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Describe prototyping (2)

-A model is built and evaluated

-To enable an approved version to be put into production

- A working user interface is created

- This can be repeated until an interface is satisfactory

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Describe the 3 types of data used in a test plan (


This is where incorrect data is inputted to make sure the system identifies the data as incorrect and produces error messages.


Data that is expected to be inputted is input to make sure error messages are not generated


Data at the upper/lower boundaries of tolerance

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Describe two ways in which Gantt charts are used (

- Lists the order that tasks need to be completed in and any necessary follow up tasks.

- An overall plan can be constructed and the total time of the project can be calculated

- Individuals can be allocated to tasks

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Describe a stock control system (4)

- Maintains minimum stock levels for each product so that the user knows how quickly stock is used and decides when to re-order.

- Can adjust re-order amounts for each product

- Keeps a track on purchase date of goods to make sure they are sold within a date.

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What is a router?

  • A communications device (can be hardware or software) which receives data and forwards it to the correct location via an appropriate route.
  • Can be a modem as it allows an internal network to connect to the internet.
  • Can be used to connect two LANs together even if they use different protocols
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What is a repeater?

A device used to link two cable segments. With a loss of signal over distance, a repeater amplifies the signal before passing it on. Allows you to extend the distance of a cable run and the overall length of the network.

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What is a bridge?

A connection between two (same protocol) local area networks. Creates a logical network which can appear to users as a single network although it may physically be several different networks. Bridges use a different OSI layer for addressing to a router.

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What is a switch?

A switch is sometimes known as a multi-port bridge. It receives data and forwards it only to the correct port. Switches have dropped in price and now form the network backbone for large installations. Some devices can manage the flow of data in the network.

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What is a hub?

  • These are sometimes referred to as multi-port repeaters. That is they receive data and broadcast it to all the output ports.
  • A hub cannot screen network traffic unlike a switch.
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What are protocols?

  • A set of rules used to ensure proper transfer of data between devices. The protocol determines:
  • The format of the data packets, such as header content and the type of error checking to be used the data compression method (if any)
  • how the receiving device indicates that it has received
  • how the sending device indicates it has finished sending.
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DSL – Digital Subscriber Line

  • The common standard for broadband, need to be within approx 5km of the DSL enable telephone exchange
  • It uses the same copper lines as for normal telephone calls, but is able to uses a much wider range of frequency for data transmission in addition to voice calls
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ADSL – Asymmetric DSL

  • A refinement to DSL that assumes people will download more data than they will upload (a typical home user!) and allocates available bandwidth/frequencies on this basis (e.g. 3:1) to maximise download speed.
  • Voice calls can be made at the same time as data transmission and proximity to the exchange is the same as DSL
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Features of cable television

  • E-mail
  • Shopping
  • Different Camera Angles
  • Notification that selected program is starting
  • View On demand (films, sports events, etc) – often pay per view
  • Multiple Channels (including +1 hour channels)
  • Subtitles in different languages
  • Radio stations
  • Recording and playback of live television
  • Different commentaries for sports events
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Satellite communications


  • Continuously available for the transmission of data
  • Three geostationary satellites can cover the globe
  • Can transmit and receive from any point on the globe
  • High bandwidth means it can carry thousands of phone calls and video
  • Cost is distance independent (same cost to send a few miles as a few thousand) and no longer notably expensive


  • Geo-stationary orbit can only hold a limited number of satellites above the equator, hence the use of low Earth orbit satellites
  • Distance between satellites and the earth has consequences:
    • Messages take time
    • Signal can degrade and become contaminated by interference or the weather
    • Vulnerable to blackout following solar flares or nuclear explosion in time of war!
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Examples of satellite communication

  • Weather Satellite Systems
  • Sun monitoring
  • Navigation (GPS)
  • Communication Systems – e.g. mobile phones, video phones
  • Electronic Funds Transfer (SWIFT)
  • Mapping the Earth using a wide range of sensors for military or peaceful purposes
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System life cycle stage 1

Definition of the Problem

  • Determining what the problem is that is to be solved
  • Can be generated by the management
  • Should be very specific not general in nature
  • Series of criteria are stated that must be met for the problem to be eradicated (often known as “Objectives” or “User Requirements”)
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The 3 types of distributed databases

1. Replicated

Instead of holding only the data that is relevant at each node, copies of the entire database are held at each node.

Hardware requirements are heavy as each node needs enough equipment to be able to handle the entire database.

2. Partitioned

Not every location (node) needs to have all the data. Therefore the partitioned approach is giving each node the data that is relevant to itself.

3. Centralised

No data is held at the local node, instead an index is held locally and this is used to find and then access the data is in the central database.

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System life cycle stage 2

Investigation and Analysis

  • Verification of the Problem
  • Must make sure that the problem given is the problem to be solved – is it the ‘real’ problem
  • You need to find out more about the existing system and the problem
  • Use of variety of techniques
  • Questionnaires/interview & Observation
  • Following a paper trail (documentation of current methods)
  • Ways of organising the information gathered include:
  • System diagrams
  • Data flow diagrams
  • Organisational charts
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System life cycle stage 3


  • Designing a solution
  • Interfaces
  • Input/Output documents
  • Procedures – what happens to the data
  • File structures
  • Access, search and sort routines
  • Design of testing
  • Prototyping
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System life cycle stage 4


  • Taking the design and putting it into practice
  • May be done by a different team of people from the Analysis
  • Writing programming code
  • Creating documents/reports
  • Screen designs become reality
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System life cycle stage 5


Testing data includes:

