Computer Science Course

TOPIC 1: SYSTEM FUNDAMENTALS (20 hours)

1.1 SYSTEMS IN ORGANIZATIONSPlanning and system installation

1.1.1 Identify the context for which a new system is planned - Extent and limitations of a new system- Organizational issues related to the installation of a new system (e.g user role,

underlying technologies)

CONTEXT = the organizations´ environment (it defines the limits of an organization).

When systems are built, they are defined by the needs of their users. The environment affects the functioning and the performance of the system.

When a new system is planned it is generally the result of a change in the environment.

An outdated or archaic system might exist and, as technology progresses, a more efficient and dynamic entity may replace the system.

1.1.2 Describe the need for change management - Factors that need to be managed to ensure change is successful

Change management = a systematic approach to dealing with change on an organizational and individual level.

Change management includes: - Adapting to change

- Controlling change

- Effecting change

Change management is defining and implementing procedures and technologies to deal with changes in organizations.

Change management is necessary because:

It is an enabling framework for managing the people side of change It helps us to realize the benefits and desired outcomes of change During any change within a company problems arise and they need to be fixed People need to be retrained to do a different job if needed People that are resistant to change need support The employees need to be kept happy and work needs to continue to be smooth.

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When implementing a new system we must:

- Understand how to help ease in new system- Make sure existing system work with the new one- Be aware of what is going to happen when the change occurs

1.1.3 Outline compatibility issues resulting from situations including legacy systems or business mergers. - Software compatibility- Language differences

LEGACY SYSTEMS = old or outdated computer systems, that are used instead of available upgraded versions

COMPATIBILITY ISSUES:

- Historic data may not have been converted into the new system format and may exist within the new system as a separate partition. The old data might have to be converted into the new one manually to not upset the new system.

BUSINESS MERGERS = a merger happens when two companies agree to go forward as a single new company rather than remain separately owned and operated.

COMPATIBILITY ISSUES:

- The system from one company must be moved into the other one or both have to be moved to a new system, resulting in a variety of difficulties due to the different system being handled.

1.1.4 Compare the implementation of systems using a clients´ hardware with hosting systems remotely. - The benifts and drawbacks of a SaaS

SaaS = Software as a Service

CLIENTS HARDWARE:

- Can directly test with the possible user- If multiple clients, will need to test each hardware, especially if they are different- Hardware cost and maintenance cost needs to be considered- Easy access to hardware

HOSTING SYSTEM REMOTELY:

- May be accessed from anywhere- Multiple platforms can access the server- No need for a server technician

The remote host may be in a different time zone and this can have significant effects on end-user.

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SaaS:

= a software distribution model in which applications are hosted by a vendor or service provider and made available to customers over a network, typically the internet.

BENEFITS OF SaaS:

- Easier administration (less maintenance required and less hardware required)- Automatic updates and patch management- Compatibility: All users will have the same version of software- Easier collaboration, for the same reason- Global accessibility, from search cloud computing - Lower costs

DRAWBACKS OF SaaS:

- Security issues- Latency issue (data is stored in cloud far away from end user, it may take more

transactional time as compared to traditional approach)- Total dependency on internet- Switching between SaaS vendors is difficult (it may involve the slow and difficult task

of transferring very large data files over the Internet)

1.1.5 Evaluate alternative installation processes - Methods of implementation/ conversion: - Parallel running- Pilot running- Direct changeover- Phased conversion

Training issues may require organizations to restructure their workforce.

PILOT IMPLEMENTATION:

= the new system is introduced into one part of the company and its performance assessed.

ADVANTAGES DISADVANTAGES- If the new system fails, only one part

of the company is affected- More expensive than direct

changeover, since each pilot scheme needs to be evaluated before the next stage is introduced

- It is possible to train staff in one area only, which is much faster and less costly than parallel running

- Takes longer to roll out the system to the whole organization than other methods

- Less costs than parallel running, since only one part of the system is being used in the pilot

- Expensive both money and time

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DIRECT CHANGEOVER:

= the old system is stopped overnight and the new system is introduced immediately.

SOCIAL IMPLICATIONS ECONOMIC IMPLICATIONS- Staff may feel under great pressure/

stress during this type of changeover.

- Customers may also dislike changes – at least initially.

- Training costs- The cost of hardware/ software may

also have to be paid at one time rather than spread out over time

- Always a risk of failure turning away potential customers

ADVANTAGES DISADVANTAGES- The benefits are immediate - It can be disastrous if the new

system fails- Costs with personnel is reduced

(since only one system is used there is no need to pay for two sets of staff)

PARALLEL RUNNING:

= the old and new systems are run side by side for a time before the new system takes over altogether.

ADVANTAGES DISADVANTAGES- If the new system fails, the old

system is still available as a back-up- More expensive than direct

changeover, since extra staff are needed to run both systems together

- It is possible to train staff gradually - Duplicate of effort and system hardware adds cost to this approach

- Staff have time to get used to the new system

- There may be needed to keep synchronised copies of database records. One set is used by the old system and the other by the new system

SOCIAL IMPLICATIONS ECONOMIC IMPLICATIONS- More work for employees or they

may have to work longer hours to cope with the extra work

- Staff may have to be paid more or extra staff employed. Mistakes less critical for the business.

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PHASED CONVERSION

= initially, only part of the new system is introduced. Only when it proves to work satisfactorily is the next part introduced, and so on, until the old system is fully replaced.

ADVANTAGES DISADVANTAGES- If the latest part fails, it is only

necessary to go back in the system to the point of failure, hence failure is not disastrous.

- More expensive than direct changeover, since it is necessary to evaluate each phase before moving to the next stage

- It is possible to ensure the system works properly before expanding

- The system must be able to be partitioned into sub systems for this approach to work

- It does assume that a problem in one module has no effect on another module

- Can take a long time to roll out the whole system, especially if there are a large number of complicated subsystems

- Expensive in terms of the time taken up by staff to evaluate each module and loss of productivity

SOCIAL IMPLICATIONS ECONOMIC IMPLICATIONS- More hours to work- Different people may be affected in

different ways at different times – it could cause disatisfaction

- Costs associated with extra work- Longer period of changeover- Difficulties with system may become

drawn out - the company´s reputation for efficiency may suffer

1.1.6 Discuss problems that may arise as a part of data migration - Incompatible file formats, data structures, validation rules- Incomplete data transfer- International conventions on dates, currencies and character sets

FILE FORMATS: - different formats use and accept different types of data

DATA STRUCTURES: - new systems may require data different to what had been previously used. This data must be appropriately handled or loss of data precision may occur.

VALIDATION RULES: - methods or procedures used periodically during data migration to check that the migration is running smoothly.

Data must be altered to reflect different time zones/ currencies.

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POSSIBLE PROBLEMS:

- Data loss- Poor data quality in the old system- Incompatible data for new system- Loss of employee efficiency as data is presented differently in new systems- Old systems might be dependent on a source of data. New systems must be able to

properly interact with those same sources. - Cost (more storage devices media needed for transfer)

1.1.7 Suggest various types of testing - User acceptance testing- Debugging - Beta testing

There are programs that can test other programs, resulting in automating parts of the testing process and reducing costs.

