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3. Introduction to ICTs
Today’s FIVE IT assets
Security
Network
Programming &
Data management
Interface
Web system
NETWORKING
Definition
• Process of inter-connecting two or more
computers so that users can
– Communicate
– Share resources
– Overcome shortfalls of standalone computers
• Speed up computation
• Distribute processing tasks and/or data
Advantages
• Hardware resource sharing
– E.g. Processor, space, computer peripherals
•
•
•
•
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Database sharing
Software sharing
Communication between users
Decentralised data processing
Security of data
– Backing up with duplicate storage hence guarding
against accidental loss
Types of networks
Wide Area
Network
(WAN)
Metropolitan
Area Network
(MAN)
Local Area
Network
(LAN)
• Computers distributed over wide geographical area
• Can be public (government)
• Can be private (e.g. SWIFT (society for worldwide interbank financial
transactions, INDONET, SBINET)
• Microwave/ satellite transmission/ international telephone network
• Lower speeds of data transmission than MAN
• Consists of single nodes, clusters and/or LANs
• Covers wider area than LAN but smaller than WAN, covering a city
• High data transmission speeds over metropolitan distances
• System of interconnected microcomputers in a limited geographical area like a building or
campus
• High sharing of network resources (common communication link)
• Central storage facility
• Network operating system to manage network resources and microcomputers
• Low error rate as network contains built-in components for detecting system errors
• Private ownership by user
• Not subject to regulation by public telecommunications authority
• Devices on network can operate independent of network
• Can support heavy traffic over sort distances compared to a telecommunications network
Advantages of WAN
• Allows access to databases at remote sites
– Caution: increased security risks
• Failure of remote node (i.e. computer on network) means
remaining nodes can still communicate
• If network fails, local node can still access its own database
• Daily data kept locally results in quick access
• Local office can maintain data more easily whilst corporate
office can access data as needed
• Upgrade of storage capacity can be done without affecting
data transfer between nodes.
• Communication governed by public telecommunications
authority (with strict rules of adherence) as opposed to
relative freedom of the LAN
Types of LAN
• Client/server
– Server:
• Is a computer that manages shared resources as well communication
between nodes
• Has large processor, RAM and secondary storage capacity
– Client:
• Computers on the network that request for services from the server
• Peer-to-peer
– Each computer with equal status and functioning
– Independent communication of computers without using server
– Less expensive than client/server
– Performance slower than client/server
Network topologies
• Topology
– The way computers are physically connected
on a network
• Network architecture
– Specifications of the components that can be
connected to a network
• Types of topologies
– Star, Ring, Bus, Hybrid
LAN Components
•
Workstation
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•
File server
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Manages communication in network and shared resources, including file access and shared software
Application software
–
•
Coaxial or fibre optic cables (with high data transfer speeds) for networking computers
Network operating system
–
•
Hub that does not use power or active devices on network connecting up to 4 nodes covering maximum distance of
300ft.
LAN cable
–
•
Powered distribution point/ electronic device to which multiple computers are attached using twisted pair cables
Connects up to 8 nodes covering maximum distance of 2000ft
Passive hub
–
•
Facilitates communication between two networks with different technologies
Network interface unit/ network card/ network adapter
Active hub
–
–
•
Powerful computer with special-purpose software to serve files to other workstations on the network
Gateway
–
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User workstations and server workstations
Software that is meant for a multiple-user environment: shared copies
Protocols
Protocols
• Sets of rules and procedures to control data
transmission between a computer and other devices
• Must be the same for two devices that want to
communicate
• Include TCP, FTP, UTP etc.
• Send and interpret data
• Provide continuous feedback during data transmission
• Engage recovery procedures when errors occur
• Provide safe termination for all communicating devices
PROGRAMMING LANGUAGES
Differentiating Programming Languages
Language
Features
Advantages
Disadvantages
Machine
language
Denoted using 1’s and
0’s
High speed -very efficient in
computer circuits
Translation free
Tedious
Machine dependent
Error prone
Complex language
Assembly
language
Used mnemonic codes
Easier than machine
language
Provision of program
statement and syntax error
listings
Considerable time writing
Require translation
Good memory required
High level
languages
Similar to English
language - shortened
statements
Use compilers to check
syntax then convert to
target language
Interpreter translates
statement and executes
it immediately before
reading next statement
(e.g. LISP)
Readability
Platform independent
Easy debugging
Easier to maintain
Low development cost
Easy documentation
Poor control on hardware
Less efficient
Evolution of languages
LANGUAGE
DEVELOPERs
YEAR DEVELOPED
BASIC
Prof. John Kemeny and
Thomas Kurtz, USA
1964
FORTRAN
IBM, USA
1957
PASCAL
Prof. Niklaus Wirth, Switzerland
1971
ADA
Honeywell Computer Company,
USA
1980
C
Bell Telephone Laboratories,
USA
COBOL
JAVA
VISUAL BASIC
C++
PYTHON
1960s
Sun Systems
1994
DATA/INFORMATION
MANAGEMENT
Databases
Definition: database
system
Set of logically connect data files that have common
access methods between them
Importance
Data treated as an organisational resource offer following
advantages: data independence, data sharing, data
integrity, data availability
Components
Database files, DBMS, host-level language interface system,
natural language interface, application programs, data
dictionary, report generator
Users
Application programmers, end-users and database
administrators
Models/Architectures
(1) Hierarchical, (2) Network, (3) Relational
Disadvantages
Higher data processing costs, increased hardware and
software costs, increases security and integrity risks
Exploring & harnessing
information
Data mining and Data warehousing
THE INTERFACE
Human Computer Interaction (HCI)
DEFINITION
A set of programs that facilitates the interaction
between the user and the hardware
VARIATIONS
Command-driven and graphical user interface (GUI)
EVOLUTION
Require input from mouse, speech, images, cameras,
touch-screens
Output graphics and videos, sound, etc.
Require concurrent triggers from various input devices
MODERN
CONCERNS
Growth in user diversity, holographic input/output
SMART COMPUTING
HUMAN FACTOR
GOALS – DESIGN
INTERFACES THAT
(1) Minimise learning time
(2) Maximise speed of performance
(3) Minimise rate of user errors
(4) Maximise user satisfaction
(5) Maximise user’s retention of knowledge over time
WEB-BASED AND
MULTIMEDIA SYSTEMS
Web-based and Multimedia
Systems
“a picture is worth more than a thousand
words”
• Pushed by and used for
–
–
–
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Growth in GUI
Market economy (e-commerce)
Social networking
Globalisation effects of the Internet and World
Wide Web
– Learning, Entertainment
– Diversities of users
Conclusion
• Five major technologies
– Drive one another
– Consider user’s needs or demands first
– Are now moving in the age of Smart
Computing
• Food for thought
How will they evolve??