COMPUTER
The Bold
type are specially important for SLC questions
3D: Three Dimension
4GL: Fourth Generation Language
ABC: Attansoff Berry Compute
ADSL: Asynchronous Digital Subscriber
Line
AI: Artificial Intelligence
ALGOL: Algorithmic Oriented Language
ALR: Advanced Logic Research
ALU: Arithmetic and Logical Unit
AM: Amplitude Modulation
ANSI: American National Standard
Institute
ARCNet: Attached Resource Computer
Network
ARPANet: American Advanced Research Project
Agency
ASCII: American Standard Code for
Information Interchange
AT & T: American Telephone and
Telegraph System
AT:
Advanced Technology
ATM:
Automated Teller machine
B2B: Business to Busines
BASIC: Beginner’s All Purpose Symbolic
Instruction Code
BCD: Binary Coded Decimal
BCPL: Beginners Cambridge Programming Language
BCR: Bar Code Reader
BIOS: Basic Input Output System
Bits: Binary Digits
BMP: Bitmap
BNC: British Naval Connector
BOF: Beginning of File
BPI: Bytes Per Inch
BPS: Bit per Sector
CAD: Computer Aided Designing
CAI: Computer Aided Instruction
CAL: Computer Aided/Assisted Learning
CAM: Computer Aided/Assisted
Manufacturing
CAN: Computer Association of Nepal
CAT: Computer Aided/Assisted Training
CAVE: Cave Automatic Virtual
Environment
CBE: Computer Based Education
CBT: Computer Based Training
CC: Computer Consultancy
CD-ROM: Compact Disk Read Only Memory
CESIL: Computer Education in School Instruction
Language
CGA: Color Display Adaptor
CIS: Computer Information System
CISC: Complex Instruction Set Computer
CMOS: Complementary Metal Oxide
Semiconductor
COBOL: Common Business Oriented
Language
CODASYL: Conference Of Data Systems
Language
COM: Computer Output to Microfilm
CP/M: Control Program For
Microprocessor
CPAV: Central Point Anti Virus
CPS: Character Per Second
CPU: Central Processing Unit
CRT: Cathode Ray Tube
CSMA/CD: Carrier Sense Multiple Access
with Collision Detection
CSU/DSU: Channel Service Unit / Digital
Service Unit
CUI: Character User Interface
DBMS: Database Management System
DCU: Device Control Unit
DDE: Dynamic Data Exchange
DIMM: Dual In Line Memory Module
DIX: Digital Intel and Xerox
DNA: Digital Network Architecture
DNS: Domain Name Server
DRAM: Dynamic Random Access Memory
DRPA: Defense Advanced Research Project
Agency
DSDD: Double Sided Double Density
DSHD: Double Sided High Density
DSI: Data System International
DSSD: Double Sided Single Density
DVD: Digital Versatile Disk
EBCDIC: Extended Binary Coded Decimal
information Interchange.
EDO-RAM: Extended Data Out Random
Access Memory
EDS: Electronic Data Storage /
Exchangeable Disk System
EDSAC: Electronic Delay Storage
Automatic Computer
EDVAC: Electronic Discrete Variable
Automatic Computer
EEPROM: Electrically Erasable
Programmable Read Only Memory
EGA: Enhanced Graphic Adaptor
eGMP: Electronic Government Master Plan
EICA: Engine Indicator and Crew Alert
System.
EISA: Extended Industry Standard
Architecture
E-mail: Electronic mail
EMI: Electro Magnetic Interference
EMS: Expanded Memory
ENIAC: Electronic Numerical Integrator
And Calculator
EOF: End of File
EPROM: Erasable Programmable Read Only
Memory
FAQ: Frequently Asked Questions
FAT: File Allocation Table
FAX: Facsimile
FDD: Floppy Disk Drive
FDDI: Fiber Distributed Data Interface
FDS: Fixed Disk System
FM: Frequency Modulation
FMC: Flight Management Comptuer
FORTRAN: FORmula TRANslation
FPM RAM: Fast Data Page Random Access
Memory
FTP: File Transfer Protocol
G2C: Government to Citizens
G2G: Government to Government
GaAs: Gallium Arsenide
GB: Giga Bytes
GIF: Graphics Interchange Format
GIGO: Garbage in Garbage Out
GIS: Geographical Information System
GPL: General Public License
GUI: Graphical User Interface
HDD: Hard Disk Drive
HLCIT: High Level Commission for
Information & Technology
HMD: Head Mounted Display
HTML: Hypertext Markup Language
HTTP: Hyper Text Transfer Protocol
I/O: Input Output
IBM: International Business Machine
IC: Integrated Circuit
ICL: International Computers Limited
ICT: Information and Communication
Technology.
IMS: Information Management System
IPX: Internetwork Packet eXchange.
IRC: Internet Relay Chat
IRTB: Industrial Real Time Basic
IRTB: Industry Real Time Basic
ISA: Industry Standard Architecture
ISP: Internet Service Provider
IT: Information Technology
ITPDC: Information Technology Park
Development
ITPF: IT Professional Forum
JPEG: Joint Photographic Expert Group
KB: Kilo Bytes
Kbps: Kilobits per second
KIPA: Korean IT Industry Promotion
Agency
LAN: Local Area Network
LCD: Liquid Crystal Display
LED: Light Emitting Diode
LISP: List Processing
LSI: Large Scale Integrator
MAN: Metropolitan Area Network
MB: Mega Bytes
MBPS: Million Bit Per Second
MBR: Master Boot Record
MCGA: Monochrome Display Adaptor
MD2D: Mini Disk Double Sided Double
Density
MD2HD: Mini Disk Double Sided High
Density
MD2HD: Mini Disk Double Sided High
Density
MDA: Monochrome Display Adaptor
MF2D: Micro Floppy Double Sided Double
Density
MICR: Magnetic Ink Character Reader
MIDI: Musical Instrument Digital
Interface
MILNET: Military Network
MIPS: Millionth of Instruction Per
Second
MIS: Management Information System
MODEM: MODulator and DEModulator
MOEST: Ministry of Environment Science
and Technology
MOS: Metal Oxide Semiconductor
MPEG: Motion Picture Expert Group
MSAU: Multi Station Access Unit
MS-DOS: Microsoft Disk Operating System
MSI: Medium Scale Integration
NAV: Norton Anti Virus
NCC: National Computer Centre
NDD: Norton Disk Doctor
NEC: Nippon Electronics Company
NFS: Network File System
NITC: National Information Technology
Centre
NITCC: National Information Technology
Co-ordination Committee
NITDC: National Information Technology
Development Committee
NPC: National Planning Commission
NT: New Technology
NTFS: New Technology File System
OAS: Office Automation System
OCP: Order Code Processor
OCR: Optical Character Reader
OLE: Object Linking and Embedding
OMR: Optical Mark Reader (Recognition)
OS: Operating System
PC: Personal Computer
PCB: Printed Circuit Board
PCI: Peripheral Component Interconnect
PDF: Platform Independent Document
Format
Pixel: Picture Element
PL/1: Programming Language -1
PM: Phase Modulation
PNG: Portable Network Graphics
POP: Post Office Protocol
POS: Point of Sales
POST: Power On Self Test
PROGLOG: Programming Logic
PROM: Programmable Read Only Memory
PS/2: Personal System-2
PSROM: Pseudo Random Access Memory
PSTN: Public Switched Telephone Network
QBE: Query By Example
QEL: Query Language
RAM: Random Access Memory
RDBMS: Relational Database Management
System.
RISC: Reduced Instruction Set Computer
RMM: Read Mostly Memory
ROM: Read Only Memory
RONAST: Royal Nepal Academy Of Science
and Technology
RPG: Report Program Generator
RPM: Rotation Per Minute / Revolution
Per Minute
SCP: System Control Processor
SCSI: Small Computer System Interface
SDRAM: Synchronous Dynamic Random
Access Memory
SIMM: Single In Line Memory Module
SMPS: Switch Mode Power Supply
SMTP: Simple Mail Transfer Protocol
SNOBOL: StriNg Oriented symBOlic
Language
SPX: Sequenced Packet eXchange.
SQL: Structured Query Language
SRAM: Static Random Access Memory
SSSD: Single Sided Single Density
STP: Shielded Twisted Pair
SVGA: Super Video Graphics Array
TB: Terra Bytes
TCP/IP: Transmission Control Protocol/
Internet Protocol
TPS: Transaction Processing System
UNIVAC: Universal Automatic Computer
UPS: Uninterruptible Power Supply
URL: Uniform Resource Locator
USB: Universal Serial Bus
UTP: Unshielded Twisted Pair
VDT: Video Display Terminal
VDU: Visual Display Unit
VGA: Video Display Array
VLSI: Very Large Scale Integration
VoIP: Voice Over Internet Protocol
VR: Virtual Reality
VRML: Virtual Reality Modeling Language
VSAT: Very Small Aperture Terminal
W3C: World Wide Web Consortium
WAIS: Wide Area Information Server
WAN: Wide Area Network
WORM: Write Once Read Only Memory
WWW: World Wide Web
XMS: eXtended Memory
XT: eXtra Technology
Computer Network And Telecommunication
Data communication: The process of
transferring data or information between computers called data communications.
