Transcript ICT4 Exam Revision

Unit 4
ICT A level
Revision
Remember!!
The focus of A level questions is on you being
the designer / advisor to organisations wishing
to develop their ICT capabilities
A level questions can contain areas from your
As knowledge
You may be asked to apply A level theory to
the applications you studied at As
Unit 4
Networks
Computer Networks
•A computer network is a collection of computers linked together so that
they can communicate with each other
•A computer that is not connected to a network is called a stand-alone
computer
•There are two different sorts of computer network:
•‘Local Area Network’ or ‘LAN’ - the computers are all in the same
building or in different buildings on one site permanently connected to
each other with special cables.
•‘Wide Area Network’ or ‘WAN’ - the computers are spread over a
large geographical area not permanently connected to each other
communicate using telephone lines, radio transmitters or satellite links.
Connected by gateways
Factors to consider when
choosing a network
1. Cost of the network
Initial purchasing of equipment
Installation and training
Maintenance costs
Size of the available budget will determine
what can be done e.g. fibre optic cable is
faster but is also more expensive. Wireless
systems are flexible but need more
maintenance.
2. Size of the organisation
Needs
can range from a small LAN to a
global WAN.
Some communications media are limited to
the distance they have to travel.
Amount of data processing required must
also be considered.
3. How the system will be used
What type of applications do users require?
Will they need large data storage?
From where will they operate the network e.g.
at home in office or remote access from
different locations
4. Existing systems to integrate
More often networks are not developed from
scratch but need to fit in with existing systems.
Sometimes an extension is required e.g. when
a new branch office opens.
Therefore any new network must fit in with the
operating systems and protocols of the
existing.
It must support any peripherals already in use
e.g. bar code readers, printers etc..
5. Performance and speed required
Performance in terms of ;
reliability
user friendliness
capacity
speed of processing.
Different parts of the organisation may have different
performance requirements. E.g. a realtime ecommerce system may require greater speeds and
capacity and security than the in house payroll
system
6. Security issues
Different organisations may have different
priorities e.g.
A large business organisation may be
primarily concerned with
– Prevention of hacking
– Avoid viruses
– Secure payment site
A school may be equally concerned with
blocking the downloading of illicit material
Clients (Terminals)
Thin clients (‘Dumb terminal’)
•Has no built in hard drive, expansion slots and only has enough
RAM and processing capacity to run applications and output to a
monitor
•Suitable for client server networks.
Fat clients (‘Intelligent terminal’)
•This is a workstation with full stand alone capacity. It has its own
hard drive for storage and a CPU.
•Stations have a processor so can share the processing. There are
many different ways to do this e.g. a station could act as a printer
server etc. A station could store programs on its disc and load
them while data files are stored elsewhere perhaps upon a central
fileserver.
•Suitable for peer to peer networks
Both LANs and WANs may be either
Client/Server
or
Peer-to-Peer networks.
Peer to peer network
All stations are joined together in the network have
equal status.
Each station can communicate directly with every
other workstation on the network without going
through a server.
They are both client and server sharing resources.
Are often a form of distributive processing sharing
the processing between intelligent terminals.
Hardware and data files can be access from several
computers.
Applications may be stored on different computers
and accessed by all as longer as the owner gives
permission.
Work is backed up on individual user PCs.
Client Server Network
The term Client/Server is used to describe networks that
have computers or terminals (clients) that are connected
to a more powerful computer called the NETWORK
SERVER.
A central file server store the data and programs
Access is determined by user access privileges controlled
by their logon names and passwords
A print server would spool data ready fro despoiling to a
printer when the printer is ready
A communication servers e.g. web server; email server
may control all email and internet access.
Peer to Peer
Client server
Cheaper: initial start up costs and
network operating system less
complicated
More expensive as software system
more complex and need to but servers.
Less vulnerable to central server
crashes
If server crashes or cable fails no user
can continue work
Simpler to set up and maintain
Require specialist personnel to manage
system
Slower processing of tasks
Faster processing of tasks
Only works well on small networks <15
Can manage large networks
Security and backup are not centralised
and difficult to manage
Centralised control with servers often
doing many management functions
themselves e.g. regular backups,
auditing
Access to data depends upon the
owner’s permission.
Offers easy access to centralised data
Network Topology
Network topology refers to the layout used to connect the
computers together. There are three common topologies:
• Bus
• Ring
• Star
Any of these topologies can be used regardless of whether a
network is local or wide area, server based or peer-to-peer.
BUS
•Workstations are connected to the main central cable/bus
•Data can travel in both directions
•Two nodes could attempt to transmit at the same time and a collision
will
occur.
To avoid
this, network
a node waits
until no
2.This
is the
cheapest
topology
as traffic
the on the bus and
pauses
slightly
beforeoftransmitting.
If a collision occurs both nodes wait
smallest
amount
cabling is required
and try again at a random time interval.
•The main bus standard is known as Ethernet the communications uses
a broadcast channel so all attached workstations can hear every
transmission.
Fileserver
Terminator
Terminal
Terminal
PLOTTER
PRINTER
Advantages
Less cable need than a ring. Relatively cheaper and
easier to install and maintain.
Easy to add new nodes by removing terminator
If a workstation/terminal goes down the others will
continue
Disadvantages
Heavy traffic can cause network failure and delays
Heavily dependent upon the cable backbone and
cable damage can cause network failure.
RING NETWORK
RING
CABLE
The Cambridge ring
T1
T8
has no central host
T2
computer and none of
T7
the nodes need to
have overall control of
HARD
DISK
access to the network.
T6
T3
Messages in the ring
T5
T4
flow in one direction
from node to node.
The ring consists of a The choice of cable depends upon
the distance to be travelled and
series of repeaters
required speeds. Fibre optic cabling
which are joined by
is the best but the most expensive.
cables.
Fibre optic cabling would allow a
ring of about 100 kilometres.
PRINTER
SERVER
COMMUNICATIONS
SERVER
FILESERVER
SCANNER
Token passing technique
An imaginary token is continuously passed around the RING.
A token is a small packet that contains bits of data which
passes around the ring (Always the same way around)
The token is recognised as a unique character sequence.
If a device is waiting to transmit it catches a token and with it
the authority to send data. It attaches its data. The packet will
contain the destination address.
As long as one device has a token no other device can send
data.
A receiving device acknowledges it has received the message
by inverting a 1 bit field.
