1. Memory:
It is used to store data, instructions and
results permanently or temporarily.
(a)Primary memory – It is a semiconductor
memory capable of sending and receiving data ,
storing data, intermediate results temporarily.
3. The Three types are:
(i) RAM (Random Access Memory)
• Volatile memory ( Contents are lost when the device is
powered off ).
• It allows reading and writing. It contains OS, currently
used application program, data , instructions to be processed
by the CPU.
4. (ii) ROM (Read Only Memory )
• It is non – volatile (contents are safe even when power is
off ), its content cannot be modified easily, it stores booting
program, and usually allows reading only.
• The types of ROM are:
1. PROM (Programmable ROM - once programmed and
cannot be modified further )
2. EPROM (Erasable Programmable ROM – we can
rewrite using ultra violet rays )
3. EEPROM (Electrically EPROM – data’s can be erased
electrically and can reprogrammed – Pen drive etc).
6. (iii) Cache memory
• It is a fast memory in between the processor and
RAM. Frequently accessed data, instructions etc, are
stored here for quick access.
• When processor needs to read or write from RAM,
it first check a copy of it in cache memory.
7. Secondary storage :
It holds data and information permanently. It
is slower, it stores programs and data but the processor
cannot access them directly.
It is also known as auxiliary storage. It has
huge storage capacity and the storage is permanent.
Usually we store data, programs and
information in the secondary storage, but we have to
give instruction explicitly for this.
8. 1. Magnetic storage device ( magnetic tap, Hard Disk )
2. Optical storage devices (CD, DVD, Blue-RAY ),
3. Semi conductor( Flash Drive – it is faster and
durable ) .
10. Input devices: These devices feed data and instructions from
the user into the computer.
Output devices: These devices present information from a
computer system to the user.
11. Keyboard: Allows the user to input text data
consisting of alphabets, numbers and other
characters.
Mouse: A small handheld device used to
position the cursor or move the pointer on the
computer screen by rolling it over a mouse
pad / flat surface.
12. Light pen: A pointing device shaped like a
pen. Has the advantage of ‘drawing’ directly
onto the screen.
Touch screen: Allows the user to
operate/make selections by simply touching
on the display screen.
13. Graphic tablet: Consists of an electronic
writing area and a special ‘pen’that works
with it. Allows artists to create graphical
images with actions similar to traditional
drawing tools.
Joystick: Used to play video games, control
training simulators and robots.
14. Microphone: Accepts sound in analogue
nature as input and converts it to digital
format.
Scanner: Allows capturing of information, like
pictures or text and converting it into a digital
format that can be edited using a computer.
15. OMR: Scanning device that reads predefined
positions and records where marks are made on
the printed form. Useful for applications such as
objective type tests and questionnaires.
Bar Code Reader: A bar code is a set of vertical
lines of different thicknesses and spacing that
represent a number. Barcode readers are used to
input data from such set of barcodes.
16. QR (Quick Response) code is similar to
barcodes. Barcodes are single dimensional
where as QR codes are two dimensional.
The QR code can be read using a barcode
reader or a mobile with a camera and special
software installed.
17. Biometric sensor: Identifies unique human
physical features like fingerprints, retina, iris
patterns, etc. to identify, verify and authenticate
the identity of the user.
Digital camera: Takes pictures and videos and
converts it to the digital format. Web camera is a
compact and less expensive version of a digital
camera.
18. Smart card reader: These are used to access
data in a smart card.
Smart card is a plastic card that stores
and transacts data. Used in banking,
healthcare, telephone calling, electronic cash
payments and other applications.
19. Monitor: Display devices include CRT
monitors, LCD monitors, TFT monitors, LED
monitors, gas plasma monitors, Organic Light
Emitting Diode (OLED) Monitors, etc.
LCD projector: An LCD projector is a type
of video projector for displaying video,
images or computer data on a large screen or
other flat surface.