Telecommunication: It refer all types of
data transmission like characters, numerical, photos, audios and videos etc
using electronic or light emitting media.
Cables (Guided Media): Cables are the most
common transmission media. Two or more devices are connected directly using
cables. Three types of cables are used in computer networking they are:
Twisted pair cable: Twisted copper
cables are used only for lower bandwidth. It consists of two isolated strands
of copper wire twisted around each other. There are two types of twisted pair
cables they are as follows:
UTP (Unshielded Twisted Pair): UTP
cables does not have metal shield expect plastic coating. It contains number of
twisted pairs of wires with a simple plastic casing. It commonly used to for
LAN and Telephony. It is cheaper and easier to work with, but do not offer high
bandwidth and good protection from interferences. It can support data
transmission rates from 10 to 100 mbps.
STP (Shielded Twisted Pair): STP is
similar to UTP but it is shielded with metal sheath along with plastic coating.
It offers high bandwidth and good protection from interferences. It is cheaper
than fiber optic cable. It can support data transmission rates from 10 to 500
mbps.
Co- axial cable: A co-axial carries
higher bandwidth than twisted pair, it is easy to connect. It does not bend
readily. This cable consists of one or more small cables in a protective
covering. It offer very high data transfer rate and can be placed underground
and laid on the floors of lakes and oceans.
Fiber Optic cable: Fiber optic cable is
a thin filament of glass fiver wrapped in a protective jacket. It consists of
strands of glass like thread, each about the diameter of a human hair. It offer
high-speed data transmission rate because data travel as high-speed pulses of
light.
Summary of Cable Types (Not important for
examination point of view)
Cable Type Susceptibility
to Interference Transmission Speed Maximum Distance Installation Difficulty
Thin coax Low
10 Mbps 185 meters Low
Thick coax Very
low 10 Mbps 500 meters Difficult
UTP High
10 to 100 Mbps 100 meters Easy
STP Low
10 to 500 Mbps 90 meters Moderate
RS-232 N/A
20 Kbps 50 Feet N/A
Infrared High
115 Kbps-4 Mbps 1 meter Easy
Fiber-optic None 100 Mbps to
1Gbps and beyond Up to 30 miles Difficult
Wireless (Unguided Media): It is used to
transfer data with in a large geographical areas or globally without the use of
interconnecting wires or cables. It uses other components such as radio
signals, microwaves, or infrared to connect network.
Types of wireless communication:
Microwave Systems: Microwave signals
are similar to radio and television signals and are used to transmit data
through the space without the use of cable. It provides high-speed data
transmission. These signals cannot bend or pass obstacles like hills and tall
buildings, so very high towers are used to mount the signals. The transmission
is limited about 30 miles. Chain of towers is required to transmit the
microwave signals in a long distance
Satellite communication: Both microwaves
signals and telephone signals can be relayed to a earth station for
transmission to a communication satellite. The earth station consists of a
satellite dish that functions as an antenna a communication equipment to
transmit and receive data from satellite passing overhead. It is not disturbed
by hills and tall buildings and visible from any point. So sender and receiver
easily communicate with each other using antenna by aiming the satellite. It is
very expensive for placing satellite along the earth orbit.
Modulation: The process of changing some
characteristics (amplitude, frequency or phase) of carrier wave in accordance
with the intensity of the signal is known as modulation.
Types of
modulation:
Amplitude Modulation (AM)
Frequency Modulation (FM)
Phase Modulation (PM)
Mode of communication:
Simplex mode: Simplex is one-way data
transmission that takes place only from sender to receiver. An example of this
would be a television that allows the signal to pass in only one direction.
Computer network connections do not use simplex.
Duplex mode: Duplex is two-way data
transmission that takes place both directions over a communication channel.
Computer use duplex channel. For example if computer A and computer B are
connected together than both computer can share data or information. From
computer A to computer B or computer B to computer A.
Types
of Duplex Mode:
Half duplex: Half duplex is two way
data transmission that takes place in only one direction at a time
Full duplex: Full duplex is two-way
data transmission that takes place in both directions at a time.
Computer Network: A computer network is a
logical or physical interconnection between two or more computers such that
they could communicate with each other. It is used to provide users with the
access to share resources. These shared resources include data files,
application software and hardware.
Components of computer network.
Computer
Transmission media
Network software.
Protocols.
Networking cables.(Transmission media)
Advantages and disadvantages of computer
network.
Advantages
of computer network:
Resources, data, software and hardware
can be shared.
Faster & cheaper communication and
data transmission.
It provides as the tools for e-mail
teleconferencing videoconferencing which facilities communication.
Flexible working condition.
Office automation can be making very
effective well managed.
Disadvantages of computer network.
High installation and administrative
cost.
Attack on the privacy of the people.
Computer virus spread most easily
through network.
Technologically very complicated.
If the server is out of order, then all
workstations are hang up.
Well trained technical support is
required.
Network architectures or (Types of Network
Architecture) or LAN Architecture:
Client server: This is old model of
computer network. In this kind of network model one main computer equipped with
very powerful processor, large memory and network operating system works as a
main computer or service provider. Other computers connected with server, which
are also called workstation or node or terminals can use the hardware and
software resources of server computer. There are different types of server such
as file server, print server, network server or email server.
Advantages
of client server network:
It works with any size or physical
layout of LAN.
It does not tend to slow down with
heavy use.
The network can be expanded to any size
as we wish.
It provide very high level security
It reduces software installation time
and cost to all computers.
Disadvantages of client server network:
It is very difficult to setup and well
trained technicians are required to handle and setup.
It is expensive compare to peer to peer
network.
All software and operating systems are
installed in server computer so that other client computer has to depend on it.
Peer to peer: It is also called
workgroups also. Because all computers in the network have equal
responsibilities. All computers in the network have access to at least on e or
more computers. It mostly used in LAN and every organizations, research centers
such as banks, travel agencies, airlines educational institutions etc.
Advantages
of peer to peer network:
It is easy to setup.
Users in each computer can determine
the resources to be shared among other computers.
Any required software can be installed
on individual computers , they don’t have to depend on the server.
It is suitable at home, office, banks
and small organization.
It is cheaper compare to client server
network.
Disadvantages of peer to peer network:
It is slow because of heavy load.
It is suitable for limited area such as
school offices and small organization.
The network expansion is limited and
can not be expanded as the wish.
It has limited security level.
Types of computer network:
Local Area Network: The way of
connecting two or more computers in a very limited area (about 100 to 300
meters) or within a same building or a group of adjacent building is called
LAN. It enables very high speed communication through wire connection or
wireless connection some times. Small organizations prefer it because of less
expensive and faster communication.
Metropolitan Area Network: The way of
connecting computers inside a metropolitan area is called MAN. The area may be
a part of city, whole part of city, district, zone or country. Radio wave is
used to transmit the data for communication between the workstation and server
in the system. Many different systems of networking and computing are brought
together to form a MAN.
Wide Area Network: The connection of
computers of networks covering more distance or the world by the help of wave,
frequency and satellite is called WAN. Different types of LAN and MAN are
connected to form a WAN. It covers more area but it is slower than LAN and MAN.
Network Topology: Set of rules and
regulations, which are essential for networking are called topology. It may
contain software, hardware or geographical situation of the networking. Or in
another words it is the pattern in which the computers are interconnected.
Types of Network Topology:
BUS Topology.
Key Features Advantages Disadvantages
Uses a single length of cable to
interconnect network devices. The
failure of one computer does not affect the performance of the rest network. It tends to slow down under the heavy
load.
Uses terminators to dampen signal
reflection at the ends of the cables. Computers
can be easily added or removed from the network. Commonly uses coaxial cable, which is prone to cable
breaks. This will disrupt network use.
Network devices connect directly to the
cable. Less physical cable is required
to make the network. So it is cheaper and easy to implement. If a cable break or problems occur, the
entire network goes down.
Ring Topology:
Key Features Advantages Disadvantages
Devices are connected in a ring formation. 1. Each computer does not have to
depend on the central computer as each computer controls transmission to and
form it self. 1. If a single computer
fails, at least a portion of the network will not work.2. It is difficult to
change the network structure.
A star ring uses an MSAU (Multi-station
Access Unit) to form the ring function internally. 2. Devices in a star ring configuration can be added and
removed without network disruption.3. It has short cable connection, which
increases the network reliability.
4. It support very high data transmission
rate
3.
The MSAU in a star ring provides a single point of failure.4. An extensive
rewriting must be done to maintain the ring structure when computers are added
or removed.
Star Topology:
Key Features Advantages Disadvantages
Most commonly implemented network topology
used today. 1. Computer systems
can be added or removed from the network without disrupting network users. 1. If centralized device (hub/switch)
fails whole network goes down.