Once the sending workstation has received acknowledgement
that the message has been received the token is free for use
by another device.
Advantages of a Ring network
There is no dependence upon a central host as data
transmission is supported by all devices on the ring. Each node
has sufficient intelligence to control the transmission of data
from and to its own node.
Works effectively when processing is distributed across a site.
Very high transmission speeds are possible.
It is deterministic i.e. different performance levels can be
determined for different traffic levels.
Routing between devices is simple because messages normally
travel in one direction.
As data is in one direction it can transmit large volumes of data
Disadvantages Systems depends upon the reliability of the ring repeater
although it can be designed to bypass faulty repeaters. If one
node malfunctions this can affect the operation of the network.
Cabling costs
Difficult to extend the ring.
STAR NETWORK
Each node is connected to a CPU at the
centre. Popular topology for a WAN.
Messages pass through host which
interconnects different devices on the network.
The central host switches messages point to
point.
T7
T6
T8
Scanner
HARD
DISC
FILESERVER
COMMUNICATIONS
SERVER
T5
T4
PRINTER
T1
T2
T3
Advantages of a Star network
Suitable for WANs where large organisations rely on a central
computer for the bulk of data processing tasks
Central control of message switching allow a high degree of
security
Each spoke is dependent upon the rest. If one spoke breaks
down the others can continue and the central CPU can
identify any faults
Data transmission speeds can vary from spoke to spoke so
one can use a high-speed device and another a low speed
e.g.. disc drive.
Saves cabling.
Disadvantages
Network is vulnerable to central hub failures.
As a distributed system, some processing is still possible at
the nodes but internode connection is lost.
If servicing a WAN a mini or mainframe system is needed for
control of messaging. So hardware and software is
expensive.
A Wide Area Network (WAN)
Workstation
Workstation
Workstation
Print Server
File Server
Printer
Gateway
Modem
Remote PC
Remote PC
Modem
network cables
telephone lines
LANs and WANs
Internet, Intranet and Extranet
The Internet is a Wide Area Network - actually it is a huge collection of networks
connected together by what are called gateways - these make the system act as
if it was one huge network.
Many networks in industry, business, higher education and government institutions
are all connected to the Internet although anybody can now get connected to the
system with the appropriate hardware and software and access to an ISP (Internet
Service Provider )...eg Freeserve, AOL, Demon and hundreds of others.
A user can get information on just about everything. There are search tools which
allow you to search the World Wide Web for any topic, and each page has links to
another and so on....
- it is also possible to download software and files (eg NASA graphics)
- bulletin boards (forums) or newsgroups are also set up where you can leave
messages, or communicate directly with other users.
Businesses set up websites on the Internet because...
..they can advertise. It enables people to find out what they do and what they sell.
..people can email them with enquiries; orders; requests;
..they can reach an international audience.
Intranets
An intranet is set up entirely within a LAN. Web pages can be
stored and accessed from anywhere on the network and email
can be sent internally within the LAN.
A company can set up an intranet and allow its workers to send
messages to each other and use a browser to access company
information saved as web pages. It can also be used for staff
training.
Extranets
If a company allows some access from outside to its intranet,
then it becomes an extranet. Access would normally be through
a firewall (software which only allows permitted users to access
the data).
Wireless Media
Infra-red
Radiowaves
Bluetooth
Broadband
Microwaves
Mobile phones use microwaves. Ideal for linking
computers in two separate buildings fairly near to each
other. Satellite systems also make use of microwaves.
Infra red light.
Infrared refers to light waves of a lower frequency
than human eyes can receive and interpret.
Infrared is used in most television remote control
systems, and with a standard called IrDA (Infrared
Data Association) it's used to connect some
computers with peripheral devices. For most of
these computer and entertainment purposes,
infrared is used in a digital mode -- the signal is
pulsed on and off very quickly to send data from
one point to another.
Advantages Infrared communications are fairly
reliable and don't cost very much to build into a
device.
Disadvantages
It can only travel short distances.
Infrared is a "line of sight" technology.
Infrared is almost always a "one to one"
technology.
Wireless networking- cableless
connectivity
Radio Transmission
Devices have radio transmission facilities and radio
receivers. These radio receivers constantly scan the
airways for incoming signals. When it detects the
signal it recognises it captures it and converts it to
digital form. The digital signal can be transmitted to
the CPU by wireless routers
Examples
People now need to be mobile and still access their
networks, email accounts e.g. at wireless nodes in
an airport
Part of a WAN or Virtual Private Network e.g. a
delivery driver using a hand held device to confirm
deliveries with a central database
More examples….
Landscape gardeners use a laptop with wireless
connectivity to access a library of garden designs
back at HQ
Doctors at the scene of an accident can accessing
patient records.
Wireless networks may be used as part of a LAN
e.g. a mobile bar code reader in a warehouse
transmitting data to a shop or HQ
Hand held chip and pin data entry in restaurants for
entering details of cars payments.
Wireless devices such as Printers/ keyboards/mobile
phones and description of use.
Bluetooth technology
The Bluetooth PDA Adapter Card,
PC Card, and USB Adapter plug
into
your PDA, PC, or notebook
computer, enable the user to
effortlessly transfer data to other
Bluetooth devices such as desktop
or
notebook computers, input devices,
PDAs, scanners, printers, and even
mobile phones. Connect with up to
seven other Bluetooth devices at a
time.
Broadband and
wireless networking
The broadband connection gives faster access
speeds to the Internet and wireless routers
give wireless connection to the wireless
adaptor in your PC. Average home speeds of
about 54 Mps are possible.
Wireless technology means no cables
Allows remote use in wireless zones such as
airports an dhotels.
Advantages of Broadband
Faster connection when you want to be online
Savings on telephone bills
Faster downloading of programs, email, attachments
songs, graphics-rich sites, animations and video
clips
Play interactive games at top speed against gamers
around the globe
Use telephone and be on the Internet
Realtime services such as web cams, radio better
quality
Work from home with high speed access to
corporate networks
Disadvantages
Higher subscription costs
Local exchanges may not be capable of very
high speed digital transmission
Software components of a network
User accounts and logs
Each user must have an account with a user name
and password.
The account will have permissions i.e. access rights
to files and data such as read only, right only, read
and write, and there will be restrictions of programs
or data they can access. e.g. a member of the
Personnel Department may be able to write, add and
delete files of workers but a worker may only be able
to read their personnel file.
