Characteristics
(Advantages) of Computer
(1)
Speed :
The computer can process data at an extremely fast rate. Speed of computer is
majored in mili seconds (10-3) or even micro second (10-6)
or neno second (10-9) or in Pico second (10-12). it is
able to perform million instruction per second (MIPS)
(1)
Accuracy : Computer performs each an every calculation
with the same accuracy. Errors can occur
in a computer but they are mainly due to human, that is a person who
right instructions for a computer to solve a particular problem or due to
in accurate data.
(2)
Diligence :Un
like human being is free from monotony
tiredness etc. and hence can work
for hours together without creating any errors .
(3)
Versatility: (vU; fo’k; dks fopkjus dh “kfDr)
A computer is capable of performing any task provide a particular program is
available to perform that task.
(4)
Power of
remembering : In human brains store only that
information which is important and discard which is not important. Human brain
can also forget the information with computer it never happens. A computer can
store and recall any amount of information because of it storage capability it
does not forget any information.
(5)
No. I.Q
(intelligence) A
computer has no IQ of it self. It perform the things which humans asked to
perform. A compute can not take its own decision.
(6)
No feeling :
Computer have no emotions based on feeling
tasted knowledge and be human being often make certain judgment in our life but
computer can not make such judgment. Computer can only follow the instruction
given by human begin.
Classification of Computer
Classification
of computer
 |
Measuring
technology size
& speed  |
|||
 |
|||
Analog digital
Hybrid
 |
Micro Mini Main frame Super
Computer have been classified in three categories according to
measuring technique.
(1)
Analog computer :- Here be represent the quantity in a continues meaner. Analog
computer operated by measuring rather than counting.
These
computer are mostly use in engineering and scientific calculation.
Ex- Thermometer, represent temperature in terms of the length of a
tried of mercury.
(2)
Digital computer:- Here be physically count the quantity of a given material by
using standard number system that is decimal system.
It convert the data into digits and than all operation
Are done
on these digits at externally fast rates. Digital computer basically knows how
to count the digits.
(3)
Hybrid computer:- It utilize the best qualities or both digital and analog computer.
These computer use digital memory for storage of inter migrate result and
analog devise are used for computational purpose. Digital to analog and analog
to digital Converter are used in hybrid computer.
According to size and speed computer can be classified as follower:-
(1)
Micro computer (personal
computer /pc):- A micro computer built around
micro processor such as intel 80386, 84486 etc
A micro processor c.p.u. made on a single micro chip.
Word length:- The number of bits
which we can Manipulates (,d
lkFk use djuk ) simultaneously the word size of
micro computer various 8 to 32 bits.
It a single user system
(2)
Mini computer:- mini computer can support server user working simultaneously.
They are mainly use in offices the word size of the cpu of such system is
generally 32 bits or more.
Ex:- P.D.P.11, S.C.L.-HP
(3) Main frame:- The term main frame is use per large and very powerful computer system.
this system have a very high capacity of main memory and can process
calculation at externally fast rates. The word size of main frame computer
generally 32 to 64 bits.
Ex:- CDC-6600
(4)
Super computer:- These computer can execute billions of instruction per second.
The word size of super computer is equal to 64 bits
Ex:- PARAM 10,000
ANURAG
CRAAY
1
|
Intel 800386,84486
|
0-8
|
2
|
PDP-11, SCL-H.P
|
8-32
|
3
|
CDC-6600
|
32-64
|
4
|
PARAM 10,000
ANURAG
CRAAY
|
64
|
Classification of Computer
Classification
of computer
|
Measuring
technology size
& speed |
|||
|
|||
Analog digital
Hybrid
|
Micro Mini Main frame Super
Computer have been classified in three categories according to
measuring technique.
(1)
Analog computer :- Here be represent the quantity in a continues meaner. Analog
computer operated by measuring rather than counting.
These
computer are mostly use in engineering and scientific calculation.
Ex- Thermometer, represent temperature in terms of the length of a
tried of mercury.
(2)
Digital computer:- Here be physically count the quantity of a given material by
using standard number system that is decimal system.
