COMPUTER FUNDAMENTAL
DATA AND INFORMATION
1. What is
data?
Data is fact any character number or special character
such as:- 2, 3, 5, +, - * &, % $ etc.
Example
Name
address, Age is facts related to people
Data
can be of three types:-
(a)
Alphabetic
(b)
Numeric
(c)
Alpha numeric
2.
What is Process?
Work is done on data according to
the work on programmer is known as process.
3. What is Information?
Information means data in better
form that is in the form we want it for daily use.
Such as:-
When we
require the name of the student, name of subjects and marks obtained by him in
these subjects.
AVANTAGE OF A COMPUTER
The computer one of the most
powerful machines produced by man provides the following advantage.
1. Speed: - The computer is capable of performing calculation at
very high speed and generator complex result. Data stored in the files can also
be retrieved at a very high speed.
2. Reliability: -
The computer performs repetitive jobs without making any mistakes and without
getting tired. Human beings can make they can get tired.
3. Versatility:
- The. computer can be used for a
variety of jobs calculation, data retrieval, controlling machines,
entertainment.
Evolution
of computer
The word computer is derived
from the word "compute" which means to "calculate".
·
If
we look back at the history of computer it can be tracked back 3000 B.C. The
stone age man used small round stones (pebbles) for counting cattle.
·
Later
a device called abacus was developed by Chinese. This is supposed to be the
first mechanical computing device.
·
In
1647, John Napier, a Scottish mathematician developed a devices which is called
Napier's bones. With the help of these devices, multiplication and addition
were possible.
·
In
1642, Blaise Pascal, a French mathematician invented the first mechanical
calculator.
·
In
1673, Gottfried wilhelm Leibniz, A German invented the Leibniz calculator which
was word for addition, Subtraction and multiplication.
·
A
French weaver's sun named joseph marie jachquard made the next significant
contribution in 1804. After observing his father making different weaving
patterns on the loom, he thought of storing these patterns for future use so
the developed a plate with multiple holes to control the weaving pattern, not knowing
that one day his idea of storing the weaving patterns would be used to store
data and would called the punch card.
·
A
punched card is a thin rectangular card be divided into so columns and 12 rows
in which the various characters could be represented by punching holes in
different rows and columns. One character per columns, thus it is possible to
store so characters of data.
·
Around
1822, charle's Babbage a professor of mathematics a the combridge university
devised an automatic calculating machine called difference engine.
·
The
next significant invention came from Dr. Herman Hollerith, an Americans
Hollerith built a computer to analyze the census data of the united states of America
·
Howard
Alken, build the first fully electro mechanical computer named Mark-1
·
In
1945, a significant contribution was made by john Von Neumann, a Frenchman
working for IBM. He designed the basic structures of a computer to included the
capacity to :
1. Perform Logical Functions.
2. Perform Repetitive Functions.
3. Store data and instructions (Memory).
In 1945, the fully
electronics computer named ENIAC was build by prosper FCKERT and John W mauchly
ENIAC stands for electronic numerical integrator and.calculator.
The above three capacities also forms the
major differences between a calculator (which is also used calculations) and a
computer.
The computer has built in logic, the
capacity to make a selection. Logic means some rational thinking like, 2 is
bigger than 1.
The computer is capable
of ITERATION OR REPETITION Suppose,
you have to calculate interest for 100 fixed deposit accounts, in a computer
the instructions are stored only once, and these instructions can be executed
automatically, any number of times.
The data and instruction can be stored and retrieved using the
computer.
GENERATION OF COMPUTER
Now, in order to have
these three features i.e perform logical functions, perform repetitive
functions and store data and instruction (Memory) in a computer, certain
components were made use of which made a lot of difference in the capacity of
the computer. so depending on the technology of the computer are said to belong
to different generation.
Ø 1st Gen computers (1945-1955):- The main component in use was the vacuum tubes (like those
in the old radios, which warned up after a minute or so, and glowed red). The
vacuum tube was also called as various.
The first computer used
1700 vacuum tubes, weighed 30 tons and occupied an area of big hall. Vacuum
tubes or valves took age to warm up and consumed massive amounts of electricity.
Some of the computers of this generation are ENIAC, UNIVAC-1.
Ø 2nd Gen computer (1955-1965) :- The real break through in computers stared with the
discovery. In this generation to used of transistor a smaller an more reliable
successor to the vacuum tube was invented in 1947. The second generation
emerged with transistor being the brain of computer.
Ø 3rd Gen computer (1965-1970):- The second generation computers were well suited to do
either scientific or non-scientific applications but not both. Thus, in 1964,
in IBM announced the system 360 family of mainframe. Where each processor had a
set of large build in instruction. Some of these instruction could be used
effectively for scientific calculation while the other were more suited for
record keeping applications, The computers in this generation used the
technology of integrated circuits (IC). Since the ICs were small in size, there
was a further reduction in size of these computers.
Ø 4th Gen computer (1970-1975):- In this generation work on IC and there in integration
technique. In this generation which become Microprocessor but we invented to
fabricate the various transistor and IC. To compare the third generation
computer these were most reliable miniature in size having all most list heat
generating component fast in speed.
Ø 5th Gen computer (1975 yet to come):- yet to come: - In fifth generation term artificial
intelligence logical inference and speed recognition become the base of fifth
generation AI in turn of fourth generation will be the ability of system to
respond to natural language input they launch the project in 1981 company
research of (VLSI) Very large Scale Intelligence) logical programming knowledge
base system, pattern recognition.
Understanding a computer System
The application areas of computers are unlimited. We find a
computer in very aspect of our life. From a simple operation as playing a video
game to more complicated applications as weather forecasting computers are
found everywhere. Let us take a simple example of a person who needs to
purchase a can of juice from proceeds to the cash counter. The counter person
scans the code that is present in the label to generate a bill. This scanning
of the code is computerized. The man pays his bills with his credit card and
walks off the super market. He just used a computer, which will transfer the
cost of the can of juice from his bank account to the super market. The man
then moves across the street and enters the office of his travel agent. The
tells the agent that he plans to take a vacation and inquires about the places
that he can possibly go. The agent turns to his computer, presses a couple of
keys and gets the list of the prospective places immediately. The agent just
used a database application of the computer. The man selects a place and
confirms his travel. The agent again turns to his computer and moments later
hands him the air tickets to that place. The agent actually connected to a
computer that did the reservation. The man then happily comes to his office and
decides to inform his wife about the vacation. He, therefore, sends e-mail to
his wife. The man used a network application of the computer. Numerous examples
of such kind can be sited. With the advent of technology, newer and newer
application domains of the computer are created everyday. It is just a matter
of time when life without computers cannot be imagined.
What is a computer system?
Computer is an
electronics device which accepts data and performs calculation give output in a
meaningful manner.
Types of computer
Computer can either be
classified on the basis of purpose they serve (cater on the basis of size too)
into following three classes:-
1. Analog Computer
2. Digital Computer
3. Hybrid Computer
Analog Computer:- A computer in which continuous physical variable are
processed and represented in the form of data is known as analog computer. It
is an early type of computer which was designed to obtain data directly from
measurable quantities and process them, such as resistance, voltage, current,
temperature, speed, acceleration, deceleration etc. The input numbers are
represented by varying a physical quantity. A good example of analog device may
be clock with arms representing hours, minutes and seconds.
The quantities represented by analog devices may be termed as
analog quantities. A device is needed to convert these analog quantities into
digital is known as Analog to Digital Converter.
Digital Computer:-
A computer in which data
held as number of discrete or distinctly separate item is manipulated by
arithmetical /logical operations is said to be digital computer. These are
capable of representing data by producing and sensing discrete or off states
represented by binary digits '0s' and '1s'. A good example of digital device
may be digital clock.
Hybrid computers:-
Hybrid computers are
designed and developed by combining feature of analog and digital computers.
They can accept a varying input and convert it for digital processing. Recently
a hybrid computer has been designed and build for line calls in tennis matches.
This device senses whether the ball has dropped on the boundary line, within
boundary line or outside it. After sensing the spot where the ball bounced, it
processes the discrete data and displays the actual distance from boundary
line, reprocesses the same and displays the logical results on LCD (Liquid
Crystal Display) screen of personal computer or hand held palm top computer.
Digital computer is divided into four types:-
(a) Micro computer
(b) Mini computer
(c) Main frame computer
(d) Super computer
Micro computer: - It is a fairly small computer build around a microprocessor
and associated storage & input/output components. Most microcomputers are
single user oriented. However, multi-User oriented micro computers have been
developed. These are mostly desktop sized in which additional units or
peripherals may be attached. Most microprocessors produced in 1970s were 4 bits
or 8-bit machine and within 15 years 32 bit microcomputers had been designed
with almost equivalent feature of late 1970s mainframe computer systems. Microcomputer
has networking features through special microcomputers. Research and development
made possible to reduce the size and enhance the performance, speed, capacity,
networking features etc. This made them truly portable.
Ex: - Laptop computer, notebook
computer, palmtop computers etc.
Mini computer: - It is microcomputer overlap with features of mini computers.
It varies in size from desktop to a file cabinet with on line storage capacity
than pc (for multi-user environment) with ability to support greater variety of
peripheral devices. These are also known as ‘Midrange Computer’. Most minis
produced in 1970s faced challenging microcomputers developed with equivalent
and advanced features. Mini computers adopted distributed computing and multi-user
concept. In distributed computing concept, number of small computers is
distributed in organization offering central computing facilities’. In multi-user
computing concept, number of users can use computer in time sharing basis at a
time. Some example of minicomputers are NCR
32/800, ICL -101, VAX 8800 etc.
Main frame computer: - These are even more powerful than minicomputer. The features
of large mini and small mainframe may overlap in cost as well as in
performance. It may have large on-line storage capacity for multi-user environment
with high speed processing, complex data handling and centralized computing
capability. Some example of mainframe computers are Unisys 2200/600, IBM Systems/390, IBM
Systems/370, IBM Systems/360 etc.
Super Computer: - Super computer with sophisticated hardware are large in
size, have extraordinary processing speeds and designed altogether for
different type of processing capabilities known as parallel processing. The
speed of super computer is in MFLOPS, GFLOPS or TFLOPS.
1 MFLOPS= 1 Million Floating Pointing operation per second.
1 GFLOPS= 1 Giga
Floating Pointing operation per second.
1 TFLOPS= 1 Tera Floating
Pointing operation per second.
Some example of the super
computer is Cry-XMP, Cray-2, ETA-10, PARAM etc. PARAM was designed and
developed in India
HARDWARE
Computer system
Computer System is a
group of parts that are integrated to achieve some objective. A group of parts
or components of a computer system are:-
(a) Hardware
(b) Software
(c) Liveware
Simple grouping of above
components are of no use until and unless they are integrated logically in
order to accomplish a set of specific objective. Thus all these are logically
inter related.
Hardware
Computer hardware is defined as a set of physical components
and devices used in conjunction with these components that make up a computer
system. These physical components and devices can be visualized or sensed by
touching. A computer system generally consists of following components:-
(a) Central Processing Unit(CPU)
Control Unit
Memory
Arithmetic Logic Unit (ALU)
(b) Peripherals
Input Devices
Output Devices
Mass storage Devices
(c) Power Supply
SOFTWARE
Computer software is defined as a set of sequenced
instruction that controls operation of a computer to accomplish a set of
specific objectives. Software may be pre-written or custom-made. We will study
software in the next chapter.
