Introduction:
Now a days computer is playing a main role in everyday life as it has
become the need of people just like t.v., mobile or other electronic devices at
home. Some of the major parts of a personal computer or PC include the
motherboard, CPU, memory (RAM), hard drive. While personal computers are by far
the most common type of computers today, there are several other types of
computers.
Characteristics of a Computer
Computer solves the problems very quickly as well as accurately. Apart
from the accuracy and speed there are many other characteristics of computer.
It can store large amount of date. The important characteristics are described
below:
1.
Speed:
The computer is a very high speed electronic device. The operations on the
data inside the computer are performed through electronic circuits according to
the given instructions. Computer can perform million of billion of operations
on the data in one second. The speed of the computer is measured in mega hertz
or gega hertz. Different computers have different speed.
2.
Storage:
A computer has internal storage (memory) as well as external or secondary
storage. In secondary storage, a large amount of data and programs (set of
instructions) can be stored for future use.
3.
Calculation/Operations:
A computer can perform arithmetical and logical operations. In arithmetic
operations, it performs the addition, subtraction, multiplication and division
on the numeric data. In logical operation it compares the numerical data as
well as alphabetical data.
4.
Accuracy:
Computer is accurate in doing the
calculations. It gives accurate output result provided that the correct input
data is given to the computer. The output is totally depended on the given
instructions and input data. If wrong input is given, the result generated with
also be incorrect. This concept is called as garbage in garbage out.
5.
Reliability:
The electronic components in modern computer have very low failure rate. The
modern computer can perform very complicated calculations without creating any
problem and produces consistent results.
6.
Versatility:
Versatile means flexible. Variety of tasks can be performed on the
computer. At one moment you are playing game on computer, the next moment you
are composing and sending e-mails etc.
7.
Communications:
Today computer is mostly used to exchange messages or data through computer
networks all over the world. The information can be received or send through
the internet with the help of computer.
8.
Diligence:
A computer can continually work for hours without creating any error. It
does not get tired while working after hours of work it performs the operations
with the same accuracy as well as speed.
Components of a Computers System
basic components:
(a) Input Device: The input is given to the
computer through the input device. The commonly used input devices are:-
(i)
Keyboard:
You type with the key board. You also use it to scroll up or down on the
screen using arrow buttons.
(ii) Mouse: A device that allows you to
point to things on the screen of the monitor and ‘click’ to move to that
location, or ‘open’ things.
(b) Output Device: These devices are used
to show the result of the operation performed by the computer. Commonly used
output devices are:
(i)
Monitor
: This device which operates like a TV set lets the user see how the
computer is responding to their commands.
(ii) Printer: It is used to get the hardcopy
(also called as the printout of the output generated by the computer).
(c)
CPU
(Central Processing Unit): This component tells your computer how fast to
do things. It basically comprises of three major parts. They are Storage/Memory
unit, Control Unit and Arithmeti and Logical Unit.
(d)
Storage/Memory
Unit holds information. Different storage devices are:
(i) Hard disk drives: This is where your
files are permanently stored on your computer. The operating system is
installed here.
(ii) CD ROM drive: These are used to store
large amount of data. It has a capacity of approx. 650 MB.
(iii) Floppy drive: A floppy is a small disk
storage device which has 1.4 Megabytes of capacity. It rarely used now days.
(iv) DVD Drives: It stores a large amount of
data, which is much more than the capacity of a CD.
(v) Memory Stick/Pen drives: They are
smaller in size but can hold good amount of data.
CPU
(Central Processing Unit
The central processing unit is responsible for
performing all of the mathematical calculations that are required for a
computer to function properly. Because a computer cannot function without the
CPU, it is not uncommon to hear people refer to the CPU as the ‘brains’ of a
computer. A CPU is the brain of the electronic system it controls. The most
familiar CPUs also called microprocessors – are found in desktop and laptop personal
computers. CPUs are programmable. In other words they can be programmed to
execute a range of instructions, to perform arithmetic and logical operations
on data, and control input/output of data. This makes CPUs very versatile. They
may as we see in the familiar example of PCs run lots of different programs.
They may also be programmed to perform the specific functions required in a
range of different types of electronic equipment, ranging from consumer
electronics for the home to mobile devices to enterprise IT equipment for the
data centre.
Companies
which make CPU
While there are numerous companies that make CPUs
for different purposes, the two best known makers of CPUs for consumer
computers are AMD (Advance Mitro Devices) and Intel. AMD’s current line of
processors includes Athlon, Phenom, Sempron and Turion processors, while
Intel’s current line of processors includes the Celeron, Pentium, Core Duo,
Centrino and Centrino 2 processors.
