Computer

● The electronics device that solve your problems according to the instruction given to it is called computer.

● Computer is called mathematical problem solution device but 80% work done by computer is non mathematical.

● The computer can store ,process and retrieve data as and when required so that’s way we called it data processor.

● The word data processor mean following operation perform through computer.

● Mixing and putting data together , sorting in ascending and descending order and format according to our desire.

Data And Information

● The collection of facts and figure is called data.● The arranged form of data is called information.

Data + Meaning = Information

Directions of computer development

● Smaller in size ● More power (efficient small component )● Less expense ● Removal of unpredictability● Removal of complexity

History of computer

● The first device that qualify a digital computer is called abacus or Sorbian in 600 B.C.

● The first mechanical adding machine was invented by French mathematician named Pascal in 1642.

● In 1671 Baron Gottfried Wilhelm of Germany invented the first calculator of multiplication.

● In 1822 Charles babgabe professor at Cambridge university who is the father of modern digital computers designed a machine called it “Difference engine“.

History Takes Jump

The mark -1 computer (1937-1944)

Known as automatic sequencecontrolled calculator.

● Designed by Howard A Aiken of Harvard university .

● Draw back complex in design and huge in size.

● Time taken 0.3 sec to add and 4.5 sec to multiple.

● Size of computer 50 ft long and 8 ft high.

The Atanasoff Berry Computer (1939-1942)

● Developed by Dr john Atanasoff and Clifford Berry named ABC.

● Used to solve mathematical equations.● Used 45 vacuum tube.

The ENIAC (1943-1946)

Electronic Numerical integration and Calculator was the first electronic computer developed at Moore school of Engineering university of Pennsylvania, USA.

Size 20 x 40 square foot and used 18000 vacuum tube. Faster in speed as compared to mark -1.Limited use because it difficult for him to detect error.

The EDVAC (1946-1952)

● New concept of stored program.

● Stored program mean information are stored in memory.

● Dr john von Neumann goes credit to introducing the concept to store data in binary form.

The EDSAC (1947-1949)

Electronic Delay storage Automatic calculator developed by British at Cambridge university headed by Prof. Maurice Wilkes.

Addition is performed in 1500 microseconds and multiplication in 4000.

Manchester Mark -1 (1948)

● Developed at Manchester university by a group of scientist head by professor M.H.A Newman.

● Storage capacity was 32 words.

● It was not popular and hardly of any practical use.

The Univac -1 (1951)

● The universal Automatic computer was consider first digital computer.

● First machine was installed in the census Bureau in 1951 and was used in 10 year.

● The first business user of Univac was General Electric Corporations in 1954.

● In 1953 IBM produce the IBM -650 and sold over 1000.

Use of computer in different fields

● Medicine and health care ● Education ● Home● science ● Archaeology ● Engineering and Architecture● Manufacturing ● Legal practice ● Law Enforcement ● Improved safety● Government ● The military● Music ● Theater and Film

Types Of Computer By Technology

First Generation Of Computer (1942-1955)

Technology used vacuum tubesInput punched cards Output punched cardsLanguage Machine Language Storage punched paper Tape

Advantages

● Vacuum tubes are used● Fastest calculating device

at that time ● Perform computation in

milliseconds(1000)

Disadvantage

● Bulky in size● Non portable● Unreliable● Produce large amount of

heat● Air condition required● Commercial production is

difficult● Constant maintenance

required

Second Generation Of Computer (1955-1964)

● Technology used Transistors● Input punched cards● Out put paper ● Language Assembly language ● Storage Magnetic cores ● Transistor invented in 1947

Advantage

● Smaller in size ● Better portability ● More reliable ● Less heat generated● Less hard ware failure● Calculate in

microsecond(10 -6)● Wider commercial use as

compare to Ist generation

Disadvantage● Air condition ● Frequent maintenance

required● Commercial production

was difficult and costly

Third Generation Of Computer (1964-1975)

● Technology used Integrated circuits● Input key board ● Out put Monitor ● Language High level language● Storage Improved disk storage

Advantages

● Smaller in size● More reliable easily

portable ● Low heat generated● Computation speed 10-9

nanoseconds● Personal computer

introduce ● Maintenance cost is low● Labor and capital cost

reduce ● Commercial production is

cheaper

Disadvantages

● air condition required ● High technique required

for circuits manufacturing

Fourth Generation Of Computer (1975 – ONWARD)

CHIP

Integrate large number of circuits into very small surface of silicon and in chip or micro chip is a tiny piece of silicon that contain millions of electronic circuits.