The resources; disk space, printers they can use etc
will be allocated to their account.
Auditing
Auditing software keeps a record of who has
logged on, when, how long, what programs
and data was used and what was amended.
Therefore any illicit use of the system can be
tracked and evidenced.
Remote management
Networks can now be managed remotely from
other rooms, buildings or across many sites by
network management companies. e.g.
A workstation left unattended can be logged
off.
Network managers can observe what users
are doing.
Remote technicians can find and fix software
problems with the network
Security and backup strategy – See Disaster
planning
Factors to be considered when
making configuration choices.
Applications Software choices
What applications e.g. an ‘Office type’ suite would
allow easier maintenance and support from IT staff
and documents and other data can be shared.
What appearance on the desktop will be allowed?
Restrictions on downloading to prevent harmful
software for personal use.
Operating systems and network management
software
What operating systems and network is suitable?
Windows 2000/ XP network; UNIX ??
Hardware
What hardware is on the network? Ideally everyone
should have identical workstations to make
maintenance simpler but this does not often happen
as existing workstation have to be added to a newer
network. Replacing all workstations would be too
expensive for most organisations and time for
installation needs to be staggered so the company
can continue functioning. What peripherals should be
on the network and who has access to them.
Range of User needs
Some users will have different skills and
requirements. Some may only use 1 package
occasionally whilst other uses very technically
demanding software constantly. The skills users
have already and their confidence in using them
must be considered and retraining given if required.
Future proofing
Make sure the system has a reasonable life span. Many companies
replace computers every 3 to4 years as they become too slow to
cope with modern software.
The format of the data must be considered. Old archived data must
be able to be processed as well as new data.
Storage mediums must be capable of being read in the future.
Programs must have backward compatibility.
Network cabling and network infrastructure such as routers, bridges,
switches and servers installed must be capable of taking an
expansion in future traffic at reasonable speed
When making choices it must be flexible and able to expand. Avoid
over reliance on one supplier as if they go you may not have the
expertise to fix problems.
Having an up to date ICT system can inspire confidence in customers
and give staff better working conditions.
The Internet
Network of networks connected by gateways.
Wide Area Network
Things you can do on the Internet :
FTP File transfer protocol
Online shopping
On-line banking
News groups or bulletin boards
Download software or data e.g. music, videos...
On-line chat rooms
Email
Video and teleconferencing etc
How to access a web page
Type in URL
Type in the exact address of the website into the
address bar
Web crawlers /search engines
Type in a key word and select from given list
Boolean searches
Type in key words with AND and OR etc to give more
precise list
Use hyperlinks from other sites
How to navigate a website
Bookmarks to parts of the web
page -Predefined links which take you
directly to part or the page
Hotspots – click on graphic images
Key word searches -Type in a word
and it will find it in the index
Drop
down / pop up menus
-Click and select from predefined list
E-commerce
Businesses set up websites on the Internet because...
they can advertise. It enables people to find out what they do and
what they sell.
people can email them with enquiries; orders; requests;
they can reach an international audience
More and more businesses are selling goods or services over the
Internet.
Companies can advertise goods and services only
Companies sell goods and services e.g. Tescos. music or
making customised tea shirts.
Subscription services which sells information e.g. Metcheck or
gives access to research papers e.g. Endnote
Interactive sites which encourages feedback on products.
Sites which allow users to bid for goods e.g. Ebay
What you must have to offer online
interactive shopping
Maintaining a company web site and
keeping prices etc up to date
Keeping a catalogue of stock for sale
Methods of secure payment
Database of customer’s orders.
Some sites allow you to keep track of the
progress of your order.
Advantages to Companies
Overheads cut. Large savings on shops, warehouse and office space.
A wider catchment area for customers (the world is the limit!)
Customers can be kept in touch with by email and informed of new
products etc. Money doesn’t have to be spent on normal business
overheads like renting shops and paying employees.
Customers can be offered a much wider choice of goods because they can
be ordered from suppliers as required rather than having to be kept
available on the shelves all the time.
Money is not tied up in unsold stock or wasted on products that aren’t
popular.
Data about customers and their buying habits can be collected directly and
used to offer a much more personalised service tailored to suit the needs
of an individual customer.
Advantages to Customers :
there is no travelling - it can be done from home so
saving in costs and time
Advantage disabled people who may not get to the
shops
365/24 shopping no sticking to shopping hours - it
can be done 24 hours a day.
it is much quicker to check out a lot of different shops
for the best price
obscure goods may be hunted for globally - your
local shop may not stock it!
Disadvantages
Credit card fraud use secure payment methods or
use of agreed words
Some websites are set up with the deliberate
intention of taking customers money but never
delivering the goods
Fake / copy cat websites such as those that copy a
banks homepage – do not give personnel details
such as bank account numbers over the Internet.
Fewer shops on the High Street needing fewer shop
assistants.
People lack the social interaction of shopping
becoming more isolated from society
Increase in commercial delivery transport.
How to cut down errors in online
transactions
Accuracy of the data
Customer : Verification procedures
Read data in forms carefully before submitting
Double entry keying
Company: Validation procedures
Range checks; presence checks; check digits;
format checks; input masks etc
Distributed Databases
Distributed databases are different databases
stored at different locations but linked together
so they appear to be one large database.
Distributed computing using the
Internet
Shared processing across the Internet
A distributed system is one where the
processing is carried out by several physically
separated computers on a network.
Computers on this network can share
resources and processing. Distributed
databases are different databases stored at
different locations but linked together so they
appear to be one large database.
SETI research into radio signals.
e.g. SETI, or the Search for Extraterrestrial
Intelligence, is a scientific effort seeking to
determine if there is intelligent life outside
Earth. SETI researchers use many methods.
One popular method, radio SETI, listens for
artificial radio signals coming from other
stars. SETI@home is a radio SETI project
that lets anyone with a computer and an Internet
connection participate
Distributed databases
e.g. A hotel chain may store details
of guests booking on its local
network but because each hotel is
networked a distributed database
can be used and staff in one hotel
can see booking in another hotel and
managers can monitor booking
across the whole chain. Similarly for
a chain of shops looking up stock
HEALTH SERVICE and distributed databases
Patients being treated for a new drug can record
medical data e,g bloodpressure, side ffects at home
and this data will be stored on a large bcentral
database which can be used for further medical
research
Radiology databases can be distributed to world
wide medical experts.