LIVEWARE
Liveware is a jargon for
the people running computer systems. Liveware is the most important component
of computer systems. Liveware, or human ware, or people running computer are
the basic coordinating components who work together to determine processing
needs, provide input data, select hardware and software, design processing
procedure and use the processed output. People running computers may include
executives, Managers, system Analysis, software/Hardware English, Data entry
operation/computer operators etc.
Computer.' hard ware' and 'soft ware' are the most commonly
used terms in computer science an Computer science and represent inter- related.
aspects. One can do nothing useful with computer Hardware alone or with
computer software by itself. We will discuss software later in next chapter. This
chapter is depicted to computer hardware.
§ ANATOMY OF COMPUTER
Recalling
Charles Babbage's Analytical Engine, we find that its anatomy is quite
analogous to the anatomy of the modern computer. Theoretically you must know
the entities of computer system common for all types of typical computer. It
can be evidenced by the following block diagram of computer components.
Flow of Instructions
Flow of Data 
Flow of control
As discussed above in the definition
of hardware, we find that the basic organization comprises of following three
entities:
a.
Central
Processing Unit (CPU)
b.
Peripherals
c.
Power
Supply Unit
Central Processing Unit
(CPU)
Central Processing Unit is the electronic brain of computer
system and its following parts help it to perform the electronic thinking
process:
a.
Control
Unit
b.
Memory
Unit
-
Main
memory unit
-
Auxiliary
memory unit
c.
Arithmetic
& Logic Unit
d.
Busbar
System
Finally, as a heart of
computer system, it performs the following major operations:
a.
Accepts
data/instructions from input device.
b.
Stores
programmed instructions and data.
c.
Controls
the sequence of operations.
d.
Controls
the transfer of information amongst storage device, input devices, output
devices etc.
e.
Performs
the Arithmetical & Logical operations according to instructions
f.
Sends
results/data to output devices.
Control Unit
This unit consists of circuitry which looks after operations and
activities of every component of CPU and other related parts .it controls and
co- ordinates all hardware operations.
It performs the following
major functions:
Þ Controls flows of data form input
devices to memory (main or auxiliary) or to ALU. It further controls flow of
resultant data form ALU to memory and to output devices.
Þ Controls the function of storing program
in the memory takes step by step instructions, interprets them and controls
other hardware components, synchronizes and co-ordinates then according to
programmed instructions or instructions provided through input devices.
Memory units
Before stepping in the world of memory units lets us see what
is computer memory and basics of computer operation
Memory is a device or media that can accept, store and
deliver data on demand and consists of magnetic cores or semiconductor devices.
Not only computer memory, all parts of computer understand
and work on 1s and 0s or binary system. Binary
system is also known as 'base two system'.if you would have an in de like to have an in depth knowledge of
various numbering system you may go through "Number Systems and Codes used
in computers.
There are two types of memory.
(a) Random Access Memory (RAM)
(b) Read Only Memory(ROM)
Random Access Memory (RAM)
Random
Access Memory is a storage device where in time required to retrieve data is
independent of the physical location of data. It is a volatile sort of memory
because it loses its contents when the computer is switched off or at the time
of power failure fluctuation. It is also known as temporary memory due to its
characteristics. Computer can read, write and erase information on them.
There are two types of RAM
a. Dynamic RAM(DRAM)
b. Static RAM(SRAM)
Dynamic RAM
It needs regenerator circuits to
retain stored date. These are used as primary memory in most computers.
Static RAM
These
are so designed that it does not need regenerator circuit to retain the data hence,
these are more complicated, costly and take more space for a given capacity
than dynamic RAM.
Read Only Memory (ROM)
Read
Only Memory often referred as ‘firmware’ is storage device which programmed
while manufacturing and can not be reprogrammed by computer user known as Read
Only Memory. It is also known as permanent memory due to its characteristics.
Normally, it contains information that is needed by CPU when you first turn
your computer ‘on’ as well as frequently when you use programs. A part of disk
operating system programmed resides in it which is needed to initialise or boot
your (BIOS). BIOS checks and tests hardware part of your system so that you may
be able to operate. The term ‘booting’ has been taken from boot strapping. It
is quite natural that before leaving or proceeding for somewhere you have to
wear and strap your boots.
Similarly, PC checks every part of
connected hardware and readies it with the help of initializing or boot strap
loader program.
It is non-volatile because it does
not loose its contents in the event of power failure/interruption. Now the
specific ROMs which can be programmed by experts with the help of special
hardware are being manufactured. We will not go in depth of ROMs as it is
beyond the scope of this book. Some of such ROMs are listed below:
a. Programmable Read only Memory(PROM)
b. Erasable and programmable Read Only
Memory(EPROM)
c. Electrically Erasable and.
programmable Read Only Memory
– Programmable Read Only Memory (PROM)
The Programs are written in to these
memory chips before assembling of
of computer according to the need.
– Erasable and programmable Read Only
Memory (EPROM)
Its contents can be erased
by ultra-violet light so that it can be re-used for other programs.
–Electrically Erasable and programmable
Read Only Memory (EEPROM)
With special electronic
pulses generated by EEPROM Programming equipments.
Most memory devices are
semiconductors/IC and they pack in more storage space, compact in size and have
faster performance than earlier storage units.
Memory units comprise of
two types of memories or storage devices.
a. Main Memory or Primary storage device
b. Auxiliary Memory or Secondary Storage
device.
Main Memory
It is known as primary storage Device
(PSD) OR Immediate Access storage Device (IASD) generally referred as RAM. As
per the block diagram it can be sub divided in to following components
according to its working.
(a) Program Storage Area
(b) Input Storage Area
(c) Working Storage Area
(d) Output Storage Area
Program storage Area
It stores the processing instruction
waiting to be obeyed or currently being obeyed by other components of CPU.
Input storage Area
It stores data awaiting processing.
Working storage Area
It stores data being processed and
its intermediate results which are further fed to output storage area.
Output Storage Area
It
stores processed data until it can be immediately released to output devices.
Thus, any data or instructions stored
in the main memory can be retrieved. at high speed. Which may be in nano
seconds, too. The main fact to be noted is that main memory provides and
retains space for instructions and data until the power supply. or program is
terminated i.e. on the temporary basis.
Another type of memory is ROM which
may be termed as intermediate memory on which certain basic functions necessary
for initialisation or booting purpose are permanently etched. It loads DOS from
bootable hard disk/ floppy disk.
Auxiliary Storage device
It
is also known as Secondary Storage device, Backing storage device or Extended
Storage Device. As discussed above the main memory stores information and data
on a purely.temporary basis. Auxiliary storage device fulfills the need or
storing data and information permanently which may be furtherer erased when not
needed. This may be further divided.in to.
(a) On line auxiliary storage device
(b) Off line auxiliary storage device
On line auxiliary storage device
When the storage device is online
with the processor it is said to be on line storage device e.g. Hard Disk.
Off line auxiliary storage device
Storage
device not directly on line with the processor are know as off line storage
device e.g. Floppy diskette, Magnetic Tape etc.
Auxiliary memory stores information
and data which may be transferred to and from the main memory while processing
and when needed as per programmed. It is virtually higher in capacity and less
expensive than main memory, but retrieving time is more than main memory.
Arithmetic Logic Unit (ALU)
Ii
derives data from main memory, performs arithmetic and logic operations, and
places intermediate results in worming storage area of main memory further,
results are fed to output storage of main memory for further feeding the
data/information to output devices. Typical arithmetic operations may be +,–,*
and/ (where * stands for multiplication and /stands for division). Similarly,
logic operation may be AND, OR, NOT and EXCLUSIVE OR. The operation of control
Unit and ALU are performed at very high speed with the help of electrical logic
gates or electronic circuits.
Busbar system
In fact the busses are conductor
lines etched or the printed Circuits boards (PCB) usually motherboard along
which data which data travels from one part to another. There are three main
kinds of buses:
–
Address
Busto carry address or memory location through the Control Unit to ALU and
back.
–
Data
bus to carry data/information from memory chip to CPU and back.
–
Control
bus to carry control signals to enire CPU, perihpherals, input/output devices
etc.
We may summarise function
of these buses in to system bus peripheral bus
System Bus :- It connects CPU and memory.
Peripheral Bus :- It connects CPU with other peripherals.
PERIPHERALS
Peripheral Controllers
Peripheral controllers or interface device are usually printed
Circuit Board(PCB).hardware or daughter boards which control, interpret and
coordinate the activities of peripheral devices by providing path for the
movement of data/control signals between peripheral devices and CPU. Peripheral
devices and CPU. Peripheral controllers are usually connected to the
motherboards at one end and respective peripherals at the other end e.g. CTD
controller, FDD controller, HDD controller etc.
All input, output and
auxiliary storage devices (i.e. other than CPU) are known as peripherals. These
may be divided in to:
a. Input Devices b. Output
Devices
c. Interactive
Devices d. Storage
Devices
e. Data Entry
Machines
-On-line Data
Entry Machines
-Off-line
Data Entry Machines
Input Devices
Devices used for
communication from humans to computers which reads data instructions, converts
them in to machine readable form and inputs them to computer are said to be
input devices.
There are two types of input devices.
On-line input devices
Off-line input devices
On-line input devices
Input devices which are directly connected to the processor are
said to be on-line input devices e.g. Keyboard, mouse, touch screen etc.
Off-line input devices
Input devices which are not directly connected to the processor
are said to be off-line input devices. There devices allow to record data on
medium e.g magnetic tape, floppy diskettes etc.
Output Devices
There are devices to communicate from computers to human beings
or to other computers. They accept machine coded output from CPU and convert it
into formats understandable to human beings to other machines for further
processing e.g. printers, VDU magnetic tape, floppies etc.
Interactive device
Devices which helps users to communicate directly with
computers Processors are said to be interactive devices e.g. Automated Teller
Machines, cash Dispensers, touch screen devices etc.
Storage devices
Devices
which store the data are said to be storage devices e.g. magnetic tape, floppy,
compact disk, cartridge tape etc.
Data Entry Machines
These machines are used to entry data
in to computers through input/inter-active devices.
On-line Data Entry
Machines are directly connected with the CPU of computer.
On-line workstations are
also example of On-line data entry machines.
Off-line Data entry
Machines are directly connected with the CPU of computer. Stand alone or
independent personal Computers, palm top / Lap top computers can also be used
an Off-line data entry machine other than from such machines
Power Supply Unit
Computer also needs electric power to operationally its parts
and accessories, or it will idle like other familiar appliances which need electric.
Power e.g. radio, television,. refrigerator, audio systems etc. there is slight
difference in the power need of supply of computers because they need specific
current, voltage for various circuits for specific operations. They also need a
steady power supply which is usually provided through Voltage Stabilizer or
Constant Voltage Transformer (CVT). A part from external (and optional) devices
that provide constant as well as stable electric supply e.g.. Voltage
stabilizer, CVT etc. it has a built-in Power supply unit Known as Switch Mode
power Supply (SMPS) unit. It provides necessary current/ voltage to different
part of computers with necessary safety precaution arrangements.