Technology used Chip (VLSICs) Input keyboard Out put Monitor Language High level language Storage Hard disk

Advantages

● Smallest in size ● Easily portable ● Very reliable ● No air condition

required ● No hardware failure ● Cheapest among all

generation● Computation speed 10-9

● minimum labor and cost involved

Disadvantages

● High sophisticated

Types Of Computer On Principle Of Working

Digital Computer

● The computer you use commonly at your offices ,universities ,colleges and homes are digital computers.

● These are light speed ,programmable electronic device that perform mathematical calculations , compare values and stores results.

● They recognize data by counting discrete signal representing either on or off voltage state of electricity.

● Numbers (digits ) that represented either on or off. Voltage state of electricity .number (digits) that represents numerical ,letters or other special symbols are reduced to representation by 1’s or o’s.

● That is why they known as digital computer.

Analog Computers

● Does not produce number but produce its results in the form of graph.

● Analog machines are usually special purpose devices dedicated to a single task.

● They are used by them for research and development and in some process control equipment like oil refinery chemical industry and robots making.

Hybrid Computer

● Combination of both analog and digital computer.

● Computer used in intensive care (ICU) and cockpit of fighter plain.

Types Of Computer Depending On Size

Super Computer

● The largest and fastest and most expensive computer available.

● Some times called “Number Crunchers” because they perform millions of instructions per second.

● The high speed is due to number of processor working in parallel and high storage device.

● The unit for processing speed is “FLOPS” ( Floating point operations per seconds).

● Used for weapon research and development rocketing ,atomic ,nuclear, weather forecasting.

● Examples are CRAY-1,CRAY, X-MAP.

Mainframe Computers

● Second largest computer after super computer.● The unit for processing speed is MIPS (millions of

instruction per second).● Used for handling large amount of data. ● Used in research organization , large industries, large

business and government organizations ,banks and airlines reservations .

● First installed in 1988.● Examples are IBM 3090, IBM 4331 ,NEC610 , ICL 2900.

Mini Computers

● Smaller and less power full than mainframe.● Used for payroll preparation ,accounting and scientific

computation .● Unit of processing speed is “MIPS”.● Used as a single unit or tied as a network with several

computer .● Now a days mini computers are replaced by micro

computers.● Examples are VAX 11780, IBM-AS/100, IBM RISC 6000.

Micro Computer

● Design to use one person “Single User”.● Common use in our life.● Cheapness ,versatility and performance combined with

the variety of soft ware allow their use in almost every business.

● Unit of processing is MHZ (Mega Hertz), and GHZ(“ Giga Hertz”).

● Used in LAN and WAN and linked with mini computer.

Component Of Computer

Five basic elements of computer

1- Input unit

2- Output unit

3- Storage unit

4- Control unit (C U)

5- Arithmetic unit (A U)

1- Input Unit (Device)

Key Board

Similar to a type writer (KEYS 100-108)

Three main partFunction keys (F1--F12)Main key board Numeric keyboard

Additional keys(mid of key board)

Mouse Point & Draw Device

A mouse is a device that is rolled about on a desktop and directs a pointer on the computer's display screen

Moving the mouse allows you to reposition the pointer ,or cursor and indicator on the screen that shows where the next interaction with computer take place.

Mouse allows you to give an speedy interaction.

Track Ball

A variation in the mouse is track ballA track ball is like an upside-down mouse The popularity the trackball blast with the advent of

laptop computer User prefer trackball because it require less desktop

space

Joy Stick

Joy stick is another cursor controlling device. Used in computer game. Joy stick moves the cursor in the direction the stick is

pushed.

Sensitive Screen Input

The light pen is device connected to the computer terminal.

The user brings the pen to the desire point on the display screen and press the pen button which identifies the screen location to the compute.

Light pen work on a light sensitive screen.

Touch Sensitive Screen

A touch screen is a video display screen that has been sensitized to receive input from the touch of the finger

Effect is similar to that of light pen on a light sensitive screen

When a finger touches that it blocks out the light emitted from that portion of the screen

Uses in banks ,factory.

Digital CamerasLook No Film

A digital camera used a light sensitive processor chip to capture photographic images in digital from on a small diskette inserted in the camera or on a flash memory chip.