It convert the data into digits and than all operation
Are done
on these digits at externally fast rates. Digital computer basically knows how
to count the digits.
(3)
Hybrid computer:- It utilize the best qualities or both digital and analog computer.
These computer use digital memory for storage of inter migrate result and
analog devise are used for computational purpose. Digital to analog and analog
to digital Converter are used in hybrid computer.
According to size and speed computer can be classified as follower:-
(1)
Micro computer (personal
computer /pc):- A micro computer built around
micro processor such as intel 80386, 84486 etc
A micro processor c.p.u. made on a single micro chip.
Word length:- The number of bits
which we can Manipulates (,d
lkFk use djuk ) simultaneously the word size of
micro computer various 8 to 32 bits.
It a single user system
(2)
Mini computer:- mini computer can support server user working simultaneously.
They are mainly use in offices the word size of the cpu of such system is
generally 32 bits or more.
Ex:- P.D.P.11, S.C.L.-HP
(3) Main frame:- The term main frame is use per large and very powerful computer system.
this system have a very high capacity of main memory and can process
calculation at externally fast rates. The word size of main frame computer
generally 32 to 64 bits.
Ex:- CDC-6600
(4)
Super computer:- These computer can execute billions of instruction per second.
The word size of super computer is equal to 64 bits
Ex:- PARAM 10,000
ANURAG
CRAAY
1
|
Intel 800386,84486
|
0-8
|
2
|
PDP-11, SCL-H.P
|
8-32
|
3
|
CDC-6600
|
32-64
|
4
|
PARAM 10,000
ANURAG
CRAAY
|
64
|
Classification of Computer
COMPUTER
 |
Hardware
Software
 |
 |
||
CPU Memory I\o Devices
Application System 
Software Software
ALU
CU
|
|
|
Primary Secondary
|
Ram Rom
P.Rom E.P.Rom
Computer :-
The word
Computer comes from the word “Compute” which means to calculate¼x.kuk djuk½. So a computer is normally considered to be a calculating device¼x.kuk djus dh e”khu½ that can perform arithmetic ¼xf.krh;½ &
logical ¼rdZ laxr½ operation ¼fØ;k,½
at a very high speed.
More accurately a computer may be define as a electronic device that
operates upon information or data under the control of program.
A
computer is a binary system that take only Zero’s (0) & one’s (1).
(I)Hardware :-
|
Hardware is term given to the
machine it self and to the various individuals pieces of equipment. It refers
to the physical device of a computer system. Thus the input, storage,
processing, control & output devices are hardware. When all the hardware
units are link together compute is installed.
(1.)
CPU
(CENTRAL PROCESSING UNIT)
It is
the brain of the computer system. All measure calculations & comparisons
operation are made inside the CPU & CPU is also responsible for activating
the operations of all other unit of a computer system. CPU has two unit :-
1.
ALU
2.
CU
] ALU (Arithmetic & Logic Unit)
ALU used for performing arithmetic calculation &
comparisons operation & number of register are provided inside the ALU to
store the data.
] CU (Control Unit)
It find out which of the operation is to be executed &
it tells the ALU what to do? And then ALU does the real operation on the
operands. It transferred the data and addresses between CPU & memory and
CPU & input output devices. CU used for fetching both instruction &
data. So the working of CPU with CU is also known as “FETCH EXECUTION CYCLE”.
(2.)
MEMORY
There
are two types of memory or storage in a computer system.
i.
Primary Memory
ii.
| Secondary Memory |
i. Primary Memory (Main Memory)
It is within the computer that is computer can communicate directly
with primary memory. It is very fast in operation. Now memory came in the form
of silicon chips. This chips contains memory capacity 1 K.B. to 4 M.B. or even
more. This memory is also call MOS (Metal Oxide Semiconductor) memory. Each
location in few memory has address. That is each bytes is addressable. Primary
memory has two part :
a)
RAM
b)
ROM
a) RAM (Random Access Memory)
The term RAM access means that any word in the memory may be access
without having to go through all the other words to get to it. All the contains
of RAM are last when we switch off the power.
b) ROM (Read Only Memory)
There are some higher-level operations that are very frequently use
but they require very complicated electronic circuit for implementation.