Memory
Memory is that area of computer, where all the
data and instructions are stored. The memory storage device are of two types
basically one is the primary memory which is a must in any computer system and
the other is the secondary memory. The primary memory is also known as the
temporary memory as it cannot hold the data when there is any a kind of
disruption power services. The primary memory is the volatile memory. This
means that if the power switched off or there is a power failure then the data
in it is all lost. This is the temporary memory. The other one is the secondary
memory or the hard disk, floppy disk or the CD discs etc. there are called as
the non volatile memories or the permanent storage devices. The RAM is the
example of the primary memory or the temporary storage media. RAM considered
‘random access’ because you can access any memory cell directly if you know the
row and column that intersect at that cell.
Input-Process-Output
A computer basically works on the principle of
IPO i.e. Input-Processing-Output. The IPO’s cycle is how a computer intakes
data, processes the data, outputs information, and then saves the information.
Input:
The input is first given to the processor by the
input devices. The devices which supply the feed or the information to the main
machine, i.e. the CPU for the beginning of the IPO cycle is called as an Input
Devices. Some of the Input devices are:
(i)
Keyboard
(ii)
Mouse
(iii)
Scanner
(iv)
Joystick
(v)
Digital Camera
(vi)
Microphone
Processing
After the input is received from the Input
Devices, it goes to the Processing Unit. The central processing unit is called
the CPU, processor or microprocessor. It is also known as the brain of the
computer. The CPU is the device that receives various types of input and
produces specific outputs. The CPU of the computer has three major parts. They
are : Control Unit, Arithmetic and Logic Unit and Memory Unit.
(i)
The control unit gets the instruction from
memory.
(ii)
The control unit decides what the instruction means
and directs the necessary data to be moved from the memory to the arithmetic
logic unit.
(iii)
The arithmetic logic unit performs the actual
operation on the data.
(iv)
The result of the operation is stored in memory.
Control
Unit
The various parts of the computer’s CPU are
directed by the control unit. The control unit can be described as the manager
of the CPU. Its sole purpose is to guide other mechanisms in the system to
complete specific tasks. The control unit fetches instructions from memory and
decodes them to produce signals which control the other parts of the computer.
These signals cause it to transfer data between memory and ALU or to activate
peripherals to perform input or output. The CU talks with the ALU and memory.
Arithmetic
Logic Unit (ALU)
The arithmetic logic unit is one of the most
important parts of the computers CPU. Its comprised of electronic circuits that
make it capable of executing arithmetic and logic operations. It works with
different registers to store data or hold information about the latest action
performed by the logic unit. The ALU has the ability to perform four types of
arithmetic operations: addition, subtraction multiplication and division. The
ALU also has the means to perform three kinds of logic comparisons: equal-to,
less-than and greater-than. The ALu is capable of comparing letters, numbers or
special characters.
Memory
Unit
Memory Unit is a part of a computer in which
information is stored for use by the central processing unit. Computer systems
consist of two types of memory, the Main/Primary memory and one or more
auxiliary or secondary storage units.
The main memory consists of RAM and ROM. RAM
stands for Random Access Memory. It offers a very fast memory access. It is the
memory where all your data and software files are written. It is the type of
memory that computers use to process programs. This type of memory is called as
Volatile memory because when the computer is turned off all the data in RAM is
wiped.
ROM which stands for Read Only Memory is memory
that has data permanently written on it and is usually not reusable. It is
therefore known as non-volatile memory. Auxiliary or Secondary storage devices
include hard disks, floppy disks, magnetic tape drives, CD & DVD drives,
Pen Drives etc.
Difference
between Primary and Secondary Device
RAM is volatile memory having a limited storage
capacity. It is a primary memory. Secondary Auxiliary storage is storage which
include devices that are connected and controlled by the computer to enable
permanent storage of programs and data. Examples of secondary storage divices
are hard disk, Pen Drives, CDS.
Output
After the processing is done, the result is
finally displayed on the output device. The device which puts the result of the
input given by the user after the processing is done is called as output
device. It is also a device which communicates the result of data processing.
Some of the Output devices are:
(i)
Monitor
(ii)
Printer
(iii)
Speaker
Unit of
Memory
Computer Memory is measured in terms of Bytes,
where a Byte is a sequence of adjacent bits. The word bit is short for binary
digit. A bit consists of one of two values, usually 0 or 1. A byte usually
consists of eight bits. Amounts of computer memory are often expressed in terms
of megabytes or giga bytes.
1 Byte = 8 Bits
1 Kilo
Byte = 1024 Bytes
1 Mega
Byte = 1024 Kilo Byte
= 1024 x 1024 Bytes
1 Giga
Byte = 1024 Mega Bytes
= 1024 x 1024 Kilo Bytes
1 Tera
Byte = 1024 Giga Bytes
= 1024 x 1024 Mega Bytes
Some of
the I/O Devices
Key Board:
is one of the primary input devices used with a computer. The keyboards
design comes from the original typewriter keyboards, which arranged letters and
numbers in a way that prevented the type bars from getting jammed when typing
quickly. This keyboard layout known as the QWERTY design, which gets its name
from the first six letters across in the upper left hand corner of the
keyboard. A keyboard usually includes alphabetic, numerical and common symbols
used in every day transcription. Keyboards for personal computers connected to
the machine through serial or USB plugs.