Inadequate testing can reduce employee productivity and lead to end-user dissatisfaction.

ALPHA TESTING = a group of programmers may examine an early version to see how it performs.

BETA TESTING = is used when the product is nearly ready for release and the developers believe that there are few or no errors.

The software is released to the users outside the company who can try it out in a range of different environments.

Credible companies always let the users know that the product is at the beta stage and may not perform perfectly.

TEST DATA:

Example: the months of the year

NORMAL DATA: valid data, with an expected outcome (6, 7, 11)

EXTREME DATA: data at the limits of acceptability (1, 12)

ABNORMAL DATA: data outside the limits of validity and should be rejected or cause an error message. ( -3, July, 3.5)

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User focus

1.1.8 Describe the importance of user documentation. - The quality of user documentation can affect the rate of implementation of the new

system

USER DOCUMENTATION = is designed to help users to learn how to use the software or system. This can consist of any of the following:

- The purpose of the system- How to log in/ log off- How to load/ run the software- How to save files- How to do a search- How to sort data- How to printouts- How to add/ delete or modify records- Screen layouts (input)- Print layouts(output)- Hardware requirements- Software requirements- Sample runs (with test data and results)- Error handling/ meaning of errors- Troubleshooting guide/ help lines/ FAQ- Tutorials

IT IS WRITTEN FOR THE NON-TECHNICAL USER OF THE PROGRAM!

SYSTEM DOCUMENTATION = TECHNICAL DOCUMENTATION = is designed to help programmers and analysts who need to make improvements to the system or repair/ maintain the system. This can consist of any of the following:

- Purpose of the system- Program listing/ coding- Programming language used- Flowcharts/ algorithm- Input formats- Hardware requirements- Software requirements- Minimum memory requirements- Known bugs in the system- List of variables used (and their meaning/ description)- File structures- Sample runs (with test data and results)- Output formats- Validation rules- Meaning of error messages

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SYSTEM DOCUMENTATION

- Internal documentation (comments which accompany the source code listing)- External documentation

o Purpose of the programo Data flow in the systemo Hardware and software requirementso Structure of the program (a module diagram)o The module interface – what parameters it has and any value it returnso Any testing and debugging actually carried outo A list of identifierso Description of methods, data structures

1.1.9 Evaluate different methods of providing user documentation - Help files- Online support- Printed manuals

HELP FILES:

- can be accessed by the user any time as long as files have been copied over to the hardware.

- The user might have a hard time finding the appropriate section where the help is being offered

- Can be updated frequently as the software does through patches- Can be updated frequently as the software does through patches- Can be accompanied by a search option to guide users to the right section

ONLINE SUPPORT:

- Can be accessed by the user anytime and anywhere- The user must have a connection to the internet- Can be accompanied by a search option to guide users to the right section- Can be updated easily- Similar benefits as help files

PRINTED MANUALS:

- similar benefits as help files- the users must find the help in the manual themselves and they must hold on to the

physical manual- can get outdated when software undergoes update- resources wasted in printing and packaging the manual

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1.1.10 Evaluate different methods of delivering user training - Self-instruction- Formal classes- Remote/online training

SELF INSTRUCTION:

- Least resource needed- If the user needs to receive the training beforehand, they have to be able to access the

system in their own time or an agreement must be met on when the user can access it- The extent of user competence will depend on the ability of the user to learn the new

system- If the system is not a straight forward, self-explanatory system, then this method should

be avoided

FORMAL CLASSES:

- Resources needed to host the class and the teacher, as well as devices- The extent of user competence will depend on the ability of the teaching- The users can only come back to their notes or experience when they operate

REMOTE/ ONLINE TRAINING:

- Resource needed to make the documentation/ videos to teach the system- The users can have the opportunity to re access the archives to come back to it when

necessarily- The user will need to find someone to refer to if they need to find something out that

they couldn’t understand- The extent of user competence will depend on the ability of user to learn the new

system

System backup

1.1.11 Identify a range of causes of data loss - Malicious activities- Natural disasters

MALICIOUS ACTIVITIES:

- Physical damage to the storage devices- The result of activities by employees within the organization or by intruders/ hackers- User error (the user may accidentally delete some files, over write them or just simply

forget to save)- Theft, people may steal your data, either physically or through hacking- Viruses and malware- Hardware malfunctions (defects)

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NATURAL DISASTERS:

- Earthquakes, floods, wars- Volcanic eruptions- Fires

1.1.12 Outline the consequences of data loss in a specified situation- Loss of medical records- Cancellation of a hotel reservation without the knowledge of the traveller

LOSS OF MEDICAL RECORDS

This may result in serious consequences for the patient and quite possibly his family. Medical records include a range of data such as current or old diseases, allergies, vaccination and previous diseases or conditions that have run in your family. If all this data was lost it would cause a huge health risk to the patient, due to the unavailability of vital information regarding their health and conditions.

Employee Records - When companies lose data like these they’re punished and have to pay fines. Employees might sue the company in order to

Banking Records - As well as many other organizations and companies, banks still hold a lot of your personal information such as name address age etc, but quite possibly the most important data that they hold is that of your own bank accounts. If this data is lost by deletion then safety issues aren’t that huge, since all you have to do is recollect this data from all your customers. Although, if the data is actually stolen by someone, the safety issues are huge, since they will have access to all the data regarding all the customers’ bank accounts as well as their personal information.

Government Agencies - Governments will quite possibly be the sector that will own the most information regarding a certain individual, anything ranging from your address to your social security number and so on, and would cause serious social and security risks and damage if someone was to gain access of it. The reason governments keep this is because it´s very personal data that is to be kept to one person only, and if someone would be able to steal or gain access to this data it could cause serious risks. Although, if this data was deleted, unlike the banking data, it would still be a huge threat due to it being much harder to obtain all this data again from everyone, and people may provide fake data once they are asked for their personal information again.

Credit Card records - Losing data may damage the company’s reputation. For example when companies like Amazon are hacked, important data like personal details and credit card information might be used against the users and this creates a feeling of insecurity between the company and the customers. Privacy is also a big issue with data loss. Customer’s information might be put available on the internet.

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1.1.13 Describe a range of methods that can be used to prevent data loss- Failover systems- Redundancy- Removable media- Offsite/online storage

FAILOVER SYSTEMS:

- A secondary system that can assume the functions of the primary system should it falter- Requests are automatically re-routed from the primary to the secondary (failover )

system in case of primary system failure.- Tasks are offloaded to a standby system at the same time that transition from the

primary to secondary system is as seamless as possible.

Example: Websites hosting their data on more than one server in more than one location.

