COMPUTER INTRODUCTION
The computer is just a dead collection of plastic, silicon and metal until you press the ‘Power’ button. One little burst of electricity and it starts a string of events that puts life and power into the machine. But, even at this stage, the computer is unaware of the potential that it holds within itself. The computer, today, is a fundamental part of the information age.
A computer can be defined as an advanced electronic
device that takes raw data as input from the user. It uses a set of instructions
(called program) to process the data and give the result (output). The result
can be used immediately or saved for future use.
1.
Hardware and Software
In the process of converting data to information, a
computer uses hardware and software. At the simplest level, all computers
consist of these two basic components; the hardware and the software.
Hardware is
any part of the computer that has a physical structure that can be seen and
touched, though some may be so tiny that they are invisible to the naked eye.
Software
is the instruction set that
tells the computer how to perform tasks. Software is intangible i.e., that
cannot be seen and touched, but its effect is clearly defined.
Hardware components are classified into following categories:
I. Input Devices
Input devices are
the devices that allow a user to enter data and instructions into a computer
such as keyboard, mouse, microphone, scanner, trackball, joystick, graphics
tablet and digital camera.
The various functions of input devices are:
❖ They
accept data and instructions from the user.
❖ They
convert these instructions and data from human readable form to machine
readable form.
❖ They
supply the converted instructions and data to the CPU for further processing.
II. Output Devices
Output devices are used to display the result or
information to the user through monitor or VDUs, LCDs, printers, plotters and
speakers.
Functions of output devices can be summed up as
follows:
❖ It
accepts the results produced by the computer which is in the coded form or
machine readable form.
❖ It
converts these coded results into human readable form.
❖ It supplies the converted results to the user.
III. Storage devices
Storage
devices are the
devices which are used to retrieved from and saved to the data and information
such as hard drives, memory sticks (pen drives), compact discs, DVDs and tape
drives.
. Hard Disk is made up of a
metal disk and coated with a metal oxide used to store bulk of data. These
disks can store more information than floppy disks, up to tens or hundreds of
gigabytes.
Compact Disk
– Read Only Memory or CD-ROM is a read only or read-write
disk. It can store large amount of data which can be distributed to large number
of users. It is inexpensive and fast, but its access time is longer than that
of magnetic disk.
There
are two types of CDs: CD-R and CD-RW.
CD-R
stands for Compact Disk – Recordable which can store 700 MB of data, but only
once.
CD-RW
stands for Compact Disk – ReWriteable which can read, write and erase data as
many times.
4. DVD, short for Digital Versatile Disc, is
an optical storage disc similar to CD-ROM, as this is double sided with dual
layer disc and can hold 4.7 GB of data.
PEN DRIVE : USB
stands for Universal Serial Bus. It is a portable
memory device which is used to store data that needs to be transferred to the
other device using USB port of the system.
Memory Card or flash memory card is a memory device. It is used as an easy,
fast and reliable medium to store and transfer data from one device to the
other. It is used in digital cameras, game consoles, mobile phones etc.
CPU(Central Processing Unit)
The system unit is the box that protects the
internal electronic components from damage. It contains the central processing
unit (CPU) and memory. The CPUinterprets and carries out the basic
instructions that operate the computer. Memory is where data and
instructions are held.
The heart
of the computer system is the processor unit. It consists of the Arithmetic
and Logic Unit (ALU)
which executes most computer
operations (arithmetic and logical) and the Control Unit
which acts as the nerve centre
that sends control signal to all other units.
Memory
There are two categories of memory, primary memory
and secondary memory (or external memory).
Primary Memory is very fast as data and programs must be in the primary memory
for execution. Random Access Memory (RAM) and Read Only Memory (ROM) are both
primary memory.
Random Access Memory refers
to memory that can be selected and used randomly. The information stored here
disappears the very moment the machine is turned off. It is also referred to as
volatile memory.
Secondary Memory or Auxiliary
Memory: The content on the RAM is erased when electric power is switched
off. So, it becomes necessary to store this data for future use, somewhere
else. Since, primary storage is expensive too; we need a relatively cheaper
form of backup storage which can store vast quantities of information. Thus, Secondary
Memory devices become an important part of the computer.
Units of
Memory
Memory, storage, files and folder sizes are all measured in bytes.
