- Created by: harry plowright
- Created on: 09-06-13 19:21
Standards and Communications
Standards allow hardware and software to achive its highest performance.
For software it is important that the software follows the rules so that it will work accordingly on the hardware.
As well as hardware it standards apply due to law for example wiring and some which are accepted practise.
Set of rules must be followed such as:
software will work on the hardware no matter what manufacturer,
third party techinical help,
peripherals fit one another
communication between devices become possible
The internet operates on the Transmission Control Protocol/Internet Protocol (TCP)
A data network uses a Open System Interconnection (OSI)
Downloads and Uploads operate on File Transport Protocol (FTP).
Applications of ICT- Resources
All ICT systems rely on internal resources, These can be defined as human resources, technological resources and accommodation.
Human resourses are people employed to operate the system, these are valuable as they make the system efficient and maintain it.
However these need:
ongoing training sessions, good pay, safe working conditions, and to be valued.
Technical resourses are the mains and software that make it work, such as:
computers, application packages, input and output devices
Regular updates, proper maintenance and reviews should take place
As well as this accomodation should be took into consideration.
Applications of ICT- Information
Information is important to companies, this includes:
Details of customers, products, suppliers, plans, balance sheets, projections for the future, reports and analysis.
When information is excanged it must be accurate and in a timely manner, if a company keep to this they will likely be more more successful.
To achive reliable information the following must be used.
Input checks such as validation and verification checks.
encoding of information
the correct level of detail
Applications of ICT- Telephone Systems
Telephone systems offer a range of services, such as:
Answering Services, automated messages- voice mail, fowarding messages
Call-back, 1471, traces calls
Ring-back, phone engaged therefore automatic rings when free
Call waiting, alerted if a caller is waiting while on a call
Automated control of a system using phone keypad, checking bank statements
Ex-directory, directory classification, block your number
Call barring, dialling preminium rate numbers
Personalised ringtones, allows personalisation
Conference Calls, links mutiple callers
Applications of ICT- Banking
Banking has used computers for a number of years,
Magnetic ink character recognition (MICR) such as cheques,
Automated teller machines (ATMs) allow customers to access there money when banks are closed
Electronic funds transfer at point of sale (EFTPOS)
Electronic funds transfer (EFT)
Applications of ICT- Production control
ICT Stock systems: checking storage and restocks
Robotic devices: Allow production to continue with out the need for humans
ICT Models: Mathmatical and Object
Human resource management systems
This is the administration and management of the people who work for a company.
Recruitment, hiring, job placement, performance appraisals, employee benefits, training developments, health, safety and security
Use of ICT to assist
Tracking employees and there personal information
Time and Labour management
Benefits administration with employee participation
Applications of ICT- ComputerAidedDesign/Manufactu
The main features of CAD and CAM packages are:
calculating stresses and strains
working out costs
linking directly to the process in factorys
helping with the supply of manufacture
Applications of ICT- Expert Systems
Is a database of knowledge known as a knowledge base, there is a set of rules which are based on asking questions via an interactive interface, the expert and non-expert work together to reach a solution.
There are a number of areas, these can be found:
oil and mineral exploration
creating other expert systems
The user should use common-sence judgement when considering a solution as it is not always right.
Applications of ICT- Digital television
It was first broadcast in analogue format and this restriced the services abd screen however digital television is now widely used and fixes this problem. Although this means people need to buy new television sets in the long run they get better picture and more services such as:
email and internet
remote control shopping
changing the ending
programmes on demand
Applications of ICT- Computer Aided Learning
CAL is when instrucional information is provided to a students/employees, to pose questions and evaluate reesponses.
Cheaper, any time any place, study at your own pace, sections can be repeated, fast track
Trainee needs access, knowledge learned may be incorrect, cannot check with teacher straight away, may not be up to date or accurate, no human contact
A distributed database is one in which files are shared across the network, because the database is distributed. The data must be synchronised regulary to ensure data consistency.
Distributed databases- Partitoned between sites
Each remote processor has data with which it is primarly concerned, such as its own customers or stock. Security is improved as everything is on the computer and there is no physical copies.
This occurs when there are one or more tables which are split in such a way that certain rows or records are delt with by one location, such as the postcode relating to the office. In large databases, attributes of the entities and often collected and stored but not used resulting in wasted speeds and slower searching.