  • Normal data - Everyday correct data
  • Extreme data - Correct data on the boundaries of tolerance
  • Erroneous/Invalid - Data that is incorrect
  • Test individual routines
  • Test whole components
  • integration between components
  • Test entire system
  • User acceptance testing
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System life cycle stage 6


  • Changeover methods
  • Direct - Old system stops and new one begins
  • Parallel - Systems run together for a set period of time – results compared
  • Phased/Pilot - Part of a system is brought on line
  • Requires:
    • Equipment in place (hardware and software)
    • Training
    • Data changeover/conversion/importing
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System life cycle stage 7


  • Does the finished solution meet its requirements.
  • Does it solve the problem?
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System life cycle stage 8


  • Corrective
  • Fixing bugs
  • Adaptive
  • Adapting the system to changes in the environment
  • Perfective
  • Improving the performance of the system – tweaking
  • Maintenance is ongoing – never stops.
  • Can include things such as checking paper in the printer, backup of files, etc
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Requirements specification and Systems specificati

The contents of the requirements specification:

  • What the system should do
  • Individual targets it needs to meet
  • It is needed for evaluation

The contents of the system specification:

  • How the system meets the requirements
  • What is needed to make the system work
  • Technical documentation - the user interface design, its functionality, how it relates to systems data and other system functions.
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Describe the three main components of an expert sy

·        Knowledge Base – This is factual knowledge generated through real life experts, likely to only be on one topic.

·        Inference Engine – This is software that directs the user through the system depending on the answers to the questions and will provide a suitable answer at the end.

·        User interface – Form based (e.g. option boxes), Displays questions for the user to input data.

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What is a code of conduct?

Codes of conduct provide a voluntary extension that determines how individual should conduct themselves when using ICT, predominantly in the workplace.

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Why would a company want a code of conduct


-          Setting boundaries clarifies to the employees what they are allowed to do and what they are not.

-          If an employee breaks these codes of conducts the company does not have liability because the employees have signed the code of conduct meaning it is their responsibility.

-          To give the organisation a good reputation because they keep control of their employees through this.

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Types of HCI

  HCI Type     How is the user prompted     Method of Input     Feedback     Type of Application     Command Line     Cursor flash             Keyboard Error Messages Used in Batch operating system Menus Submenus, arrows     Mouse Selections change colour Used in ATM’s GUI Menus, colours     Pointer device Text response, pointer changes state Mobile phones Natural Language Flashing cursor, asked to do something through speakers     Keyboard based/ or microphones Search results Search engines Form Error messages Form controls   Keyboards and mouse Error messages Application form      

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Identify two characteristics of a LAN

Characteristic 1

The networked devices will have to be in a small vicinity of the LAN


Characteristic 2

Usually have peripherals that the LAN can connect to things such as printers.

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Describe the Model Human Processor

This is the theory that uses an analogy of the way a computer processes information and how a human brain processes information. When a stimulus is received by the person or computer, it then looks in the internal memory models and see’s if it can find the correct response in its memory. They then come up with the correct response and then the action is taken.

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How can the model human processor be applied to in

The Model human processor can be looked at to incorporate stimuli into a HCI so the use receives a correct stimulus.

For example a beep from the computer is a stimulus to the auditory system.

Another example would be a vibrating controller for a games console would be a stimulus through touch.

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Network Components






NIC (Network Interface Card)


This is the card that you plug into the back of a computer and it connects it to the network, this contains the computers specific MAC address.

Wireless access point

WAP is a hub that contacts wirelessly without needing physical contact.


This is an advanced version of a switch and sends the connection around


This re-amplifies the signal of routers along long cables


This connects 2 local access points together wirelessly


A server is a powerful computer that carries out actions on behalf of the systems connected to it.

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Operating systems 1

Single User

-       A single user operating system only provides access for one user at any one time.

-       The OS can support more than one user account but only one can be accessed at any one time.



-       A multi-user OS allows more than one user to access the system at any one time.

-       The multi-user system is usually networked and manages all the users requests so they do not interfere with each other.


Multi Tasking

-       This involves the OS carrying out more than one request at the same time.

-       The system is continually switching between individual requests.

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Operating systems 1


-       An interactive OS is one in which there is direct user interaction 

Real time

-       This OS has been designed for processes that need to be completed in real time

-       These are typically used for embedded applications

Batch Processing

-       This is given a set of tasks to do without any user interference.

-       This leads to the tasks being carried out at off-peek times.

 Distributed processing

-       This consists of a number of computer systems joint together

-       Each computer completes part of the process

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Perception, Attention in a HCI


This is how the user will view the interface. The user will receive sounds and sights from the HCI which will mean generally mean a universal instruction, eg. Red= Stop, Green= Go.


The user will have a limited attention span so the designer must keep in mind when designing the interface that they need to keep the attention of the user.

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Memory and Learning in a HCI


The interface will need to take advantage of the user’s short term memory. The gardening company will need to make sure there is a consistent layout and uncluttered. This will increase the users confidence in the interface and increase the speed that it takes the user to learn how to use it.


The company will need to include error messages to help the user learn if they do anything wrong. The user may not be provided training so they need to make it as easy as possible to learn how to use it.

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Mental Models

Describe mental models and how they can be applied to the design of a user interface;


A mental model is the users preconception of what they think will happen when they do a particular action when they feel they have done it before on a computer or with their life skills.

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How do phone calls work

First of all you type in a number and then click dial. Then you connect to the base station transmitter with the best signal quality. Then the base station transmitter is connected to the local base station controller, this then begins to route the call. The base station then contacts the mobile switching centre which checks whether you have enough credit to make the call and whether the number you have dialled exists. If everything is fine the mobile switching centre routes your call to the landline. If during the call the base station transmitter with the best signal changes it just drops off the bad signal and rejoins on the better one.

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