Computers work in the base 2 system, also called binary number system, using
only the digits 0 and 1. A single numeric value using either 0 or 1 is called a
bit. A sequence of ‘bits’ make a byte. Usually eight bits make a
byte (sometimes it could be sixteen, thirty two or even sixty four). Bits are
grouped into bytes to increase the efficiency of the computer. To describe
large capacities, the terms Kilobyte (KB), megabyte (MB), gigabyte (GB),
terabyte (TB) and Petabyte (PB) are used.
1 nibble = 4 bits 1 byte = 8
bits
1 KB =
1024 bytes 1 MB = 1024 KB
1 GB = 1024 MB 1 TB = 1024 GB
1 PB =
1024 TB
Software
A computer
system’s hardware must have software to function. There are two primary types
of softwares: Application software and Systems software.
It includes programs that direct the computer to carry out specific tasks.
Often, multiple programs are integrated to create an application. For example:
To write error free documents, Word Processors are used such as OpenOffice.org
Writer, MS Word etc. For calculations, Spreadsheets are used such as
OpenOffice.org Spreadsheet, Ms Excel etc. For making presentations,
Presentation Softwares are used such as OpenOffice.org Impress, MS PowerPoint
etc. For designing images, Desktop publishing softwares are used such as Gimp,
Adobe Photoshop, Corel Draw, Picasa etc.
Whereas, at the same time, there are application
softwares that are created to address specific needs of a group of specialized
users and are, therefore, known as tailored or customized software to perform
the required tasks in a specific manner. There are many packaged softwares
available, addressing specific needs of small or big groups of users. You have
a ‘Tally’ or a ‘QuickBooks’ to address a small businessman’s accounting needs,
but it can also serve a large multinational company.
System software
System software includes the programs that enable the computer’s
hardware to work with and run the application software. System software is the
interface between user and the other programs and the computer’s hardware.
Here
are two categories of system software: operating systems and system utilities.
The operating system, also referred to as the OS, is
a computer program that manages all the other programs on your computer, stores
files in an organized manner, and coordinates the use of the computer hardware
such as the keyboard and mouse. The operating system frees one from having to
interact directly with the hardware— other than clicking the mouse button or
pressing keys on the keyboard— to complete tasks.
Utility software is a form of system software. It
is used to analyze, configure, optimize or maintain the computer. This software
performs all the housekeeping functions.
The utility softwares are categorised into
the following categories:
1. Text Editors facilitate the creation of
flawless text documents. WordPad and Notepad are the commonly used text
editors.
2. Compression Utilities are used to compress the selected files. It helps to save the
space on the disk and to transfer heavy files on a network.
3. Disk
Fragmentation utility helps the user to arrange used and free space on the
hard disk which in turn increases the processing speed of the disk.
4. Scan
Disk utility checks for the problems on the hard disk such as bad
sectors, viruses etc.
5.
Encryption or Decryption utility is used to hide the data for
secured transmission. At the source, data is encrypted and at the destination
device, data is decrypted to reveal the original message. Decryption requires a
secret key or password.
Computers Characteristics
Speed: A
computer computes problems much faster than a human being.
Accuracy: With
the high computation speed, computers are able to produce accurate results. If
the input is valid, only then correct output will be produced as computers
follows GIGO i.e. Garbage In Garbage Out principle.
No IQ: It
is programmed to carry out tasks and performs exactly as instructed, since it
has no intelligence of its own.
Diligence:
It can carry out tasks over and over again with exactly the same result every
time, and it does so without tiring.
Data Storage: Using
different kinds of storage devices, it can store huge quantities of data over
long periods of time.
No Heuristics: As computer is a dumb machine, thus it never ever learns from its
past experiences.
Categories of Computers
Computers are classified into many categories
depending upon their size, functioning and processing capabilities.
According to how it functions, computers can be classified
into three categories
Analog: According
to the Merriam Webster Dictionary, computers in which continuously variable
physical quantities, such as electrical potential, fluid pressure, or
mechanical motion, are used to represent (analogously) the quantities in the
problem to be solved are called analog computers.
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Digital: These computers deal with data
in the form of numbers. They mainly operate by counting and performing
arithmetic & logical operations on numeric data. Such computers are ‘many
problems’ oriented.