REDUNDANCY:

- A group of computer systems that contain duplicated data.- Provide another copy of data if a system fail- Unlike a failover system, this is just a copy of the data and does not take over the

primary system´s requests if the primary system fails

Example: Copying a database or file system to another server

REMOVABLE MEDIA:

- Often though as backing up files- Include USBs, Floppy Disks, Memory Cards, DVDs, CDs- These function to store data and programs which can be retrieved for later use

OFFSITE STORAGE:

- It describes location arrangements for records. The storage might be leased by the agency or held by a storage provider

- It will help prevent data loss by having a location in which all your data can be accessible and protected for the use of the client

ONLINE STORAGE:

- A backup and storage service on the Internet- Dropbox offer online storage services in which you can save data from your laptop and

access it anywhere including your mobile phone.- Helps prevent against data loss caused by natural disasters

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1.1.14 Describe strategies for managing releases and updates

MANAGING UPDATES

Before releasing updates, one should consider a few things:

- is it needed, do the users require a new update

- does it function properly, has it been thoroughly tested

- will it last, or is there going to be a new release soon after.

There are several consequences to releasing updates too early, these include:

- Loss in reputation due to malfunction in the update- Loss in sales due to malfunction in the update- High losses since they need to release a patch for the update.

AUTOMATIC UPDATING

= the system checks automatically for updates over the internet from time to time. If updates are available, they are downloaded and installed automatically.

Advantages:

- This strategy eliminates the need for constant user approval (user allowing updates) and facilitates the process of distributing and installing updates

- User is prompted to approve automatic updating only once; after the approval, updates are distributed and installed without the need for the Users involvement

- Updates get installed automatically. Inexperienced users have an easy chance to get the updates

- No need for software manufacturer to contact every user about the new update

Disadvantages:

- Users miss updates if they are not connected to the internet.- If updates bring a major change of system functions, users might not be informed

about it

Systems often have pop-up windows that are designed to begin appearing only once a new update is available; the User may choose to install or not install the updates from these windows.

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TIMED UPDATING

- This strategy ensures that the system does not become too outdated- The system automatically checks for available updates after a set period of time and

provides the end User with a report of these available updates; the User may then choose to install or not install the updates from this report

Companies release groups of updates in packs:

- Service Pack: A collection of updates and fixes, known as patches, that are released together for an easy, single installation.

- Feature Pack: A collection of new system functionality components distributed between full product releases; these components have usually already been approved to be a part of the next full product release.

- Security Update: A widely released fix for a system-specific, security-related vulnerability; these updates are usually accompanied by a severity rating indicating how critical the security vulnerability is.

MANUAL UPDATES: the software manufacturer contacts every user about the new update and supplies the installation package to him to be installed.

Advantages:

Users have more control what updates they want to install Users get to know if an update brings major changes to how the system works

Disadvantages:

Users might miss an update fixing security issues Users might not know how to install the update Users might harm system by wrongly installing update Users might lose medium containing the update

Patching:

A patch is a piece of software designed to update a computer program or its supporting data, to fix or improve it. This includes fixing security vulnerabilities and other bugs, and improving the usability or performance. Though meant to fix problems, poorly designed patches can sometimes introduce new problems. In some special cases updates may knowingly break the functionality, for instance, by removing components for which the update provider is no longer licensed or disabling a device.

Patch management is the process of using a strategy and plan of what patches should be applied to which systems at a specified time.

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Types:

Patches for proprietary software are typically distributed as executable files instead of source code. This type of patch modifies the program executable—the program the user actually runs—either by modifying the binary file to include the fixes or by completely replacing it.

Patches can also circulate in the form of source code modifications. In this case, the patches usually consist of textual differences between two source code files, called "diffs". These types of patches commonly come out of open source projects. In these cases, developers expect users to compile the new or changed files themselves.

Bigger updates are referred to as "service packs" or as "software updates".

1.2 System design basics (10 hours)Components of a computer system

1.2.1 Define terms: hardware, software, peripheral, network, human resources.

HARDWARE = the physical parts of a computer.

SOFTWARE = programs that run on a computer.

PERIPHERAL = a device that is connected to a host computer, but it is not part of it. It expands the hosts capabilities but does not form part of the core computer architecture (a printer, a mouse, a monitor, a keyboard)

NETWORK = two or more devices connected together in order to share resources.

= a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain subnetworks.

HUMAN RESOURCES = the group of individuals who make up the workforce of an organization, business sector or economy.

1.2.2 Describe the roles that a computer can take in a networked world. - Client - Server- E-mail server- Router- DNS server - firewall

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CLIENT = the computer that requests information from a server

SERVER = the computer that stores and shares information to clients over the network

E-MAIL SERVER = the computer that acts like a post office. It can process e-mail by receiving, storing and sending it.

ROUTER = the computer that connects to networks and decides where to send information which is received from one network and then send to another.

DNS SERVER = it is basically a router, but in this case it translates a web address that is written in letters to the IP address of that webpage.

FIREWALL = it decides on what connections to let through to protect the integrity of the client computer which uses the firewall.

1.2.3 Discuss the social and ethical issues associated with a networked world

SECURITY

- Computers must protect their data and make sure that data is not accessible for anyone that does not have the right to access it

PRIVACY

- You should be able to choose what information you share and with who you share it

CENSORSHIP

- Suppression of speech, public communication or other information which may be considered objectionable, harmful, sensitive, politically incorrect, inconvenient as determined by governments, media outlets, authorities or other such entities.

Reasons:

o National securityo To control obscenityo Child pornographyo Hate speecho To protect children / other vulnerable groupo To promote/ restrict political or religious views

ADDICTION

- Compulsion to use social media to excess

DEPENDENCY

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System design and analysis

1.2.4 Identify the relevant stakeholders when planning a new system - The role of the end-user

STAKEHOLDER = a person who has an investment, share or interest in a business/ industry.

A stakeholder in computer systems is anyone who:

- Operates the system- Benefits from the system (in either function, politics, finances, social benefits)- Is involved in buying or taking control of the system- Regulates and takes care of finances, safety and other aspects of the system- Opposes the system (negative stakeholder)- Is responsible for subsystems of the system

Example of types of stakeholders:

Users

- A person who is involved in testing a system- A person who chooses to purchase the final version of a system- A person who chooses to purchase a competing version of a system

Developers

- A person who is involved in developing the system

Legislators

- Organizations or governments who impose regulations that affect the development of a new system

Decision-Makers

- Any group or person that makes decisions affecting the final system; these can be development team manager, financial controllers, or any other group holding influence in the development

A single person may be classified under more than one of these groups.

1.2.5 Describe methods of obtaining requirements from stakeholders - Surveys- Interviews- Direct observations

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Name of method Description Advantages DisadvantagesObservation Involves watching personnel using the

existing system to find out exactly how it works

The analyst obtains reliable data It is possible to see exactly what is

being done It is a relatively inexpensive

method

- People are generally uncomfortable being watched and may work in a different way

- If workers perform tasks that violate standard procedures, they may not do this while being watched

Questionnaires Involves sending out questionnaires to the work force and/ or to customers to find out their views of the existing system and find out some of the key tasks are carried out

The questions can be answered quite quickly

It is a relatively inexpensive method

Individuals can remain anonymous if they want

It allows quick analysis of the data

- Often the number of returned questions is low

- The questions are rather inflexible since they have to be generic

- There is no immediate way to clarify a vague or incomplete answer to a question

Interviewing Involves a one-to-one question-and-answer session between the analyst and the employee/ customer.