2- Out Put Devices

Monitor

Monitor is also called display screen or cathode ray tube (CRT) or video display terminal (VDT)

Types of monitor

Cathode Ray Tube (CRT)Liquid Crystal Display (LCD)Gas Plasma

Cathode Ray Tube (CRT) Cathode rays strike phosphor

beads on the monitor screen

Liquid Crystal Display (LCD) Consist of substance called

liquid crystal, the molecules of which line up in a way that alerts their optical properties.

Gas Plasma Gas plasma display is like a

neon bulb, in which the display uses a gas that emits light in the presence of electronic current.

Graphics Adapter

CGA Initial color graphics adapter standard offers four colors.

EGA Enhanced graphics adapter offers 16 colors at 320 X 200

pixels. EGA is called 4 bit color.

VGA (Video graphics adapter) Offers 256 colors at 800 X 600 pixels. VGA is called 8 bit

color.

SVGA (Super video graphics adapter) Also called XGA (Extended graphic adapter) offers up

to 16777216 colors at 1600 pixels. Range from 16 to 32 bits also called true color.

Printers

Printer is an out put device that produce hard copy

Types of printer

Character printer

Daisy wheel printer Dot matrix printer Thermal printer Inkjet printer

Line printer

DRUM PRINTERSCHAIN PRINTER

Page printer

LASER PRINTER

Character Printers

1- Daisy wheel printer

Characters were embossed at the end of the arms of a wheel called the daisy wheel.

It has only one strike hammer which strikes on an inked ribbon kept above the paper.

The wheel is in between the paper and the hammer.

The speed of this printer ranges 10 to 50 characters per second.

Low speed is due to lot of mechanical movements of the printer head.

Fixed shape is allowed and no other shape ,fonts ,size and style is allowed.

2 - Dot matrix printer

Dot matrix printer form one character at a time as the printer head moves across the paper.

The dot matrix printer is an impact printer It use tiny pins to hit the ribbon and the

paper like a typewriter. Several vertical column pins are contained

in a rectangular print.Dot matrix or either 9 or 24 pins. The print head moves horizontally across

the paper Dot matrix printer print 600 character per

second (cps).Dot matrix printer are flexible .They do not

have fixed character font.

3 - Thermal printer

Thermal printer employ non- impact technique and are thus noiseless.

This type of printers uses special heat sensitive paper.

Such paper have special heat sensitive coating.

When spot on special paper is heated it becomes dark.

To print a character the printing head is moved first to the correct character position and then the heating elements for the desire character are turned on and these heated pins are touched to the heat sensitive paper, after a short time they are turned off.

Then print head is moved to the next character.

4 - Inkjet printer

Inkjet printer spray small, electrically charged droplets of ink from nozzles through holes in a matrix at high speed onto paper.

The print head move back and forth across the paper to write text.

Price tag about equal to a dot matrix printer and a print quality close to that of a page printer the ink jet printer is emerging as the choice for the budget minded consumers.

Line Printer

1 - Drum printer

A drum printer consists of a solid cylindrical drum that has raised character on its surface.

The drum rotates a rapid speed. For each character there is print hammer

behind the paper. The hammer strikes on the paper along

with the inked ribbon. Speed of drum printers are in the range of

300 to 3000 lines per minute.

2 – Chain printers

They use a rapidly moving chain called a print chain Each link of a chain is a character font. Some models of printers use metal band having raised

print character on it. For each possible print position there is a print

hammer behind the paper. As the chain rotates the properly timed print hammers

strikes the paper along with the inked ribbon. The character set is repeated several times on the

chain. Hence it is not necessary to wait for a chain to make a

complete revolution for the desired character. Speed of chain printers range from 400 to 4000.

Page Printer

1- Laser printer

A laser printer uses the principle of dot matrix printers of creating images with dots.

The images are created on drum treated with a magnetically charged ink like toner powder and transferred from drum to paper.

The majority of laser printers print shades of gray however color printers are also used

Speed up to 32 pages per minute. 600 dpi printer is capable of printing 360,000

dots per square inch.For commercial use 1200 and 2000 dpi printers

are used.

Storage Devices

Internal Storage

Read only memory (ROM)

Random access memory (RAM)

External Storage

Sequential

Access

Punched paper card Magnetic tape Tape cartridge

Direct Access

Floppy disksHard disksWinchester disks Magnetic drum Optical disks Rewriteable optical disksMagnetic bubble memory

Binary System(Units Of Storage)

Each o or 1 in the binary system is called a bit abbreviation of binary digit.

