Fundamentals
of computer
Computer is a machine. It is an electronic machine
which works on data and instruction given to it. So it is known as data
processing machine too. Computer today has wide range of fields of use. It has
become an indifferent part of our life. The world can’t be imagined today
without computer.
A
computer, in simple term, can be defined as an electronic device that is
designed to accept date, perform the required mathematical and logical
operations at high speed, and output the result. It accepts date, processes it
and gives information as output. Hence, a computer can be defined as a high
speed electronic device which accepts data, process the data and gives
information as output.
Characteristics of
computer:
We
have seen that a computer is an electronic device that performs a function
based on a given set of instructions known as a program. Here data refers some
raw facts or figures, and information implies the processed date. For example
if 12.12.92 is the date of birth of a student, then it is raw data to find out
present age of the student. And the outcome is information.
Date-Process-Information
Today,
computers have become a crucial part of our everyday lives, and we need
computers just like we need the television, telephones, or other electronic
devices at home. Computers are basically meant to solve problems quickly and
accurately.
Speed: computers can
performs millions of operations per second, which means that date that may
otherwise take many hours to process is output as information in the blink of
an eye. The speed of computers is usually given in nanoseconds and picoseconds.
Accuracy: a computer is a very fast, reliable and robust
electronic device. It always gives accurate result, provided the correct data
and set of instructions are input to it. Hence in the event of an error, only
the user who has fed the incorrect date or program needs be held responsible. This
clearly means that the output generated by a computer depends on the given
instruction and input data. If the input data is wrong, then the output will
also be erroneous. In computer terminology this is known as garbage in garbage
out.
Automation: Besides being very
fast and accurate, computers are automatable devices that can perform a task
without any user intervention. The user just needs to assign the task to the
computer, after which it automatically controls different devices attached to
it and executes the program instructions.
Diligence: unlike humans,
computers never get tired of a repetitive task. It can continually work for
hours without creating errors. Even if a large number of execution requires the
same duration, and is executed with the same accuracy.
Versatile: versatility is the
quality of being flexible. Today, computers are used in our daily life in
different fields. For example, they are used as personal computers for home
use, for business oriented tasks, weather forecasting, space exploration,
teaching, railway, banking medicine, and so on indication that computers can
perform different task simultaneously. On the PC that you use at home, you may
play a game, compose and send e- mails, listen to music etc. therefore
computers are versatile devices as they can perform multiple tasks of different
nature at the same time.
Memory: similar to humans,
computers also have memory just the way we cannot store everything in our
memory and need secondary media such as a notebook, to record certain important
things computer also have internal or primary memory as well as external or
secondary memory. While the internal memory of computer is very expensive and
limited in size, the secondary storage is cheaper and of bigger capacity.
First generation
(1940-1956): vacuum tubes.
First
generation computers used a very large number of vacuum tubes for circuitry and
magnetic drums for memory. These computers were so big in size that they often
required an entire room to be installed. The first generation computers were
very expensive and were hence mainly used for scientific purposes. In addition
to a large amount of space, they also needed a lot of electricity and thus
generated enormous heat which often the cause of malfunctions. UNIVAC
(universal automatic computer) and ENIAC (electronic numerical integrated and
calculator) are prime examples of first generation computing devices.
Second generation
(1956-1963): Transistors.
Second
generation computers were manufactured using transistors rather than vacuum
tubes. Transistors were far superior to vacuum tubes. Computer manufactured
using transistors were smaller, faster and more energy efficient and reliable
then first generation computer. These computers had faster primary memory and a
larger secondary memory. But production of such computers was difficult and expensive
due to transistors.
Third generation
(1964-1971): integrated circuit.
The
development of the integrated circuit (IC) was the hallmark of the third
generation computer. Integrated circuit were smaller, less expensive more
reliable and faster in operation, consumed less power and generated less heat
than the components used earlier. The third generation computers were also much
more powerful than their predecessors. These computers had faster and larger
primary memory and secondary storage. Third generation computers were widely
used for scientific as well as business applications. But these computers were
difficult to maintain. They got heated very quickly.
Fourth generation
(1971-1989): microprocessors.