It gives the opportunity to motivate the interviewee into giving open and honest answers to the analyst´s questions.

It allows the analyst to probe for more feedback from the interviewee, as it is easier to extend a question

It is possible to modify questions as the interview proceeds and ask questions specific to the interviewee

It is good method if the analyst wants to probe deeply into one specific aspect of the existing system

- It can be rather time consuming- It is relatively expensive, due to the use

of the analyst´s time- The interviewee cannot remain

anonymous

Looking at existing paperwork

Allows the analyst to see how the paper files are kept, look at operating instructions and training manuals, check

It allows information to be obtained which was not possible by any of the other methods

- It can be very time consuming- Because of the analyst´s time, it is a

relatively expensive method.

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the accounts etc. The analyst can see for themselves how the paper system operates

It allows the analyst to get some idea of the scale of the problem, memory size requirements, type of input/ output devices needed, etc.

Surveys Involves collecting information from a selected group of people through standardized questionnaires.

Requires minimal human resources

Allows for information to be collected from large group of people over a relatively quick amount of time

- Generalized questions- Requires follow-up using another method

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1.2.6 Describe appropriate techniques for gathering the information needed to arrive at a workable solution- Examining current systems- Competing products- Organizational capabilities- Literature searches

EXAMINING CURRENT SYSTEMS

- Diagnosis of current systems identifies problemso PC scanners

- Self – diagnosiso Figuring out a problem within the system without the help of a troubleshooting

guide- Examination tools for computer systems

o Including digital forensic toolso Including computer-aided assessments

COMPETING PRODUCTS

- Microsoft Support- PC Support- Windows Updates

ORGANIZATIONAL CAPABILITIES

- Search within the company for finding a solution- Examine your:

o Quality of workerso Quantity of workerso Worker´s experienceso Financial resourceso Intellectual resources

- Literature research:o A literature research is a well thought out and organizes search for all of the

literature published on a topico Includes the following steps:

Create a question Finding sources of information Search with key words Uses valid sources only

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1.2.7 Construct suitable representations to illustrate system requirements- System flow charts- Data flow diagrams- Structure charts (UML IS NOT REQUIRED)

1.2.8 Describe the purpose of prototypes to demonstrate the proposed system to the client- The need to effectively collaborate to gather appropriate information to resolve

complex problems

The purpose of prototyping is to show the user an interface and to give some indication of how the system is expected to work. The prototype is not a full working version of the software but it does allow the user to propose changes at the design stage. The prototype could be produced by a different system than the one eventually used for the project. A developer could present an interface using an applications package (presentation software for example) even though the eventual solution might be implemented using Java.

By using prototyping at an early stage in the project, the analyst/designer can produce different prototypes showing alternative solutions. The user can then give concrete feedback to the designer to indicate whether they are implementing the solution the user desires. The earlier that changes can be made to a system the less time is wasted completing the system and therefore less money will be spent. Early changes are not as costly as late changes!

1.2.9 Discuss the importance of iteration during the design process - Design cycle

Iteration is a methodology based off the process of prototyping, testing, analyzing, and refining a product or system.

Iterative design allows products to be improved and refined quickly based off testing results

Example: Windows 8 was followed by an updated design and implementation named Windows 8.1 after receiving customer feedback.

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1.2.10 Explain the possible consequences of failing to involve the end-user in the design process- The failure to involve the end-user may lead to software that is not suitable for its

intended use, which may have adverse effects on user productivity

CONSEQUENCES:

- Customer feedback is lost in what the product needs to accomplish- Early identification and elimination of product or process failures is reduced- Knowledge of the requirements of the program are not really know- Talk over potential risk is avoided and the customer does not know the risks

- May result in having to undergo major changes later in the process and the costs associated with needing to change the program

- Customer might not like the final product.

1.2.11 Discuss the social and ethical issues associated with the introduction of new IT systems- Legal decisions often lag behind new IT systems, and therefore ethical decisions often

govern the usage of newly introduced IT systems for a significant period of time.- While the internet and new systems often introduce a new form of community, often

times a sense of anonymity removes people's sense of commitment.- In many countries, the government does not and cannot exert power over what users

post, so people are only bound by their moral and ethical compasses.- Different networks create acceptable use policies to help define acceptable behaviour.- Data stored electronically is both easier to copy and easier to replicate than physical

data, so there is an increased ability to steal data.- In a business setting, the introduction of a new system often places more stress on the

employees because they have to learn and adapt to a new system while completing their work.

1.2.12 Define the term usability - ergonomics- accessibility

Usability is the ease of use and learnability of a man-made object.Usability can be defined as the extent to which a product can be used by users to achieve specified goals with efficiency, effectiveness, and satisfaction in its specified contexts of uses.

What are the benefits of making something more usable:

More efficient to use —takes less time to accomplish a particular task Easier to learn —operation can be learned by observing the object More satisfying to use

When creating something new an individual should consider these points:

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Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?Efficiency: Once users have learned the design, how quickly can they perform tasks?Memorability: When users return to the design after a period of not using it, how easily can they re establish proficiency?Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?Satisfaction: How pleasant is it to use the design?

1.2.13 Identify a range of usability problems with commonly used digital devices- PCs- Digital cameras- Cell phones- Games consoles- MP3 players

PC:

- If you are blind, you cannot see the screen- If you have no hands, you cannot use the keyboard or mouse- If you do not have the technical knowledge, device connection may be difficult.

CELL PHONE:

- If the OS is too complex then users may have issues navigating through the OS- If the user as bad eye sight then they may find it hard to see the screen if it is too

small and if the text is too small a size.- If the user has certain health issues and limited hand mobility such as arthritis

then the user input method may pose various issues such as small qwerty keyboard wont be usable.

- If the user has bad hearing then it would be hard to use a phone with low speaker volumes.

- If the user is outdoors in the sun then the screen brightness must be high to be visible.

- The phone must fit in your hand comfortably and should not slip.

DIGITAL CAMERA

- Blindness or partial sightedness can mean using digital cameras is very difficult as the user can’t or will struggle to see what is on the screen as well as connecting them to a computer to transfer files.

- People with physically debilitating conditions may not be able to hold a camera or push the shutter button.

- Users with conditions such as Parkinson’s Disease may be unable to hold a digital camera steady.

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MP3 PLAYER

Ergonomics

Some MP3 players have relatively small screens. People with limited eyesight Buttons and controls may be too small and users with less mobility on their hands

may find it challenging and difficult.

1.2.14 Identify methods that can be used to improve the accessibility of systems- Touch screen- Voice recognition- Text-to-speech- Braille keyboard

1.2.15 Identify a range of usability problems that can occur in a system- Ticketing- Online payroll- Scheduling- Voice recognition- Systems that provide feedback

AUTOMATIC FEEDBACK SYSTEM - Is the feedback of good enough quality, is it clear enough, is there enough feedback and is it given quickly enough.

Furthermore with online feedback system where people provide feedback - Are the people providing feedback of the right skill level and is their feedback valid?