Patients can now ask to be sent to a hospital of their
own choice. A hospital may store details of
patientsbeds available on its local network but
because each hotel is networked a distributed
database can be used and staff in one hospital can
see bed availability in another hospital and
managers can monitor booking of beds across all
the hospitals.
The Care Portal The Care Portal is defined as any port of
entry tele-linked to a medical network and database.
The Docking Station The Docking Station is the site
where the medical expert provides consulting services,
education and collaborative input over the medical
network.
The Bridge The Bridge is an intelligent medical
communication hub which optimizes the flow of
information between the Care Portals and the Docking
Stations..
HCI The interface is a key component. For example,
when designing the interface for a Care Portal,
considerations should include some knowledge about the
specific needs and knowledge level of the users which are
most likely to use it.
Advantages of distributed
databases
•Allows the local processor to be used to share
processing when not being used for other activities
•Data used locally can be stored locally and
network traffic kept to a minimum
•If data lost on central site it could be reduplicated
from local site
•Allows sharing of data and of the results of
processing of the data.
•New locations can be added to the database
without the need for rewriting the entire database.
Disadvantages of distributed
databases
Complex software involved than a centralised
database system
Because data is transferred it presents more of a
security risk by hackers
As all the data is not stored in one location if a local
site does not have location adequate backup then
this data might be lost to the others.
If data is stored and updated in more than one place
there is an increased chance of data inconsistency
Video Conferencing
(Tele-conferencing).
With a small video camera fixed to your
microcomputer, your image can be sent down the
network to another user (and vice versa). Digital
cameras send digital images and Audio signals are
picked up by a microphone and are also sent.
Companies can set up meetings with face to face
communication between people who are not in the
same room, building or even country!
Advantages
Video conferencing allows regular meeting to take
place between employees or companies located in
different places.
Employees especially those abroad can get together
for regular meetings without wasting time and money
travelling
Disadvantages
Cost of setting up a videoconferencing room and purchase
and maintenance of hardware
Subtle communications between people e.g. face and body
language can be lost because not picked up by cameras and
microphones or lost on the compression of data when being
sent.
Technical, compression and signal problems can occur.
Pictures are a bit 'jittery' at the moment but advancing
technology such as fast broadband connection will improve
quality of pictures
In the health service
Skin /dermatology conditions can be remotely seen by an
expert
Facial injuries can be examined and treatment planned before
patients have to travel
Remote meetings of doctors and health service
administrators.
Moral, Social and Ethical
Issues
associated with the Internet
Censorship Issues
No-one owns the Internet. It is international.
Material which would be illegal if published in hard
copy form is freely available on the Internet e.g.
racist propaganda, bomb making instructions,
pornography. Some say the Internet should be
censored but who will do the censoring and how
can centralised control be implemented
Accuracy of information
There is no guarantee that any
information on the Internet is accurate
or true. Some web sites giving
medical advice have been known to
give wrong information but they are
not held liable. Magazines can write
untrue stories. Individuals can spread
malicious rumours about people in
emails.
Privacy
It is relatively easy to capture internet traffic.
Do we have the right to the privacy of our
emails and data files?
Do we have the right to encrypt our data?
In the light of the increase in Internet crime,
security scares and increased terrorist activity
should the security services be allowed to
monitor all Internet traffic?
Effects upon communities
Some argue that the Internet has increased;
the number of valuable interactions e.g. keeping
people in touch with families whilst travelling using
Internet cafes.
increased awareness of geographically separated
cultures
Others argue that it has led to a lack of individual
social interaction by frequent Internet users e.g. you
can work, shop or bank from home without ever
having to mix with others. This could cause small
local business to go out of business thus increasing
social isolation.
Ownership and control
Who owns the Internet?
Who controls the Internet
Because of the increased commercial value of
activities on the internet will a few media giants take
control and effectively determine content?
The law of individual countries is beginning to
address some of the legal issues such as intellectual
property rights on the Internet but laws only apply to
the country which passed them. International laws
may go some way to address misuse of the Internet
but this is still along way off.
HCIs
Human Computer Interfaces
GUIs (Graphical User Interfaces)
Windows
to allow multitasking and display file structure
Icons
are symbolic representations of files
Menus
to list appropriate facilities
Pointer
to select and choose the command or facility
you want.
Advantages
of GUI’s
User friendly because you don‘t have to remember all commands
The menus limit the commands available to avoid confusing and
ambiguous options.
Can be customised to suit the needs / preferences of the user.
The use of graphical icons provide intuitive, easily recognisable
shortcuts for the novice user e.g. printer icon
Easy to use with minimum training. Intuitive and 'user-friendly'
method. The mouse corresponds to the movement of the pointer
on the screen and allows an intuitive way of communicating
commands.
Suitable for users with lower IT skills. A number of different
applications will use the same icons and methods - so each one
'feels' the same.
Multitasking. Can run more than one piece of software so easy to
transfer data between them e.g. importing clipart pictures.
Disadvantages
of GUIs
Such environments do take up more RAM and
storage space on the disc but this has not proved to
be much of a problem the cost of memory and disc
storage has become cheaper and machines contain
bigger hard drives.
Can make the machine run slower
GUI’s take more time to develop. These increased
development costs will be passed on to the user.
Customising an interface
Toolbars There are standard toolbars which can be shown or hidden.
Each of these can be altered by adding own macros or removing icons
that you do not use. E.g. the equation toolbar may never be used by some
users but mathematicians would use it frequently and may wish to add
other functions to it.
Menus
Menus can be pull down or pop up The most commonly used commands
often only appear on the menu to avoid clutter but other greyed out
command are available upon selection.
Font
The default font can be altered e.g. partially sighted people might want to
have a larger font on their menus.
Templates
This is an outline document which provides a framework for writing e.g.
business card, leaflet, memo, flier Screen view
Screen views can be changed to allow the user to see more or less of a
document. E.g. Print view, normal view etc.
Screen colours
Screen colours can be altered to meet the needs of the users. E.g. users
with severe dyslexia might find blue writing on a white background more
conducive. Colour blind people may prefer no red or green.
Command driven
The ICT technician would use this
These are systems like MSDOS which require
a degree of technical ability and are not user
friendly. Commands are typed in response to a
prompt.This is not very user friendly and you
need to know the commands of the operating
system in order to perform jobs.