All of the above
components are synchronized by system’s clock which emits number of pulses per
second. That is why the speed of microprocessor is related to its clock speed
in Mega Hertz. Also size or power of CPU is determined by data bus size i.e.
8-bit, 16-bit, 32-bit, 64 bit etc.
I am sure that you are
able to outline a typical computer system which may be summarized by following
block diagram:
 |
How if logical explanation elaborated
above are illustrated with an example of typical Personal Computer along with
Peripheral devices.
Understanding Personal Computers
A computer based
on microprocessor as the central Processing Unit (CPU) usually targed to the
information processing needs of a individual is known as Personal Computer.
You might have
heard terms such as PC, PC-XT, PC-ATs etc
Microprocessor :- A Microprocessor executes all the
program instruction and is truly the heart of the personal computer. It
consists of a silicon clip on which tiny circuit are engraved through a
photochemical processor. Such as :- P1, P2, P3, P4
Evolution of Intel’s Microprocessor
Chips
|
Year
|
1979
|
1982
|
1985
|
1986
|
1993
|
1993 on/wards
|
|
Microprocessor
chip
|
8088
|
80286
|
80386
|
80486
|
Pentium
|
Pentium Pro
|
|
Bits
|
16 Bits
|
16 Bits
|
32 Bits
|
32 Bits
|
32 Bits
|
32 Bits
|
|
Transistors
|
28,000
|
1,34,000
|
2,75,000
|
1,200,000
|
3,000,000
|
6,000,000
|
|
Clock Speed
|
5 MHz
|
8MHz
|
8 MHz
|
25 MHz
|
25 MHz
Upgradable upto 120 MHz
|
200 MHz
|
|
MIPS
|
0.33 MIPS
|
1.2
|
6
|
20
|
44
|
250 to 300 MHz
|
GREEN PC
Some manufacture have designed and
developed the computer hardware components environment friendly in view to save
power when the system is on but not in use. Basic features of green pc include
display power management, disk shut off. Clock switching to lower frequencies. When
the system is on but not in use simultaneously cutting down running costs.
Till
now we have studied about the internal Anatomy of a personal computer. Now, let
us share some information about external anatomy of a pc known as peripherals
that surrounds the processor and memory.
Peripherals may be classified as
under:
·
Input
devices.
·
Output
devices
·
Mass
Storage devices
·
Interactive
devices
·
Data
communication equipments (DCEs)/ Cards/Interfaces
Input Devices
Devices which are used to transform
data into digital into digital codes understandable to computers are known as
input devices. Input process may be also transformed or direct input from the
source. In transforming process the data is transformed from source documents
to another media or directly to computer for processing e.g Keyboard touch
screen. In direct input from source process, the data is captured directly from
source documents without transforming with the help of any techniques/devices
e.g. scanner, MICR, voice input etc.
Keyboard
Keyboard
is the most common input device which is not only used on a PC but also used
Telephone, Cash Register, FAX, Telex, Typewriter etc. Keyboard being used in
computer are generally contain electromechanical key switches or membrane keyboard
having flat sealed surface. It is almost impossible to interact with a computer
without keyboards.
This keyboard may be either build in
build or detached. Most general purpose keyboards are typewriter like standard
QWERTY keyboards and have the keys Q W E R T Y......in the top row of
alphabets. Now bilingual keyboards are also available in Indian market which
helped us to use the same for working in Hindi as well as. English.
Here add Picture of Keyboard
Function of some special keys of a slandered 101-Keys-AT
Keyboard is as under:
1. Escape (Ese) :-
Its function is based on application program and differs from program to
program. Usually, it is used to interrupt printing, operating moving from one
mode to another or escaping from current processing job.
2. Control & Alternate: - It is also based on application program and always used in
conjunction with one or two other keys to perform some pre-determined
functions. User has to hold down Ctrl or Alt key with other
pre-programmed/defined keys.
3. Print Screen/Sys Req :- It sends output of screen to printer. If printer does not
support bit mapped graphics and screen contains graphics, the output printer
will be a rough approximation.
4. Scroll Lock -
It pause a program's operation or interrupts scrolling.
5. Pause/Break-
It pauses or break/spots the running of a program.
6. Caps Lock & Shift :- It toggles all alphabetical keys from Upper to lower and
vice-versa leaving all non alphabetical keys uncharged. Page Up, Page Down,
Home, End, Ins, Del key keys of other set are digits from 0 to 9 with duplicate
cursor keys, NumLock, =,/*,-,+. And enter key.
7. Insert - It
toggle keyboard function between insert mode and normal mode. In normal mode
character right to the cursor moves one space right of the cursor while keying.
In insert mode character are overwritten on previously typed matter.
8. Home: - It
brings cursor at the top of monitor screen or line or file.
9. End - It
brings cursor at the end of the screen or line or file.
10. Page Up & Page Down – Page Up scrolls upward screen at a time Page Down scrolls
downward a screen at a time while editing. These keys are also activated with
combination of Ctrl and Alt keys.
11. Delete :- It
erases character lies under the cursor. It also erases character right to the cursor
speedily when held down.
12. Back Space:-
It moves the cursor to the left while erasing character in its path.
13. Return or Enter- It usually performs two functions. It instructs computer to executed
command just entered and brings cursor at the beginning of the next line
providing one carriage return.
How it works?
Whenever a user presses any key on keyboard the device
translates the key stroke into the equivalent binary code or key stroke is
encoded. The encoded strings of 'ons' or '1s' or '0s' and sent to computer from
keyboard. Computer sends the encoded strings to monitor to represent the
pressed key's character and shifts one space right. The diagram is self explicit.
The above diagram
explains that on pressing key 'A' a string of equivalent binary '10100001' is
sent to monitor through system unit for displaying character A.
POINTING DEVICES
Pointing devices are peripherals used for moving
pointer/cursor/ object on display screen and interacting with computer such as
mice, joystick, track ball, touch, screen etc, Most of the pointing devices are
based on touch technology. Some important pointing devices are discussed below.
TRACK BALL ROLLERS
These track ball rollers are in fact
upside down mice. The track ball roller device can be placed at any convenient
surface or can be fixed on keyboard. This device became very useful for Note
Book/Laptop Personal Computers. It also needs special track ball roller driver
program.
MOUSE
Mouse is an input device which controls the cursor and move the
any file from one place to other place.
Mouse can be further
divided into four types:-
1. Normal Mouse
2. Scroll Moue
3. Optical Mouse
4. Cordless Mouse
Normal Mouse:- In normal mouse to
used ball roller for moving the mouse pointer one place to another place.
Left button :- From this button we can select of any program
which is represent inside the computer system.
Click:- Whenever You can press
the left/right button of mouse on any function is called click.
1. Single click :- Whenever you can select of any file and program them click at a one times
are known as single click.
2. Double click:-
Whenever you can load/open of any folder or file and program then use to double
press of it key are called as double click.
3. Triple click:-
Whenever you can select of any word/contain then press triple times of it key
are known as triple click.
Right click:- From this button to you gets of
details information to related any folder or file act like show the properties
of any type documents.
Such
as:- When you right click on the desktop screen under this located the
following command in the pop up menu.
Scroll Mouse:-
It is type of mouse. In this mouse to used for moving the mouse pointer as ball
roller and distinguish to add scroll button between left and right button.
Use of scroll button:- It button is use for
scrolling of page from left to right and up to down.
Optical Mouse:-
It is types of mouse. In this mouse to used for moving of mouse pointer as
laser light.
Wireless Mouse:- this type of mouse but dot not used in wire to connected from CPU.
JOY STRICKS
It is a device that fits
into contours of user's hands enabling user to use various buttons to control
movement of cursor/pointing/objects on the monitor screen. The shapes and size
of joy sticks differs from hardware to hardware and games loaded on the system.
Mostly this device is useful for video/computer games.
TOUCH SCREENS
It is
the best way to make your personal computer interactive. In fact the human
finger is the most common and natural pointing device which has been used as an
input device for interacting with computers. In this technique user operates or
activates menus or gives command by touching monitor screen at specified place.
It is the most convenient pointing device. The major drawback in this technique
is that user becomes tired due to continuous operation and also the screen
becomes dirty due to continuous touch.
How it works?
There are basically two methods to convert the screen as
touch sensitive.
a. Infra-red Light
b.
Overlaying
Infra-red light- The entire monitor screen is crisscrossed with invisible infra red beams
which are sensed by photo detectors and other side when user touches any point
of screen it interrupts vertical and horizontal invisible beams and help user
to select/activate the loaded computer
program.
Overlaying:- In this technique the monitor screen is overplayed with a
thin layer of placed having sensing grids built into it. When user touches at
any point of the monitor screen the predetermined option is selected to
activate concerned program.
Aslo according to the software loaded
user can freehand draw or sketch on the screen.
Light Pen
You will accept that it is quite
difficult pinpoint on monitor screen with human finger. Light pen device has
rectified this drawback. It is similar to that of a pen that could be placed at
any point on screen and can be used to draw accurately than human finger.
Touch/Digitiser Tablet
Touch/ Digititer tablet function as a
touch screen. These are also known touch pads or digitizer pads. These are easy
and convenient to use because we are habitual to write on horizontal surface
rather than on vertical surface such as monitor screen.
Scanners
This is photo copier shaped device
wihch converts text or graphics images into digital images that can be
processed (capture, crop, resize, retouch etc.) by computers. These processed
images can be further used in multimedia application such Desk Top Publishing
(DTP), Video Animation, Slides for advertisement/teaching etc. These digital
image files can aslo be stored and communicated through e-mail, fax, mdem etc.
How it works?
A beam of light passes across
document or object which is read by means of photo sensing device. The sensor
of photo sensing device senses and differentiates lighter and darker areas then
translates the intensity digitally into 1s and 0s with the help of Analog to
Digital Converter (ADC) circuits representing black, write and gray shades. The
scanner must pass three times over the object for colour scanning for three
basic primary colour; red, green and blue to form the final digital coloured
image. All scanner software. Let us share some information about various
scanners and their working.
There are four types of scanner:
a.
Handheld scanner :-
It fits into palm. It can be held in hand and sided over document also steady
hand.
b.
Flatbed Scanner :-
It is quite similar to the shape of photo copier. The document is either placed
facing down on glass plate or fed through bin stacker.
c.
3-D Scanner :- The
object to be scanned is placed at a pre requisite place and scanned from
overhead camera or camera mounted on adjustable copy stand with light on moreover
side. The distance from camera is adjusted according to magnification level and
range of coverage of the apperture of lence of array type 3-D scanners. Other
scannners have cammeras at fixed distance from the object.
d.
Film Scanner:- The
slide or negative or photo films are inserted in scanner and focus is adjusted
to set the desired resolution, size colours etc.
OCR ( OPTICAL CHARACTER RECOGNITION)
Optical
Character Recognition (OCR) is the technique that scans the text or printed image
of document with the help of scanner, reads the symbols and transcribe them
into computer readable format. The OCR software does this tremendous job of
direct data entry from the source document readable format. The OCR software
does this tremendous job of direct data entry from the source document. This
technique has helped the publishing industry to entry and manipulated the
printed text for further reprinting. Now Intelligent Character Recognition
software can read variety of type styles.