20. Plotter: A plotter is an output device used to
produce hardcopies of graphs and designs on
the paper.
3D printer: A 3D printer is an output device
used to print 3D objects. It can produce
different kinds of objects, in different
materials, using the same printer.
21. Printer: Used to produce hardcopy output. The
output printed on paper is known as hardcopy.
Classified as Impact or Non-impact printers.
Dot-matrix uses impact mechanism.
It can print carbon copies with less printing
cost. These printers are slow and noisy.
22. The impact printer creates immediate contact
between the ink ribbons and paper. They can be
noisy yet are very popular.
There are a variety of impact printers
1.Dot matrix printer
2.Daisy wheel printers
3.Drum printer
23. Non-impact printers do not make direct
contact between the paper and ink ribbon. They’re
less noisy and do not have mechanical
components that perform printing.
•These are a few types of non-impact printers:
1.Inkjet printer
2.Laser printer
3.Thermal printer
24. Inkjet printers are non-impact printers that
form the image on the page by spraying tiny
droplets of ink from the print head.
Ink jet printers are inexpensive, but the
cost of ink cartridges makes them costly.
25. Laser printers are non-impact printers
that produce good quality images.
Monochrome and color laser printers are
available.
Laser printers are faster and their speed
is rated in pages per minute (ppm).
26. Thermal printer is a non-impact
printer that produces a printed image by
selectively heating heat sensitive thermal
paper when it passes over the thermal print
head.
It is popular as a portable printer.
27. e-Waste : It refers to electronic products nearing the
end of their “useful life”. It includes discarded
computers, mobile phones, TV's, refrigerators etc.
E-Waste is considered as dangerous threat to the
world as it contains toxic materials such as mercury,
lead, cadmium , which are harmful to our health, soil,
water & air.
Lead can cause damage in blood systems,
kidneys.
28. Mercury found in Printed Circuit Board
will affect our brain, nervous system ,
reproductive disorders etc.
Cadmium found in chip resistors and
semiconductors can cause cancer.
It is found that e-waste may be
responsible for up to 40% of the lead found in
landfills.
29. E-Waste disposal methods:
(a) Reuse: It refers to second-hand use or usage after the
equipment has been upgraded or modified.
(b). Incineration: It is a controlled and complete combustion
process in which the waste is burned in specially designed
incinerators at a high temperature.
(c). Recycling of e-Waste: It is the process of making or
manufacturing new products from a product that has originally
served its purpose.
(d). Land filling: It is one of the most widely used, but not
recommended methods for disposal of e-Waste.
30. Students Role in e-Waste disposal :
➔ Stop buying unnecessary electronic products,
➔ Give electronic equipment to recycle.
➔ Buy products with good warranty and take back
policies.
➔ If possible, buy rechargeable battery products
31. Green computing / Green IT :
It is the process of designing, manufacturing,
using and disposing computers and associated
components efficiently and effectively without
affecting the environment.
It includes proper turn off system, using
printers & other peripherals only when needed,
using hardware with energy saver, using solar
energy.
32. Green computing can be achieved through
a)Green design: Developing energy saver and
eco-friendly electronic equipment.
b)Green manufacturing: Reducing the waste
during production process.
c)Green use: Efficient and wise electricity
consumption
d)Green disposal: Eco-friendly disposal of
electronic waste. .
33. Software : It is a set of instructions given to
various activities in a system.
The two types of software are:
(A)System Software : - It is a collection of
programs that directly control the computer’s
internal operations. and other electronic device
efficiently.
34. System software is classified into three:
(i) Operating System ( OS ) : OS is a set of programs
that act as an interface between the user and the
computer hardware.
(ii)Language processors : Language processors are used
to convert HLL or assembly language into machine
language.
(iii)Utility software : They are set of programs that help
users in system maintenance tasks, and inperforming
tasks of routine nature.