The parts are distributed by headquaters and this is where the overall data is stored, although on rate occasion where unusual data was needed, the information would take longer to build up, this would be offset by the increase of speed in the analysis of any section.
Distributed databases- Duplicated at each site
The database is uploaded each night and alterations made to include the local changes by merging the different versions. This means that mutiple versions exist, this means backing up is easy however data interception is easier as any can be duplicated, although this means searches can be made quickly it means it is not always up to date.
Distributed databases- Central with remote local i
Every database consists of tables and indexes, indexes help to speed up the searching efficiency of a database by indicating where to find records which might be needed when queries are run, using this method the central database does not hold the actual data is just a collection held on remote sites.
Limitations of ICT- Identity Theft
This is when the purpose is to steal your identity, the find out your bank account details, addresses and name and then use this to apply it to your credit cards and have access to your money because this can be easy for criminals and allow them to take advantage of us and our data if we are not vigilant. we must be careful as our data can be copied and allow false personallisation and make running debts and open bank accounts pretending to be us.
Limitations of ICT-Personal Data
Data is becoming more and more held on computers, we needs laws to govern this data and keep it safe. The difficulties are that with data held electronically it is easy to steal enormous quanitities of data in seconds and in case of stealing, leave no trace.
Limitations of ICT-Commerce and Data
Commercial organisations want to know our habits: whether we are married, how much we earn and what we get up to. All this informations allows advertising to be targeted at us. Much of this is legitimate however we need to be constantly aware that our computers are now linked and potentially to any computer in the world. We need to keep our personal files secret and we need to have spyware, firewalls, off-line data, virus checkers etc.
Limitations of ICT- Human error
Garbage in and Garbage out, if incorrect data is put into the system incorrect data will come out of the system. This is a limitation which affects everyone who uses a compute, just becomes numbers are fast and reliable does not make them correct.
Limitations of ICT- Over-dependency on ICT
Computers are becoming more relied on by us, most of our data is now stored on ICT-based devices. The danger of becoming over dependent on ICT is something we shall all take into consideration, we should not become too trusting and we should reserve our judgement and take into consideration common-sense and a range of sources. We need to have alternatives and never hand over our lives to computer completely.
Limitations of ICT- Problems of disposal
As a consumer society we are always upgrading our ICT systems and throwing away the old. This must be done responsibly as it may lead to the enviroment being spoiled. Many of these devices contain dangerous components such as printed circuit boards, cables, wires, plastics containing flame retardants, mecury switches, desplays, batteries, data storage media, capacitors resistors.
Limitations of ICT- Politics
The goverment take threats seriosly and therefore place laws to protect themselves and us.
There is two types of software, Off-the-shelf when the software is readily available and custom-written software when a programmer is employed to write the software.
The software has most bugs removed as it has been in the public domain for sometime, there is also existing users/groups and online for help. The staff may be familer to the software so they need less training. It can be purchased straight away and is relatively cheap.
It may require significiant training changes, the software will need to be adapted adding to further costs, and the soft may habe a larger memory usage than custom-written softwares.
Software will fit its purpose exsactly, small memory footprint, software copyright belongs to the firm.
More expensive, more bugs than other software, require more training, limited help, no user groups, not immediatly available.
Choosing the right software
How much knowledge do the staff have?
Do benefits out weigh cost?
Will the system be more efficient than the old one?
Methods of installiation
How will the system be installed?
There a four main methods of installing a new computer-based system, these are
The new system replaces the old system without any overlap.
The new system is only tested at one location before being fully installed.
The systems operate together for a short period of time before it is fully installed.
Part of the new system replaces the old system while other tasks are still on the old system, completed over time.
Maintainance is necessary as a computer-based system grows old, bugs may be found in the syste, due to failed or not enough tests as well changes in technology and laws.
If changes in work practise are indentified in a review - If there is an increase in customers - if new legalisations are introduced
If bugs and errors are found in the system need correcting or fixing
If new technology becomes avalible which might allow the performance of the system to be improved.
If a review indicates ways in which the system could be changed to enchance performance.