OMR (OPTICAL MARK RECOGNITION)
Optical Mark Recognition is the
process in which assignment of values to marks placed at specific place upon
the specially designed document. The marking may be done in ink pencil,
typewriter etc. This method is popularly used by various recruitment/placement
agencies, professional bodies, and educational establishment to evaluate
multiple choice examination answer sheets.
MICR (MAGNETIC INK CHARACTER
RECOGNITION)
This technique is specifically being
used by banking and financial industry since its origin for handling banking
instruments/documents such as cheques, drafts etc. MICR is technique permits
reader to recognize human recognizable characters printed in special
magnetisable ink capable of processing with related machines.
BAR CODE
Bar codes are thick and thin black
strips to represent numbers and character. These are prices form of encoding
the detailed information. Bar code scanner or reader are used the bar coded
information. It is useful in inventory control. It is also used as information/
price tag of books and various products in departmental stores.
Video input
Photograph and full motion films can
be captured through electronics cameras or VCRs and fed to computer through add
on cards that can be plugged into an expansion slot of personal computer.
How it works? - Video signals are
received from output of electronics camera or VCR .
Personal computer equipped with add on card such as frame grabber, Video,
blaster etc. Converts graphic image and full motion video signals into digital
files through Analog to Digital Convertor (ADC )
and other circuits.
Web camera:- A webcamera is an input device. Which a web camera allows a
computer to accept input a just by focusing on an object. A camera is focused
on the input object to capture a picture of the object to transferred over
networking to a distant place of the picture the image of the can be seen on
the monitor of the distant computer connected through a network or through
internet thus, two or more persons can talk and see one another in the way.
Digitizer :- Digitizer is an input device which is
used for converting picture maps, and drawing into digital form for storage in
computer for storage in computer. Such as X and Y co-ordinates of points in a
drawing.
Digitizer
commonly used in the area computer aided go design cars, building, mechanical
device etc.
Voice/Audio Input
Voice/audio or music signal can be
stored, processed mixed further stored in the wave form. These processed files
can be heard with the help of speakers. Audio processing technique has helped a
lot to develop voice recognition system, creating, innovative musical notes,
audio-video mixing and other multimedia applications.
We may segregate the voice recognition
& music processing as under:-
Voice Recognition:- In voice recognition technique firstly various voice
patterns are stored in the form of digital files. The voice to be recognised is
fed into the computer, the computer and the relevant software analyses the
input audio pattern with the stored one. If both patterns match with each
other, the computer allows user to perform certain pre-derermined operation.
Some software also allow users to give certain voice commands that computer can
understand and follow.
Music Processing:- Music can be stored, mixed and new tunes can be
composed with the help of waveform files and innovative waveform can be created
through MIDI keyboards. Usually, a picture of
switches of tape deck appears on screen which helps user to control play,
pause, reverse fast forward, rewind etc.
Audio & Video - Graphics presentation,
animation or advertisement slides/films can be processed and prepared with the
help of sound/video card and relevant compatible software.
OUTPUT DEVICES
Such devices that
can be used for converting machine comprehensible forms into human compressible
form are said to be output devices. Usually, output devices can provides output
in printed form of text/graphics, display text/graphics, produce audible
signals or machine readable signals, which can be further, stored on storage
media or communicated to remote computer.
PRINTERS:- This is the most commonly used output device
without which enduser find himself helpless to present his work done on
computers. Your selection must be based on the job to the performed.
The following table is self explicit for
the classification of printers:
Printers
can be classified into two groups:
(a) Impact Printer
(b) Non-Impact Printer
IMPACT PRINTER
These printers
generate a mark by the impact of typeface or typefaces against paper through
inked ribbon. Mulitple copies may be obtained by using carbon paper or
carbonless chemical coated paper. Impact printer may be further classified
into following two classes :
(a) Low speed impact character printer
(b) High speed impact line printer
Low speed impact character printer
These printers print a character at a time these may be
further classified into following three sub groups:
(a) Dot Matrix printer
(b) Daisy wheel printer
(c) Golf/Type Ball Printer
Dot/Marix Printer
These are capable of printing text
and graphic images.Some dot matrix printers are equipped with multicolour
ribbons. Speed of dot matrix printers vary between 40 and 500 character per
second (cps)
Daisy Wheel printer
These are also known as letter
quality printers. These are best for text printer graphic images cannot be
printed through these printers. Its speed may vary between and 60 cps.
Golf/Type Ball Printer
These are letter quality printer but
almost obsolete now. These were equipped with plastic or metallic ball embossed
with characters. Graphic/image printing was
not possible with this printer. Its speed varied between 25 to 60
character per second.
High speed impact line printer
These printers construct a line of
output at a time. Usually its speed varies 150 to 3000 lines per minute
depending on printer device used. These are primarily used with
mini/mainframe/super computers. Some printing devices used in line printers
are:
(a) Print chain device
(b) Steel Print band device
(c) Drum or Barrel print device
Print chain device :- Printing of graphic image is not
possible with this printer.
How it works? – it consists of a
chains with character engraved on each link which composes a line of output on
paper.
Steel Print band device :-It is similar to print chain device.
How it works?- It uses a horizontal
rotating steel band with engraved characters instead of a chain that produces
output on paper.
Drum or Barrel print device
It
consists of a set of bands around the drum or barrel. This technique is also known
as fly printing The number of bands are equal to the printing position of
printer usually 132. One revolution of drum is required t print one line. Band
and barrel of characters are moving all the time is this technique.
NON IMPACT PRINTERS
The printing process is done without or
with minimal impact of type faces on paper in these printers. Owing to this
peculiarity, these printers cannot produce multiple copies.
These may be further classified as :
(a)
Low speed non-impact character/page printer
(b)
Low/High Speed non-impact/page printer
Low Speed non-impact character page
printer
These printer print a character/page
at a time. The most popular technique are:
(a)
Thermal transfer technique
(b)
Ink-jet technique
(c)
Bubble-jet technique
Thermal transfer technique
These printers are also known as
solid ink printers. These can print at a speed of apx.500 cps.
Ink-jet technique
These printers are capable of colour
printing using three primary colour cyan magenta and yellow apart from black
& white printing.
Bubble jet technique
These are capable of printing at the
speed of 110 cps to 220 cps for high quality printing.
Low/High speed non-impact page
printer
These printers construct a page of
output on paper in a single cycle. Some of the most popular techniques are:
a) Thermal Transfer Technique
b)
Magnetograghy Technique
c)
Laser Technique
d)
Led Technique
Thermal Transfer Technique
This technique is similar to that of
thermal transfer technique adopted for character printer. This technique is
used for high resolution printing. It is inexpensive and quiet in operation,
speed is handicap.
Magnetography Technique
A japanese company Iwasaki Tsushinki
claimed the development of super fast speed of 115 pages per minute using
conventional toner.
Lazer/Optical Technique
Laser is abbreviated form of light Amplification
by stimulated Emission of Radiation. We have discussed about the term resolution
which refers to dots per inch (dpi).Higher the dpi, higher the resolution and
lower the dpi, lower the resolution. opatiocal/laser printer arrived in 1980's
in the market. A typical laser printer may handle A-4 size of paper and capable
to print 8 page paper per minute (ppm) to 16 ppm. Standard resolutions are
300,600,1200 dpi etc.
GRAPH PLOTTER
Graph Plotter is an output device
which is used for drawing graphics and text computer’s processor direct6ly
controls the movement of one or more pens over a paper by sending a series of
digital signals representing X,Y co-ordnates for two dinmension and X,Y and Z
co-ordinate for 3 dimension graphics. Some dot matric printers are capable for
pripnging graphics but, their quality and resolution are limited. Graphics
plotters have replaced them due to high quality and resolution. Thus higher the
resolution; finer the graphics output.
VIDEO OUTPUT
Video output is the most important
aspect without which user may find himself handicap to interact with computers.
It would be something like a blind person reading with the braile technique
without visual sense. In computer jargon Visual Display Units the (VDUs) are
termed as monitors. Most of the monitors consist of a CRT (Cathode Ray Tube),
LCD (Liquid Crystal Display) or ELD (Electro Luminescent Display) and related
circuitry for visual display of text and video graphic output.
A
light pointer appears on screen to assist a user is known as cursor. The cursor
moves automatically alongwith keyed character,
A typical monitor displays 24 or 25 lines with
80 character in each line. User can view/read a full screen or page. User may
also scroll line by line or page by page the text/graphics upwards or
downwards. Some software also provide facility of scrolling the text/ graphics
horizontally left wards or right wards.
A
basics tip to purchase a good monitor is to judge the monitor from your eyes.
Technically speaking you must be comfortable to use the monitor with industry
level specifications. Apart from size of monitor such as 9" , 12" ,
13", 14", 17" etc. other factors are resolution, dot pitch, phosphor coating etc.
It would be obvious to understand some of the terms related to monitors.
Pixel- It is a light or dark
point of tiniest patch of light that can be displayed on the screen of monitor.
Grid- A screen of monitor is
divided into columns and rows known as grid.
Resolution – Number of pixels in
a grid is known as resolution. Higher the density of pixels, higher the
resolution and lower the density of pixel, lower the resolution.
Video Memory – A part of memory
is arranged to represent characters according to grids of rows and columns on
the screen in known as video memory.
Dot pitch- Dot pitch is the
vertical distance of centre of two adjacent pixels in B&W monitor. In color
monitor dot pitch is the vertical distance between two adjacent pixels of same
colour. It is measured in millimeter (mm).
Phosphor Coating- It is a
special coating on inner surface of the monitor screen, which glows at the spot
where electronic beam’s negative charged particles strike. The glowing retains
till the beam strikes and glowing vanishes as soon as beam lefts the spot. The
retention time of growing should be neither too long nor too short. Imbalanced retentively
may damage the text/graphic display.
Scanning – Scanning is the
process of electronic beam’s movement from top left of screen to the right
bottom of screen horizontally and vertically.
CATHODE RAY TUBE (CRT) BASED MONITORS
These monitor can be classified in
two classes according to display colours.
a. Monochrome Monitors
b. Colour Monitors.
Monochrome Monitor
Monochrome
monitor can only display one colour. The colour displayed by these monitors are
black & white, or one colour such as green or amber.
How it works? – It consists of CRT
which is a vacuum tube having an electronic gun, a yoke and phosphor coated
screen. Video signals received from peripheral controller or adoptor circuits
of computer’s CPU is passed to CRT through relevant circuits of monitor which
controls darkness brightness, contrast, colour, shades and other fine tuning
controls. While scanning process text and graphics images are formed by turning
on or off the electron beam.
Colour Monitor
Colour
monitor can be further classified as under:
a. Analog Monitors
b. Digital or TTL (Transistor to
Transistor Logic) Monitors
Analog Monitor
Its
function is similar to that of TV monitor capable of displaying variable
degrees of brightness and shades. The pixel in this monitor is either
completely on or completely brightness and shades. The pixel in this monitor is
either completely on or completely off.
Digital or TTL
Monitor
In
this monitor a fixed low voltage is being applied for pixel in either off or an
state. It means that when on a signified higher voltage is applied whereas in off
condition a fixed low voltage is applied.