Uses individual cables to connect each
device to the network. 2. A
cable failure affects only the network device connected to it. 2. Because each device requires its own
length of cable, more cable is required than in a bus topology.
Problem isolation is straight forward. 3. When a device fails in a star
topology, it can be easier to trace the location of the problem.4. It support
very data transmission rate.
5. It is more reliable
3.
Additional network equipment such as the hub or switch is needed to make the
network connection. So it is costly.4. It is difficult to expand.
Different devices and terms used in
Network:
MODEM:
Modem is a device that directly converts digital signal from a computer or
other digital devices into analog form for transmission over analog link i.e
telephone line and vice versa. MODEM stands for Modulation and Demodulation.
There are two types of modem used in computer they are as follows:
Internal modem b. External modem.
NIC: It is a Network Interface Card,
which connects each computer to the wiring to the network. A NIC is a circuit
board that fits in one of the computer’s expansion slots. It provides a port on
the back of the computer to connect in the network.
Hub: Hubs are
connectivity devices, which contain multiple ports for connecting to network
components. Hubs connect the computers in a star topology. It lies between
server and clients computers.
Connector
: Bridge and Gateway are the two different connectors, which play role to
link between two network systems.
Bridge: Bridge connects networks
using same communications protocols or similar networks so that information can
be passed from one to the other.
Gateway: Gateway connects networks using different communications
protocols or dissimilar networks so that information can be passed from one to
the other.
Switch:
A device that capable of forwarding packets directly to the ports associated
with particular network addresses. Hubs and switches are almost same but switch
is new technology and intelligent compare to hub.
Repeater:
A device used on communications circuits that decrees distortion by amplifying
or regenerating a signals so that it can be transmitted onward in its original
strength and form as they pass through a network cable.
Protocols: Protocols are the set of rules
and formats for sending and receiving data. It works as guidelines to govern
the exchange between equipments. There are different types of protocols that we
can use. Some of popular protocols are TCP/IP, HTTP, FTP, IPX/SPX.
Router:
A router is a device that is used to connect different LAN in the network. It
receives transmitted messages and forwards them their correct destinations over
most efficient available route.
NOS: The
operating, which can support network environment, is called Network Operating
System. For example Windows XP, 2000, server, unix, linux, Novel Netware etc.
Note:
Band width : The amount of data that which is sent through a data-transmitting
medium, such as a computer network, telephone line, or coaxial cable, in a
given amount of time is called band width.
Note:
Bits : In computer processing and storage, a bit is the smallest unit of
information handled by a computer and is represented physically by an element
such as a single pulse sent through a circuit or a small spot on a magnetic
disk capable of storing either a 1 or a 0.
Chapter:
Multimedia Multimedia : The
technology of combining speech, hypertext, text, still graphics, animation,
moving pictures and sound using the computing power of PC is known as
multimedia. For example TV shows, because it has a feature of interactive. Multimedia Technology: Multimedia technology
is a special computerized technique, which helps the user by providing
techniques to combine texts, pictures, sound and video films including
interactive facilities. It also provides facilities to the user to create
store, edit, delete and copy those data in the computer with the help of
specific computer program such as Microsoft Power point, Adobe Acrobat,
Macromedia Flash etc.
Multimedia Hardware: Multimedia system requires
some additional set of hardware to support such multimedia presentation are as
follows. Computer set Sound card Sound
blast DVD-ROM Microphone Headset Digital camera Video adapter etc. Multimedia
Application: Multimedia is used for any computer application in which text
alone does not work. Multimedia has become a prerequisite for computer games of
all kinds. Its use is growing in computer
based education (CBE) and computer
based tanning (CBT). Now a days computer’s use is increase day by day and
almost all sector of the world is computerized and use of multimedia technology
is also increase. There any different types of computer application available
in the market. The choice is depend on the requirements and the performance of
the computer itself. Some of them are categorized as follows: Paint program format such as: Bit Mapped
Graphics (BMP or Windows Bitmap. Graphics Interchange Format (GIF). Joint
Photographic Expert Group (JPEG). Protable
Network Graphics (PNG). Image Editors or Software such as: Adobe Photoshop
PhotoDeluxe CorelPhotopaint Drawing programs or software such as: Macromedia
Freehand Adobe Illustrator. Core Draw Video Editors Software and format such
as: Motion Picture Experts Group
(MPEG-2) Quick Time (Format) Video for windows (AVI format) Adobe
premiere software Video VisionML Software Video Vision Studio Software Avid
Cinema Software Fusion Recorder Software Maya Software Audio software and
format such as: MP3 format Sun/Next (AU) sounds. Microsoft Windows Wav sounds
format. Musical instrument digital
interface (MIDI) format. Sound Forge (Sound Editor) SoundEdit (Sound
Editor) Multimedia Deck (Sound Editor) Creating multimedia: The process of
multimedia work involves several steps. Some of the important steps are listed
below: Planning the work. Creating and
collecting the elements to be included in the work. Combining the elements to
create the work Testing, evaluating the refining the work Writing the work to a
portable storage medium such as a CD-ROM or posting the work on the web. There
are three common ways to organize or planning the multimedia work. They are as
follows: Sequential page based
multimedia: The simple pages which containing slides of text, pictures, still
graphics, videos is called sequential page based multimedia. This type of
multimedia presentation is used in college and school for lecture and
advertisement in sales company and other various purposes. Hypertext based multimedia: This type of
multimedia is attached with hypertext document in the web. It provide link to
the containing folder or files or pictures and articles. Any type of multimedia
can be used such as graphics, sound, video animation. Movie based multimedia:
the work can be a movie or series of movies that stop from time to time to
enable the user to follow a link. Virtual Reality: Creation of 3D animations
and games to control flying and running items is virtual reality. Some time
while using such multimedia with Head-Mounted Display (HMD), a helmet like
contraption equipped with stereo LCD displays. We feel like exploring in the
room or earth in a very complex virtual environment. The most advanced immersive technology to
date is the Cave Automotive Virtual
Environment (CAVE). In WWW Virtual
Reality Modeling Language (VRML) is used to create such virtual reality
animation. It is mostly used in computer games to give real experience in
virtual environment. Advantages of
Multimedia: It helps to create effective
presentation and tutorial material for all subjects. It is very portable so
that it can be used at any time anywhere by anybody. Very easy to use, handle,
carry, copy and store. Very helpful to transfer messages and advertisements in
WWW. It provides very powerful presentation tools with colored pictures, motion
pictures and other. Disadvantages of Multimedia: Very expensive installation cost. Require a
well trained manpower or technician. Expensive hardware components.
Inaccessible to poor due to high cost.
IT Policy Of Nepal 2002 A.D (Suchana
Prabidhi Niti 2057 B.S)
The information technology (IT) policy,
Nepal was adopted in 2002 A.D i.e 2057 to define the visions, background,
objectives and strategies of computer education in Nepal. Below, we briefly
discuss the important ones:
Vision: “To place Nepal on Global Map of
Information Technology within next five years,” is the main vision of IT policy
of Nepal 2002.
Objectives
/Purposes of the IT policy 2002 of Nepal are as follows:
To create knowledge based society
To create job opportunities for the
people.
To establish knowledge based
industries.
Main polices
of IT policy of Nepal
To flow the information after the development
of web site of all ministries and departments of government.
To develop E-commerce
To develop E-education
To develop E-health
Work policies of IT policy of Nepal
To develop the communication system if
local areas
To develop the needed and ablest
manpower in local areas
To develop the communication system
globally
Strategies if IT policy 2002:
Carry on research, develop and expand
information technology with a high priority. So as to increase participation of
the private sector in IT development.
Prepare capable manpower with the
involvement of both public and private sectors for sustainable development and
expansion of information technology.
Encourage native and foreign investment
for the development information technology infrastructure.
Legalize and promote e-commerce by
using information technology.
Utilize information technology in the
development of rural areas.
Include computer education in
curriculum from the school level.
Increase export of services related to
information technology.
IT policy: some of
the policies to be followed for the implementation of the above mentioned
strategies are as follows:
To declare information technology
sectors as a prioritized sector.
To follow a single door system for the
development of information technology.
To create a conductive environment that
will attract investment in the private sector, keeping in view the private
sector’s role in the development of information technology.
To provide internet facilities to all
village development committees of the country.
To computerize the records of each government
office and build websites for them.
To increase the use of computers in the
private sector.
To develop physical and virtual
information in technology park in various places with the private sector’s
participation.
To use IT to promote e-commerce,
e-banking, e-health, e-education, among others and to transfer technology in
rural areas.
To establish National Information
Technology Centre.
To establish a national level fund by
mobilizing the resources obtained from Government of Nepal, donor agencies and
private sectors so as to contribute to research and development of information
technology and other activates associated with it.
To establish capital funds with the
joint participation of public and private sectors.
To draft necessary laws that provides
legal sanctions to the use of information technology.