The Definition Stage
The problem myst be understoody by the client and the systems analysts who solve this problem, making the nature of the problem apparent and agreed between them both. This will form an inital contract and undertake an investigation followed by a feasbilty study to inform the client whether it is possible to solve the problem. A few reasons for why not are:
Solving the problem is too expensive
The hardware or software does not exsist and cannot be produced
There is no realistic solution to the problem.
Would take too long to produce.
In order to understand the exsisting system the analysts should undertake a detailed study of the company and how it operates at the moment, with paticular attention to how the defined could be solved. There are several metods, such as interviewing and observing people, however people often exageratte and or lie about tasks.
Analysists will examine the exsisting documents and records and note how the system inputs, outputs and records the data.
The findings from the investigation need to be analysed and a set of proposals made as to how the problem is to be solved and what is to be included in the new system. This is then summarised in the requirements specification.
The requirements specification is a written document that clarifies for both the client and the analyst what will be proposed for the new system including:
Details of proposed performance
Details of proposed security
Time scale of completion
any major constraits
The system should meet these requirements
Once the analysts have understood what is neeed and the present system, they design the new system. To aid them they need,
the previous requirement specification
The design specification which includes the purpose of the system, validation rules. inputs/outputs and processes, the links between the system, data flow diagrams, assumptions limitations and constraits, data structures and the house style.
The system specification which includes the hardware to be used, the software to be written with, the people involved in the design of the system, the software it is written with and how the system will be organised.
And finally the test plan which is a series of tests devised to make sure it is working correct and fulfils its purpose. It normally includes what is to be tested and what the outcome is as well as any test data used.
The Implementation Stage
Once the design is finalised it is to be built and installed, this involves:
obtaining the hardware
writing the software
writing the documentation
training personnel use of the new system
discussing changes of working practise
testing the system with and without users
Installiation and transfer of data
writing documentation for the user and any technicians
This is the more formal approach to make sure the client agrees that the analysts have made a good job of the system and so that the new system can begin to be used.
At this point however the analysts remain on call in case of any glitches. bugs and general help until the system is put fully into action.
Rapid Application Development (RAD)
RAD techniques enable the traditonal systems cycle to be speeded up although there are compromises. This is done by:
The use of prototyping when the designer creates part of the system and has it tested by a user or group of user who then make comments on the users judgement. the designer then refines this and the design-refine-design cycle is repeated until the system meets the designers wants.
Working in small teams allows the individuals to carry out the tasks and be more motiviated and flexible bypassing the values of a large team.
Time boxing allows the life cycle to begin without the need to wait for one stage to finish, and allows refinements to come later.
Automated Code Generators allow part of the systems code to be produced by computers used mainly on the program code and then other developments which come later.
The Project Manager
The project manager oversees the running of the project and worries about the deadlines, finances and makes sure that all technical documentation is completed as well preparing reports on what needs to be done.
The Systems Analyst
The Systems Analyst examines the system and prepares the ground for the designer, as well as deciding whether an upgrade is necessary or it is more feasible to go ahead with a completely new system.
A systems analyst must have:
Good technical knowledge
Good understanding of problems
Good intepretation skills
The system life cycle diagram
Draw the diagram below.
Critical Path Analysis (CPA)
This is used to establish the shortest and most pratical route through the construction of the system, bearing in mind that someparts take more time and some need to be completed before the next can be. CPA answer the following questions:
What are the tasks to be carried out?
Where can parallel activity take place?
What is the shortest time in which it can be completed?
What resources are needed?
What is the sequence of activities scheduling and timing?
What are main priorities?
Critical path analysis Diagram
Draw diagram below!:)
Programme, evaluation, and review technique (PERT)
A PERT chart allows the analyst to plan the task using milestones represented through circles, the mile stones are numbered in steps of ten so they can be added up easily if necessary.
PERT chart Diagram
Gantt charts make it possible to plot the progress of the project through time, each activity is shown as a block of time.
Slate transition Diagrams
STDs are used to describe every possible state of an object and everything that can or will affect the state of this object, these changes are known as transistions and are used to describe every possible situation.
State transition diagrams diagram
Draw it nao
Data flow diagrams
These are useful representations of data input and the processes the data goes through and when it outputs from the system, the following symbols are used to create data flow diagrams:
Flow Charts are visual representations of processes involved in a system, symbols have been developed to represent the processes and are connected by flow lines to indicate data flow through the system, the systems look like below.