Sometimes
colour monitor are also classified in two types, composite colours & RGB
type monitors. Composite color monitors produce image similar to TV, whereas,
RGB type monitors separate colour signals and produce sharp images than
composite colour monitors.
What is an adaptor?
An
adaptor is a Printed Circuit Board (PCB) fixed in an appropriate expansion slot
on mother board of PC. It receives digital signals from the CPU, converts them
into analog signals, sends them to the monitor’s PCB for controlling intensity,
colours, beams to create desired shades, size of text etc. Basically, any
adaptor consist of two components video controller chip and display memory
chip. Most of the monitors are named on the names of relative adaptors.
Various
most popular Graphics Adaptor circuit used to translate computer signals into
graphic signals are as under:
Monochrome Display Adaptor (MDA)
It
displays single colour e.g Green, amber or white against a dark background.
HGA (Hercules Graphic Adaptor)
A typical HGA provides 720 X 348
pixel resolution with no colours. It is named on its manufactured Hercules Computer
Technologies.
CGA (Colour Graphic
Adaptor)
A
typical CGA provides 320 x 200 pixel resolution and 16 colour palette.
EGA (Enhanced Graphic
Adaptor)
A
typical EGA provides 640 x 350 pixel resolution and 16 colour palette.
VGA (Video Graphic Array)
A
typical VGA provides 640 x 480 pixel resolution & 256 colour palette.
Super VGA
It
is a least expensive way to upgrade the performance of VGA by putting SVGA card
into appropriate expansion slot which can increase 2,62,000 to several million
colours which further depends on video RAM with resolution mentioned above in
VGA or beyond.
Flat Panel Display Devices (FPDD).
Flat panel Display devices are
gaining popularity due to its light weight, compact design and low power
consumption. These are most popular display devices for portable computers e.g
note book PC. Laptop PC, hand held/Palm top PCs etc.
FPDD uses any of the following
techniques.
a. Liquid Crystal Display(LCD)
b. Electro Luminescent Display(ELD)
c. Gas Plasma Display(GPD)
Liquid Crystal display (LCD)
In
this technique a liquid filled display surface us used which creates
images/text using ambient light when electrically charged.
Electro Luminescent Display (ELD)
In this technique light is produced
on a sensitive surface through the application of electric current.
Gas Plasma Display (GPD)
In this technique an inert gas usually mixture
of neon and organ is trapped between flat glass plates and a grid of electrodes
permit the turning ‘on’ and ‘off’ of pixels. These monitors are least portable
than others.
MASS STORAGE DEVICES/SECONDARY MEMORY
You have studied about various types
of input and output devices needed to store data. Mass Storage Devices (MSDs)
are necessary to store computer programs, software and mass data. The term mass
storage means the quality of data larger than the amount that can be stored in
computer’s memory at any one instance.
There are further types divided into
mass storage devices.
1.
Hard disk Drives (HDD)
Disk drives are known by various
names such as fixed disk, rigid disk, Winchester (code name for the IBM project
that developed this product) disk, hard disk drive etc. and come various sizes
e.g 15", 8", 9", 5'-1/4", 3'-1/2" etc. Here, size
refers to the diameter of a set of rigid aluminum platters coated with magnetic
oxide and read/write heads assembly in a sealed unit. These hard disks are
being used in almost all computers from portable to mini/mainframe computer as
single/double floppy drive based systems became obsolete now days. Hard disks
are about 20 times faster than floppy disks with a capacity to store and f
Offer access to hundreds of data
files/programs. Also it can provide faster access to large amounts of data
files/programs. Also it can provide faster access to larger amounts of data
with a single move of the access arm. The major disadvantage is that it is
shock sensitive and it must be backed up regularly.
Hard
disk drives can be either fixed in the system unit or can be used as an
external storage device making them portable. Various important part of the
hard disk are as under:
There are three types of HDD.
1. Zip/Bernoulli Disks
2. Disk Packs
3. Winchester
Zip/Bernoulli Disk:- In this hard disk, a single hard disk
platter is encored in a plastic cartridge. A commonly in a used zip disk is of
3-1/2 inch size having a storage capacity of about 100 MB, Depending on the
formatting style used by a particular computer system. In a zip disk can be
easily inserted into removed from a zip drive or video cassette in a VCR.
Disk Packs:-
In this types a disk pack consist of multiple (two of move) hard disk platters
mounted on a single central shaft these two surface are not user for data
recording in a disk pack. When not in use, disk packs are stored in plastic
cases. This gives virtually inherited storage capacity to disk packs.All the
disks of a disk pack revolve together at the same speed as metioned before the
disk drive of a disk pack has a separate dead/write head for each disk surface,
excluding the upper surface of the topmost disk and the lower surface to the
bottom most disk.
Optical Disk:-
In optical disk storage system consist of a rotating disk which is coated with
a thin matter or some other material that is highly relative laser been
technology is used for recording of data on the disk optical disk are also
known as laser disk or optical laser disks.
Optical disk drive:- An optical disk drive contains all the machenical,
electrical and electronic components for holding an optical disk that can be
used for reading or writing of information.
Type of writing disk:- All optical disks are round plotters. They come in
different size and capacities.
1.)
CD-ROM
2.)
Worm disk
CD-ROM:- CD-ROM stands for (COMPACT
DISK READ ONLY MEMORY). It is read of audio/Video CD and other programs.
The CD-ROM disk is a shiny, silver color metal disk of 5-1/4" diameter. It
has a storage capacity of about 650 MB.
Worm disk:- Worm disk stands for (Write
Once Read only Memory) worm disk allow the users to creates their own
CD-ROM disk by using a CD-Recordable drive which look like standard CD-ROM disk
are purchased black and encoded using a CD/R drive.
Magnetic tape: - Magnetic tape is the most popular
storage medium for large data the magnetic tape medium is a plastic ribbon
which is usually ½ or ¼ inch wide and 50 to 2400 feet long. It is coated with a
magnetically recording material such as Iron oxide or chromium dioxide magnetic
tape just like audio or video tape.
Disk Drive: - A magnetic disk has to be mounted on a disk drive before it
can be used for reading or writing of information.
A disk drive contains all the mechanical
electrical and electronic components for holding one or more disk and for
reading or writing of information or to it otherwise.
By which devices to read and write of any types of information
from CD (Compact disk) and floppy is called disk drive.
Disk formatting: - Disk formatting is one of the base
takes handled by the computer’s operating system. If the formatting is done by
the remove and add of newer operating system.
Note: - That, this is not possible by he user
of disks between computers having in compactable disk drive.
Magnetic disk:- It is secondary storage device. It is
most popular storage medium for direct access secondary storage. It is made of
metal or plastic which is usually coated on both sides with iron oxide.
All magnetic disk are round platter
they comes in some different sizes, different types of packing and it can be
made of rigid metal or flexible plastic.
Floppy disk: - A floppy disk is a round, flat piece
of flexible plastic coated with magnetic oxide. It is encasing in a square
plastic or jacket cover capacity of floppy: - 1.33MB size of floppy 3-1/2 inch,
5-1/4 inch.
NUMBER SYSTEM
Number System:-
–Every Computer understand for only on
binary number but human being understand
decimal number letter and other
special character in coded form .
Number System is basically of two
types.
1) Non positional number system.
2) Positional number system.
1) Non positional Number
system- Non positional number system human beings counted on fingers. In this system but do not calculate the accurate
result this method to use for counting
is stones , pebbles or sticks, were used to indicate values .
Such as – I for 1
II for 2
III for 3
Iv for 4
V for 5
2) Positional Number
System- In this number system there are only a few symbols called digits this
symbol represent different values depending on the position they occupy in the
number. There are four types of number system.
1) Decimal Number System.
2) Binary Number System.
3) Octal Number System.
4) Hexa Decimal Number
System.
Decimal Number System – 9n this system that we used in day
life is called the decimal number system .The decimal number system to be 9ets
(0,1,2,3,4,5,6,7,8,9,) is total Ten digits
Binary Number System – In this system is used to (0,1) is called binary number system . We have only two digits or
symbols.
Such as-(0,1)
Octal Number System - In Octal number system the base is 8.50 in this
system there are only eight symbols or
digit 0,1,2,3,4,5,6,7 and (8 or 9 do not exist in this system.
Hexa Decimal Number System- In Hexa decimal number system is one
with a base of 16. The base of sixteen
suggests choices of sixteen character digits or symbols. The first 10 digits
are the digit of decimal system .0,1,2,3,4,5,6,7,8,9 the remaining six digit
are denoted by A,B,C,D,E and F.
Binary Coded Decimal (BCD) – The BCD is the simplest binary code
that is used the BCD code bits represent number .9n number. Such as -0010
If a
decimal consists of move then one digit, each decimal digit is represent
individually by its 4 bit binary equivalent of the decimal number. For ex – the
binary equivalent of 45 is 101101.
ASCII CODE- ASCII Stand
for American standard code for information Interchange. ASCII code is used
extensively in small computers, peripherals, instruments and communications
devices. This code replaced by many on the special codes that where previously
used. It is an even bit code. Micro computer using 8.bit word length use 7 bit
to represent the basic code. The 8th bit is used for parity or it
may be permanently 1 or 0 with 7 bits. We to 128 characters can be coded. It includes
upper and lower case alphabet number and punctuation mark and special characters.
SOFTWARE
SOFTWARE:- Software
is the only media through which we can interact with computers. Of course, its
is the invisible media quit similar to the invisible notes in the mind of a
musical composer or a person driving vehicle as quoted in the above example.
That is why sometime hardware is defined as the computer components those are
physically visible while those set of instruction which drives the computer
components in the invisible form are termed as software. Nothing useful can be
done with the computer hardware, even if hardware is linked logically together
to form an effective working unit, unlike and unless it is driven by a set of
instruction understandable to computer called as software.
System Software
It is a collection of
complex programs which help to operate, control and enhance the processing
capabilities of computer usually supplied by manufacturers.
There are two of system software
(a)
Operating
Systems
(b)
Programming
Language
Operating system :- Operating manages the computer’s overall resources
and schedules its operations.
ANSI’S ( American
National standard Institution’s) definition of Operating system is software which controls the
execution of computer programs and which may provide scheduling, debugging,
input/output control, accounting, compilation, storage assignment, data
management and related services.
The
main tasks of the operating system involve:
a. Helps to communicate between operator
and computer
b. Monitors and controls computer
peripherals
c. Offers software monitoring and
multiprogramming services.
It acts as an interface
between user program and components of computer comprising of
(a) Control Programs
(b) Processing Programs
Control Programs
Control programs are useful to control the entire
hardware internally and user has no control to alter it.
It
is further made up of following three modules:
(a)
Operating System supervisor
Operating System
Supervisor, also known as OS Master Program controls the over all management of
computer system. It co-ordinates all parts of OS and resides in the primary
storage section of the processor whereas the other programs resides in an
on-line system so that supervisor can call up and store them temporary in the
processor when needed. In most of the Personal Computers Os Supervisor and
other OS Programs are stored in a floppy disk/hard so that it is automatically
loaded into primary storage. It works with BIOS (Basic Input/Output System).
BIOS is a part of operating System that links the specific hardware devices to
the software.