The
microprocessor launched the fourth generation of computer with thousand of
integrated circuits built onto a single silicon chip. This computer could fit
in the palm of hand. During the fourth
generation, semiconductor memories that were very fast were used and HDDs also
become cheaper smaller in size and larger in capacity. Fourth generation also
saw the development of graphical user interfaces (GUI) the moue and handheld
devices. These computers were consuming less electricity so generating less
head. GUI help user to learn and work easily. Network allowed sharing of
resources thereby enabling efficient utilization of computer hardware and
software.
Fifth generation
(Present and Beyond): Artificial intelligence.
Fifth
generation computers are completely based on the new concept of artificial
intelligence (AI) although such computers are still in development, there are
certain application such as voice recognition that are widely being used today.
Parallel processing and superconductor technology have made AI a reality. In
the computers the aim is to develop devices that respond natural language input
and are capable of learning s and self-organization.
On the basis of speed in performance:
1.
Supercomputer
2.
Mainframe
computer
3.
Minicomputer
4.
Microcomputer
Supercomputer
Among
the four categories the supercomputer is the fastest, most powerful and most
expensive computer. Supercomputers were first developed in the 1980s to process
large amounts of data and to solve complex scientific problems. Supercomputers
use parallel processing technology and can perform more than one trillion
calculations in a second. A single supercomputer can support thousands of users
at the same time. Such computers are mainly used for weather forecasting,
nuclear energy research, aircraft design, automotive design, online banking,
and controlling industrial units’ etc. examples- CRAY-1, CRAY-2, CYBER 205 etc.
Mainframe computer
Mainframe
computers are large scale computers. These are very expensive and need a very
large clean room with air conditioning, thereby making them very costly to
deploy. As with supercomputers, mainframe can also support multiple processors.
IBM S/390 mainframe can support 50000 users at the same time. These are also
used in large organization such as banks, airline companies and universities
etc.
Mini computers
As
the name suggests, minicomputers are smaller, cheaper and slower than
mainframes. They are called minicomputers because they were the smallest
computer of their times. The capability of such computer falls between
mainframe and PCs. Such computers are widely used in business, education,
hospitals, government organizations etc. while some of such computers can be
used only by single user. These computers are designed for complex task.
Microcomputer
Microcomputers
are commonly known as PCs, are very small and cheap. The first microcomputer
was developed by IBM named IBM-PC. Desktop, laptop, workstation, network
computers, handheld computers and cellular phones etc. are the different type
of microcomputer of today.
Basic computer
organization
A
computer is an electronic device that basically performs five major operations.
Such as
1.
Accepting
data and instruction. (input)
2.
Storing
data.
3.
Processing
data.
4.
Displaying
results (output).
5.
Controlling
and coordinating all operation inside a computer.
When
the first computers were developed they were used only in the fields of
mathematics and science. In fact the first effective utilization of computers
was for decoding messages in military applications. Later on computers were
used in real time control systems such as for landing on the moon. However,
with the advancement of technology the cost of computes and their maintenance
declined. This opened the way for information processing. Today computers are
widely used in fields such as engineering, health care, banking, education,
internet, digital video composition, desktop publishing, government, traffic
control, legal system, retail business, sports, music, movie, travel and
tourism, business and industry, hospitals, geology, astronomy, weather
forecasting, online banking and robots etc.
Input
devices
An input device is used to feed data
and instruction into the computer. In the absence of an input device, computer
would have only been a display device. Keyboard, mouse, joystick, barcode
reader, image scanner, audio input devices, video input devices are some
examples of input devices.
Keyboard:
The keyboard is the main input
device for computers. Computer keyboards look very similar to the keyboards of
type writers. Most keyboards have between 80 to 110 keys which include the
following keys. Typing Keyes (alphabets), numeric keys (0 to 9 natural numbers),
function keys (these are the specific command keys placed on top of the key
board in a row), control keys (all arrow keys are used to handle and control
the cursor on the screen. Home and end key to move the cursor to the beginning
and end of the current line. Page up and page down keys to move to the previous
and the next page. Insert to enter a character between two existing character.