In a structure diagram the system is described as a number of levels, each level describes the whole design. As the levels increase so does the detail, the diagram is sometimes known as a top-down design. They look like below.
A single-user system
A single-user system is a system such as a home computer which is not connected to any other computers or networks however with recent techlogical developments it its possible to run several programmes at once.
Multi-user or Multi-access system
These are when a single computer is connected to a number of terminals but each user is made to believe that they have control and complete access of their own system. It allows a number of users to use the same computer at once and this is achieved by giving each user a brief time to process data so that they do not notice a time delay and sometimes at the end of the day a batch process will be run.
Multi-tasking systems allow several applications to be run at once, this is useful if the user wants to cut and paste between the applications as well as allowing more important software applications to be run in the background such as the operating system and anti-virus software to be constantly running without the users knowledge. Peripheral devices can also be used on the system without the users knowledge.
Data is collected before the processing begins which is usually when the system is in least demand such as after work hours this allows little user interaction and an example of its use it a payroll at the end of the month.
This implies direct user interacting during the process, the system responds immediatley with this interaction and inputs from the user performimg the output very quickly and is useful where dialogue is needed and an example of its usage is in ATM machines.
This is where each individual term of processing is processed before the next can be started and is a first come first serve order such as when a bank transaction is put into place.
The input is immeditly affected by the output and the communications happens in less than four seconds such as when you press a brake pedal in a car the car will automatcally brake.
The is sharing out tasks between mutiple processors that are attached to the same network, this speeds up complex tasks with repetitive numbers such as number-crunching.
The Human-computer Interface
A HCI defines the communication between human and machine. The way in which this is enabled and the care with which the method is designed leads to the success or failure of the system. Many factors have to be taken into account.
The Human-computer Interface, Color
The use of colour must be used correctly it can be used to highlight important features however too much is distracting and confusing, it should also contrast the background making it stand out aswell as this colour can have traditional meanings so choose carefully.
The Human-computer Interface, Layout
The western eye reads left to right so put the most information in the top left, it should also be kept in a logical order and any important actions or buttons on screen should be clearly labelled.
Quantity of information
The following should be took into consideration:
Dont present too much information-short term memory will store little from a casual read.
Instructions should not be unneccasarly repeated.
Use hyperlinks effectively so that key points and words can be expanded.
Dont highlight too much information, or it will not be special.
The Human-computer Interface, Font
Should be appropriate to the text such as children requiring larger fonts.
Visually impaired people may need to adjust the size of the font for the prefered taste.
The font should be proffesinol and not fancy.
The Human-computer Interface, Complexity of Langua
Bear in mind the user when writing the information, technitions may require more complex text compare to unexperinced users.
The Human-computer Interface, controls
These should be appropriate to the task such as:
buttons to run a specific task
hyperlinks to jump to another document or elsewhere
Drop-down boxes which limit choice
check boxes which allow a number of choices
randio buttons which limit choice
A dialogue is a two-way flow of information and instructions between two systems, these may be human or computer. Dialogue between human and human involes the use of such things as speech, body language, and touch these have became protocols for the way in which our dialogue takes place. Within the ICT communication there are also protocols.
It is important to take the user into account when designing the interface, there are many differences which may affect this such as who the user is, what enviroment will the interface be in place in, and is it being capable of being used.
The Mental Model
The mental mode is a way of approaching an interface and having an idea of how it will work, such as how people will operate a system by intution or trial and error, it is important to take into account the user when producing the HCI.
The Model Human Processor
This is the analogy between the processing and the storage based on both human and computers.
Perceptual - we recieve information through our senses - our input devices
Cognitive - We think about things and work them out - our processing unit
Motor - we act on this knowledge - our output devices
Memory - we retain the information for future knowledge - our internal memory
Local Area Networks LAN
A local area network usually covers a defined area such as a building or site, it allows direct connections between computers through cables or wireless and the communication media is owned by the owners of the network.
Wide Area Network
This network usually covers a much greater geographical area and is usually linked through public communications such as telephone lines however the communication methods are owned by third partys.