Advantages
faster and more versatile as a number of
different 'switches' can be used to moderate
the command. Better for the technical user as
they can work faster.
Takes up less memory
Disadvantage is that commands need to be
known, typed and spelled correctly – need
technical experience.
Forms Dialogue
Administrators/secretaries might use this
Voice interfaces:
- speech recognition systems
- natural language interfaces
- speech synthesis
Speech recognition systems
Use
Voice control in car navigation systems
Security systems
Control systems
Problems
Have to train computer to recognise voice which
takes a long time
Delays in getting commands recognised
Adv – No typing
Natural language interfaces
USE
Giving instruction / asking question such as in expert systems
Problems:
users may speak different languages;
local accents may not be recognised;
some words sound the same - two, to, too : there, their,
whether, weather
punctuation has to be said e.g. user must say ‘comma’ which
is not a natural way of talking.
Use of sound makes high demands on memory and
processor speed
Adv – No typing
Speech synthesis
This is the computer speaking to the user
USE
Giving out telephone numbers or telephone
selection systems.
In car navigation systems
Problems
The sound is very flat
Users complain of confusion and a lack of personal
contact if your enquiry isn’t on the list of options
given or you don’t know which option it is in.
Touch sensitive screens
USE
POS systems such as at McDonalds.
Adv
– Don’t have to remember prices
– no typing so more accurate
USE
Public information system such as in
museums
ADV
– No need for a mouse or keyboard which could get
stolen or broken easily
– Disabled use – overcomes difficulties with
spelilng/dyslexia
Biometric devices such as iris recognition,
hand prints and fingerprint recognition.
Use
Retina scan/iris recognition to gain access to
room, thumbprints to take out a library book
Adv
– Individual / difficult to copy
– Accuracy – can’t get someone else to scan in for
you
– Can lose smart cards
Dedicated keys
Soft keys Some keyboards may have
programmable 'function' keys.
Pointing devices
OCR Handwriting.
Graphical devices such as graphics pads
used in CAD by architects who want to draw
on the screen as though drawing on paper.
Game playing devices such as joysticks
,steering wheels, game pads
HCI’s Factors which must be taken
into account when designing HCI’s
1. Task What is the program designed
to do?
Layout appropriate to task.
There should be standard ‘feel’ to software which builds up
user confidence. Use of colour friendliness will put the user at
ease but take up a lot of RAM as would use of graphical
images
– Example 1 A business program would reflect the ethos
of the business; business colours, muted colours,
business like graphics, minimum clutters
– Example 2 A children’s learning program would be
colourful ; large text; lots of graphics and sound
2.Who is going to use it?
HCI’s need to differentiate between
non technical and technical users.
E,,g.
An expert user would require command line interfaces
and ‘hotkeys’ i.e. short cut to commands because it is
faster
A non technical user would probably require a
graphical user interface which is more intuitive and
uses Windows Icons Menus Pointers
3. Consistency of layout and
navigation/signposting/ pop up
information techniques.
Navigation around the program should be
clear consistent and easy to follow
Example every Next’ should be in the same
place using the same icon. Pop up menus
must be in the same position and have the
same format. Hyperlinks could all be in a
frame to the right on every web page
4. Online and Offline Help
Example
On screen help
Customised user environmentsfavourites/background/wallpapers
On screen assistants
Tutorials
Help and error messages
Many systems can restrict the level of help screen available. A
good help system is important for the new user and may
provide a complete online tutorial or online manual or menus
activated by help keys.
Error messages or diagnostics are useful to all users.
They must give some indication of the type of error that has
Occurred not simply say 'error'
Telecommuting
(Teleworking)
‘Working from home using computer networks’.
Use and associated hardware.
Conditions needed for teleworking to take place.
The type of work must be conducive e.g. computer
programming, data entry, design work, clerical support
The company must be able to monitor the work output of the
employee
Appropriate hardware and software must be provided .e in
addition to the PC a means of accessing a network such as a
modem or broadband router. Email and file transfer facilities.
This could be through the Internet or through a company’s
extranet link to its own Intranet.
A work space environment in the home.
Advantages to employees
Savings in journey to work time and travel
cost
More flexible working hours especially for
worker with young children
Working in a known environment. Some
people feel quieter, safer, more creative
Advantages for the Employer
Improved retention of employees - for example, teleworking
can help retain working parents with childcare
responsibilities a wider pool of applicants from which to
recruit - for example, disabled people who may prefer to
work from home
possible productivity gains through staff having fewer
interruptions and less commuting time
increased staff motivation with reduced stress and sickness
levels Cut down on absences due to babysitting problems
savings on office space and other facilities
possible location of sales staff near clients rather than being
based in your premises
Hiring on short term basis of productivity or hire only when
needed e.g. processing orders in a batch processing system
Disadvantages of teleworking for the employee
Social isolation - loss of personal contact with colleagues
Never get to ‘leave the working environment’
Disadvantages for the employer
Difficulties in monitoring productivity and managing homeworkers
and monitoring performance
initial costs of training and providing suitable equipment, including
adaptations to meet health and safety standards and the needs of
disabled employees
More difficulty of maintaining staff development and upgrading
skills and therefore a possible deterioration in employees' skills
and work quality
Security issues in transferring data electronically across the
Internet/extranet
increased telecommunications costs
risk of communication problems
can be harder to maintain team spirit
working from home is unsuitable for certain types of job
A shift towards homeworking doesn't mean
employees have to work only at home. Often
splitting time between home and the
workplace is the most productive solution and
you may want the homeworker to attend
meetings to keep them fully involved and
informed.
Video Conferencing
(Tele-conferencing).
With a small video camera fixed to your
microcomputer, your image can be sent down the
network to another user (and vice versa). Digital
cameras send digital images and Audio signals are
picked up by a microphone and are also sent. This
means you can see and talk to another user.
Companies can set up meetings with face to face
communication between people who are not in the
same room, building or even country!
Advantages
Video conferencing allows regular meeting to take
place between employees or companies located in
different places.
Employees especially those abroad can get together
for regular meetings without wasting time and money
travelling
In conjunction with the Internet it can facilitate
presentations. e.g. An employee can create a
presentation which is viewed by others in other
locations perhaps using the companies website
Disadvantages
Cost of setting up a videoconferencing room and
purchase and maintenance of hardware
Subtle communications between people e.g. face
and body language can be lost because not picked
up by cameras and microphones or lost on the
compression of data when being sent.