35. The major functions of an OS are
➔ Process management (program execution )
➔ Memory management (Allocation and deallocation of memory space
for programs )
➔ File management( OS takes care of file organization, storage,
retrieval, naming, sharing, and protection of files )
➔ Device management ( OS provides a simple and easy to use interface
between the devices such as I/O devices and the rest of the system )
➔ Security management ( It protects the resources of the system against
unauthorised access and destruction ) and
➔ Command interpretation ( OS helps to interprets user commands and
directs system resources to process command ).
36. Computer languages are classified into Three.
➔ Machine language – only zeros and ones. Writing program
is very difficult.
➔ Assembly language – here letters and symbols
( Mnemonics – symbolic name given to an operator.
Ex. ADD is used for addition. ) are used instead of binary
digits. It is machine dependent.
➔ High Level languages – English like languages. HLL is not
understandable to the computer.
37. There are three types of language processors:
➔ (a). Assembler : It converts instructions in assembly
language into Machine language. It is machine dependent.
➔ (b). Interpreter : It translates HLL into machine
language but conversion takes place statement by
statement only.
Eg. BASIC uses interpreter.
➔ (c) Compiler : it converts HLL into machine codes as a
whole and list out all errors if any.
Eg. C++ compiler.
38. Some of Utility software are:
➔ (a) Compression tools : it is used for
compressing/Zipping large files into small size without
affecting the content. It can also be unzipped into
original file.
Eg. WinZip, WinRAR.
➔ (b) Disk defragmenter : It is a program that
rearranges files that are stored in different locations as
fragments to contiguous memory and free space is
consolidated in one block.
39. ➔ (c) Backup software : used to make a duplicate copy
of information, which can be used if the original data is
lost.
➔ (d) Anti virus software : Virus is a piece of code
attached to a program that when executed, infects other
programs in a system by replicating and attaching itself
to them. Antivirus scans the computer system for
viruses and removes them.
Eg.Norton Antivirus, Kasperesky, etc.
40. Application software : They are used for specific applications.
They are of two types.
(i) General purpose software packages.
✔ Word processing software – MS Word, Open office writer
etc.
✔ Spreadsheet software - MS Excel, Open office calc,
✔ Presentation software - MS power point,Open Office
Impress etc.
✔ Multimedia software - VLC Player, Adobe Flash, Real
Player, Media Player, etc.
41. Database software – Data base is an organized
collection of data arranged in tabular form.
Data Base Management System (DBMS) consists of
collection of interrelated data and a set of programs to
access those data.
Eg:Microsoft Access, Oracle, MySQL etc.
42. (ii) Specific purpose software(Customised
Software) :
They are developed to solve an individual or
organization’s need.
Eg: Pay roll, Air line reservation, sales and
inventory control, Hospital management, Library
management, Supermarket management, banking,
insurance, accounting etc.
43. Free and open source software : They give the user the
freedom to use, copy, distribute, examine, change and improve
the software. The Free Software Foundation (FSF) defines the
four freedoms for free and open source software:
✔ Freedom 0 - The freedom to run program for any purpose.
✔ Freedom 1 – providing the source code of the software to
user.
✔ Freedom 2 - The freedom to distribute copies of the
software.
✔ Freedom 3 - The freedom to improve the program and
release your improvements.
44. Proprietary Software : It is a computer program which
is the property of the developer/publisher and can not
copy , change or distribute without permission. Eg.
Microsoft Windows, Mac OS, MS Office etc.
Free ware and shareware : Free ware software which is
made available for use free of charge for an unlimited
period. All the features are free. They can be freely
download from the internet.
Shareware soft ware have trial version. All features are
not available. If all features are needed, it is to be
purchased.
45. Humaneware (Liveware):
This refer to users and professionals of
computers. The various categories of humane ware are
System Administrator (Administrator of server
computers ),System analyst (Design new IT solutions
for improve business productivity ), Computer Engineer
(Design either hardware or software of a system ),
Computer programmers ((Writes programs ), Computer
Operators ( operates and oversee the system).
