COMPUTER DEFINATION :
Computer is a modern electronic device which takes input from the user and process the input and gives accurate output to the user.
Block Diagram :
The main parts of the computer are
1) Input devices
2) Output devices
3) Central processing Unit
4) Memory.
Computer is a modern electronic device which takes input from the user and process the input and gives accurate output to the user.
Block Diagram :
The main parts of the computer are
1) Input devices
2) Output devices
3) Central processing Unit
4) Memory.
Input device: Input devices are the Hardware components of
computer system which are used to give input like characters, numbers and
symbols etc to the computer system.
Example: Keyboard. Mouse (It is used in graphical representation).
Output device: Output devices are the Hardware components of
the computer system which are used to give output to the users from computer.
Example:
1) If
out put is soft copy then we use Monitors
2) If
out put is Hard copy we use Printers.
Memory:
Memory is a Magnetic Hard ware Material which is used to store the data in the
form of Bits (Which is a Machine Language).It is measured in the form of unit
called “byte”.
Example: RAM ROM, Hard Disk, CD, Floppy etc.Memory is measured in bytes like kilobyte(kb),Megabyte(mb),Gigabyte(gb).....
Central Processing
Unit (CPU): CPU is Main part (Heart)
of Computer system which is also a Hardware component.CPU is mainly consists of
three parts, it contents Hardware components like Registers, transistors,
Circuits etc.
a) Arithmetic and Logic unit: This is used to perform all
Mathematical Calculations and all decision making operations.
b) Control Unit: It is a main part which control all CPU
Signals, Memory signals etc.It controls both hardware and software components
of computer system.
c) Memory Unit: This is used to store the data.
Computer History:
Computers are the machines which
are designed to perform large calculation and to store data. In olden days for
calculations people use their fingers for calculations, and then they develop
Abacus like Chinese Abacus, Russian Abacus etc…
In Early 1820’s A Mechanical
Engineer designed a calculating Machine which is mechanical and this is our
First Computer Machine which performed calculations of large size. He is FATHER
OF COMPUTER named “Charles Babbage”.
Many changes were done to this
computer from mechanical to electrical and then Analog to Digital .
Computer history is mainly divided
into Generations
1) First
generation computer
2) Second
generation computer
3) Third
generation computer
4) Fourth
generation computer
First Generation Computer:-(Period: 1940-1955)
First generation computers were very
large in size they use Vacuum tube, punched card and magnetic tapes. They
occupies large place in large air-conditioned room.
Disadvantages:
- Occupies large place
- Produces large heat so requires Air-condition.
- Speed is very low
- Cost very expensive
- Required High power
- Access only by programmers
Second Generation Computer :-( Period: 1956-1963)
Second
generation computers were faster and smaller computer machines which uses
transistors in place of vacuum tubes, they used programming languages like
FORTRAN.
Advantages:
When compare to first generation computers second generation
computers are very fast and small in size, they uses computer programming
languages which are single operating systems.
Third Generation Computer :-( Period: 1964-1969)
Third generation
computers used Integrated circuits and these computer speed and storage
capacity is very larger when compare to previous generation computer systems.
Advantages:
- Very fast
- Small in size
- High storage capacity
- Low cost
Fourth Generation Computer :-( Period: from 1970-till date)
In early
1970’s fourth generation computers were introduced which uses Very Large
Integrated chips (VLSI) technology chips.
Advantages:
- Very fast
- Small in size
- High storage capacity
- Low cost
- Portable
- Reliable
- Low power consumption
- Very easy to access.
Computer components:-
Computer is
mainly divided into 2 components,
1)
Hard ware components: these are the physical components
like computer peripherals example CPU, keyboard, mouse, monitor, printer,
memory devices, circuits etc...
2)
Software components: these are the collection of
programs which are used to run hard ware components example System software
like operating system, Application software like MS Office, database software
like DBMS etc…
Hardware
components are the physical components which human being can see and touch
.where as software components are the collection of programs which human being
cannot see and touch. Software components are the programs which are used to
run the hard ware components.
Hardware components:
1)
Input devices: Input devices are used to give input to
the system in form of data and instructions like alphabets, numbers, symbols,
images etc…these are the physical components/Hard ware components which we can
see and touch.
Example: Keyboard, Mouse, light pen, joystick, optical character reader,
optical mark reader, CCD camera etc…
KEYBOARD: Programs and data
are entered in to a computer through keyboard, it is similar to type writer it
contains alphabets, numbers, special characters and some special control keys.
When a key is pressed an electronic signal is produced which is detected by an
electric circuit called keyboard encoder .it will send this signal to cpu and
cpu process the signal and give out put on output device.
It contains different collection of keys like
standard typewriter keys which are in QWERTY format of alphabets, numbers, control keys
like space bar, shift, Tab and caps lock, Enter key etc…
Cursor movement keys like PgUp, PgDown, and uparrow, down arrow, left and
right arrow, which are used to control the page on the screen.
Numeric keys like numbers from 0-9 and special keys like (+,-,*, /,).
Function keys it contains function keys from F1 to F12, each key have
different functions according to the application.
MOUSE: mouse is a small object that can roll on a hard
surface which controls the movement of cursor on screen. There are different
types of mouse
Mechanical Mouse: it has a rubber ball on its surface that can roll in
all directions. Mechanical sensors within mouse detect the direction of ball
and move the cursor on the screen in that direction.
Optical Mechanical: it is same as
mechanical mouse but it uses optical sensors to detect the motion of ball.
Optical: it uses laser light to detect
the mouse motion it not need rubber ball it gives response quickly but
expensive.
SCANNERS:
SCANNERS:
scanning device are
Input devices which translates data/information in the form of Images and give to
computer system.