ONLINE PAYROLL

The inputs to a payroll system are:

Employee code (used to lookup the employee's other details, e.g. name, bank account, etc.)

Hours worked Rate of pay (e.g. $25 per hour)

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The outputs from a payroll system are:

A printed payslip (given to the employee to show how his/her pay was calculated) A cheque, or an EFT payment directly into the employee's bank account

Disadvantages

Internet Service Provider (ISP) downtime Depending on the complexity of the system, employees may have trouble

learning how to work with it. Employees might not have a bank in order to be paid This system might be complex to set up

VOICE RECOGNITION

Several problems may occur with a voice recognition system, they include but are not limited to:

The dictionary of the voice recognition software may be limited and doesn’t include certain words such as slang terms.

If the user has a speech impediment then the software may have trouble recognizing what they are saying.

People from different regions of the world and backgrounds will all different dialects as well as accents which the system may not be able to deal with.

The system may not be able to recognize different words if the user speaks very quickly or too slowly.

Users may not want to speak about important and sensitive information in a public space. As well as people speaking in a lower volume when in public, the system may not be able to ‘hear’ the user.

Depending on the security capabilities of the voice recognition system. If the user is in an area with a lot of ambient noise then the system may not be

able to cancel out this noise. If the word database is not stored locally and there are network errors then the

system is not able to work.

1.2.16 Discuss moral, ethical, social, economic and environmental implications of the interaction between humans and machines

ECONOMIC:

- May allow more technologically advanced countries to take jobs from less technologically advanced companies

- Created new ways for goods to be sold (e-commerce)

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SOCIAL:

- The greater interconnection in the world that arises from network and human interaction with machines has the ability to redefine our concept of towns and communities

- Computer systems have spread English and many other Western traditions to other cultures- Provides entertainment- Fear that young people spend too much time online- Allows people to meet people in distant places through chat rooms and the internet

MORAL/ETHICAL:

- Data should be acquired through appropriate means- Consent should be requested when collecting personal data- Personal data should be relevant to the purpose for which it will be used- Reasons for data collection should be explicitly available prior to the data being collected- Personal data should be protected by reasonable safeguards- Individuals ought to have access to their own personal

ENVIRONMENTAL:

- Computers use large amounts of electric energy- The use of paper initially increased because of printing but is starting to show some signs of

decline- High use of bleach and paper mills to create paper for printing- Allows people to communicate without physically being in the same place, decreasing

pollution due to transportation

TOPIC 2 – COMPUTER ORGANIZATION (6 hours)Computer architecture

2.1.1. Outline the architecture of the central processing unit (CPU) and the functions of the arithmetic logic unit (ALU) and the control unit (CU) and the registers within the CPU.

- reproduce a block diagram showing the relationship between the elements of the CPU, input and output and storage. The memory address register (MAR) and memory data register (MDR) are the only ones that need to be included.

CPU = Central Processing Unit

- The heart of the computer- The engine of the computer, the chip or processor- It performs all the work required for the computer´s operation

The CPU works with a fixed number of bits, usually a multiple of 8-bits. This is known as a WORD.

WORD-SIZE = measures the maximum amount of data that can be processed by the machine in a single step.

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WORD = the amount of data that fits in a register.

REGISTER = a very small, extremely fast blocks of memory within the CPU. It provides for temporary storage of critical information.

CPU:

- CU (Control Unit)- ALU (Arithmetic Logic Unit)- 2 communication bus systems (primary memory bus and address bus)

The BUS provides a pathway to transfer data to different parts of the computer.

CU – controls the sequence of the execution of the program that is stored in the computer´s memory.

ALU – performs the logical operations such as comparisons and arithmetic operations such as addition

FUNCTIONS OF ALU

The ALU carries out all the arithmetic and logical operations Performs the following operations:

o ADD; SUBTRACT; AND; OR; NOT Contains registers for storing temporary data Input quantities relate to the word size of the computer (e.g. 32 bit or 64 bit)

FUNCTIONS OF CU

Manages the ALU Controls communication between CPU and memory Step by step processing Contains registers such as:

o IR (Instruction Register – stores the current instruction)o PC (Program Counter – stores the address of the instruction)

The ADDRESS BUS carries a memory address from the CPU to the RAM. The RAM responds by sending the data from the memory location back through the DATA BUS. The width of the address bus determines the maximum number of bytes in RAM:

E.g. 32 bit address bus – the largest address is 232 = 4 billion, so it supports 4 Giga Bytes in RAM.

MEMORY ADDRESS REGISTER [MAR]

The MAR is connected to the address bus The MAR is how the CPU communicates with the address bus The MAR can hold either an instruction address or a data address

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MEMORY DATA REGISTER [MDR]

The MDR is connected to the data bus Data can go in both to and from memory The MDR can load its data from:

o The data bus (for reading data)o One of the CPU registers (for storing data)

BLOCK DIAGRAM OF CPU AND MAIN MEMORY

2.1.2. Describe primary memory.

- Distinguish between random access memory (RAM) and read-only memory (ROM) and their use in primary memory

READ ONLY MEMORY (ROM)- Is smaller than RAM, but provides non-volatile storage (that means, when the computer is

turned off, its contents are not erased)- Unlike RAM, the contents of ROM cannot be changed- The information in ROM can be read, but cannot be written- ROM is used to store instructions and data that will never change (e.g. instructions that

control how a computer starts up, reads input, writes output)

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INPUT

CPU

RAM

ROM

OUTPUT

CU

ALU

REGISTERS

MAR

MDR

RANDOM ACCESS MEMORY (RAM)- Stores information- It provides volatile storage (temporary). When you turn off the computer, volatile storage is

erased.- While the computer is running, the CPU writes information to RAM and reads information from

RAM- RAM stores 2 types of information:

o Instructions (tell the computer what to do)o Data is the input or result of an operation

- It is the primary location where information is stored while the computer is running- In RAM – the stored information is encoded as sequences of 1´s and 0´s

BIT – Binary digIT Data stored in memory is organized into bytes1 byte = 8 bitsThe BYTE is the smallest addressable unit of storage (the smallest amount of data we can read from memory or write to memory at a time)Each location in memory has a unique addressMEMORY SIZE = refers to the number of bytes of storage available

1 KB = 1024 B = 210 B1 MB = 1024 KB = 210 KB1 GB = 1024 MB = 210 M B1 TB = 1024 GB = 210 MB

2.1.3 Explain the use of cache memory

- explain the effect of cache memory in speeding up the system as well as being able to explain how it is used

CACHE is a small, very fast memory that stores the data from frequently used main memory addresses. When the processor has to look for the next instruction, chances are it can be found in this temporary store named Cache.Modern processors also contain a small amount of fast memory incorporated into the processor itself, internal cache, which is speedier still because of the very short distance travelled. The cache on the microprocessor itself is referred to as LEVEL 1 CACHE and that between main memory and the processor as LEVEL 2 CACHE.