Delete to delete a character at the cursor position.). Other common control
keys on the keyboard include control (Ctrl), alternate (Alt), escape (Esc),
print screen, pause the window or start key (window logo) and shortcut keys.
The shortcut key has a mouse pointer printed on it and is used to access the
options available by pressing the right mouse button. The escape key cancels
the selected option and the pause key suspends a command or process in
progress. Finally the print screen key captures everything on the screen as an
image. The image can be pasted into any document.
Advantage: the keyboard is easy
to use and cheap.
Disadvantage: the keyboard cannot
be used to draw figure. The process of moving the cursor to another position is
very slow. Mouse and other pointing devices are more apt for this purpose.
Pointing
device, Mouse:
A pointing input device enables
the users to easily control the movement of the pointer to select items on a
display screen, to select commands from commands menu, to draw graphs etc.
Mouse is one of pointing device. It is an important device that was invented by
Douglas Engelbart in 1963. It is the key input device used in a graphical user
interface. It can be used to handle the pointer easily on the screen to perform
various functions such as opening a program or file. The mouse has two buttons
and a scroll wheel. It can be held in the hand and easily moved. Without
lifting, along a hard flat surface to move the cursor to the desired location
--up, down, left, right. Once the mouse is placed at the appropriate position
the user may perform the following operations. Point placing the mouse pointer
over the word or the object on the screen by moving the mouse on the desk is
termed as pointing. Click pressing either the left or the right button of the
mouse is known as clicking. Clicking a mouse button initiates some action. Drag
means pointing to desired location while pressing the left button. Scroll wheel
which is placed in between the left and right buttons of the mouse is used to
vertically scroll through long documents.
Advantage: a mouse is easy to
use and can be used to quickly place the cursor anywhere on the screen. It also
helps to quickly and easily draw figures. It is cheap. Its point and click
capabilities make it unnecessary to remember and type in command.
Disadvantage: the mouse needs extra
desk space to be placed and moved easily. The ball in the mechanical muse must
be cleaned to remove dust from it.
Any device that outputs
information from a computer can be called an output device. Basically output
devices are electromechanical devices that accept digital data from the
computer and convert them into human understandable language. The output
devices are monitor, projector, speaker, printer etc.
Soft
copy devices:
soft copy output device produces an electronic version of an output. For
example a file that is stored on a hard disk, CD, or pen drive—is displayed on
the computer screen. Monitor is soft copy output device used to display video
and graphics information generated by the computer through the video card.
Computer monitors are similar to television screens but they display
information at a much higher quality. The monitor is connected to either the
VGA or the digital video interface (DVI) port on the video card. Monitor come is three variants- cathode ray
tube (CRT), liquid crystal display (LCD) and plasma. The CRT monitor looks much
like traditional television and are very huge in size. LCD monitors on the
other hand are thinner, offering equivalent graphics quality. However these
days LCD monitors are replacing CRT monitors as they are cheaper and occupy
less space on the desk. Most monitors have a size range of 15 inch to 21 inch
or more as a diagonal measurement from one corner of the screen to the other.
CRT
Monitor:
CRT monitors work by firing
charged electrons at a phosphorus film. When electrons hit the phosphor coated
screen, they glow, thereby enabling the user to see the output.
Advantage:
1.
CRT
monitors provide images of good quality.
2.
CRT
monitors are cheapest when compared to LCD and plasma monitors.
3.
The
images are clear even when you try to view from an angle.
Disadvantage:
1.
CRT
monitors occupy a large space on the desk.
2.
They
are bigger in size and weight and therefore difficult to move from one place to
another when compared with other types of monitors.
3.
Power
consumption is higher than the other monitors.