Technical, compression and signal problems can
occur. Pictures are a bit 'jittery' at the moment but
advancing technology such as fast broadband
connection will improve quality of pictures
Codes of Conduct
What is a Code of Conduct?
It is an undertaking by an employee to follow the
rules of the company and work within the specific
guidelines set out.
The code of conduct will set out what is expected
of an employee and set out the disciplinary policy
o=if those rules are broken. Employees are
normally expected to sign the code of conduct as
part of their employment contract.
Why do we need a Code of Conduct?
Problems that could arise.
Introduction of viruses e.g. by downloading illicit software or
careless opening of emails
Abusive emails to colleagues
Distribution of material of a sexually or racially offensive
nature.
Use of company data for illicit purposes e.g. Blackmail,
computer fraud or selling to other organisations.
Violating terms of copyright or software agreements by
copying software
Misuse of company equipment e.g. using company time for
personal email; using company printers for personal work;
using the Internet and running up telephone bills for own
purposes; inappropriate use of mobiles phones – in
restaurants, schools, public transport
How to prevent these problems
Problem
Viruses
Abusive
email
Prevention
Ban use of outside discs and
automatically scan all emails or
downloaded files. Instruct staff not to
open unsolicited emails
Respecting rights of others
Penalties for misuse include;
informal warnings
written warnings
dismissal
prosecution
Violating terms of
copyright or software
agreements by
copying software
Abiding by current legislation
abide by any relevant legislation e.g.
Data Protection Act, Equal
Opportunities Act, Computer Misuse
Act, Copyright Act etc
Complying with licensing
agreements
Use of company data Authorisation and permissions on
for illicit purposes
data access: what the employee
e.g. Blackmail,
can and can’t do to data
computer fraud or
Security: don’t disclose passwords,
selling to other
personal use of email logging on and
organisations.
off procedures, encryption of
transferred data etc.
Misuse of company
Protecting hardware and
equipment e.g. using
software from malicious
company time for personal damage
email; using company
printers for personal work;
using the Internet and
running up telephone bills
for own purposes;
inappropriate use of
mobiles phones – in
restaurants, schools,
public transport
The code of conduct will set out
what is expected of an employee
and set out the disciplinary policy
if those rules are broken.
Employees are normally expected
to sign the code of conduct as
part of their employment contract.
It will set out;
Responsibilities ( abide by company rules )
Respecting rights of others
Abiding by current legislation
Authorisation and permissions on data access:
Security:
Protecting hardware and software from malicious
damage
Complying with licensing agreements
Penalties
–
–
–
–
–
Penalties for misuse include;
informal warnings
written warnings
dismissal
prosecution
Codes of Conduct in the Workplace
Moral, Social and Ethics
NOT on THE INTERNET
1. Disinformation
Not fully informing potential customers or
clients of all available facts concerning
products or services e.g. imminent introduction
of new models.
Disinformation Examples
Estate Agent
Legal requirements
Moral example
= Properties Act
= A property developer not telling his client the property
has subsidence problems or a violent history.
For a hospital treating a patient;
Legal requirements
Moral example
= Data Protection Act
= Response times might be part of the code of practise
Hardware & software sales ;
Legal requirements
Moral example
= Trades Descriptions Act
= prohibit salespersons from selling hardware and
software soon to become obsolete
= ensure salesmen do not pressurise unwilling
customers to accept e.g. loyalty cards , in store
credit accounts or particular brands.
2. Privacy
Informing data subjects of their legal rights and
processes for complying with those rights.
ICT systems have enabled many organisations to
hold data on the public. People are not always aware
of their rights under data protection legislation and
not all organisations are ethical in their use of this
data.
Legal requirements = Data Protection Act
Ethics
= An employee using company data
to create mailing lists for his own private home
business
Monitoring company emails. Electronic monitoring
systems can be used to track emails. A systems
technician might open other people’s emails to
detect misuse or simple to be nosey
3. Employment patterns
Effects upon the workforce.
Some people have been de-skilled by the arrival of ICT and
their skills are no longer required and they loose their jobs
Call centres have caused many people to lose jobs as they
have been moved abroad where labour is cheaper leading to
ICT ‘sweat shops’.
Others have gained and have the required skills e.g.
computer programmers.
Personal empowerment.
There have been changes in working patterns e.g.
teleworking
Businesses are able to reach a wider market via the Internet
Individuals can sell goods on Ebay
Health and Safety at Work Act governs working
conditions using computer systems – do companies
provide these for teleworkers
Disabiltiy Rights Act deals with the rights of disabled
people and their access to work – do companies
have stairs or other facilities which restrict disabled
people in wheelchairs from getting jobs in the
company?
Minimum Wage Contracts – lllegal immigrants
working below th minimum wage
Ethics : not complying with these and many other
employment laws to provide unsafe or poor access
to computer systems
Hazard
Prevention
RSI repetitive strain injury
caused by prolonged working at
computers or computer games
Ergonomic keyboards ; wrist
and foot supports: correct chair
positioning
Eye Strain and epileptic fits
Non flickering screens; Screen
filters t remove glare; correct
lighting in the room
Back problems
Adjustable chairs; foot
supports:; tilting screens
Ozone irritation from laser
printers
Locate personal laser printer 1
metre away from user
Radiation affects embryos
leading to miscarriages
No real evidence for this
4. Equity
Legal requirement
Patent laws / Data
Protection Act
Moral Example
Ownership and access to information can often
determine which organisations will be successful and
which will fail. As these technologies have to be paid
for the richer organisations can afford the technology
whilst poorer organisation cannot. Consequentially,
the rich organisations get richer and the poorer ones
get relatively poorer and the gap between them gets
greater.
5. Intellectual property rights- Ownership
rights to data.
If you put a joke on the Internet do you own it?
If you see a joke on the Internet can you sell that joke to a
professional comedian?
If you scan in the text of the book ‘The Da Vinci Code’ and put
it on the Internet for all to be freely read; are you breaking the
law?
Can you sue someone who sells you an essay which is full of
factual errors?
The growth and exchange of ideas on the Internet has led to
many legal disputes and lack of legal clarity as to ones
intellectual property rights.
Do the Copyright Laws of one country apply to another
country?