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Fetch instruction from memory to CU

Decode instruction in CU

Execute instruction (data may be fetched from memory )

Store results of execution (if any).Check for next instruction

Start

Stop

finished

more to do

2.1.4 Explain the machine instruction cycle

- include the role of data bus and address bus

When a computer program is stored as a series of instructions in machine code in primary memory, the following steps are carried out:

1. FETCH The next instruction is fetched from the memory address that is currently stored in

the Program Counter (PC), and stored in the Instruction Register (IR). At the end of the fetch, the PC points to the next instruction that will be read at the next cycle.

2. DECODE The decoder interprets the instruction. During this cycle the instruction inside the IR

(instruction register) gets decoded.

3. EXECUTE The Control Unit passes the decoded information as a sequence of control signals to

the relevant function units of the CPU to perform the actions required by the instruction such as reading values from registers, passing them to the ALU to perform mathematical or logic functions on them, and writing the result back to a register. If the ALU is involved, it sends a condition signal back to the CU.

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4. STORE

The result generated by the operation is stored in the main memory, or sent to an output device. Based on the condition of any feedback from the ALU, Program Counter may be updated to a different address from which the next instruction will be fetched.

DATA BUS = a connection between the different parts of a computer that information is sent on.

ADDRESS BUS = a data bus that is used to specify a physical address. A CPU will specify the memory location.

Secondary memory

2.1.5 Identify the need for persistent storage.

- persistent storage is needed to store data in a non-volatile device during and after the running of a program

Persistent storage means that data is retained or kept after the power is turned off to the device.

Volatile = the data is lost when the computer is switched off.

Non-volatile = the data is not lost when the computer is switched off.

Operating systems and application systems

2.1.6 Describe the main functions of an OS.

1. Peripheral communication The O.S keeps track of the device drivers (software designed to interface directly with

the hardware) It provides a standard interface between hardware devices and applications

2. Coordinating concurrent processing The O.S handles the loading and unloading of the processes (jobs that are running on a

computer the entire period it is on) to and from primary memory.3. Memory management

The O.S ensures that each process operates in its own (virtual) memory space and doesn’t change memory belonging to another process

The O.S deals with the moving parts of processes to the swap file.4. Accounting and security

The O.S makes sure that only those users who are registered with the O.S can get access.

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2.1.7 Outline the use of a range of application software.

- application software should include: o word processorso spreadsheetso database management systemso emailo web browserso computer-aided design (CAD)o graphic processing software

WORD PROCESSORS

- used for creating, editing and printing documents. Example: Microsoft Word.

SPREADSHEETS

- used for modelling financial possibilities as well as other numerically based operations. Example: Microsoft Excel.

DATABASE MANAGEMENT SYSTEMS

- software that manages and controls the different pieces of information stored in an electronic database (an organized collection of information relating to a certain subject). Example: Microsoft Access.

EMAIL

- used to send electronic emails. In order to send and receive emails you must have an email client and an account setup with an email provider.

WEB BROWSERS

- used to locate, retrieve and display content on the WWW, including web pages, images, video and other files. The browser is the client run on a computer that contacts the Web server and requests information. The Web server sends the information back to the Web browser which displays the results on the computer. Example: Google Chrome.

COMPUTER-AIDED DESIGN (CAD)

- a CAD system allows engineers and architects to design everything from floors to ceilings to airplanes to robotized kittens. CAD systems require a high-quality graphics motor, a mouse, a light pen or digitizing tablet for drawing and a special printer.

GRAPHIC PROCESSING SOFTWARE

- allows the user to manipulate visual images on computer.

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2.1.8 Identify common features of applications.

- include:o toolbarso menuso dialogue boxeso graphical user interface (GUI) components:

Windows Icons Menus Pointers

Toolbars

- a set of icons which enables you to use the operations built by a program such as crop, insert text box, etc.

Menus

- a set of commands usually located above the toolbar

Dialogue boxes

- a pop-up that appears in response to the user. It is more user-friendly since they typically only contain two commands such as ok or cancel.

Graphical user interface

- allows users to drag and drop objects rather than typing it in the command line.

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Binary representation

2.1.9 Define the terms: bit, byte, binary, denary/decimal, hexadecimal.

BIT

- the smallest unit of data in a computer. BIT – Binary digIT. It is only one binary value (1 or 0).

BYTE

- 1 byte = 8 bits.

BINARY

- A numbering system of base 2, therefore may only have values of 1 or 0.

DENARY/DECIMAL

- A numbering system of base 10, therefore may only have values of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

HEXADECIMAL

- A numbering system of base 16, therefore may only have values of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.

2.1.10 Outline the way in which data is represented in the computer.

Integer:

Each integer is represented in binary. If there is a single it will be represented in one byte.

Characters:

Each character is usually one byte, represented in binary.

Unicode is a standardisation of assigning values to a specific character, this is needed as there are hundreds of different characters in different languages and if done by each community there would likely be overlaps.

Strings:

- Represents a concatenation of characters. Will be represented in binary. A word is 16 or 32 bits.

Colours:

- Is represented in hexadecimal number system. Will be 6 hexadecimal values: two for each prime colour, in the order of Red, Green, Blue (RGB).

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For example the colour red will be FF 00 00. When viewed on a screen it will usually have a hash tag before the value, e.g. #FF 00 00.A maximum of around 16.8 million different colours may be input (16 to the power of 6 or 2 to the power of 24).

Simple logic gates

2.1.11 Define the Boolean operators: AND, OR, NOT, NAND, NOR and XOR

AND

A B A and B1 1 11 0 00 1 00 0 0

The output is true if both inputs are TRUE.

OR

A B A or B1 1 11 0 10 1 10 0 0

The output is true if one of the input is TRUE.

NOT

Negate the input.

NAND

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A not A 1 01 00 10 1

A

B

AND

AND

O

A B A and B A nand B1 1 1 11 0 0 10 1 0 10 0 0 0

NOR

A B A or B A nor B1 1 1 01 0 1 00 1 1 00 0 0 1

Negate OR

XOR

A B A or B A xor B1 1 1 11 0 1 10 1 1 10 0 0 0

2.1.12 Construct truth tables using the above operators.

2.1.13 Construct a logic diagram using AND, OR, NOT, NAND, NOR and XOR gates.

Topic 3 – Networks (9 hours)

3.1 Networks (9 hours)

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Network fundamentals

3.1.1 Identify different types of networks.

- Local area network (LAN)- Virtual local area network (VLAN)- Wide area network (WAN)- Storage area network (SAN)- Wireless local area network (WLAN)- Internet- Extranet- Virtual private network (VPN)- Personal area network (PAN)- Peer-to-peer (P2P)

Local area network (LAN)

- It covers a small area (an office, home or school)

Virtual local area network (VLAN)

- A subgroup of computers on a LAN, that are treated alike (in terms of security or bandwidth) regardless of their physical proximity on the network

Wide area network (WAN)

- Any communications network that connects geographically dispersed hosts, usually across regional or national boundaries. Often a network of LANs belonging to a multinational company linked by leased lines.

Storage area network (SAN)

- A network not normally accessible from the main LAN on which the hosts are predominantly high-capacity storage devices, such as tape drives.