Computer
Mouse: is a hand operated electronic device that controls the coordinates
of a cursor on your computer screen as
you move it around on a pad; on the bottom of the device is a ball that rolls
on the surface of the pad; “ a mouse takes much more room than a trackball”.
There are three main types of Mouse. They are:
1.
Mechanical:
This is a type of computer mouse that has a rubber or metal ball on its
underside and it can roll in every direction. There are sensors within the
mouse, which are mechanical, detect the direction in which the ball is moving
and moves the pointer on the screen in the same direction. A mouse pad should
be used under the mouse to run on.
2.
Optomechanical:
This is the same as the mechanical mouse except that it uses optical
sensors to the motion of the ball.
3.
Optical:
This type uses a laser
for detecting the mouse’s movement. Optical mice do not have any mechanical
moving parts. The optical mouse responds more quickly and presely than the
mechanical and optomechanical mice and now those they have been around awhile
the price is pretty comparable.
4.
Cordless
Mouse: These are not physically connected to the computer. They rely on
infrared or radio waves to communicate with the computer. Cordless are more
expensive than both the serial and bus mouse. The nice thing is that there is
no cord to constrain or get in your way.
Printer
A Printer is a device that
converts computer output into printed images. Printers can be divided into two
main groups, impact printer and non-impact printer. Impact printer produces
text and images when tiny wire pins on print head strike the ink ribbon by
physically contacting the paper. Non impact printer produces text and graphics
on paper without actually striking the paper. Printers can also be categorized
based on the print method or print technology. The most popular ones are inkjet
printer, laser printer, dot matrix printer and thermal printer. Among these,
only dot matrix printer is impact printer and the others are non impact
printers.
Storage Devices: There are a number of secondary storage devices
available to store your data for future use. Some of the secondary storage
devices are listed below:
Hard Disk: When you save data or install programs on your computer,
the information is typically written to your hard disk. The hard disk is a
spindle of magnetic disks, called platters, that record and store information.
Because the data is stored magnetically, information recorded to the hard disk
remains intact after you turn your computer off.
CD ROM and DVD: The CD and the DVD are the commonly used removable
storage devices used for the purpose of backup and archiving of the data. The
main reason for storing the data over the removable devices is that the data
can be easily moved physically from on place to another. The CD ROM devices can
contain the multiple media data in addition to the text. However only one type
of the data can be accessed from the drives at a time. The CD ROM drive is the
device that is used to only read the data from the CD disk. CD RW is the
rewritable drive that can perform both the functions of reading the disk well
as writing to the disk. The writing of the data is possible ony with help of
software that is called as the CD burner software. The CD ROM presently has the
capacity of about 700 mega bytes.
Pen/Flash Drive: USB flash drives are often used for the same
purposes as floppy disks were. They are smaller, faster, have thousands of
times more capacity, and are more durable and reliable due to their lack of
moving parts. Storage capacities can range from 64 MB to 256 GB.
Computer Software
Computer software is
defined as a set of programs and procedures that are intended to perform some
tasks on a computer system. A software program is a set of instructions that
are aimed at changing the state of computer hardware. At the lowest level
software is in a form of an assembly language, a set of instructions in a
machine understandable form. At the highest level, software is in a form of
high level languages, which are compiled or interpreted into machine language
code. There are three main types of software used: They are system software,
application software and Utility software.
System Software: System software is specifically used for the
functioning of the computer system. System software is any computer software
which manages and controls computer hardware so that application software can
perform a task. System software performs tasks like transferring data from
memory to disk, or rendering text onto a display device. Specific kinds of
system software include loading programs, operating systems, device drivers,
programming tools compilers, assemblers, linkers etc. The operating system is
the system software that makes the computer work. An operating system is
software that acts as an interface between the user and the hardware. It not
only contains drivers used to speak the hardware’s language, but also offers
you a very specific graphical user interface to control the computer. An OS can
also act as an interface to the other software. Some of the commonly used
operating system are Window, Linux or Mac Operating system and the latest
Windows 7.
Application Software: Application software is the software that you
install onto your Operating System. Application software utilizes the capacities
of a computer directly to a dedicated task. Application software is able to
manipulate text, numbers and graphics. It consists of the programs that
actually let you do things with you computer. These applications are written to
run under the various operating systems. These include things like your word
processing programs, spread sheets, email clients, web browser, games etc.
Without the applications, all you can do is change settings and navigate among
the folders. It can be in the form of software focused on a certain single task
like word processing, spreadsheet or playing of audio and video files.
Utility Software (Disk/Folder/Files Management, Virus
scanner/cleaner/Decryption tools): Utility program is a program that
supports the application or development environment in the computer. Utility
software typically perform a limited number of tasks. Some of the commonly used
utility programs are file management.