To gradually use information technology
in all types of government activities and provide legal sanctions to its uses
in such activities.
Action Plan: These are
some action plan to fulfill the objectives of IT policy.
Participation of private sector in
infrastructure development.
Infrastructure development.
Human Resource Development.
Dissemination of information
technology.
Promotion of E-Commerce.
Other related Facilities.
Legal
provisions: Government of Nepal will design, update and implement the cyber
laws from time to time as per national international situation. The law will be
related to e-banking, digital signature, software piracy, data protection by
encryption copyright protection and privacy protection act, etc.
Modification
of IT policy: Government of Nepal will supervise the running of cyber law
from time to time and rewrite them to update. In every two alternate years
continuously, it will be updated.
NITCC: NITCC stands for National Information
Technology Co-ordination Committee; its main purpose is to assist the
development of IT in our country. Main functions of NITCC are as follows:
It provides the text books of National
Communication System
It increases the status of people
It develops the man power and
intentional works
NITC: NITC
stands for National Information Technology centre. It is also governmental body
to work for the development of IT in our country. It is established to develop
the field of information system, to re-observe, to know yearly development and
to solve the problems. It is form by twelve members including science and
technology minister as president.
NITDC: It stands for National Information
Technology Development Committee. It is form by eighteen members, where prime
minister work as president and science and technology minister work as
vice-president.
Cyber Laws, Ethics and Policies of Nepal.
Computer
crime: Computer crime is a crime committed by the people through the use of
computers.
Example
of computer crime:
Unauthorized access of computer
Altering web pages of web site.
Denial of Service (DoS) attacks.
Malicious computer programs: viruses,
hacking and cracking the software.
Harassment and talking.
Privacy defiance
Password guessing etc.
Effects of
cyber / computer crime.
Consumption of time of staff member in
detecting intruders and managing safety methods.
Physical theft of computer and computer
accessories which cause a huge damage of the assets.
Due to the attackers, the banks and
financial companies get adverse publicity.
Vandalize the original web page with
the different contents in WWW.
Lost of privacy due to the unauthorized
access of information.
Safety
from computer crime:
Protection of computer from power
related problems by using power surges and power outrages.
Controlling and managing database and
other very imp computer with authentication systems such as numbers.
Using call back systems to track the
phone number which is used to connect.
Using firewall system to protect
computer from external threats.
Using computer to protect from viruses.
Making backup regularly.
Computer
related legal problems:
Plagiarism: The presentation of
somebody’s work as if it were your own is known as plagiarism. For example some
people or students copy the material from the internet and present them as if
it is their own creation without prior permission from the authorized person to
copy from the copyrighted material.
Software Piracy: Copying software CD or
DVD is another big problem. People copy software and install in their computer.
Some programs are freely available in the public domain under the provision of
General Public License (GPL).
Digital
signature: A security mechanism used on the internet that relies on tow
keys, one public and one private, which are used to encrypt and to decrypt them
on the receipt.
Public
key infrastructure (PKI): PKI is a security management system including
hardware, software, people, processes and policies, dedicated to the management
of Digital Certificates (keys) for the purposes of secure exchange of
electronic messages.
Private Key: One of
the two keys in digital signature’s public key encryption. The user keeps the
private key secret and uses it to encrypt digital signatures and to decrypt
received messages.
Public
key: One of the two keys in public key encryption. The user releases this
key to the public, who can use it for encrypting messages to be sent the user
and for decrypting the user’s digital signature.
Cyber
law : The law which is practiced to control The following three basic types
of computer crimes such as: theft of computer time for development of software,
theft, destruction or manipulation of programs or data and alteration of data
stored in the computer file is called cyber law. Cyber law is the legal field
that maintains the order of track in the internet access and communication.
The scopes
that are covered by boundary of cyber law are as follows:
Intellectual property:
Computer crime law
Jurisdiction law
Digital signatures system
Privacy
Freedom of expression.
International cyber law: Now a day’s several cyber laws are
applied to provide all types of computer security, software security and avoid
computer crimes. Some famous and cyber laws are as follows.
Fair Credit Reporting Act in 1970- free
access of personal credit report.
Freedom of Information Act in 1970-
access of information posted by the government.
Federal Privacy Act in 1974- access
right of government to see any record.
Video Privacy Protection Act in 1988-
prohibition of personal record without judiciary order.
Copyright Act 1992- Unauthorized copy
of software. (5 years Jail or US$ 25,000 or both)
Computer Matching and Privacy - right
of government to keep the personal key record
protection Act 1988
Computer Ethics: Computer Ethics covers all
the practical principles that deal with how the computer experts should make
decisions in regard to the social and professional behavior. The term ‘computer
ethics’ first devised by Mr. Walter Maner in mid 70s. But it is practiced from
the beginning of 90s. The core issues of computer ethics incorporate:
Technological impact on the society.
Plagiarism
Intellectual property rights
Copyrights
Piracy
Hacking
Internet pornography and adult sites
Harassment and stalking etc.
Computer
ethics for the computer user:
Respect yourself and do not give
passwords to any second person.
Do not ask password and never try to
know other’s password for any purpose.
Always give the credit to your
originality.
Ten Commandments for computer ethics: The
computer Ethics Institute of the Brookings Institute, Washington D.C has
developed the following ethics:
Thou shalt no use a computer to harm
other people.
Thou shalt not interfere with other
people’s computer work.
Thou shalt not snoop around in other
people’s files.
Thou shalt not use a computer to steal.
Thou shalt not to use a computer to
bear false witness.
Thou shalt not to copy or use
proprietary software for which you have not paid.
Thou shalt not use other people’s
computer resources without authorization or proper permission.
Thou shalt no appropriate other
people’s intellectual output.
Thou shalt think about the social
consequences of the program you write or the system you design.
Thou shalt use a computer in ways that
show consideration and respect for you fellow humans.
Computer Ethics for computer professionals:
The codes of conduct and good practice for certified computer professionals are
the essential elements of activity. They are:
A high standard of skill and knowledge.
A confidential relationship with people
served.
Public reliance upon the standards of
conduct in established practice.
The observance of an ethical code.
Ethical
standards: A number of definitive sets of ethics have been developed to
restrict the professionals in making harsh decisions and redirect them towards
the right behavioral approach. Some of them include:
Association
for Computing Machinery (ACM) codes of ethics is four point
standards that govern the ethical behavior among the computer professionals.
Uniform Computer Information Transaction
Act (UCITA) defines a set of standards related to the legal ethical behavior
during the computer contract process.
Computer security:
In the 21 st century computer is most
important part of our life. The computer itself is our great and very important
property which holds several important data for the future use. So like other
asset’s security computer security is very important.
The protection of computer system from
accidental or intestinal harm, including destruction of computer hardware and
software, physical loss of data, deception of computer users and the deliberate
invasion of database by unauthorized individuals is called computer security.
In short protection of computer, its accessories, data and programs for a long
lasting of computer system is known as computer security.
Computer security is classified into two
parts:
Hardware security
The protection of all hardware components
used in computer system is known as hardware security. For the proper
management of physical security of the computer, we have to maintain
Regular maintenance
Computers are delicate machines. They need
regular maintenance, cleaning, and configuring new hardware removal of
unnecessary hardware.
Insurance
Insurance is a very good method to protect
other assets. Computer insurance helps us to insure our computer, if we lost it
or parts are damaged or in case of calamities of theft loss of data.
Free of dust
Computer parts are very sensitive to dust.
Dust can damage internal and external both parts of computer so to protect from
dust we must put computer in very neat and dust free room. And we should use
dust cover also to protect computer.
Protection from fire
Computers are easily damaged by fire.
Electronic circuits of computers will get damage by fire or even smoke also. So
we should not smoke near to computer and we should manage proper wiring because
it may cause firing.
Protecting from theft
As computer is very valuable device like
other assets, there is equal risk of theft for computer. We must keep it in
very secure room. There must be lock in our computer and it is advised to keep
grills in windows and safety lock in rooms.
Air condition system
Most of the electronic device gets damage
in excessive heat. So room must be cool and dust free for computer. If there is
excessive heat then computer parts may not work properly or it may stop
functioning. It is suggested to maintain temperature between 18 o to 24 o
Celsius and relative humidity of 50 to 60 percent. Micro computers can work up
to maximum 30 oC also. But today’s new personal computers are designed to work
even between 0 oC to 40 oC.
Power supply
Power supply is another cause of damage of
computers. Computer needs 220V to 240V AC constantly. The voltage fluctuation
may damage integrated circuits of computers chips because these are the most
sensitive parts of computers. To protect from voltage fluctuation we must use
UPS to protect our computers from sudden interruption of power because in such
cases UPS provide power for some minutes to hours from backup battery inside
it. Volt guard and Spike guards and Stabilizers are common device used in these
days.