Wireless local area network (WLAN)

- Same as LAN but using wireless technologies (Wi-Fi)

Internet

- A worldwide collection of networks which allows a subscriber to send and receive emails, chat (using text or voice) or browse the world wide web.

Intranet

- A computer network based on internet technology that is designed to meet the internal needs for sharing information within a single organisation/ company.

Extranet

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- An intranet that is mapped onto the public Internet or some other transmission system that is not accessible by the general public, but is managed by more than one company´s administrators.

Virtual private network (VPN)

- A Virtual Private Network that acts like a LAN allowing computers to connect to each other within the VPN. VPN technology relies on the internet to create this network.

Personal area network (PAN)

- A short-range network of personal devices, such as cell phones, tablets, printer, PDA, laptop and audio headsets, often utilizing Bluetooth short-range radio.

Peer-to-peer (P2P)

- Is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the application.

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3.1.2 Outline the importance of standards in the construction of networks.

- standards enable compatibility through a common “language” internationally

Standards are necessary in networking in order to ensure that all network hardware communicates with the other pieces of hardware without any issues.

Through the use of the OSI layer model if any standards change then the rules set out can easily be changed without having to rewrite the complete rule set.

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3.1.3 Describe how communication over networks is broken down into different layers.

- Awareness of the OSI seven layer model is required, but an understanding of the functioning of each layer is not

A network is two or more computers connected together allowing the computers to communicate and collaborate with each other. When one computer sends a signal to another across a network there is a range of different activities that have to take place. Think of each of these as a layer. The layers range from the physical layer where voltages are placed on wires to transmit the data to the software (video calling, mail applications and antivirus software for example) that wants to use the network to send or receive a signal. Each layer performs its own specific task/job and happens at a different stage within the process of sending/receiving across a network.

Notice that

on each layer the packet is added to with all the necessary information (shown in the middle column)

each layer communicates with the layer below it at the sending computer we start at layer 7 and work down at the receiving end we start layer 1 and work up the middle column represents the packet that will be 'packaged up' send and 'unpacked'

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3.1.4 Identify the technologies required to provide a VPN.

VPN (Virtual Private Network) : A secure network that uses primarily public, telecommunication infrastructures, such as the Internet, to provide remote offices or travelling users an access to a central organizational network.

There are three types of VPN:

1. Secure: All traffic on the VPN must be encrypted, authenticated and is the sent along virtual tunnels.

2. Trusted: All traffic on the VPN relies on the security of a providers network to protect the traffic.

3. Hybrid: A combination of both secure and trusted technologies.

Site to Site VPNA site to site VPN allows offices in different locations to connect securely over a public network, such as the internet. Each site has a VPN gateway, like a router, firewall or concentrator. The VPN is in charge of encapsulating and encrypting all outbound traffic and sending it through a VPN tunnel over the internet to a peer VPN gateway at the target site. On receiving the packet the VPN gateway strips the headers, decrypts the content and relays the packet towards the target host inside the private network.

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Remote Access VPNIn a Remote-access VPN, clients, such as telecommuters, mobile users, and extranet

consumers, are able to access a company network securely over the Internet. Each host and client typically has VPN client software loaded or uses a web-based client. Whenever the host tries to send any information, the VPN client software encapsulates and encrypts the information before sending it over the internet to the VPN gateway at the edge of the target network. On receiving the packet the VPN gateway strips the headers, decrypts the content and relays the packet towards the target host inside the private network.

http://computer.howstuffworks.com/vpn.htm

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3.1.5 Evaluate the use of a VPN.

- The use of VPN has led to changes in working patterns

Data transmission

3.1.6 Define the terms: protocol, data packet.

PROTOCOL = Set of rules or guidelines to enable different devices to communicate with each other.DATA = anything that is sent over a network, files.DATA PACKET = data that has been broken down to ensure integrity and reliability since packets are smaller than data, which means if you lose a packet you don't need to resend the whole file only the packet which is missing.

3.1.7 Explain why protocols are necessary.

Include:

- data integrity- flow control- deadlock- congestion- error checking

Protocols are necessary as their function is to allow two or more devices to be able to interact with each other. Protocols are a method of neutral mediation. Protocols do not need to be public, and can be kept confidential.

DATA INTEGRITY = maintenance of accuracy despite natural events (hardware failure, data entry error, fire...)

A DEADLOCK is a situation in which two or more competing actions are each waiting for the other to finish, and thus neither ever does.

FLOW CONTROL = statement whose execution results in a choice being made as to which of two or more paths should be followed.

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CONGESTION occurs when a link or node is carrying so much data that its quality of service deteriorates. Typical effects include queueing delay, packet loss or the blocking of new connections. A consequence of these latter two is that an incremental increase in offered load leads either only to a small increase in network throughput, or to an actual reduction in network throughput.

ERROR CHECKING

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3.1.8 Explain why the speed of data transmission across a network can vary.

Different factors affect the speed of data transmission being:

the computer processor speed - a computer with dual Pentium IV processor will most likely get faster connectivity compared to one with a Pentium III or Pentium II processor;

internet speed will depend on distance that the data travels, how many servers it has to go through and the different speeds of each server (the shorter the cables or the closer the computers are to the router the faster the connection);

heavy traffic on the network (ISPs are allocated a certain amount of bandwidth which is shared among all the incoming and outgoing connections);

Malware, Spyware and Viruses hinder the operation of programs, slows down the speed of connectivity;

Modem speed - can slow down the speed at which data is transmitted; hardware problems- can seriously reduce the speed of the data being processed by your system;

software problems; memory available- each thing you open is using RAM memory and has to write this to the

disk and the more memory you are using up to open programs the less memory there is a available to receive data etc.

3.1.9 Explain why compression of data is often necessary when transmitting across a network.

- Compression has enabled information to be disseminated more rapidly.

A network has limited bandwidth, in that only a certain number of bits can be push through it at any one time without losing data.

To reduce the use of bandwidth in a network, and hence ensure that the network does not becomes congested, redundancies in datacan be removed. This process is called compression.

The following excerpt from St. Julians:

You can assure speed in data transmission by compressing data. There are two types of data compression:

Lossy data compression: This type of compression removes the unnecessary data. It is mainly used in pictures, example: conversion of a picture from GIF to JPEG and conversion of an audio file from WAV to MP3. Example of how this works: imagine a picture with a blue sky, almost every pixel in that part of the picture has a different shade of blue even if the change from one shade to another is almost null.

When you apply lossy compression it takes a number of different shades and turns them into an 'average' shade. It is a very efficient and smart type of data compression because you can't really notice the difference unless you zoom in on the picture. The main difference between this and lossless compression is that with lossy compression you can't get the original file back.

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Lossless data compression: This type of compression allows you to recreate the original file. It involves breaking the original file into a smaller version while it is transmitted or stored in a way that when it reaches its destiny it can be put back together and used as before. Example of lossless data compression is when you zip an amount of files into a file (usually done with 7-zip).