LCD
Monitor:
An LCD
monitor is a thin, flat, electronic visual display unit that uses the light
modulating properties of liquid crystals which do not emit light directly. LCD
screens are used in a wide range of application ranging from computer monitors,
televisions, instrument panels, aircraft cockpit displays etc to consumer
devices such as video players, gaming devices, clocks, watches, calculators and
telephones. These days LCDs have become so popular that there are replacing the
traditional CRT displays at a fast pace. LCD screens are more compact,
lightweight, portable, more reliable and easier on the eyes. LCDs are more
energy efficient and offer safer disposal than CRTs. It is because of their low
electrical power consumption that they are widely being used in battery powered
electronic equipment. LCD technology is based on the principle of blocking
light; an LCD monitor consists of two pieces of polarizing filters that contain
a liquid crystal material between them. A backlight creates light, which is
made to pass through the first substrate. Simultaneously the electrical
currents cause the liquid crystal molecules to align thus allowing varying
levels of light to pass through to the second substrate and create the color
and hence images are seen on the screen.
Advantages:
1.
LCD
monitors are very compact and lightweight.
2.
They
consume less power.
3.
They
do not suffer from geometric distortion.
4.
There
is little or no flicker of images.
5.
They
are more reliable than CRTs.
6.
They
cause less eye fatigue.
7.
They
can be made in almost any size or shape.
Disadvantage:
1.
They
are more expensive than CRTs.
2.
Images
are not very clear when tried to view from an angle.
Speakers
Initially
computers were designed to be used only for scientific purposes, but later with
the advances in technology computer became so popular and cheap that they are
now used in almost every sphere of our day to day lives. Today all business and
home users demand audio capabilities from their computers for this purpose
speakers were developed in different sizes and shapes and with different powers
and sound quality. With all these types
of speakers, the user can enjoy music, movie, or a game, and the voice will be
spread through the entire room. With good quality speakers, the voice will also
be audible even to people sitting in another room or even to neighbors. Users
often use headphones to chat with people over the internet. With headphones,
they are assured that the conversation is heard only by them. However, in
addition to the headphones, they are also required to use a separate microphone
to talk to the other person. Hence, another device called the headset was
developed to allow user to talk and listen at the same time, using the same
device. Headsets are widely used in call centers and other telephone intensive
jobs and for personal use on the computer to facilitate comfortable
simultaneous conversation and typing.
Printers
A printer is a device that takes
the text and graphics information obtained from a computer and prints it on to
a paper. Printers are available in the market in various sizes, speeds,
sophistication and costs. Usually more expensive printers are used for higher
resolution color printing.
Classification of printers
Printers can be broadly
classified into two groups: Impact and non-Impact printers
Impact printers
These printers print characters
by striking an inked ribbon against the paper. Example: dot matrix printers,
daisy wheel printers and most types of line printers.
Advantage
1.
These
printers enable the user to produce carbon copies
2.
They
are cheap
Disadvantage
1.
Impact
printers are slow
2.
Poor
print quality
3.
Extremely
noisy
Non impact printers
These are much quieter than
impact printers as their printing heads do not strike the paper. They offer
better print quality, faster printing and the ability to create prints that
contain sophisticated graphics. Such printers us either solid or liquid cartridge-based
ink, which is either sprayed, dripped drawn onto the page. The main types of
non impact printers are inkjet, laser and thermal printers.
Advantage
1.
Prints
good quality
2.
Noiseless
3.
Fast
Disadvantage
1.
Printers
are expensive
2.
The
ink cartridges used by them are also costly
Memory
is an internal storage area in the computer, which is used to store data and
programs either temporarily or permanently. Computer memory can be broadly
divided into two groups- primary memory and secondary memory.
Primary
memory
Primary
memory or main memory or internal memory is the only type of memory that is
directly accessed by the CPU. The CPU continuously reads instructions stored in
the primary memory and executes them. Any data that has to be operated by the
CPU is also stored there. There are two types of primary memory i.e. RAM
(Random Access Memory) and ROM (Read Only Memory).
RAM is volatile storages are within the computer that
is typically used to store data temporarily, so that it can be promptly
accessed by the processor. The information stored in the RAM is basically
loaded from the computer’s hard disk, and includes data related to the
operating system and applications that are currently being executed by the
processor. RAM is considered random
access because any memory cell can be directly accessed if its address in
known. When the RAM gets full, the computer system operates at a slow speed.
When multiple applications are being executed simultaneously and the RAM gets
fully occupied by the application’s data, it is searched to identify memory
portions that have not been utilized. The contents of those locations are then
copied onto the hard drive. This action frees up RAM space and enables the
system to load other pieces of required data. RAM is two types i.e. Static
RAM and Dynamic RAM.