Furniture
Good and properly managed furniture is
another factor to protect computer hardware. Tables and chair used in computer
itself and to keep different storage devices of computers like floppy, pen
drive, CD and DVD etc
Software security
The software is very important part of the
computer. It includes programs and data or information store in computer. The
protection of data and programs used in computer system is known as software
security. Software security is required for the,
Prevention of loss of data,
Prevention of data and software program
piracy
Prevention of corruption of data and
Prevention from error reading of data.
For protection of data and programs in our
computer system, we should apply some security measures. Some common software
security measures are as follows:
Password protection
Password is a set of characters that act
like a key to unlock the system and other files and programs. Setting password
in our files and user account to control the access of data and information in
our computer is very good and effective method of software security. Password
must be difficult to guess so we should not use common words as password. It is
suggested to use the set of numbers, symbols and characters to create password.
Some common rules to create password:
Password length must be at least 6
characters.
The words used to set password must be
difficult to guess
We should keep our password
confidential
We must change password frequently
Files, which store password must be
encrypted
Backup system
If data and information is very important.
We must backup data regularly to other computer or other disk location and
folders of the same computer so that we can restore it if data is corrupted or
lost.
Data encryption and decryption
We can prevent the access of data or
information by encrypting it. Windows operating system have built in feature to
encrypt the data. If we encrypt the data computer will change the forms of this
data and will not be readable or understood to other users. And if we have to
give access we can decrypt it into original form.
Defragmentation
Defragmentation is the process of a file to
contiguous sectors on a hard disk to increase the speed of access and
retrieval. Because during long time files and folders store in computer will
get fragmented or will be unmanageable in such case disk head will consume more
time to read the data from the disk means computers becomes slower. So it is
necessary to defragment the disk to increase the performance of the computer.
Firewall
protection
Windows firewall is very important and
useful tool to protect our computer from external and internal threat in LAN
and Internet. While downloading files and programs form internet viruses and
other person may try to access the resources of our computer. In such case
windows firewall block such threats.
Scanning disk
Computer store all information in its disk
surface. And hard disk is a main part where computer store all its information.
So we must scan the surface of the to increase the performance of the computer.
Windows provide some built in tools to scan the disk such as Scandisk and
CHKDSK and several other utilities software are available to scan disk.
Hard
lock key
Hard lock key is very important for
software security. It is specially used to protect from software piracy. It is
a kind of checking point available within the software during its running time.
DBMS and
Microsoft Access
Introduction to Database System : In our
daily life we encounter with various software. There is hardly any software
that does not use database systems. The following are some of the widely used
database systems:
Banking software
Airlines systems
University systems
Telecommunication systems
Finance
Sales
Manufacturing
Human resources
Data: Plural of
the Latin datum, meaning an item if information. In practice, data is often
used for the singular as well as the plural form of the noun. Data are
information to the computer which are processed to get desired result and are
the piece of information.
Information: The data
which gives meaning or suitably arranged for communicating interpretation, and
processed by human being by automated means such as computer is called
information.
Database:
A database is a collection of data that is organized so that its contents can
easily be accessed, managed and updated.
File: A file is
a collection of electronic information store in computer.
Record:
A record is a information about an element such as a person, animal, students,
place etc.
Filed: A filed
is a piece of information about an animal, person, students, place etc. And
these fields are the titles in the table of Ms-Access.
Data processing steps:
Data collection
Filtering
Coding
Data entry
List printing
List checking and editing
Updating
Final list printing
Final data preparation
Processing of final data
DBMS: A
database management system (DBMS) is a computer program designed to manage a
database (a large set of data), and run operations on the data requested by
clients. For example Oracle, Microsoft Access, Ms. SQl, MySQl, dBASEIII+,
dBaseIV, FoxPro, IMS, IDS, IDMS, ADABASE, CDS/ISIS, OMNIS, RBASE, SYSBASE,
FOXBASE etc. are the well known database management system.
RDBMS: Relational
Database Management System (RDBMS) is method of viewing information from
several, separate database that relate to one another through the keyword or
values. The main advantage of RDBMS is that we can simultaneously use more than
one database to see information stored in them.
Importance
of database:
Database stores the data.
Computerized database saves data from
being lost.
Computerized database protects from
unauthorized access and use of the data.
Data can be stored in a small area or
space in computerized database.
Features of DBMS:
Easy to access data.
Ease to modify data.
Delete existing data.
Organize the data in proper sequence.
Sorting and indexing of data.
Easy queries in data.
Retrieve the data easily.
Print the formatted reports, labels
etc.
Linking between two or more databases.
It can be used as SQl (Structured Query
Language)
The Internet and E-mail:-
Internet: The internet is worldwide
collection of computer networks and gateways that use TCP/IP suite of protocols
to communicate with one another using telephone lines modems or satellites.
Internet is network of networks. At the heart of the internet is a backbone of
high speed data communication lines between major nodes or host computers,
consisting of thousands of commercial governmental, educational and other
computer system, that route data and messages.
Some of the
common services provided by the internet are:
Electronic mail (E-Mail)
Information sharing and resources.
Business communication
Advertising
Online shopping
Stock trading
Discussion and chat
Entertainment
E-banking
Virtual library
Equipment used in internet/ components
required to use internet:
A set of computer
A modem and regular telephone line or
broadband internet connection.
An account in ISP to access the
internet host.
A communication software for example:
Internet Explorer, Netscape Navigator, Mozilla Firefox or Opera etc.
Terms related to the internet:
WWW: WWW is a series of services that
are interconnected through hypertext. It provides link in the web documents.
Advantages of www:
A link in a web document can be
used to open other documents.
Web pages can contain pictures,
buttons and even links to sound files in addition to text, thus allowing
multimedia applications.
Sophisticated web document allow
users to interact with applications through dialog boxes and forms.
Web site: Website is a location of the
web pages created by any organizations, universities and government agencies to
provide information regarding them like: http://www.bbc.co.uk/nepali,http://www.nepalnews.com
etc. Each website has its own address that is also called internet address.
Web pages: Webpage is a collection of
information that is stored in website. The www consists of huge collection of
documents with related website called webpage. Webpage provides vast collection
of information of related websites.
Browser: Browser is client software
that allows the users to display and interact with the web page. For example:
Internet Explorer, Netscape Navigator, Mozilla Firefox or Opera etc.
Web server: web server is a site on
which the web pages are kept. It is a server computer that responds to requests
from web browsers to relative resources.
Domain name: It is a name of specific
internet area controlled by any organization, company or government.
Home page: The home page is the first
hypertext document regarding the web address displayed when a user connects to
any web server.
ISP( Internet Service Provider) A
company that provides individuals or companies access to the internet and the
world wide web is called ISP.
Firewall: software or hardware that
limits the certain kinds of access to a computer from the internal network or
external network.
E-Mail: E-mail stands for electronic
mail. It is most widely used feature on the internet. Sending and receiving
messages electronically through the internet is called E-mail. We can exchange
any message with the people around the world by using e-mail. It is very easy
and quick means of communication available in the computer world. We can write
an e-mail message in an mail program like Eudora, Outlook Express, Netscape
Navigator etc. and several web base program like Yahoomail, Hotmail, Gmail and
Zapakmail are also used to send and receive e-mail.
E-mail address: Each E-mail address is
identified by a unique name is called E-mail address. For example
mailme@yahoo.com, ram@fewanet.com.np, etc. It has five parts they are as
follows:
Ram : User’s name
@ (At the rate) : A separator
symbol
Yahoo, fewanet : ISP address or
domain name
.com or .edu or .net : commercial
or educational groups
.np : Country code
Advantages of using E-mail:
It is cheapest and fastest means of
communication and as compared our conventional postal mail.
It is more reliable than postal
mail.
E-mail can be accessed from any
part of the world and at any time.
Information can be share globally.
We can send photos, songs, video
clips and other file with e-mail attachments.
A single mail can be send to
multiple people at a time.
E-fax: E-fax stands for electronic fax.
It is very powerful desktop application that allows us to send and receive
faxes directly on our computer. It is very similar to e-mail. The E-fax first
goes to the internet server then the internet server sends it to its
destination whereas E-mail means first goes to the local file server.
Different between E-mail and E-fax:
E-mail E-fax
1. It is very cheap. 1. It takes more cost than E-mail.
2. Message first goes to the local server. 2. Message first goes to the internet server
and then to its destination.
3. Message is to be stored in the hard disk
of the destination computer (server). 3.
Message directly goes to print in the printer of the destination computer.
Computer
language:
Programming:
The method used to develop a solution or a
program is called programming. It is way of writing program using specific
computer language to perform specific task.
Computer Language : The set of codes which
is used to write computer program is called computer language . It is
artificial language and can be used to define a sequence of instructions that
can ultimately be processed and executed by the computer.
Types of computer language. :
Machine level language: The program
written using machine code or binary numbers (0 and 1) is called machine level
language. It is computer’s own binary-based language, or machine language, is
difficult for human beings to use. It is machine dependent complicated and time
consuming. It is also called first generation language.
