Bridges
Routers
A router is a device that connects multiple networks that use similar or different
protocols. It manages the bet rout between any two communication networks. It consists of
hardware and software. The hardware can be a network server or a separate computer. The
software includes operating system and routing protocol.
Routers are used when several networks are connected together. They can connect
networks of different countries. They transfer data in less time.
Gateway
Gateway is a device that connects two or more networks with different types of
protocols. Two different types of networks require a gateway to communicate with each
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other. It receives data from one network and converts it according to the protocol of other
network.
Bridges
Bridge is a device that connects two network segments. It is used to connect similar
types of networks.
LAN
LAN Stands for Local Area Network. It is the most common type of network. It
covers a small area.
WAN
WAN Stands for Wide Area Network. This type of network covers a large area.
MAN
MAN Stands for Metropolitan Area Network. This type of network covers an area of
a city. MAN is larger than LAN but smaller than WAN.
NIC
NIC Stands for Network Interface Card. It is also known as LAN adapter. It is used to
connect computer to a network.
Ethernet
Ethernet is the most commonly used LAN protocol. It use a high speed network cable
and bus topology.
Token Rings
Token Ring is also a LAN technology. It allows network devices to access the
network by passing a special signal called token. Token is a like a ticket.
ARC net
ARC net stands for Attached Resource Computer Network.
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TCP/IP
TCP/IP Stands for Transmission Control Protocol/Internet Protocol.
Lines for communication over Telephone Network
ISDN = Integrated Services Digital Network
DSL = Digital Subscriber Line
Internet
The work on the internet was started in the 1960s during the cold war of Russia and
America. DARPA= Defense Advanced Research Project Agency. In 1989, all previous
networks were replaced by NSFNET of National Science Foundation.
Father off Internet Vinton Gray Cerf. (U.S.A)
World Wide Web (WWW)
Invented by Tim Berners-Lee and Robert Cailliau in 1989. HTML→ Hypertext
Markup Language.
HTML invented by Tim Berners Lee in 1989.
World Wide Web is being standardized W3C.
Email stands for Electronic Mail. First Email sent in 1971. Ray Tomlinson is the
founder of Email. Invent in 1965.
Shiva Ayyadurai is also called the founder of Email, Yahoo, Hotmail and Gmail are
emails.
FTP
FTP stands for File Transfer protocol.
Intranet
Intranet is a private and secure business network.
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Extranet
Extranet is a collection of two or more intranets.
HTTP
HTTP stands for Hyper Text Transfer Protocol. It is a communication protocol used
to connect to servers on the World Wide Web.
OSI Model
OSI Stands for Open System Interconnection. OSI Model was developed by
International Standards Organization (ISO) in 1983.
Different Layers of OSI Model.
(7). Application Layer
(6). Presentation Layer
(5). Session Layer
(4). Transport Layer
(3). Network Layer
(2). Data Link Layer
(1). Physical Layer
ASP → Application Service Providers
DMS → Document Management System
ATM → Automated Teller Machine
CBT → Computer Based Training
CAL → Computer Aided Learning
CAD → Computer Aided Design
ICT → Information communication Technology
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CIM → Computer Integrated Manufacturing
CAM → Computer Aided Manufacturing
Application Software
Application Software is used to perform various applications or tasks on the
computer. Application software use to perform hundred of tasks such as?
- Writing Letters
- Making Presentations
- Managing Finances
- Managing Business Inventory
- Preparing Tax Returns
- Designing and Editing Images
- Accessing the Web Based Resources
- Playing Games