OMR :
Special marks
such as squares/bubbles are prepared on examination answer sheets with pencil
or pen are detect by this OMR and sends
signals to the computer as input.
1)
Output devices: Output devices are physical components
which are used to provide output to the user.
Example: Based on
the output, the devices are divided into two types
Monitor
if the output is soft copy,
Printer if the output is Hard copy.
MONITOR :
Monitors are the
screens which are used to display the data on it. the data may be in any form
like images, alphabets, numbers,special characters etc…there are many types of
monitors based on the color,size,shape.
Monochrome
monitors: Monochrome monitors actually display two colors, one for the
background and another for foreground. The color is black and white.
Color Monitors: These
monitors can display output in colors which supports 16 to 256 different
colors.
CRT: cathode ray
tube monitors are commonly used display screens which contains vacuum tube to
display data on screen. It produces a light beam which reflects on the flat
surface which coated with phosphorus material which produces picture on the
screen. But it consumes more power and occupies more space.
Flat panel Display:
This flat panel display is much thinner and is less in weight and consumes less
power and thus they are more useful in portable computers.
LCD (Liquid
Cristal Display) and LED (Electro Luminescent Display) are two technologies
used in this flat panel display.
PRINTERS:
Printers are output
devices which are used to give output in the form of hard copy in papers. We
use different Printers in different applications.
Ink Jet printers:
It uses dot matrix approach to print text and graphics.
Earlier ink jet printers used one or more nozzles in print head that emit a steady
stream of tiny ink drops. It uses Ink cartridges contain tiny heaters. The
print quality is very neat, and speed is very low.
Drum printers:
A drum printer uses a rapidly rotating drum
which prints data in line format, first the drum heats and it dip in toner and
then roll on the paper. It prints 200 to 2000 lines per minute, they are very
fast in speed and cost is very less.
Laser Printer:
This is a type of printer that utilizes a
laser beam to produce an image on drum. The light of the laser alters the
electrical charge on the drum wherever it hits. The drum is then rolled through
toner, which is picked up by the charged portions of the drum. Finally, the
toner is transferred to the paper through combination of heat and pressure. These
are also very fast and les expensive.
Cache Memory: It is a very fast accessible memory even than RAM memory so it is sandwich between RAM and CPU. Its size very small but very fast and it is a volatile memory.
Memory :
Memory is a place where data is stored in the form of bits. It is stored
in computer system in binary form i.e. combination of 0‘s and 1’s.It is a
Magnetic material which is used to store data.
Memory is a Hardware/Physical component of a computer system and it is a
major part in central Processing Unit (CPU).
The Units of memory for measurements is Bytes
1 byte = 8 bits (combination of 0 and 1)
1 Kilo Byte = 1024 bytes (2^10)
1 Mega Byte = 1024 KB (2^20)
1 Giga Byte = 1024 MB (2^3) etc….
Memory in computer system is mainly divided in two types
1) Primary Memory and
2) Secondary Memory.
Primary Memory:
Primary storage is main memory to store temporary data.
Example RAM, ROM, Cache Memory etc…
These are very small in size but they access data very fast. They are volatile
because the data in primary memory will loss when power is off.
RAM (Random
Access Memory) : A RAM is computer main memory which is used to store data
temporarily and it is a volatile memory it loses data when system is power off.
It is very fast
to access the data, all the soft ware programs will first store in this ram
memory from main memory (Hard disk) and then access by CPU whose speed is very
high. Actually the accessing speed of Hard disk is very slow and CPU speed is
very fast so, RAM memory act as mediator to transfer data from CPU to Memory
and vice versa.
ROM (Read
only memory) : A ROM memory is also a main memory which is used to store
the primary soft ware data, this data is stored by computer manufacturers which
contains the data of system. It store critical programs of system which boots
the computer and also stores the software of input and output devices like
keyboard software, monitor software etc…It is a non volatile memory which
stores the data forever which cannot be changed or erased.
Cache Memory: It is a very fast accessible memory even than RAM memory so it is sandwich between RAM and CPU. Its size very small but very fast and it is a volatile memory.
SECONDARY MEMORY: Secondary
memory is a hardware component of computer system which is used to store data
permanently and it can store very large amount of data. Compare to primary
memory accessing speed is slow due to huge storing size and capacity. They use
magnetic material to store data and they are non-volatile which store data even
power of switch off.
Examples: Hard
Disk, Floppy disk, Magnetic tapes, Compact Disk, Pen drives, Memory Cards etc…
Floppy Disks:
Floppy disk is round pieces of flat plastic magnetic disk that store data. The
sizes of floppy disks are 3 1/2 inches to 5 1/2 inches. Its store capacity is
low up to Megabytes.
Hard Disk:
It is a magnetic disk on which you can store computer data. It can store large
amount of data compare to floppy disks i.e. from Kilo Bytes to Tera Byte. A
single hard disk usually consists of several platters. Platter is a round
magnetic plate that coated with magnetic material on both sides. And it
requires two read and write arm which are used to store the data and to
retrieve the data. Each platter is divided into several equal numbers of
tracks; each track is again divided into sectors. All plates are connected with
a rod called cylinder.
CD:
Compact Disk are Read only Memory, i.e it can write only once and cannot write
next time but read many times. It is an optical disk which stores large data.
To read data from CD disk we need CD player/Drive. Its store size is up to 700
MB.
Magnetic Tape:
Is is a magnetically coated strip of plastic on which data can be encoded.
Tapes for computers are similar to tapes used to store music. This is the
oldest storage media used till today. It needs a player to read these magnetic
tapes and while reading and wriring data on it a arm is always contact to this
tape so it will damage soon.