Low level language (Assembly language)
: The language which permits the use of mnemonics (which are combination of
codes and English phrases) for each instruction that machine can do is called
low level language. It remains in between machine level language and high level
language. It is easier than machine level language and should be translated
into machine code using assembler. It is also called second generation
language. Example pseudo programming.
High level language : The language
which uses plain English words or phrases and mathematical notation, following
the correct syntax (Certain rules which are followed to write programs) is
called high level language. It should be translated into machine code using
compiler or interpreter. So they are slower. It is also called third generation
language. Example: QBASIC, C, C++, LOGO, LISP, ADA, PASCAL etc.
Language processor : The set of program
codes, which are used to translate program written in high level language or
low level language into machine code, is called language processor. There are
three types of language processor.
Interpreter : The language processor
which converts High level language and Low level language into machine code is
called interpreter. It translates programming codes line by line so it is
slower than compilers and assemblers.
Compiler : The language processor which
translates the program written in high level language into machine code is
called compiler.
Assembler : The language processor
which translates the program written in low level language into machine code is
called assembler.
Source program : The original program
written in high level language is called source program. It should be translated
into machine code, so that computer understands and responses it.
Object Program : The program converted into
machine code by compiler is called object program.
Advantages
of high level language:
It is very simple because plain English
words are used for programming.
There are pre-defined commands, which
minimize the work of programmers.
All the commands are syntax driven, so
they are very easy to learn and implement.
Features of
high level language:
It is machine independent and problems
oriented.
It does not require extensive
mathematics knowledge and computer hardware knowledge.
It requires less time to learn and
write the programs.
Provide better implementation and
documentation.
Advantages
of low level language:
I) The computation time of an assembly
language program is less.
II) Program debugging is easier.
Disadvantages of low level language :
I) It is machine dependent.
II) Too difficult to learn and implement.
Bug and Debug : Any type of error in the
program is called bug. The process of correcting bugs is called debug.
Introductions to C
What is C?
C is a programming language developed at AT
& T’s (American Telegraph and Telephone) Bell Laboratories of USA in 1972.
It was designed and written by a man named Dennis Ritchie. In the late
seventies C began to replace the more familiar languages of that time like
PL/I, ALGOL. It is general purpose high level programming language, which is used
to develop business programs, text processing programs, database management
programs and even to develop Operating System (OS).
Structured program: Structured Programming,
in computer science, a general term referring to programming that produces programs
with clean flow, clear design, and a degree of modularity or hierarchical
structure. Benefits of structured programming include ease of maintenance and
ease of readability by other programmers.
Advantages
of C language: or Advantages of structured program:
A large and complex program can be
divided into several simpler and manageable sub modules.
Support simultaneously coding of
modules by multiple programmers at a time.
Modules and functions once built here
can be used in other programs.
It reduced testing and debugging time.
The program can be easily modified.
Characteristics / Features of C:
It is structured programming language.
It is general purpose programming language.
It contains rich and powerful set of
operators.
It contains rich and powerful set of
declaration and data types.
It allows manipulation of internal
process registers.
Various characters set in C language:
Alphabets A, B, ….., Y, Z
a, b, ……, y, z
Digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
Special symbols ~ ‘ ! @ # % ^ & * ( ) _
– + = | \ { } , [ ] : ; ” ‘ < > , . ? /
Why Use C?
In today’s world of computer programming,
there are many high-level languages to choose from, such as C, Pascal, BASIC,
and Java. These are all excellent languages suited for most programming tasks.
Even so, there are several reasons why many computer professionals feel that C
is at the top of the list:
C is a powerful and flexible language.
What you can accomplish with C is limited only by your imagination. The
language itself places no constraints on you. C is used for projects as diverse
as operating systems, word processors, graphics, spreadsheets, and even
compilers for other languages.
C is a popular language preferred by
professional programmers. As a result, a wide variety of C compilers and
helpful accessories are available.
C is a portable language. Portable means
that a C program written for one computer system (an IBM PC, for example) can
be compiled and run on another system (a DEC VAX system, perhaps) with little
or no modification. Portability is enhanced by the ANSI standard for C, the set
of rules for C compilers.
C is a language of few words,
containing only a handful of terms, called keywords, which serve as the base on
which the language’s functionality is built. You might think that a language
with more keywords (sometimes called reserved words) would be more powerful.
This isn’t true. As you program with C, you will find that it can be programmed
to do any task.
C is modular. C code can (and should)
be written in routines called functions. These functions can be reused in other
applications or programs. By passing pieces of information to the functions,
you can create useful, reusable code.
Note: What is ANSI?
ANSI, in computer science, acronym for the
American National Standards Institute, an organization of American industry and
business groups dedicated to the development of trade and communication
standards; internationally, the American representative to the International
Organization for Standardization. In the microcomputer field, ANSI is commonly
encountered in three areas: programming languages, the SCSI interface, and the
ANSI.SYS device driver.
Variable : A entity whose value keeps on
changing during the program execution is called variable. A variable is a name
assigned to a data storage location. Program uses variables to store various
kinds of data during program execution. In C, a variable must be defined before
it can be used.
Rules for Constructing Variable Names
A variable name is any combination of 1
to 31 alphabets, digits or underscores. Some compilers allow variable names
whose length could be up to 247 characters. Still, it would be safer to stick
to the rule of 31 characters. Do not create unnecessarily long variable names
as it adds to your typing effort.
The first character in the variable
name must be an alphabet or underscore.
No commas or blanks are allowed within
a variable name.
No special symbol other than an
underscore (as in gross_sal) can be used in a variable name.
Ex.: si_int
m_hra
pop_e_89
These rules remain same for all the types
of primary and secondary variables. Naturally, the question follows … how is C
able to differentiate between these variables? This is a rather simple.
Keywords: Keywords are the words whose
meaning has already been explained to the C compiler (or in a broad sense to
the computer).
Keywords are also called as reserved word.
Constant:A constant is a fixed entity. It
does not change its value during the entre execution.
Types of
constant:
Integer constants
Floating point constants
Character constants
Enumeration constants
String literals.
Operator:
An operator is a symbol that instructs C to perform some operation, or action,
on one or more operands. An operand is something that an operator acts on. In
C, all operands are expressions. C operators fall into several categories:
The assignment operator
Mathematical operators
Relational operators
Logical operators
The Assignment Operator: The assignment
operator is the equal sign (=). Its use in programming is somewhat different
from its use in regular math. If you write
= y;
in a C program, it doesn’t mean “x is equal
to y.” Instead, it means “assign the value of y to x.” In a C assignment
statement, the right side can be any expression, and the left side must be a
variable name. Thus, the form is as follows:
variable = expression;
When executed, expression is evaluated, and
the resulting value is assigned to variable.
Mathematical Operators: C’s mathematical
operators perform mathematical operations such as addition and subtraction. C
has two unary mathematical operators and five binary mathematical operators.
Unary Mathematical Operators: The unary
mathematical operators are so named because they take a single operand where as
binary takes two operands.(for example sum= 5 + 6 i.e here are two operands such
as 5 and 6). C has two unary mathematical operators, listed in Table 4.1.
C’s unary mathematical operators.
Operator Symbol
Action Examples
Increment ++
Increments the operand by one ++x, x++
Decrement –
Decrements the operand by one –x, x–
The increment and decrement operators can
be used only with variables, not with constants. The operation performed is to
add one to or subtract one from the operand. In other words, the statements.
This type of operator are extensively used with looping control statement such
as for, while, do etc.
++x; means ++x; will increase the value of
x and then processing takes place. –y; means –y; will decrease the value of y
and then processing takes place. x++; means x++; will processes and then
increases the value of x by 1. y–; means y–; will processes and then decrement
will take place.
are the equivalent of these statements:
= x + 1; y = y – 1;
Binary Mathematical Operators: C’s binary
operators take two operands. The binary operators, which include the common
mathematical operations found on a calculator, are listed in Table 4.2.
C’s binary mathematical operators.
Operator Symbol
Action Example
Addition +
Adds two operands x + y
Subtraction - Subtracts
the second operand from the first operand x
– y
Multiplication * Multiplies two
operands x * y
Division /
Divides the first operand by the
second operand x / y
Modulus %
Gives the remainder when the first
operand is divided by the second operand x
% y
The first four operators listed in Table
4.2 should be familiar to you, and you should have little trouble using them.
The fifth operator, modulus, might be new. Modulus returns the remainder when
the first operand is divided by the second operand. For example, 11 modulus 4
equals 3 (that is, 4 goes into 11 two times with 3 left over). Here are some
more examples:
100 modulus 9 equals 1 10 modulus 5 equals
0 40 modulus 6 equals 4
Relational Operators: C’s relational
operators are used to compare expressions, asking questions such as, “Is x
greater than 100?” or “Is y equal to 0?” An expression containing a relational
operator evaluates to either true (1) or false (0). C’s six relational
operators are listed in Table 4.4.
Table 4.5 shows some examples of how
relational operators might be used. These examples use literal constants, but
the same principles hold with variables.