Intellectual property rights
Legal Requirements Copyright Laws / Patent laws
Moral examples
If you put a idea on the Internet do you own it?
If you see a design on the Internet can you sell that
design to a company?
If you scan in the text of the book and put it on the
Internet for all to be freely read; are you breaking the
law?
Can you sue someone in another continent who sells
you a report on you which is full of factual errors?
Disaster
Planning and Security
Policies
Threats to data
Deliberate
Terrorism
Criminal vandalism/sabotage
White collar crime
Accidental
Floods and fire,
Accidental altering of data
Natural disasters
Companies must
Ensure data, hardware and software is not lost or
damaged.
Restore communication systems as quickly as
possible.
Consequences
Loss of business and income
Loss of reputation
Legal action
Deliberate
Terrorism e,g Oklahoma bomber Oklahoma
Federal Building on April 19th, 1995 destroyed
federal records.
Criminal vandalism/sabotage e.g. the deliberate
destruction of network servers by putting on
viruses.
Theft of data by employees to sell to competitors
White collar crime such as the deliberate altering
of data in a database e,g, transferring funds from
company accounts into private accounts.
Accidental
Floods and fire, e.g when the Buncefield oil
terminal blew up it destroyed the companuy
records in a nearby industrial estate
Accidental altering of data e.g. by inexperienced
employees deleting an order in a customer files
Natural disasters such as the Tsunami destroyed
population birth death bank records.
How to prevent accidental loss
Accidental destruction of files due to fire, terrorism, floods
Backup systems must be described
keep back up files - offsite - and in fireproof containers
use an online tape or disc streamer which automatically backs up data on
a network
use grandfather father son security system in batch processing systems.
e.g. payroll
RAID systems – mirror discs (Redundant Array of Inexpensive Disc)
Accidental destruction of files due to human error etc.
Validation and verification measures
Prevent overwriting
– put the write protect notch on your disc
– make hard discs read only
Prevention of malicious damage
Hacking unauthorised access
Spreading of a computer crime
Computer fraud
Physical destruction by vandalism and
terrorism
Hacking – unauthorised access
Prevention
Define security status and access rights for users
All authorised users should be given user names and
passwords. This will limit unauthorised access to the network.
Hierarchy of Passwords
– Identification
– Authentification
– Authorisation
User Name
Password
What files you can see and what your allowed to do
Restrict physical access to files e.g. smart cards to control
entrance to rooms. Secured areas to hold servers
Prevention of malicious damage……Hacking Cont.
Biometric scans such as voice or hand prints; retina
scans;
Firewalls. a special environment set up to trap a
hacker logging in over remote connections. It
authenticates messages coming into the network
and verifies the legitimacy of the user to enter the
network.
Proxy servers
This device tries to stop intruders from identifying the
IP (Internet Protocol) address of a user workstation
accessing the Internet.
Prevention of malicious damage……Hacking Cont.
Call Back procedures
Some companies operate a dial-back system. A user
logs on to a computer which immediately
disconnects the line and dials the user back. This
would stop a user logging on with someone else's
password.
Encryption
Data transmitted over a network is coded before
transmission. This means that anybody intercepting
the transmitted data would not be able to understand
it. The data needs to be de-coded by the proper
recipient.
Spreading a computer virus
These are programs introduced into computer systems which
destroy or alter files by rewriting over data or by copying
themselves over and over again until computer system is full
and cannot continue.
Prevention
Don’t’ download unknown programs from the Internet
straight to hard disc. Only use reputable sources.
Write protect media so can’t be written onto
Don’t copy illegal software
Use a virus scanning software and virus eradication
program. Make sure this is kept up to date with the latest
virus definitions – available from the Internet.
Use diskless workstations on networks
Computer fraud – white-collar crime
Bogus data entry when entering data
Bogus output -output may be destroyed to prevent
discovery of fraudulent data entry or processing
Alteration of files e.g. employee alters salary rate
or hours worked
Prevention or ‘White Collar’ computer crimes
Monitor all programs and users actions should be
monitored and logged. All users should be
identifiable and all files capable of being audited
keep online transaction logs
Auditing procedures to detect fraud
Threat
Consequence
Prevention
Terrorism
Loss of business and
income
Backups
Criminal
vandalism/sabotage/
Legal action
Restrict access
White collar crime
Loss of reputation
Audit trails
Transaction logs
Floods and fire,
Loss of business and
income
Backups kept offsite
Accidental altering of Loss of business and
data
income
Validation
Verification
Read only / write protection
Natural disasters
Online backups kept in
different city
Loss of business and
income
The factors to take into account
when designing security policies
Physical security
Prevention of misuse
Availability of an alternative computer system and back up
power supply
Audit trails for detection
Continuous investigation of irregularities
System Access - establishing procedures for accessing
data such as log on procedures, firewalls
Operational procedures
Disaster recovery planning and dealing with threats from
viruses
Personnel administration
–
Staff code of conduct and responsibilities; staff training
–
Policy and maintenance staff available.
–
Disciplinary procedures.
Operational Procedures
Disciplinary procedures.
Screening potential employees
Routines for distributing updated virus information
and virus scanning procedures
Define procedures for downloading from the Internet,
use of floppy discs, personal backup procedures
Establish security rights for updating web pages
Establish a disaster recovery programme
Set up auditing procedures (Audit trails) to detect
misuse.
Three phases of a Disaster
Recovery Plan
Factors determining how much a
company spends to develop
control, minimising risk.
1. What to do before?
Do a ‘risk analysis’ of potential threats
–
–
–
–
Identify potential risks
Likelihood of risk occurring
Short and long term consequences of threat
How well equipped is the company to deal with threat
Put preventive measures in place.
–
–
–
–
Establish physical protection system (firewalls etc.)
Establish security rights for file access and updating web pages
Establish a disaster recovery programme
Set up auditing procedures (Audit trails) to detect misuse
Staff training in operational procedures.
– Screening potential employees
– Routines for distributing updated virus information and virus scanning
procedures
– Define procedures for downloading from the Internet, use of floppy
discs, personal backup procedures
– .Define staff code of conduct for using computer systems e.g. no
abusive emails. No illicit use etc.
2. What to do during?
What response should staff make when the disaster occurs?
3. What to do after?
Implement recovery measures
Hardware can be replaced.
Software can be re-installed. (or de-bugged by the programming
department).
The real problem is the data. No business can afford to lose its data.