(b) Job Control Program
Job Control Program is
needed in multitasking or batch processing environment. In order to handle more
than one job the instruction are coded in Job Control Language (JCL). Job
control program reads and executes these codes. It further schedules multiple
tasks to balance input/output and processing requirements. It also handles
system interruption are signals which tell the processor to stop current task
and handle other one. It becomes duty of OS to keep track of interrupted
program so that its execution is restored later.
Monitoring System
Monitoring System
monitors status of computer system during processing operation and supplies
information about its function and operation e.g if an error is detected
Operating System sends message to Operator or operating System may put warning
message and passes control to the next job.
MS-DOS/PC-DOS
Disk Operating system
designed and developed for 16 & 32 bit machines and Intel’s microprocessors
by various software suppliers around mid 1980s. Also in 1980 Seattle
UNIX
(b)
Initially developed at Bell Laboratories in 1969 for mini, mainframe,
super computer systems. UNIX is a multitasking and multi-user operating system.
The two standard version of UNIX are Open Look, and Motif. System V.$ is open look offered by Unix international
and Sun Microsystems. OSFI is Motif offered by open software foundation led by
IBM, Digital and Hewlett-Packard. MS-DOS and UNIX currently the most popular
operating systems.
PROGRAMMING LANGUAGES :- Programming Language are set of
language used to express programs and consist of all the symbols, character and
usage permit communication between human and computer. These are having their
own vocabulary and grammar or syntax like other languages e.g Hindi, English,
Tamil etc. The term ‘syntax’ is a computer jargon which refers to the set of
rulers that determines the set of possible instruction instructions in the
particular language understandable to the computers. Programming language learning
is quite similar to learn any of the human understandable language.
These may be divided into following classes.
1. Low Level Language :- A low level language is called machine level language.It has a simple
instruction set of command through which all the tasks are done. The instruction
given to the computer is not binary codes but one of English words. Hence –
writing program is assembly language was much easier and simple then machine
code of the converts. A low level language was closely related to the hardware
configuration as the assembly instruction set refers to the memory registers of
the computer.
2. Assembly Level Language: - As programming is a difficult in a binary language. A new
language introduced as all assembly language. This language some command for
doing a certain task as Add, Subs, Pop, Push, etc. Which is being translated by
an assembler to make it machine under stable it this language programming
become easy but the problem with this language that it is complete machine
depend language as windows 98, Windows XP, Unix, Linex etc.
3. High Level Language: - These are programming language in which instruction are
given in English –like text rather than in binary digits (0s and 1s), that the
computer understands, are known as high level language – A language the user
some command on any computer system world wide such language user some key
boards to develop to a program.
Which program goes to the
computer to translate it not the machine understandable and it is being
executed by the computer system.
Eg :- Basic logo, COBOL,
C, C++ etc.
TRANSLATOR
With
help of this option or program in lower level and higher level convert the language
into machine. There are three types of translator for the language:-
- Assembler: -
This translator is used to convert the program written in low level
language assembly into machine language.
- Compiler:-
Compiler are used to convert the high level language into machine level
language. This errors and error us statement and convert the program into
machine code. A separate command is used to execute the program.
- Interpreter:-
Interpreter are also used to convert high level language into machine
level language. An interpreter checks for error statement by statement the
statement and this process is continued but steps when statement is
encountered end of the program is reached.
The
Motherboard
Understanding the Motherboard
The
motherboard is all those components that make up the actual computer. Important
units such as hard disk and interfaces (collectively called peripherals) are
attached to the motherboard.
A
motherboard has several slots onto which the circuit boards of other devices
like graphics adapters and the interfaces are located. These slots are called
bus slots. If a motherboard has such slots and no electronic components are
connected to it, then the motherboard is said to be modular. The motherboard in
a modular PC is divided into bus board and processor board. The bus board has
the slots for the adapters and the interfaces and the processor board is
inserted onto it as any other board.
The central
component of the motherboard is the main processor (in the figure, It is the
CPU 80x86). The CPU is associated with a coprocessor for mathematical
application. The motherboard, in addition to this, houses a cache controller
and a cache Ram to enhance the overall performance of the computer. Due to
technological advances, these components, now-a-days are clubbed together in a
single chip. The motherboard also houses other devices like main memory or ram,
the ROM BIOS, the DMA controller (8237)2, timer (8254), keyboard
interface and bus slots.
3.2 Components of the Motherboard
Processor and Coprocessor
we
can see that the 80x86 processor is the central unit of the board. The
processor does the actual execution of the program. The main processor is
generally supported by a coprocessor or processor extension. These are
processors, which performs extensive mathematical calculation with high
accuracy. They thus assist the main processor and increase the overall
efficiency. The coprocessor of 80x86 as 80x87. There are coprocessors exiting.
Which are manufactured by other companies such as weitek and Cyrix.
During Purchase,
a coprocessor will not be present in the motherboard. It has to be bought
externally and inserted into the slot meant for the purpose. The processor will
automatically recognize the coprocessor and will transfer controls to it as and
when required.
RAM
The
RAM (Random Access Memory) is a vital component of the motherboard. It is used
to temporarily store data because everything that is stored in the RAM will be
wiped out as soon as electricity is switched off. RAM is available in the
market in the form of memory chips.
RAMs are usually
divided into a set of banks. Each bank has to be equipped with memory chips.
The computer does not recognize banks that are partially filled.
The data
required by the processor or the coprocessor resides in the memory. When data
is needed for computation, the processor sends a request for the data to the
memory. This is done by sending the address of the data via the address bus. The
memory, after receiving the address, processes the request and puts the
requested data in the data bus from where the processor reads the data.
The performance
of RAM is generally measured in term of access time. This is the time taken for
the data to be available to the processor, after the request for the data is
sent to the memory. Modem chips typically have an access time of 60-100 Ns. For
very fast data access, there exist special chips which ahs an access time of
15-25 Ns. These special chips are called cache and are explained in section
3.2.3
3.2.3 Cache
A different type of memory exist in
the motherboard. Compared to the conventional RAM chips, the cache is smaller
and faster. Its access time is much lower than conventional RAM.The cache holds
the data that are frequently required by the processor. The processor,
therefore, has to wait a considerably lesser time for data.
When the
processor requests some data, the cache controller first checks whether the
data is present in the cache. If it is present, then it is immediately made
available to the processor. If the data is not held in the cache memory, then
the cache reads main memory and simultaneously transfers the read memory, then
the cache reads the main memory and simultaneously transfers the read memory,
then the cache reads the main memory and simultaneously transfers the read data
to the processor. Similarly, when processor wants to write to the main memory,
it Write onto the cache memory at high speed. The cache controller then writes
the data back to the main memory later.
The cache is
transparent to the processor. This means that the processor may not necessarily
be aware of the presence of the cache. The newer major powerful 80 x 83 family
processor has the processor, coprocessor, an 8-KB cache memory and a cache
controller incorporated in it.
ROM
The
motherboard also includes a ROM (Read Only Memory). The difference between RAM
and ROM is that, the contents of ROM are not lost when the computer is powered
down. The RAM, On the other hand, looses all its contents. There are various
types of ROM available in the market today. They are PROM (Programmable ROM),
EPROM (Erasable PROM), and EEPROM (Electronically EPROM). These ROM have
additional features than their ancestors. For example, a PROM chip is
programmable. The contents of an EPROM chip can be erased and rewritten.
The ROM contains
some programs and data that are required by the computer during Power up. The
ROM also houses a set of various support routines that are essential for
accessing keyboard, graphics adapter etc. They are collectively called ROM-BIOS.
BUS SLOTS
The
bus slots refer to the into which the various buses in the system are
connected. As mentioned above, data is exchanged between the devices by the
means of the data bus. The address of the data is specified by the address bus.
To control the data transfer, the processor must inform the memory whether it
wants to read data or write data. This is done by the means of a signal that is
carried by an electrical line in the bus. This signal is often called write
enable. There are various signals like the one that is mentioned above. Due to
gather varying number of singles, the bus slots often have varying number of
contact points. For instance, the address bus along with all the control
signals is called system bus. They inform all the adapter cards inserted into
the bus slots about all the operations taking place in the PC. Theoretically,
it does not matter into which bus slot an adapter card is inserted. However,
the cards may not function, as they should in some slots.
Bus divided into
three types:-
1. Data Bus: - This type of Bus that is
carries of data and file one place to another place. In real sense Bus is a
group of parallel lines. Bus affects the speed at which data can travel between
hardware components since wire can wire transfer one bit at a time. 16 wires
Bus can move 16 bits at a time.
2. Address Bus: - In types of Bus to kept
of the full location to relate to data bus. It connects only the CPU and memory
and helps in locating memory address faster today most CPU has 32 bit address
Buses that can address 4 GB of Memory.
3. Control Bus: - It controls the
direction flow origin and signals for every operation it performs.
DMA
Sometimes
it is required to transfer extensive amount of data between the secondary
memory and the primary memory or vice versa. These jobs tend to be long and
time consuming. Thus, if the processor is performing these tasks, a lot of time
is spent on transferring data rather than executing programs. Thus, to avoid
loosing precious processor time and improve the overall performance of the
processor, a separate unit is placed in the motherboard. Which exclusively
caters to these kinds of tasks? Such as unit is called DMA (Direct Memory
Access) Unit.
TIMER
Since
the computer is a digital device, its operations are based on a clock. This
clock is used for several purposes. The most important of the uses of the clock
is to supply a clock single based on which the CPU performs its operations. A
timer chip based on the single based on which the CPU performs its operations.
A timer chip based on the motherboard controls the functions of the clock. In
addition to the function mentioned motherboard controls the functions for the
clock. In addition to the function mentioned above, the timer chip also issues
timer interrupts. These are used to update to internal clock and to refresh the
contents of the RAM.
Registers
i. Introduction
Registers, in
simple terms, can be defined as small storage components that are used for a
very fast access of data. They can also be defined as interfacing devices
between the software and hardware. Command that directly access the hardware
access them through controller chip and other device controllers are all
accessed via the registers. The address, size and the meanings assigned to the
registers depend on the hardware. Registers function both as memory and as
workbench. A microprocessor typically has as number of registers. Some
registers are decicated to specific function while some are general purpose.
Registers have limited effect to the
microprocessor. For example, let us consider that the ALU has to do a
subtraction of two numbers. If the two numbers are fetched from the memory and
stored in two registers, then the operation becomes faster because the access
of data from the registers are much faster. Howerer, adding more registers to
gteh microprocessor does not benefit the processor because the processor is
designed to operate on two operands and thus, at the most requires two
registers has quite and impact on the performance of the processor. The more
the number of bits the register can hold, much faster is the operation.
Let us now see
how registers work. Consider a case where a user is using an application
program. He instructs the application program to open a file. This commandis
converted into a system call to the operating system. The operating system in
turn converts the command and accesses the BIOS routines to execute the user
command. The BION then accesses the corresponding hardware with the help of the
corresponding register. The BIOS converts the defined function call into a
command sequence for the register concerned.
Various registers
As said earlier,
there are a number of register performing various function. Some important
register and their associated functions are listed below.
·
Instruction Pointer
This register is used to print to the next instruction that is to be
fetched by the processor for execution.
·
Flag Register
The flag register is the collection of a number of flags, as shown in
figure 3.2. These are required by the processor for performing various
operations.