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Hybrid: Digital
computers could not deal with very large numbers and so, a computer with
characteristics of both analog and digital was created which was known as
Hybrid computer.
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According to the size, computers are classified into the following categories
Palmtop, better
known as Personal Digital Assistants (PDAs), are small, lightweight and tightly
integrated computers which usually do not have keyboards but rely on touch
screen technology for user-input.
Laptops and Notebooks are
portable computers. They include a battery that provides electrical backup for
a period of time.
Personal computer (PC) is small in size and is designed for general use by a
single person.
Desktop computer
is typically set up in a permanent location and is a PC that is not portable. A
desktop computer is a PC built for high performance and heavy workload. It
helps in faster rendering of complex graphics, provides power for computer
intensive applications and memory for large tasks. They are more reliable and
have less downtime.
Micro-computers came into being with the invention of the micro-processor. They
are not so expensive. The personal computer is a micro-computer.
Mini computers provide more power than micro computers in terms of speed and storage
capacity. They are also less expensive. Their performance is also lower than
that of mainframes.
Mainframe computers can also process data at very high speeds, but less than that of
super computers. Normally, they are used in banking, airlines and railways etc.
for their applications.
Super computer A super computer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second (FLOPS) instead of million instructions per second (MIPS).
Summary
1. Data is a collection of unprocessed facts, figures
and symbols.
2. Information is a data that is organised,
meaningful and useful. It helps in decision making processes.
3. Hardware refers to the components that can be seen
or touched. It comprises of input devices, output devices, system units,
storage devices and a communication devices.
4. Software is a set of instructions that tells the
computer to perform the task.
5. Primary memory helps in the fast execution of the
program and it compromises of RAM and ROM.
6. Secondary memory is also known as Auxiliary
Memory. It helps to store the data permanently using available storage devices
such as Hard Disk, DVD, USB, etc.
7. Operating system is a computer program that
manages all other programs stored on the computer.
8. IPO refers to input-process-output cycle which is
followed by the computer system to achieve the desired result.
9. Most keyboards attach to the PC via PS/2 connector
or USB port.
10. Pointing device such as mouse is connected to the
PC via a serial port, PS/2 mouse port or USB port.
11. The process of decoding data that has
been encrypted into secret format is called decryption.
A. Multiple choice questions
1. The
collection of unprocessed facts, figures and symbols is known as ____________.
(a)
Information (b) Software
(c) Data and
Information (d) None of the above
2.
______________ is the processed form of data which is organized meaningful and
useful.
(a)
Information (b) Software
(c) Data (d)
None of the above
3. Hardware
is any part of the computer that has a physical structure that can be seen and
touched.
(a) True (b)
False
(c) Not sure
(d) None of the above
4. Components
of computer hardware are ____________________________.
(a) Input
devices and output devices (b) A system unit and storage devices
(c)
Communication devices (d) All of the above
5. __________
devices accept data and instructions from the user.
(a) Output
(b) Input
(c)
Components of hardware (d) Storage
6. Which disk
is made up of a circular thin plastic jacket coated with magnetic material?
(a) Hard Disk
(b) Compact Disk
(c) DVD (d)
Floppy Disk
7.
___________ disks are used to store more than 25 GB of data with a very high
speed in less amount of time.
(a) Digital
Versatile (b) Compact
(c) Blue-Ray
(d) None of the above
8. Random
Access Memory and Read Only Memory are examples of _______________.
(a) Primary
Memory (b) Secondary Memory
(c) Auxiliary
Memory (d) Both primary and secondary memory
9. Which
system uses only the digits 0 and 1?
(a) Bits (b)
Binary number system
(c) Secondary
number system (d) Nibbles
10. There are
two primary types of softwares namely _________ and __________.
(a) General
Purpose and tailor made
(b) Operating
System and utility software
(c)
Application Software and System Software
(d)
None of the above
Answer the following questions:
1. Explain
the following terms
(a) RAM (b)
Nibble
(c) Digital
Computers (d) Ethernet Port
2. Name any
two utility softwares.
3. Why there
is a need of Auxiliary Memory?
4.
Differentiate the following
(a) Hardware
vs Software
(b) RAM vs
ROM
(c)
Application Software vs System Software
(d)
Digital vs Analog
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