Bit is the basic unit of storage.O mean off and 1 mean on. Single bit cannot store all the numbers, letters and

character so these bit are put together in a group is called a byte.

8 bit = 1 byte Computer memory is measured in bytes. Extended units of bytes is kilo bytes ,megabytes ,

gigabytes.

Bits ,Bytes and Word

Bit The smallest unit of data storage. Byte Combination of 8 bit is called a byte. Word combination of one or more byte is called

a word.

Storage Units

BIT 0,18 BIT One Byte1024 Bytes 1 Kilo Bytes 1024 Kilo Bytes 1 Mega Bytes 1024 Mega Bytes 1 Giga bytes 1024 Giga Bytes 1 Tara bytes

Read only memory (ROM)

Data can not be written on or erased by the computer user without special equipment.

Information is permanently stored in Rom. Information is only read and can not be

possible to write fresh information that is way it is called “read only memory”.

Rom holds those information which is permanently required when power is supplied to the equipment.

External Storage

Random access memory (RAM)

RAM temporarily holds data and instruction that will be needed shortly by the CPU.

Ram is a collection of memory location in which program instructions and data are stored.

Read and writing of data is done electronically with out any mechanical movement.

Ram is called volatile memory. Executed program and data which is currently

being manipulated are transferred from external memory to RAM.

External Storage

Sequential access

Sequential storage means that data is stored in sequence.

Examining all the record in sequence from the beginning to the desired records.

Types of Sequential Access Storages

Punched paper tape

Data is coded on paper tape in the form of punched holes combination.

Tape is normally one inch wide comes in rolls and may be used in any length up to several hundred feet.

There is a line of sprocket holes in the middle of the tape for the purpose of feeding the tape through the tape punching and reading device.

Magnetic tape

Magnetic tape is thin plastic tape that has been coated with an iron oxide material that can be magnetized.

The tape is plastic ribbon usually ½ inch wide that is coated on one side.

Old data on a tape are automatically erased as new data are recorded in the same area.

The tape is divided into vertical columns called frames and horizontal rows called channels or tracks.

Tape Cassettes and Cartridges

Magnetic tapes are suitable for use only with large and medium size computers.

The same magnetic is used in smaller systems in the form of cassettes and cartridges.

Direct access storage

Direct access storage means that the computer can go directly to the information you want.

Direct Access Storage is Addressable.

Types of Direct Access Storages

Floppy Disk

Introduced by IBM in 1972.Floppy disk is removable found flat piece of plastic 3-1/2

inches across that store data and programs as magnetized spots.

Direct access secondary storage medium for micro and mini computers.

3 ½ inches diskettes can store 1.44MB data and 5 ¼ inches diskettes can store 1.2 MB data.

Hard Disk

A magnetic disk is a thin, circular metal plate coated on both sides with a magnetic material.

Information is stored on both the surfaces of each disk plate except the upper surface if top plate and the lower surface of the bottom plate.

Each disk consist of number of circles called tracks.Tracks are further divided into sectors.Same sector of each platter is called cylinder.Capacity is available in different sizes, like 20Gb, 40Gb,

80Gb.

Winchester Disk

Permanently sealed in contamination free (airtight) containers.

Disk are coated with a special lubricant which reduces the friction when the read/ write heads land on the disk surface.

Technology enables greater precision of alignment, an increase in the number of tracks on the disk surface and higher storage density per track.

Winchester disks are fast and highly reliable compared with conventional hard-disk devices.

Magnetic Drum

Magnetic drum is a direct access storage device that can be used for both sequential and random processing.

Consist of a cylinder whose outer surface is coated with a thin layer of magnetize able material.

Data is stored and read from the drum by a set of read/write heads.

Zip Storage

Zip disk is a great way of storing and moving files from PC to PC.

Zip can store data 100/250 MB.Also used for make backup of files.

Jazz Storage

Jazz have more storage capacity than zip drive and can store up to 2GB.

Used for make backup.

Optical Disks

CD Rom

An optical disk is a removable disk on which data is written and read through the use of laser beam.

Optical disks can store data up to 750MB.

Data once recorded cannot be erased, this technology is also known as WORM (write once read many).

DVD Rom

DVD represents a new generation of high density CD-ROM disks which are read by laser beam.

CD-ROMs holds 650 or 750 magabytes of data.DVD technology can store almost 5GB of data on disk.

Rewritable Optical Disk

Rewritable optical disk allows users to record and erase data so that the disk can be sued over and over again.

Rewritable optical disk can store up to 1GB of data.