Instead of building of electronic circuit special program are return to perform
these operations. These programs are called micro program. ROM is used to store
this micro program. There are two types of ROM-:
·
P.ROM
·
E.P.ROM
·
P.ROM
(Programmable Read Only Memory)
Here a user can convert his own program into micro program and store
them in a P.ROM. CHIP. Once the chip has been made program record information
can’t be change.
·
E.P.ROM
(Erasable Programmable Read Only Memory)
It is possible to erase store information & the chip can be
reprogram to store new information. We can erase the chip by exposing it to
ultraviolet light.
ii.
Secondary
Memory (External Memory/Backup Memory):-
It is also called as auxiliary, back up storage or external memory.
These devices are use to permanently store information, which may be access for
use during processing it non-volatile.
Secondary storage devices are
v Floppy Disk
v Hard Disk
v Compact Disk (CD)
v Digital Versatile Disk (DVD)
v Pen Drive
v Zip Drive
v Memory Card.
(3.)
INPUT /
OUTPUT DEVICES
This
contains electronic circuit for communicating & controlling the transferred
of information between computer & I.O. devices.
v Input
Device-: An input device reads data and
program into the computer codes that the primary
memory of a computer is designed to accept.
Eg-:
·
Key Board
·
Mouse
·
Scanner
·
Light Pen
·
Joy Stick
·
Web Camera
·
Bar Code Reader
·
Optical Mark Reader (OMR)
v Output
Devices-: The job of an output device is reversing
of that an input device. It delivers result to the user.
Eg-:
· Visual
Display Unit (VDU)
· Speaker
· Printer
· Plotter
Types of output :- We can classify output as
v Hard
Copy -: By Hard copy we mean output in directly useable form. That is printed
or plotted.
Hard copy devices
produce a permanent record on paper.
Example :-
Printer, Plotter.
Types of printer :-
o
Inkjet (2000-2500)
o
Ledger (10000-40000)
o
Dot Matrix (5000-10000)
v Soft
Copy :-
By soft
copy we mean output in magnetic form that can not be used directly. Softcopy
devices do not produce a permanent record, they require some hard copy device
to produce a permanent output.
Softcopy
devices are very fast in operation as compare to hardcopy.
(II)Software :-
Computer
can not do anything on its own. It must be instructed to do a desire job. Thus
we should provide a sequence of instructions to computer to solve a problem.
Such a sequence of instructions is called program. A program controls the
processing of the computer. The set of computer program is called software. In
other words software means a collection of program whose objective is to
increase the capabilities of the hardware machine.
There are two types of software.
i.
Application
Software :-
If a program is designed to solve a particular
problem then it called Application Program.
Example :- Ms-Office, Tally, Win amp, Win zip,
Acrobat Reader.
ii.
System
Software
It is design to control the operating of a
computer system. It manages all the hardware resources (like cpu time, input –
output devices etc.) & made user interaction easy with the system.
We can run application program on the system
software.
System software directly contact with hardware.
Example :- DOS, Window-98, Server 2000, XP,
Vista, Windows 7.
(Firmware) :- Software can also made available on ROM chip. These ROM
chip can be easily plugged into the firm apart of the hardware. Such software
made available on hardware are known as firmware.
Firmware often refers to a sequence of
instruction (software) that is substitute for Hardware.
----------------------------------------------------------------------------------
Unit
of Storage Capacity
1 BIT - 1 & 0
8 BIT - 1 BYTE
1024 BYTE - 1
K.B. (Kilo Byte)
1024 K.B. - 1
M.B. (Mega Byte)
1024 M.B. - 1
G.B. (Giga Byte)
---------------------------------------------------------------------
CONCEPT OF NETWORKING
COMMUNICATION: -
Communication is the process of
transferring message from one point to another. There are three basic elements
of communication system.
- SENDER-: It creates the message to be transmitted.
- MEDIUM-: It carries the message.
- RECEIVER-: It receives the message transmitted from sender.