·
Segment Registers
This register is used by a processor in a segmented memory environment to
point to a particular memory segment. In the other memory management schemes,
various register are present which are used to point to the various memory
portions as per the scheme.
·
Address
Register
This register is used to store the address of the data that has to be
either stored in the main memory or fetched from the main memory. It is also
used when the data transfer concerns any other device.
·
Data
Register
This register is used to hold the data has to be transferred between two
devices.
·
Pointer
and Index Register
These registers are used by the ALU to perform arithmetic and logical
function. They may also be used by some instructions for some special purpose.
Scratch Pad Registers
These registers
are used by the ALU for storing temporary value and intermediate results. These
registers are not accessible by any instruction.
Accumulator
The accumulator
is a register that is used by the ALU to temporarily hold the result of a
previous operation.
Various other
register are used for a number of other purpose. These registers are explained
as and when they are required.
BUS
Introduction
Buses
are a set of parallel electrical conducting lines that connect various
components on the motherboard. The electrical lines are combined in different
ways to suit different functions and each combination is given a different
name. The internal buses also provided electrical interconnection between the
processor components and the interface device used with peripheral equipmet.
Data Handling and Addressing Limits
The width of the
bus is a limiting factor in data and address handing . so , what dddod we mean
by the width of a bus.? The width of a bus can be defined as the number of electrical lines that make up
the bus. in simple terms, the width of a bus can be defined as the number of
bits it can carry at one Instance of time . For example , if we say , “this is
a 16-bit bus”, we mean that there are 16 electronic lines that combine together
to from
The bus.
The
most important function of the bus is the transfer of data between the
processor and Peripherals or between different peripherals. Ideally, the bus
width should match the data path width of the microprocessor. The advantage of
using this architecture is that during data transfer, the entire word may be
transferred in one exchange.
This will
improve the overall performance of the processor. If the bus width is narrower,
it may take several exchanges to read the full word. From this, we can conclude
that the more the number of data lines on to the bus, the better is the performance.
However, adding more number of data lines on to the bus, adds complexity to the
circuits in the memory as well as the processor.
We know that the
number of microprocessor address lines and the number of bus address lines decide
the maximum memory range that the processor can address. Usually the bus
provides the full range of address lines. However, if the addresses that are
not included are in the upper range of the total address space, the address
lines in the bus are something shortchanged.
Arbitration and bus-matering
The buses of
today connect more than just the components of the microprocessor. A bus that
is connected directly to the processor data and address lines are called local
bus. This bus is meant to service the components near the processor. They are
connected via the PC Bus. The desilgn of the PC bus is such that the components
connected to the bus are in direct control and control the processor. The
processor, however, need not always control the operation of the bus. it may
transfer control circuits like the DMA controller.
Another technology
that is used with the buses is the arbitrated expansion bus. in this
design , the processor is not in full
control of the bus but it is connected to the bus just as any other accompaniment.
The control of the bus is handed over to specialized circuits called the bus controller.
However, the processor is still in control of bus transfers. If the processor
wants , ilt may alienate itself from the transfers between other devices in
the system.
Dual
Bus Architecture
Single
bus architecture something has devastating effects on the performance of the
computer. For example, a 50 MHz. computer may slow down to 8.25 MHz every time memory is
accessed . This is because the
processor and bus speed may not tally.
One method to
avoid such a situation is to use two buses-one for the 1/010 expansion
bus. Compaq computer corporation was the first company to introduced dual-bus PC. This PC was called desktop and had two separate buses for memory, which operated
at the microprocessor speed and a bus for 1/0 operations, which operated at a
much slower speed.
Microprocessor Bus Control
To
read or write data on to the memory, the microprocessor first sends the address
of the data then sends a special signal called Address Latch Enable to indicate
the devices attached to the bus that a valid address has been sent. The device
then locks the circuit for the address. This is called latching. The Processor
then sends a memory read command signal or a memory write command signal as
desired. These tow commands specify whether data has to be read from the memory
or data has to be written onto the memory. The data is consecutively put onto
the bus by the device or the microprocessor.
The
I/O Read Command signal instructs the device to move data placed at the input
port to the data bus from where it will be accessed by the microprocessor. The
I/O write Command signal, on the other hand, instructs the device to move the
data placed in the data lines by the microprocessor to its output port. A fact
that has to be noted here is that the I/O devices are much slower than the
microprocessor. Therefore, a provision exists in the bus to make the
microprocessor wait for the I/O device to complete its operation. This is done
with the help of the I/O Channel Ready signal. If the signal is inactive, it
means that the microprocessor has to wait for the I/O device to complete its
operation.
ALU
Introduction
The
ALU (Arithmetic and Logic Unit) is a section where all the arithmetic and
logical functions are carried out. We know that every arithmetic operation
requires two operands. The operation then produces a result. This ALU,
therefore, must be able to handle two data words and the result. This concept
is dependent on the storage and processing techniques, which may vary, from
model to model. Logical operation usually involves comparisons. Circuits in the
ALU compare two values by subtracting on from another. For example, to
determine whether number A is greater than number B, B is subtracted from A and
the sign of the result is determined. Depending on the sign of the result, the
ALU does further operations. Alphabetic data can also compare according to
their assigned order sequence.
WINDOWS
Windows is an operating system. Which provides a graphical user interface
to the underlying to the underlying operating system? The common operation such
as copying, moving and deletion of files and other similar operations are easy
because they can be done with just a few mouse operations. In the following
section, we will see how to perform some of these operations.
In the market to available the various type windows.
1.
Windows 1.0
(1985) :- It is first version of windows to allowed the PC user to
switch for the Ms-Dos method of typing command at the C, Prompt (C:\) to using
a mouse to point and click function.
2.
Windows
2.0(1987) :- In this version to release of second version of windows of
the improved processing speed of the Intel 286 processor and explorer.
3.
Windows 3.0
(1990) :- It is first widely popular versions of windows. Which offered
32 bit performance, advanced graphics and full support more powerful Intel 386
processor?
4.
Windows 98
(1998) :- In this version of windows is windows 98. It contained the above
mentioned improvements as well as integration of Microsoft internet explorer
into the operating system.
5.
Windows Xp
(2001) :- In this version to improvements the graphics and VGA and
sound and security to add with windows XP consumers and home user now have
performance to drag down process is very simplicity and tasking.
Before
we discuss the operation let us get familiar with some terminologies that are
frequently used while using windows.
- DESTOP
After windows is
fully loaded, a screen as shown in figure 1.1, appears. This screen has some
icons and the task bar. This screen is called desktop.
- Start Menu
Refer to figure
1.1 you can see a button on the leftmost corner on the bottom of the figure.
This button is called the start button. When that button is clicked, a menu
appears, as in figure 1.2 which comprises of menu option such as program,
documents, settings, Find, Help and Run. This menu is called the start menu.
Any operations, such as starting an application to shutting down the computer,
can be done from this menu.
- Task
Bar
The bar on which the start button
is placed is called the task bar. Once an application starts, that application
name is shown on the task bar. Figure 1.3 shows this.
- Icons
As can be see in figure 1.1
the screen contains some small picture below which some names are present. This
picture is called an icon. Icons are shortcuts to some files present somewhere
in the computer. Thus, when you double click on an icon, the file that is
referred to in the shortcut is executed. Therefore, the user need not know the
exact location of the file that he wants to execute.
- Title
Bar
The bar that appears at the top
of any application is called the title bar. The title bar contains the name of
the application and three buttons that are used to minimize, maximize or close
the application. These buttons are explained below.
Figure
1.4 shows the title bar of the Notepad application.
- Minimize
Once an application is running,
it occupies the entire screen or part of the screen. If more than one
application is running at a time, it is often desirable that the application
that is not currently been used be kept minimized. When minimization of an
application is done, all the active windows of that application vanishes and
only a button on the task bar is visible which has the name of the application
that was minimized. Figure 1.3 shows two application, Microsoft word the
Notepad minimized. Minimization of an application can be achieved by clicking
the leftmost button that appears on the title bar of the application, as shown
in figure 1.4
- Maximize
A minimized application can be
restored back to occupy the full screen. When this operation is done, the
application is said to the maximized. Maximization of an application can be
done by clicking the middle button in the title bar of an application.
- Folder
When referring to a folder, we
actually are referring to a directory. Thus, it can be said that folder, in
windows, is a synonym to directories in MS-DOS or Unix.
- Recycle
Bin
When a file or folder is deleted,
windows do not actually remove them from the disk. It sends the deleted item to
the recycle bin. The recycle bin, thus, contains all the deleted items. The
item is permanently removed from the disk, once the item is deleted from the
recycle bin. As long as an item resides on the recycle bin, it can be retrieved
to its original state.
Exploring My computer!
As we had seen in MS-DOS and
Unix, there is often a necessity to view the contents of a disk. This operation
can be be carried out in windows by an application, which is called windows
Explorer. It is often referred simply as explorer. Windows explorer, When
activated, activated a screen as in figure 1.4. On the left side of the
explorer, all the directories and the sub-directories are listed. On the
righthand side. The contents of a directory are listed. Thus, all the files can
be seen in the righthand side. The righthand side can be customized to view
hide details of the files.
Directory Operations
In
this section, we will discuss the common operation that can be carried out with
directories. For performing these operations, the windows explorer is required.
How
to create a new folder?
To
create a new folder, first select the parent of the folder, that is, select the
folder(or root) of which the new folder will be a subfolder. Selection can be
done by clicking the mouse once over the parent. Once the parent is selected,
select the File option form the menu and then New. Finally select the Folder
option and click on it. After clicking, a new folder will be created the name
New folder. This name can be changed as per requirement. Figure 1.5 shown the
creation of a new folder in the root directory.
How will I select more than one folder at a
time?
Windows allows more than one
folder to be operated on with a single operator. For this purpose, all the
folders that have to be operated upon must be selected. Multiple selections can
be done in two ways. In the first method, select the first folder. Press the
shift key in the keyboard and select the last folder. This action will select
all the folders between the first and the last folder. This is shown in figure
1.6
The
second method is used to select folders not arranged one after the other. In
this method, select the folders while pressing the control (CTRL) Key on the
keyboard. This is shown in figure 1.7
How to rename a folder?
To rename a folder, first select
the folder that has to be renamed. Then click the right mouse button. A menu
will appear as shown in figure 1.8
Select
the rename option and give the new name. If a fodder with the new name already
exits, windows will generated an error, as shown in figure 1.9
- How
to delete a folder?
To delete a folder, first
select the folder that has to be deleted. Then press the delete button on the
keyboard. Windows will ask for confirmation befor tit sends the file the
recycle bin. The message appears as in figure 1.10
How will I move a folder?
To move a folder form one
location to another, select the folder that has to be moved. Click the right
mouse button over the folder. The same menu, which appears for renaming, will
appear. Select the cut option. After this, select the destination folder of the
operation. Click the right mouse button and sect paste option from the menu
that appears. The cut and paste operation can also be selected from the Edit
option in the main menu.
How will I copy a folder?
The copy
operation is very similar to the move operation. In the copy operation, instead
of selecting the cut option form the menu, select the copy option. The
remaining part is exactly the same the move operation. If a folder with the
same name exists in the destination, then windows will create a copy of the
folder and name the folder as copy of folder name.