Virtual Local Area Network
This is the logical part of a local area netork its creation is due to the software as the links already exsist, this allows the user to be part of groups which allow and restrict access areas, numerous VLANs can exsist within one configuration.
Virtual Private Network
This network allows the use of a wide area network aswell as remote stations using the a server on the internet. Security is ensured by encrypting the data.
The Client-server network is organised around one or more servers to provide shared resources, the server also provides security.
All security is provided by one place
Allows the sharing of software and data
Easier to back up all data
Allows thesharing of hardware
If the server fails, the network fails.
Requires a network administrator to operate successfully.
Cam ne an expensive option, such as hiring the adminstrator
A peer-to-peer network is a simple way of sharing resources by linking all computers allowing communication.
Simple to manage
Cheap to set up
Does not require management
Resources can be shared
Security is poor
Data is not centrally controlled
Periphels are not shared as easily
each computer back up is seperate
This is the measure of capacity of communication channel such as wire. It is measured in bits per second - how many binary digits can be transmitted along the line in 1 second. A high bit transmission rate is known as broadband.
Cables are usually made of copper and are wires twisted together to give protection against electical interferance.
High electrical conductivty
Ease of connection
Prone to electrical surges
Long cables lose the strength of signal
Can only carry limitedband width
These are made from fine glass fibres and transmit data in the form of light.
No electrical interferance
Very safe and reliable
Cam be up to 5km before repeaters need to boost signal
High cost to install as specialists knowledge is needed
Transmission equipment is more expensive
Fibres cannot carry power
This is used in remotes and control units such as keyboards and mice.
Not subject to electrical interferance
An uninterrupted line of sight between sending and receiving is needed
Sunlight can interfere
This is a highly focused beam with a narrow range of wave lengths, this means that it can travel long distances.
Can link buildings far apart with fast speeds
Suitable for LANs on split sites
Direct so secure
Prone to interference if anything interrupts the beam
Radio waves are electromagnetic waves with relatively long wavelengths e.g. waves from a few centimetres in length (FM radio) to hundreds of metres (AM radio).
Useful for sights difficult to wire up
Useful for portable devices
Needs a transmitter
prone to electrical interferance
not as secure as wired systems
Microwaves use transmitting and recieving dishes, often on towers to give further coverage, used as part of the public telephone system, signals are beamed from dish to dish across the country.
More secure than some systems because the signals send a tight beam.
Useful for companys transporting data around the city
Clear line of sight needed.
A narrow signal beam is sent to the satelite from a ground base and then is sent back down to a reciever.
Useful for long-distance communications, such as between countries
Difficult to repair satelites
An individual specification for wireless personal area networks, allows devices such as computers, PDAs, mobile phones, printers, cameras etc to communicate without wires.
Normally has a range of 10m but can be boosted
Eliminates the difficulty of transvering data to mutiple devices
Not always secure
A connection point between cables in a netork, managed hubs have extra features such as being able to monitor traffic between them. It contains a number of ports and when a packet arrives at one port it is copied to every port allowing the LAN to see all segments.
A device that filters and fowards the packets to the segments of the LAN and is more intellegent than a hub, switches look at the data packets are recieved and forward the packet to an appropriate device. A switch offers better performance as it conserves network bandwidth.
Network Interface Card
A piece of computer hardware that allows devices to connect to a wired network, generally installed into the computer or peripheral.
Wireless Network Interface card
A piece of computer hardware that allows devices to connect to a wireless network.
A router fowards data packets along the network, they are generally located at gateways. They determine the best path for fowarding the packets, and they communicate with other routers to configure the best route between any two hosts.
A system to allow a local area network to connect with a wide area network such as the internet.
A device that recieves a signal and boosts it, a series of repeaters may be used if the cables are very long. They clean this up by removing noise.
A bridge connects a LAN to another LAN that uses the same protocols, they then develop a learning table which makes them remember the process to become more efficient.
The British Computer Society
The BCS is to promote the study and practise of computing it advances knowledge an the education of ICT for the benefit of the public. It 'enables individuals, organisations and society to realise the potential od and mazimise the benefits of IT'.
sets and maintains proffessinol standards for its members
produce a code of conduct which states what an IT professinol should do
produces a code of good practise
advises the government on ict-related legilsation
initiates debates on ICT subjects