E.g.-: Telephone
conversations.
DATA COMMUNICATION-:
When we transport data from one point to
another, it is called “data communication”. Here sender and receiver are
normally machine. More precisely we can say computer devices and the
transmission media may be telephone line, microwave links, satellite links etc.
DATA TRANSMISSION MODES-:
There are three modes for transmitting
data.
1.
SIMPLEX-:
|
If the
communication take place in one direction only. Then the communication is
called simplex devices connected are send only or receive only device that is
message flows in one direction only or how of information is unidirectional.
E.g.-: T.V.
COMMUNICATION,
2.
HALF-DUPLEX-:
Half-Duplex Or
In this system data can be transmitted
in both direction, but only one direction at a time. That is half duplex line
can alternately send and receive data.
Ex. wireless communication use in military.
Transmission Line in Half duplex must be
turn around each Line the direction is receivers. This process is called
switching.
3. FULL- DUPLEX-: |
|||
|
|||
Full duplex And
Here intromation how
simultaneously in both the directories on the transmission path.
Ex.- Telephone conversation.
DATA
TRANSMISSION SPEED :-
{Data communication speed }:- The
communication data transfer is measured in a unit called paud. That is Bites
per Second. It is called frequency Band width that ( I.E) higher frequency (-)
minas Lower frequency in the range of
frequencies that is available for the transmission of data.
TRANSMISSION MEDIA |
1.)
WIRE
PAIRS :-
WIRE
PAIRS :-
They are use in local telephone
communication and short distance(Up to about 1k.m.) digital data transmission.
They are made up of copper and pair of
wire are twisted together to reduce interference by adjacent wires. They are
used to connect terminals to the main computer if they are placed at a short
distance from the main computer . They are in expensive but they can easily pick up noise signals. The speed
of a digital signals transmission is “12 hundred ” bits per second.
2.)
coaxial cable:-
 |
It consist of a slift copper wire as the core srounded
by an insulating material.
The out a conductor is covered in a protective plastic covering. Coaxial
cable offer much higher band width and are cappable of transmiting digital
signal at very high rate of ten (10) mega bits per second.
Coaxial cable higher noice immunity and can provide clear data
transmition without distortion or loss of signal.
3.)
Microwave System:-
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It was very
high frequency micro wave signal to transmit data but microwave transmit in
line of sight that is instead line. There for transmitter and receiver of a
microwave system should be in Line of sight.
But for Long transmission
it not possible also the signal became week to over come this problem micro
wave system use repeater at intervals of about 25 to30k.m in between the
transmitting and receiving station. The first repeater is place in line of
sight rates of the transmitting station. And the last repeater is placed in
line of sight of the receiving station. It permits data transmittion rates of
about 16 Giga bits per second.
4.) Communications
Satellite: -
 |
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 |
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 |
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Disadvantages of
micro wave communication is that the curvature of the earth often block the
line of sight. There for we have to provide several repeaters in short
distance. It will increase the cost. To remove this problem satellite are used.
Satellite are reley station place in a out a space. It is place about 36
thousand above the equator. It is called “Geo Stationary”.
The signal is transmitted from a transmitter
on earth to the satellite placed in space. By the time this signal reaches the
satellite it become week. The satellite amplifies the weeks signal and
transmitted back to the earth. This signal is received by all the receiving
station on earth which fall under the range of a satellite.
Disadvantages: -
<1> High
cost of placing the satellite into it’s or bit.
<2> A
signal send to a satellite is broad cast to all receiver with in the satellite
range. Therefore secreacy of information can’t be assured.
(5) Optical
fibers: -
 |
 |
|
Transmitting
The fiber optics
cable transmit light signal rather then electrical signal.
It is more
affient then other network transmission media. Each Fiber has an inner core of
glass that conducts light. Towards is source side there is a converter that
converts electrical signal in to light waves. These Light waves are transmitted
over the Fiber. Another converter placed near the destination converts the
light waves back to electrical signal are emplipy and send to the receiver
optical Fiber provide high quality low error rate transmission of signal. At
very high speed. its speeds is one Giga bit per second.
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