Backups of all data should be regularly made. This means that the worst
case scenario is that the business has to go back to the situation of the
last backup and carry on from there. Backups may take a long time - often
tape-streamed at night.
Alternative communication /computer systems may be arranged in
case a network goes down or alternative power supply.
Unit 4
Normalisation
and
Relational Database
Management Systems
Computerised Databases
A database is a organised collection of
data items and links between them
structured in such a way that it allows
it to be accessed by a number of
diffferent application programs.
ie related tables of data which are linked
together and many programs can use the data in
the tables
Use a database when you need to store lots of data
Duplication in Flatfile
Members
No
Forename
Surname Address 1 Address 2
Tel No
Video
No
122
Evans
Daniel
7 High St
Aberaeron
01545588999
343
759
Lees
Anna
2 Bridge
St
Lampeter
01570422967
523
122
Evans
Daniel
7 High St
Aberaeron
01545588999
455
Title
Certificate
Category
Cost per
day
Date
loaned
Length
of loan
Date
due
Crash
12
Comedy
£3.00
12/09/05
1 day
13/09/05 £3.00
Emma
12
Drama
£3.00
12/09/05
1 day
13/09/05 £3.00
War of the
Worlds
PG
Sci FI
£3.59
14/09/05
2 days
16/09/05 £3.50
Total
cost
Members
Member number
Foreign Key
Primary Key
Forename
Surname
Loans ID
Loans
Member number
Video number
Primary Key
Address line 1
Address line 2
Telephone number
Date loaned
Length of loan
Date due
Videos
Total cost
Video number
Title
Certificate
Category
Cost per day
Linked data tables in a relational database
Primary Key
Normalisation
Terminology: Primary Key
A primary key is a unique value which allows
each record to be identified

CustomerID
FirstName
LastName
1
Brian
Smith
2
Harry
Adams
3
Joe
Jones
4
Harry
Smith
FirstName or LastName cannot be primary keys as they
contain duplicate and un-unique data. CustomerID
uniquely identifies a row and is therefore suitable
Sometimes there is no single field appropriate
as a primary key. In these circumstances, it
is possible to select two fields which, when
taken together create a unique value:
OrderNo
ItemNo
EmployeeNo
CustomerNo
ItemName
Quantity
121
3
4
1024
Nut
4
121
4
4
1024
Bolt
3
122
8
9
176
Washer
6
123
3
6
154
Bolt
5
123
8
6
154
Washer
4
There are no unique fields, so the Primary Key is best suited by
OrderNo and ItemNo taken together
Foreign Key
A Foreign key is a primary key of another table
used to link the tables
Second Normal Form (2NF)
To be in 2NF a table must:
– Be in 1NF (obviously)
– Have all non key fields fully functionally dependant
on the primary key
In English:
– A non key field is one that is not part of the
primary key
– It means that you need to use the primary key to
determine the value of the other fields in the table
– If you can find the value of other fields without
using the primary key, you should remove that
field from the table and place it in a separate table
Third Normal Form (3NF)
To be in 3NF a table must:
–Fields which do not form part of the
primary key must always be solely
dependent on the primary key and
not on anything else, such as
another non key field
Third Normal Form (Cont.)
Remove City from the table and create a new cities
table
Remove Salary from the table and create a job type
table
Staff
EmployeeID*
LastName
FirstName
CityID
TypeID
Cities
JobTypes
CityID*
TypeID*
City
Salary
DoctorID#
WardID*
Name
Specialism
ContactNo
PatientID#
Name
Illness
Gender
Address
DoctorID*
# Primary Key
WardID #
No of Beds
Type of
Ward
DoctorID*
WardID*
* Foreign Key
DoctorTable (DoctorID#, Name, Specialism, Contact No, WardID,)
WardTable
(WardID#, No of Beds,Type of Ward, DoctorID)
PatientTable (PatientID#, Name,Adress, Illness, Gender, DoctorID, WardID)
,
Advantages of using databases
(Advantages of normalisation)
1. Avoids data duplication
-data stored once
-linked by keyfields
-all data available via relational links in keyfields
2. Controlled redundancy
- Minimises data duplication
3. Ensures consistency of data
- of data to all users
4. Data independence
- data stored separately from programs so can add new
fields because data is independent of the applications
which use it
5. Increased security
What makes databases secure ?
Hierarchy of passwords
User access rights and privileges
Data is stored separately from programs
so different programs cannot overwrite
data.
Disadvantages
Complex to set up and maintain; needs team of
programmers to maintain it.
Database software is large complex expensive
and requires powerful computers.
All applications which access the data will be
affected if database fails. As the DBMS is the
only access to operational data a system failure
can have serious consequences
The management of change
Changes in work patterns and jobs
Teleworking - working from home using computer
networks saves on trnasprt cost time etc..
Video conferencing – allows remote meetings
Lost jobs – unskilled manual jobs such as filing
clerks. Call centres replacing bank clerks Call
centres have caused many people to lose jobs as
they have been moved abroad where labour is
cheaper leading to ICT ‘sweat shops’.
New skills required / retraining – acquire skills to
use databases spreadsheets emails, programming
etc.
New jobs – systems analysts , programmers.
Management of Change
1. The skills required and not required
As new systems are introduced some skills will no
lnger be need and new skills must be learnt e.g how
to use new software, new short cuts keys, habdling
new printers. Companies must have an ongoing
commitment to training.
2. Organisational structure
New technologies often make certain levels of
management or manual work redundant. e.g.
introducing scanning technology may reduce the
need for data entry clerks.
3. Work patterns
changes to the pattern of the day e.g. batch
processing might mean payroll / ICT staff may have
to do night shift
teleworking
videoconferencing
4. Internal procedures
some tasks would be automated making jobs easier
some jobs may increase in difficulty because they
may be
expected to improve productivity and perform tasks
more quickly
5. The workforce (fears caused by introduction of
change)
When an organisation restructures the workforce
will have certain worries.
Will they lose their job?
Will they have to learn new skills to do their existing
job?
Will they have to move to a new job within the
organisation?
Will they take a pay cut?
Will they have to change their work pattern, hours
of work etc?
Will they lose their current status?
Successful change management
involves
Step 1 Research
Step 2 Design
Step 3 Cost benefit Analysis/ Forecast
models
Step 4 Consultation
Step 5 Implementation
Step 6 Monitor and Evaluate
.