File Operations
Some common
operations that need to be carried on to with the files are rename, copy,
delete and move. This operation can be carried on in exactly the same manner as
with the folders. The only difference is that, instead of selecting a folder,
select the file (s) in question.
Other operations
How do I run an
application?
An application can be run
in four different methods in window. The first and the simplest method is
through icons. The desktop has number of icons for a number of applications.
Click the icon, for the application that has to be run twice. This will start
the application.
The second method is to use
the start menu. Once the start menu appears select the program option provided
in the menu. This will activate another menu, which contains a list of
applications as option. Click the desired application. Further menus may or may
not be activated, depending on how windows have internally arranged the
application. This is shown in figure 1.11
The third
method uses the Run window. This window can be activated by selecting the Run
option from the start menu. This window is shown in figure 1.12
As can be seen
in the figure, the windows explorer can be stated by typing in the file name of
windows explorer in the area provided for the name of the application to be
run. The file name can also be selected by the browse button, which will
activate a window showing the application in the current folder that can be
run. This window is shown in figure 1.13. This will require the manual location
of the application.
The fourth
method is to use the windows explorer. As in the case of the run window, this
method also required manual location of the application. Once the application
is located click the file name twice, this will start the application.
- How
do I change the date and time shown in the computer?
We know that the computer houses a clock. This
clock is used by windows to show the time. The time is shown in the task bar on
the right hand corner (refer to figure 1.1). This display can also be used to
view the current date. To view the date, just move the mouse pointer on top of
the display showing the time. The day, month, date and year will be shown
almost immediately. This is shown in figure 1.14
To
change the date time, click the left mouse twice over the display of time. A
window, shown in figure 1.15 will appear. Change the date and time as required.
How will I change the wallpaper and
screensaver?
In the desktop, the figure that
appears behind the icons is called the wallpaper. The screensaver is an
application that is used to protect the screen from damage. If the screen
constantly shows the same thing for a long time, the internal coating may be
damaged. Thus, the screensaver is used, which will display some animation after
a specified period eloped since the computer was used last.
To change the wallpaper or the
screensaver, click the right mouse button on the anywhere on the desktop.
However, the clicking should not be done over an icon. On right clicking , a
menu will appear as shown in figure 1.16.
Click the properties
option from the menu. This will activate a window that, by default, will allow
you to change the wallpaper. This window is called the display properties
window and is shown in figure 1.17
To change the wallpaper, select a
name in the list or click the browse button to select any other picture not
present in the list.
To change the screensaver, select
the Screensaver tab just below the title bar. This will change the window as
shown in figure 1.18
Select
the screensaver name from the list marked by screen saver. On selection, the
preview of the screensaver is shown above.
What is character map?
Character map is a Symbolic
keyboard notation. Which is used to write those key which is not present on the
keyboard, But we use generally in daily life .Eg:- © , ™,® etc.
How to open
character map
Goto the start
menu ->programs->Accessories->system Tools->character Map
Goto the start
menu ->run->type "charmap"
in textbox and select ok.
Calculator
it is widely known for Mathematical calculation. You can use Calculator
to perform any of the standard operations for which you would normally use a
handheld calculator. Calculator performs basic arithmetic, such as addition and
subtraction, as well as functions found on a scientific calculator, such as
logarithms and factorials.
How to open calculator.
Goto the start
menu ->programs->Accessories->Calculator
Goto the start
menu ->run->type "calc"
in textbox and select ok.
On-Screen Keyboard
On-Screen Keyboard is a utility that displays a
virtual keyboard on the screen and allows users with mobility impairments to
type data using a pointing device or joystick. On-Screen Keyboard is intended
to provide a minimum level of functionality for users with mobility
impairments.
On-Screen Keyboard has three typing modes you can
use to type data:
- In
clicking mode, you click the on-screen keys to type text.
- In
scanning mode, On-Screen Keyboard continually scans the keyboard and
highlights areas where you can type keyboard characters by pressing a hot
key or using a switch-input device.
- In
hovering mode, you use a mouse or joystick to point to a key for a
predefined period of time, and the selected character is typed
automatically.
In On-Screen Keyboard you can also:
- View an
enhanced keyboard that includes the numeric keypad, or a standard keyboard
that does not include the numeric keypad.
- Display
the keyboard with the keys in the standard layout, or in a block layout in
which the keys are arranged in rectangular blocks. Block layout is
especially useful in scanning mode.
- Display
the
- Use Click
Sound to add an audible click when you select a key.
- Use Always
on Top to keep your keyboard displayed on your screen when you switch
programs or windows.
How to open on screen
keyboard.
- To open
On-Screen Keyboard, click Start, point to All Programs,
point to Accessories, point to Accessibility, and then click
On-Screen Keyboard.
- The
program in which you want to type characters must be active while you are
using On-Screen Keyboard.
- Utility
Manager enables users to check an Accessibility program's status and start
or stop an Accessibility program. Users with administrator-level access
can designate to have the program start when Utility Manager starts. Users
can also start Accessibility programs before logging on to the computer on
by pressing the Windows logo key (ÿ) + U at the
Welcome to Windows dialog box that appears when Windows starts.
- The
accessibility tools that ship with Windows are intended to provide a
minimum level of functionality for users with special needs. Most users
with disabilities will need utility programs with more advanced
functionality for daily use. For information about accessibility products
and aids for Windows operating systems, see the accessibility page on the Microsoft Web site.
It will be shown give below:
Windows Media Player
You can use Microsoft Windows Media Player to
play and organize digital media files on your computer and on the Internet. In
addition, you can use the Player to listen to radio stations from all over the
world, play and copy CDs, create your own CDs, play DVDs, and copy music and
videos to portable devices, such as portable digital audio players and Pocket
PCs.
This
section covers:
- Common
tasks :- Highlights some of the most basic tasks that you can
accomplish with the Player.
- Special
features :- Lists the features that are only available on select
versions of the Microsoft Windows operating system.
- Player
areas and buttons :- Describes the primary user interface elements of
the Player, including the playback controls and information display areas.
- Using
the Player Help system :- Describes how to use the Player Help system.
Disk
Defragmenter
Disk Defragmenter is a system
utility for analyzing local volumes and locating and consolidating fragmented
files and folders. You can also defragmenters disks from a command line using
the defrag command.
- To open
Disk Defragmenter, click Start, point to All Programs, point
to Accessories, point to System Tools, and then click Disk
Defragmenter.
- You must
be logged on as an administrator or a member of the Administrators group
in order to complete this procedure. If your computer is connected to a
network, network policy settings may also prevent you from completing this
procedure.
- You
should analyze volumes before defragmenting them. This tells you whether
you need to take the time to defragment them.
- A volume
must have at least 15% free space for Disk Defragmenter to completely and
adequately defragment it. Disk Defragmenter uses this space as a sorting
area for file fragments. If a volume has less than 15% free space, Disk
Defragmenter will only partially defragment it. To increase the free space
on a volume, delete unneeded files or move them to another disk.
- You
cannot defragment volumes that the file system has marked as dirty, which
indicates possible corruption. You must run chkdsk on a dirty
volume before you can defragment it. You can determine if a volume is
dirty by using the fsutil dirty query command. For more information
about chkdsk and fsutil dirty, see Related Topics.
- The time
that Disk Defragmenter takes to defragment a volume depends on several
factors, including the size of the volume, the number and size of files on
the volume, the percentage of fragmentation in the volume, and available
system resources.
- You can
defragment only local file system volumes, and you can run only one
instance of Disk Defragmenter at a time.
- To
interrupt or temporarily stop defragmenting a volume, click Stop or
Pause, respectively.
- If you
start Disk Defragmenter while performing a backup, Disk Defragmenter
stops.
Windows
Movies Maker
This guide helps you start
using Microsoft Windows Movie Maker. Throughout this guide, procedures for
performing common tasks are provided. The instructions describe how to use
Windows Movie Maker with the menu commands; however, it is helpful to remember that
you can perform many of the tasks by using shortcut keys and by using the
mouse. The following topics are included in this guide.
- Getting started :- Provides
information about the technology Windows Movie Maker is based on, along
with tips for recording high-quality audio and video. This section also
describes the Windows Movie Maker interface, shortcuts that you can use,
and the different file types and default options used by Windows Movie
Maker.
- Using Windows Movie Maker :-
Provides conceptual and procedural information for using Windows Movie
Maker.
- Troubleshooting :- Provides
suggestions for resolving common issues that may arise when using Windows
Movie Maker.
- Windows Movie Maker Glossary :-
Provides definitions of terms and concepts related to Windows Movie Maker.
Note This
software is based in part on the work of the Independent JPEG Group.
Networking
Managing a myriad of network and Internet
connections can be confusing. Empower yourself with knowledge about managing
network and Internet connections for local and remote users. If you have a
network problem, diagnose and fix it with network, Internet, and hardware
troubleshooters.
Dial-up connections
A dial-up connection connects you to a network or the Internet by using a
device that utilizes the telephone network. This device can be a modem that
uses a standard phone line, an ISDN card with a high-speed ISDN line, or an
X.25 network.If you are a typical user, you may have one or two dial-up connections, perhaps to the Internet and to your corporate network. In a more complex server scenario, you can use multiple dial-up connections to implement advanced routing.
You can create multiple dial-up connections by copying them in the Network Connections folder. You can then rename the connections and modify connection settings. By doing so, you can easily create different connections to accommodate multiple modems, dialing profiles, and so on.
TCP/IP overview
Transmission Control Protocol/Internet Protocol (TCP/IP) is the most popular
network protocol, and the basis for the Internet. Its routing capabilities
provide maximum flexibility in an enterprise-wide network. In Windows XP
TCP/IP is automatically installed.On a TCP/IP network, you must provide IP addresses to clients. Clients may also require a naming service or a method for name resolution. This section explains IP addressing and name resolution for Network Connections on TCP/IP networks. It also describes the FTP and Telnet tools that are provided by TCP/IP.
Assigning IP addresses to dial-up and virtual private network (VPN)
connections
Each remote computer connecting to a remote access server on a Windows
TCP/IP network is provided an IP address by the remote access server.If you use a specific IP address, the remote access server must be configured to permit users to request a specific address.
Name resolution for network and dial-up connections
In addition to requiring an IP address, network and dial-up connections on a
TCP/IP network may require a mechanism to map computer names to IP addresses.
Four name resolution options are available: DNS, WINS, broadcast name
resolution, and the Hosts and Lmhosts files. In small networks where IP addresses do not change, network and dial-up connections can use a Hosts or Lmhosts file for name resolution. By using these files on the local drive, you do not need to transmit name resolution requests to a WINS or DNS server and wait for the response.
Internet tools
TCP/IP provides File Transfer Protocol (FTP) and Telnet. FTP is a
character-based utility that permits you to connect to FTP servers and transfer
files. Telnet is graphical application that lets you log in to remote computers
and issue commands as if you were at the keyboard of the computer. Multiple
variations of FTP, Telnet, and other programs based on earlier Internet
standards are also available on the Internet or commercially.For information about configuring a connection, see To configure a connection. Fconfiguring TCP/IP, see To c
onfigure TCP/IP settings.
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