C’s relational operators.
Operator Symbol
Question Asked Example
Equal ==
Is operand 1 equal to operand 2? x == y
Greater than > Is operand
1 greater than operand 2? x
> y
Less than <
Is operand 1 less than operand 2?
x < y
Greater than or equal to >= Is
operand 1 greater than or equal to operand 2? x
>= y
Less than or equal to <= Is
operand 1 less than or equal to operand 2? x
<= y
Not equal !=
Is operand 1 not equal to operand
2? x != y
Relational operators in use.
Expression How
It Reads What ItEvaluates To
5 == 1 Is
5 equal to 1? 0 (false)
5 > 1 Is
5 greater than 1? 1 (true)
5 != 1 Is
5 not equal to 1? 1 (true)
(5 + 10) == (3 * 5) Is (5 + 10) equal to (3 * 5)? 1 (true)
Logical Operators: Sometimes you might need
to ask more than one relational question at once. For example, “If it’s 7:00
a.m. and a weekday and not my vacation, ring the alarm.” C’s logical operators
let you combine two or more relational expressions into a single expression
that evaluates to either true or false. Table given below lists C’s three
logical operators.
C’s logical operators.
Operator Symbol
Example
AND &&
exp1 && exp2
OR ||
exp1 || exp2
NOT !
!exp1
The way these logical operators work is
explained in the table below
C’s logical operators in use.
Expression What
It Evaluates To
(exp1 && exp2) True (1) only if both exp1 and exp2 are true;
false (0) otherwise
(exp1 || exp2) True (1) if either exp1 or exp2 is true; false (0) only if both
are false
(!exp1) False
(0) if exp1 is true; true (1) if exp1 is false
Branching: Branching is based on decision
making. If the decision satisfied, then it can perform the task, otherwise it
executes the line next to it.
For example:
If ……….. else
If ……….. else if ………..else
Switch case
Looping: looping is a process which allows
the data to be repeated unless or until some condition has been satisfied. The
various statements are:
For
While
Do while
Comments : Comments are the statements that
are used for user aid or remarks. The statements which are defined as comments
are ignored by C compiler comments are non-executable statements. Comments are
defined as /*…………your words…………..*/
Note : We defined comments as REMARK in
QBASIC like REM ………. Or ‘…………
Escape sequence : The set of characters,
which are not printed when used but provide various functions. Such escapes are
start with ‘\’ back slash. For example
Character Escape Sequence
Bell (alert) \a
Backspace \b
Horizontal tab \t
New line \n
Carriage returns \r
Quotation mark \”
Backslash \\
Null
Identifiers:
Identifiers are the name givne to various program elements such as variables,
functions or arrays. It may consist both letter and digit but initial character
must me letter and maximum 31 characters can be used to name the identifiers.
For example: tax_rate, tax_year, year-2065 etc.
Library Functions: Various types of built
functions which can be used to execute different types of task such as
mathematical calculation, graphics management, memory management, data and file
handling etc. Example: sqrt(), to lower (), to uppor () etc. #include
directive: This is the most essential directive. A directive is links to a
header files, the header file makes full use of the I/O functions of the C
library. For example #include <stdio.h> Header files: The library
function which is used to declare the source of file is called header file. For
example: studio.h, conio.h, process.h, math.h, ctype.h, string.h, stdlib.h etc
Example with flowchart:
#include <stdio.h>
count = 1 ; /* Calculation of simple
interest for 3 sets of p, n and r */
main( ) { int p, n, count ; float r, si ;
while ( count <= 3 )
{ printf ( “\nEnter values of p, n and r ”
) ; d %f”, &p, &n, &r ) ; n * r / 100 ;
printf ( “Simple interest = Rs. %f”, si ) ;
1 ;
scanf ( “%d % si = p * count = count + }
} printf() : The printf a function used to
send formatted output to the standard output device (monitor or printer) based
on a format specification. scanf() :The
scanf a function used to get formatted input to the standard input device
(keyboard) based on a format specification.
getch(): The getch () function holds from screen scrolling. It is
defined in stdio.h header files. void
main(): The void main() is appear in every C program. Main without void is used
when there are no arguments. main() without any parameters has an argument.
Your First C Program
You’re probably eager to try your first
program in C. To help you become familiar with your compiler, here’s a quick
program for you to work through. You might not understand everything at this
point, but you should get a feel for the process of writing, compiling, and
running a real C program.
This demonstration uses a program named
HELLO.C, which does nothing more than display the words Hello, World!
on-screen. This program, a traditional introduction to C programming, is a good
one for you to learn. The source code for HELLO.C is in Program01. When you
type in this listing, you won’t include the line numbers or colons.
Program01 1.1. HELLO.C.
1: #include <stdio.h> 2: 3: main() 4:
{ 5: printf(“Hello, World!\n”); 6: return 0; 7: }
Be sure that you have installed your
compiler as specified in the installation instructions provided with the
software. Whether you are working with UNIX, DOS, or any other operating
system, make sure you understand how to use the compiler and editor of your
choice. Once your compiler and editor are ready, follow these steps to enter,
compile, and execute HELLO.C.
Computer
Virus
Definition: A computer program that can
replicate itself by making copies itself without the user’s knowledge is called
virus. Virus can destroys the data files, program files and system files of the
computer.
Purposes of
creating virus.
To protect software from software
piracy.
To expose the programming capabilities
of the programmer.
To sell anti-virus program and earn
money.
To entertain the user by generating
pictures and interesting messages on the screen.
For the criminal purposes such as to
hack server computer of very sensitive organization or government offices.
Symptoms of computer virus. (What a virus
can do to computer?)
Computer becomes slow by reducing
memory space.
Computer may not boot and hang quickly.
System files may corrupt and affect the
performance of computer.
Virus are self duplicating program
hence it spread it occupy more space on the disk less space will remain for
storing data or information.
Date and time change automatically.
File renames automatically.
Unnecessary and unusual messages appear
on the screen.
Antivirus Software:
The programs which can detect and eliminate
the computer viruses are called anti-virus software. For example Norton, Panda,
F-port, Pe-cilin, AVG, Avast, Nod32, Avira, MacAfee, Smart Dog, Kaspersky,
Sophas etc.
Prevention and protection from virus:
Install reputed anti-virus software and
use regularly.
Update the anti-virus program’s virus
library to detect and eliminate new virus.
Never install pirated software.
Do not open e-mail attachment and
e-mail from unknown person before scanning at first.
Write protect the disk when it need to
use in another computer.
We must make backup copy of valuable
data so it can be restored from original location in case of damage.
Practical Tips At Home: What to do if
computer is already affected?
Solution:
Open computer in safe mode.(by pressing
F8 key after you press power switch of CPU box)
Login computer by administrator or
other account having administrative privileges.
Install antivirus program using program
CD (CDs are good to install anti-virus program than Pen Drives because virus
can transmit in pen drive before we install anti-virus and thus it can damage
anti-virus program too) and scan the computer.
If cannot be install properly then we
can restore the system in previous state (if Windows XP is installed in the
computer) from System Tools option of Accessories option of Programs of Start
button.
Again try from first step after you
restore the system in previous state.
Types of computer virus:
There are many categories of viruses,
including parasitic or file viruses, bootstrap-sector, program virus or file
virus multipartite, macro, stealth virus and script viruses.
Bootstrap-sector virus:
Bootstrap-sector viruses reside on the
first portion of the hard disk or floppy disk, known as the boot sector or
Master Boot Record (MBR). These viruses replace either the programs that store
information about the disk’s contents or the programs that start the computer.
Typically, these viruses spread by means of the physical exchange of floppy
disks. These viruses are also called as start-up infector virus. Examples of
such viruses are Danish Boot, Devel 941, Disk killer etc.
Multipartite viruses:
Multipartite viruses combine the abilities
of the parasitic and the bootstrap-sector viruses, and so are able to infect
either files or boot sectors. These types of viruses can spread if a computer
user boots from an infected diskette or accesses infected files. Examples of
such viruses are Invader, Flip, Tequila, etc.
Parasitic or file viruses or program files:
Parasitic or file viruses infect executable
files or programs in the computer. These files are often identified by the
extension .exe , .bin, .sys, .drv etc. in the name of the computer file. File
viruses leave the contents of the host program unchanged but attach to the host
in such a way that the virus code is run first. Then it will affect execution
of the program and hence the computer becomes very slow. Examples of such
viruses are Acid Rain, Alien 298, Crazy, Brontok etc.
Script
viruses:
Script viruses are written in script
programming languages, such as VBScript (Visual Basic Script) and JavaScript.
These script languages can be seen as a special kind of macro language and are
even more powerful because most are closely related to the operating system
environment. The ‘ILOVEYOU’ virus, which appeared in 2000 and infected an
estimated 1 in 5 personal computers, is a famous example of a script virus.
Macro
viruses:
Macro virus contains inside files. Macro
command which is designed to infect a specific type of document files such as
Ms Word or Ms. Excel files. Examples of such viruses are DMV, Nuclear and Word
Concept.