3.1.10 Outline the characteristics of different transmission media.

- speed

- reliability

- cost

- security

METAL CONDUCTOR

FIBRE OPTIC

WIRELESS

Fibre OpticsAn optical fibre is a thin, flexible medium which conducts quick pulses of light which each represent one bit. Fibre optics can transfer humdreds of gigabits per second and can´t take electromagnetic interfearance, making it the preferred choice of long-haul transmission media.

Twisted PairThe twisted pair copper cables are the most inexpensive type of transmission media and has been used for many years by phone companies. Two copper wires are twisted together and coated with a protective layer.

Coaxial CableLike twisted pair, coaxial cable consists of two copper wires, but instead of being parallel, they are concentric. With the construction and special type of shielding and insulation, the coaxial cable can carry a lot more bits much faster than the twisted pair.

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Medium Transfer rate (bandwidth) (Mbit/s)

Relative Cost Example of Use

Coaxial cable 10

UTP cable Medium

Fibre optic cable

High

Wifi

Satellite For internet connection in remote areas e.g. Antarctica.

Microwave

3.1.11 Explain how data is transmitted by packet switching.

- Wireless networks have led to changes in working patterns, social activities and raised health issues.

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Wireless networking

3.1.12 Outline the advantages and disadvantages of wireless networks.

Advantages Disadvantages- Uses unlicensed radio spectrum

Doesn’t cost anything- LANs can be setup without cabling

Doesn’t take space or time to lay the cables. No extra cost on cables

- WiFi can support roaming between access pointsPeople can switch from router to router automatically depending in which connection is best

- Global standards- Prices are cheap

Many types are available on the market and they are affordable

- InterferenceThe 2.4 GHz spectrum is often crowded with other devices

- Limited range- WEP

This encryption is not difficult to hack - Access point

These can be used to steal data- Health concerns

3.1.13 Describe the hardware and software components of a wireless network.

- Router- Modem- Computer device- ISP- Access points (allow the network to join an existing wired network )- Managed wireless networks

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- Software for security- O.S- PIMs (software designed to help users organize random bits of information)

3.1.14 Describe the characteristics of wireless networks.

- WiFi- Worldwide Interoperability for Microwave Access (WiMAX)- 3G mobile- Future networks

WiFi

- A Wireless Access Pouint (WAP) will provide a wireless signal that allows data transfer between it and a device. The current protocol for a WAP is 802.11, which is able to communicate with approx. 30 clients over a 100m radius and has a theoretical top speed of 300 Mbps. Will normally have WPA2 encryption, which is considered secure along with a password.

o Is short for wireless fidelity

o The standard for Wi-Fi today is 802.11

o Creates local area networks that device with internet can

connect to

o Maximum range is and eighth to a quarter of a mile

o Speed is 11Mbps or greater

WiMAX

- Worldwide Interoperability for Microwave Access (WiMAX) "is a wireless communications standard designed to provide 30 to 40 megabit-per-second data rates, with the 2011 update providing up to 1 Gbit/s for fixed stations." - Wikipedia

- WiMAX Forum describes it as " a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL "

- WiMAX is a part of fourth generation wireless-communication technology (4G) and is able to cover a staggering radius of about 50 km.

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o Was designed to make high quality, long range data and voice

communications affordable

o Maximum range is 3-5 miles

o Speeds from 4Mbps to 6 Mbps

3G

- Third generation mobile telecommunications is a set of standards for mobile phones and mobile communications, and is able to deal with video and audio files for these devices. It has a potential transfer speeds of up to 3 Mbps, in comparison to 2G's 144 Kbps.

o It is the third generation of mobile networking

o Download speeds of 14.4 Mbps and Upload speeds of 5.8

Mbps

o Minimum speed for stationary user is 2 Mbp

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Future Networks

LTE - It is part of the fourth generation wireless-communication technology and is only provided in a hand full of countries. It is theoretically capable of speeds of up to 299.6 Mbps

4G

Speed can be up to 100 Mbps

Is compatible with a vast array of devices

Access to services anytime anywhere

3.1.15 Describe the different methods of network security.

- encryption types- userID- trusted media access control (MAC)

Wireless networks have led to concerns about the security of the user´s data.

ENCRYPTION

You are using encryption on your wireless network, aren't you? By now, there are extremely few manufacturers producing Access Points (AP) that aren't secured by default, or as part of the setup process. Here’s a small explanation of the various wireless LAN security methods:

Wired Equivalent Privacy (WEP)- is a depreciated method of wireless security which can be cracked by a malicious individual within minutes. So what you really need to know is don’t use it. It’s usually easily identifiable, since the password is generally a series of hexadecimal characters (that is: 0–9, A–F).

Wi-Fi Protected Access (WPA)WPA encrypts information, and checks to make sure that the network security key has not been modified.

WPA also authenticates users to help ensure that only authorized people can access the network.

There are two types of WPA authentication: WPA and WPA2.

WPA is designed to work with all wireless network adapters, but it might not work with older routers or access points.

WPA2 is more secure than WPA, but it will not work with some older network adapters.WPA is designed to be used with an 802.1X authentication server, which distributes different keys to each user. This is referred to as WPA-Enterprise or WPA2-Enterprise.

It can also be used in a pre-shared key (PSK) mode, where every user is given the same password.

This is referred to as WPA-Personal or WPA2-Personal.

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Pre-shared Key (PSK)PSK is the most common method of securing a wireless network, mostly because it’s the easiest to implement and doesn't require a separate authentication server (more on that later). In this method, everyone on your secure wireless network connects to access points utilizing the same password, which is probably known by everyone. For a home environment, this is probably OK. You’d assume that most of the people you’re letting on your network are your friends or family, and – depending on the quality of your friends and family – you can probably trust them with access to your network.The trouble with PSK is, especially for businesses, that if you want to remove one user’s access to your network, you need to give everybody else the new key. This may include all of your employees, contractors, and any other guests that have been on your network. It could be a lot of work for a large company, especially if it’s all because of one employee leaving the company.There’s a solution, and most corporations already have the tools necessary to implement the fix.

User IDAlso known as a username, a user ID is the name a user logs in to a system with. Usually used alongside a password it is one half of a set of credentials a user knows in order to access a system.

Media Access Control(MAC) Layer is one of the two sub layers that make up the OSI model’s Data Link Layer.

MAC layer moves data packets to and from one Network Interface Card (NIC) to another through a shared channel.

A Media Access Control address is a unique identifier assigned to network interfaces for communications on the physical network segment. Can be described as Ethernet hardware address (EHA), hardware address or physical address. It is assigned by the manufacturer of a network interface card (NIC) and are stored in its hardware, the card's read-only memory, or some other firmware mechanism.

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The advantage to MAC filtering is that there is no attachment cost to devices that connect to the network. The policy is set on a router or switch, and the equipment attached either is permitted or it is not. The person attaching the equipment has nothing to do.

The disadvantage to MAC filtering is that it is easy to spoof due to the broadcast nature of LAN and WLAN, an advisory can sit on the wire and just listen to traffic to and from permitted MAC addresses. Then, the advisory can change his MAC address to a permitted one, and in most cases obtain access to the network

3.1.16 Evaluate the advantages and disadvantages of each method of network security.

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