ROM refers to computer memory chips containing
permanent or semi permanent data. Unlike RAM, ROM is non volatile; that is the
data is retained in it even after the computer is turned off. Most computers
contain a small amount of ROM that stores critical programs such as the Basic
Input/ Output system (BIOS) which is used to boot up the computer
when it is turned on. The BIOS consists up of few codes that tell the computer
what to do when it starts up. Moreover ROMs are used extensively in calculators
and peripherals devices such as laser printers, whose fonts are often stored in
ROMs.
Secondary Storage Device
Secondary
storage also known as external memory or auxiliary storage which differs from
main memory in that it is not directly accessible by the CPU. The secondary
storage devices hold data even when the computer is switched off. An example of such device is Hard Disk.
Secondary storage devices are non volatile in nature, cheaper that primary
memory, and thus can be used to store huge amount of data. The secondary
storage devices are basically formatted according to a file system that organizes
the data into files and directories.
Offline storage
Offline
storage devices are those on which data is recorded and then physically removed
or disconnected. Such devices include magnetic tapes, floppy disks, optical
disks, flash memory devices and external hard disk. In order to access data
from an offline storage device, it must first be connected to a computer.
Offline storage devices are widely used to store a backup of important data.
For example if the original data get destroyed in case of a disaster, the data
can be recovered from the offline devices, which are usually stored in another
distant place, moreover offline storage also provides security of critical data
as these devices are physically inaccessible by a computer, and therefore data
confidentiality.
Optical
drives
Optical
storage refers to storing data on an optically readable medium by making marks
in a pattern that can be read using a beam of laser light precisely focused on
a spinning disk. Optical storage devices are the most widely used and reliable
CD-ROM, DVD-ROM, CD-Recordable, CD-Rewritable etc.
USB
Flash drives
USB
flash drives are removable, rewritable and physically much smaller drives,
weighing less than 30gram.these devices are good substitute for floppy disks
and CD-ROMs as they are smaller, faster have thousands of time more capacity
and are more durable and reliable.
Memory
cards
A
memory card is a small device that can store digital files. They are easily
portable from one place to another. A user can take a memory card insert it
into a computer and store files such as text documents, pictures , audio files
and video files and then remove the card and take it to another computer.
A computer system consists of two parts
·
Computer
hardware, which is constituted by the physical components of a computer.
·
Computer
software, which tells the hardware what to do and how to do it.
Since
the computer hardware is a part of a machine it can understand only two basic
concepts: on and off, called binary. Computer software was developed to use the
binary to tell the computer hardware what to do. The computer hardware cannot
think and make decisions on its own. Hence it cannot be used to analyses a
given set of data and find a solution. The hardware needs software to instruct
what has to be done. A program is a set of instructions arranged in a sequence
to guide the computer to find a solution for a given problem. The process of
writing a program is called programming.
Computer
programmers write a set of instructions using a specific programming language.
Such instructions are known as the source code. Another computer program called
compiler is then used to transform the source code into a language that the
computer can understand. The result is an executable computer program, which is
another name for software.
·
Application
software
·
System
software
Application software
It
is designed to solve a particular problem for users. In general, it is what we
mean by the word computer programs. Examples of application software include
spreadsheets, database, and desktop publishing system.
System software
System
software, according to Nutt provides a general programming environment in which
programmers can create specific applications to suit their needs. This
environment provides new functions that are not available at the hardware level
and performs tasks related to executing the application program. System software represents programs that
allow the hardware to run properly. It is transparent to the user and acts as
an interface between the hardware of the computer and the application software
that the user need to run on the computer.
Operating system
An
operating system is a group of computer programs that controls a computer’s
resources such as the central processing unit, memory and input / output
devices and provides the users with an interface that makes it easy to use the
computer. It provides users an environment to execute programs conveniently and
efficiently. Popular operating systems are DOS (it is a non graphical command
line operating system. It is command driven operating system), Microsoft
Windows family (Windows 7, Windows 8, Windows 10 are the members of such
family), UNIX, Linux and OS X etc.