Stealth viruses:
Stealth virus is one of the most dangerous
types of viruses which really give information about the presence of it in the
computer. Generally it infects the boot sector records and program files. It is
difficult to detect using anti-virus program because it can hide in memory from
the operating system and antivirus software. Some time they can hide other
files. Examples of stealth virus are Frodo, Joshi, Whale, etc.
Microsoft Access
Microsoft Access is very powerful and most
popular desktop database management system where we can create and maintain
related data. It comes in a office package with other software such as Ms.
Word, Excel, Power point etc. It is a relational database management system
(RDBMS). In multi-user environment it supports file and data sharing mechanism.
In access, we can store multiple databases and use them individually or in
groups to create queries and reports or utilize two or more tables containing
data arranged in rows and columns. Microsoft Access is a fully functional
RDBMS. It provides all the data definition, data manipulation, and data control
features you need to manage large volumes of data. It comes in different
version such as, Microsoft Access 97/2000/XP/2003/2007.
Features of Microsoft Access:
It provides very useful database
features such as tables, forms, reports and queries.
It works as front end development tool.
This provides end-user applications
developer environment.
It shares data with other application
such as Microsoft Word or Excel.
It support three computer programming
language such as: SQL, Macros and Visual BASIC etc.
Notes:
End-user
: The ultimate user of a computer, who has the need of use of computer
database management system but lacks the time to learn all the complexities of
the system or computer application in its finished, marketable form.
SQL:
SQl stands for Structured Query Language. It is a tool that allows the database.
It enables the users to extract, manipulate and related to learn data from one
or more tables.
Macros:
It is a list of actions which can be executed by clicking specific button is
called macros.
Visual
BASIC: It is very advanced and flexible and comprehensive language you can
uses to dev lop complete user interactive applications.
Typical Uses for Microsoft Access
Here are just a few of the ways Access can
fulfill the needs of a wide range of users.
Small
Business
Accounting
Order entry
Customer tracking
Contact management
Consulting
Vertical market applications
Cross-industry applications
Marketing
Product promotion
Sales information resource
Order processing
Large
Corporation
Workgroup applications
Information processing systems
Intranet publishing
Personal
Use
Address book
Investment management
Cookbook
Collections—recordings, books, movies
Parts of Ms. Access
Table:
A table is collection of data about a specific topic, such as products or
suppliers. Using a separate table for each topic means that you store that data
only once, which makes your database more efficient, and reduces data entry
errors.
Table is the primary object of Ms Access. A
table stores data in tabular form. A table is made up of rows and columns. Some
parts of table are as follows:
Fields
(column): The title name of the column that holds data is known as field. A
table can have many fields.
Records
(rows): The collection of data horizontally for each field is known as
record. A record is complete information about an entity.
Data:
The actual information stored under a filed title in a row is called data.
Index:
A table can have index attached with it. The index is used to keep the data in
organized for and helps faster retrieval of data.
Primary
key: A primary key is a field which is uniquely identified. All the records
of a table are uniquely identified on the basis of primary key. The column that
has been defined as the primary key can’t hold null value. For example a
student’s roll no. can be defined as primary i.e can’t be null and repeat.
Compound key: The primary key based on
more than one field is known as composite key. It consists of multiple columns,
because one column is not sufficiently unique.
Foreign
key: Foreign key is the linking pin between two tables. It shows the relation
between any two tables.
Queries:
a query is search or question that you make for a record or item. The record is
stored in the database file. Queries help to investigate about data records.
Forms:
Forms present the data from a table or a query in a way we want it to be
displayed. The fields in the table or query are made available to place on the
forms we create.
Note:
Use of form.
Displaying and editing data.
Controlling application flow.
Accepting input.
Displaying messages.
Printing information.
Reports: Reports are the printed results of
data processing. Reports are specially formatted collections of data, organized
according to your specification for summarizing and printing listings of
database data. While forms are designed to be used onscreen, reports are
designed to be viewed and printed.
Relationship: In a database we can
establish relation between any two or more tables. Because no data are
isolated, but they are associated or related with each other entity in one or
another ways. we can generate reports and manipulate data using such
relationship between tables.
Types of relationship:
Many to many relationship: A many to
many relation is unclear. Many to many relations often are a sign that further
analysis is required.
Many to one relationship: Many to one
relation is the same as one to many, but from a different view point. Using
this relation two or more fields of one table can be link with one field of
another table.
One to many relationship: Most relation
in tables are one to many, means one field of a table can be link with two or
more fields of the another table.
One to one relationship: A one to one
relation exception in database. It can be established using primary key and
foreign key in the DBMS.
Note:Cascaded
Delete: When deleting a row the RDBMS automatically deletes the related
data in the many tables. This is called cascaded delete.
Keyboard Shortcuts for Scrolling in a
Datasheet
Keys Scrolling
Action
Page Up Up
one page
Page Down Down
one page
Ctrl+Page Up Left one page
Ctrl+Page Down Right one page
Keyboard Shortcuts for Selecting Data in a
Datasheet
Keys à Selecting Action
Tab à Next
field
Shift+Tab àPrevious field
Home à First field, current record
End à Last
field, current record
Up arrow à Current field, previous record
Down arrow à Current field, next record
Ctrl+Up arrow àCurrent
field, first record
Ctrl+Down arrow à Current field, last record
Ctrl+Home à First field, first record
Ctrl+End àLast field, last record
F5 à Record
number box
Ctrl+Spacebar à Select the current column
Shift+Spacebar à Select the current record
F2 à Switch
between selecting all data in the field and single character edit mode
Details of Data Type of MS. Access
Data type defines the nature of the data to
be stored in the column. Access provided different types if data that can be
stored.
Text : (Default) Test or combination of text and numbers, up to 255
characters.
Memo
: Use for lengthy text and numbers, such as notes or
descriptions. Stores up to 65,536 characters.
Number:Use for data to be included in
mathematical calculations.
Date/Time:Use for dates and times
Currency :Use for currency values and to prevent rounding off during
calculations..
AutoNumber:
Use for unique sequential (incrementing by 1) or random numbers that are
automatically inserted when a record is added.
Yes/No :Use for data that can be only
one of two possible values, such as Yes/No, True/False, On/Off. Nullvalues are
not allowed.
OLE Object :Use for OLE objects (such
as Microsoft Word documents, Microsoft Excel spreadsheets, pictures, sounds, or
other binary data) that were created in other programs using the OLE protocol.
Hyperlink : Text or combination of text
and numbers stored as a text and used as a hyperlink.
Lookup Wizard Use to create a field
that allows you to choose a value from another table or from a list of values
using a combo box— -choosing this option in the data type list starts a wizard
to define this for you.
Field Properties:
Field Property: Field size property is
set to the maximum size for data stored in the field set to the text or number
data type. For next data, the default field size is 50 and maximum size is
depending on the type of data types.
Format: It allows choosing different
format of data type available.
Decimal places: It is valid for only
numeric data and currency data, where the decimal places numbers vary fro 0 to
15.
Caption: It used to display alternative
name for the field to make the field name more explanatory. It can contain up
to 2,048 characters.
Default Value: Default value is the one
that enter automatically in the database and can be changed as per required.
Validation Rule: It is used to set the
limitation while entering data in the database. It helps us to customize the
data entry and checks for error entry of data.
Validation Text: If wrong data is
entered which do not supported by given validation rule, it is used to display
messages on the screen and work as a precaution of wrong data entry.
Required: If required is set as Yes
then field should always receive a value during data entry.
Indexed: You can choose whether you
want to index the table. The available index options are unique index and
duplicate index.
Input Mask: It is usually used to set
control the data entry in the database. Using this option we can customize the
data entry by setting special commands using the following symbols:
Character Description
0 Digit
(0 through 9, entry required; plus [+] and minus [-] signs not allowed).
9 Digit
or space (entry not required; plus and minus signs not allowed).
# Digit
or space (entry not required; blank positions converted to spaces, plus and
minus signs allowed).
L Letter
(A through Z, entry required).
? Letter
(A through Z, entry optional).
A Letter
or digit (entry required).
a Letter
or digit (entry optional).
& Any
character or a space (entry required).
C Any
character or a space (entry optional).
. , : ; – / Decimal placeholder and thousands, date, and time separators.
(The actual character used depends on the regional settings specified in Microsoft
Windows Control Panel.)
< Causes
all characters that follow to be converted to lowercase.
> Causes
all characters that follow to be converted to uppercase.
! Causes
theinput mask to display from right to left, rather than from left to right.
Characters typed into the mask always fill it from left to right. You can
include the exclamation point anywhere in the input mask.
\ Causes
the character that follows to be displayed as a literal character. Used to
display any of the characters listed in this table as literal characters (for
example, \A is displayed as just A).
Password Setting
the InputMask property to the word Password creates a password entry text box.
Any character typed in the text box is stored as the character but is displayed
as an asterisk (*).