Y11 Revision Jan 2010

Testing• Validation (ensuring data is SENSIBLE)• Verification (ensures data is correct) – visual check when entering data

also retyping such as password (double entry).•  • Check digit —single digit computed from data to check for errors. • Eg 5432 4 sum5432 = 14. 14mod10 = 4 last digit. This can be used to

check other digits are correct. Mod gives remainder.•  • Checks include – Data type check, Length check and Range check. 

– Data type = if data type is number test with text i.e. A, you should get an error explaining wrong data type.

– Length—the field length for a maximum number 99 is 2 which means no more than 2 digits. A length check would be to try and enter more characters than are allowed.

– Range—for numeric fields including number, date and currency a validation rule specifies a “sensible” range. Example the cost o f items on a takeaway menu might have the following validation— price >= 1 and <= 25, check digit

Range Check• A range check will check data within, outside the range and

on the boundary.• Normal— valid within the range.• Extreme—valid but are on the boundary.• Abnormal—invalid data below and above the range

9 | 10… …20 | 21

Extreme (10,20)

Normal (11..19)

Abnormal (<10 and >20)

Data must be

>9 AND <21

Life cycle• Analysis – analyse the information requirements of the system including

inputs, processing and outputs.• Design – based on the requirements produced during the analysis stage

design the interface, processing and output (reports etc..) Also design a hardware specification to determine what hardware the system will run on.

• Development – create the system, make database tables, forms, queries, reports, write software and install the hardware.

• Test the system to make sure it meets requirements.• Implementation – put the new system “live” so the end users can start suing

it.• Evaluation – evaluate the system to ask if meets the needs of the user and

consider how it might be improved in future releases.• Maintenance – ongoing maintainence will be required to fix small bugs,

backup files etc..• Documentation – user guides and other technical documents will need to be

created to help the user understand the system and to help technical personnel maintain it.

Implementation

• There are 3 ways to “rolll out” a new system• Direct – stop using the current system and start using

the new. Adv – quickest, cheapest Disadv – if the new system is buggy and fails there will not be an old one to fall back on.

• Parallel – run the old system and new system at the same time. Adv – the old system can be used if the new system fails. Disadv – a lot of work to maintain two systems side by side.

• Phased – divide a large project into phases and release at different times. Adv – smaller phases can reduce the risk of too many problems at the same time. Disadv – it can take longer to roll out a new system.

Implementation electronic register

• Direct – all year groups use electronic register.– Adv – quick – – Disadv – no “old” system to fall back on if there are problems

with the new system.

• Parallel – Use paper register with electronic register for several weeks– Adv – if new system has problems the paper register still have

the data– Disadv – using both systems at same time means more work.

• Phased – Phasing in the system – Upper school first – once this is stable then – lower – then middle school.– Adv – problems are smaller so more managable.– Diadv – takes longer to implement the whole system.

Robots

• Robots are machines that can act automatically.

• What are they used for?– Areas that are dangerous – i.e. bomb

disposal.– Repetitive work – spot welding, spray

painting, lifting and moving boxes, drilling, stamping (metal into shapes)

Robots Advantage/Disadvantage

• Can work 24 7 365 – almost.

• Can be more accurate• Can work in hazardous

environments• Don’t take breaks• Don’t go on strike• They don’t charge by the

hour

• Expensive to purchase• If there is an error they

will need to be reset (unless capable of self detect)

• Need reprogramming for new tasks

• Expensive to repair/maintain

Robots social impact

• Workers made redundant

• Deskilling of skilled and semiskilled workforce

• Workers need to retrain /relocate

• Workers don’t need to work in dangerous environments

• New jobs are created to maintain, develop and design robots

• Production cost of goods has come down.

RAM / ROM

• RAM random access memory

• Volatile – data lost when power switched off

• Data can be changed• Data is stored temporarily• RAM – is working

memory and holds data that is being worked on.

• ROM – read only memory• Non-volatile – data not

dependent on power• Read only – can’t change

data• Data is stored

permanently• ROM – holds data that

needs to be read/copied only such as software on CDs or ROM BIOs that gives the computer basic instructions when it is started.

Control / Data Logging• Control – input/processing/output• Real time processing –• Input sensors – temp, pressure, light

etc..• Control – if input > X then swtich

output On/Off.• Output – light, buzzer, motor etc..

• Data Logging – • Input(sensors)storage (data

logger)/logging intervals/analysis• Input sensors, temp, humidity, pH.• Interval – every 30s over 5 mins =

10 data points. Every 30 mins over 24 hrs = 48 data points.

• Data copied into spread sheet to analyse and create graphs

• Analogue – continuous value – continuous temperature increase.

• Digital – exact value – i.e. 20c• Analogue Digital Convertor ADC –

converts analogue to digital data. Computers only work with digital data.

Internet as Data Source

• Lots of information on many topics

• Quick to search• Many sites updated

frequently (books can become out of date)

• Information interactive – i.e. discussion groups can ask questions and get answers

• Information can be inaccurate or wrong

• Information may be offensive

• With so much information it can be difficult to sift through.

• May be violating copyright if not sure who owns it.

Multi media

• Mutli media documents can include power point presentations and web pages.

• Can have wide variety of font sizes, styles and colours.

• Can include images.• Can include links.• Can include sounds.• Can include video.• Can include animation.

Data security 1

• Password protected– Password needed to

access data– Changing passwords

regularly prevents guesses

– Mixing letter and numbers makes password stronger.

– Forgetting password can prevent access to data

• Firewall– Prevents unauthorised

access to computers connected to the internet.

– Does not protect agains virus

– Does not protect against internal attacks – i.e. students within the school.

Data security 2

• Biometric data– Thumb or retinal scan

• Restrict physical access– Locks on computer rooms– Motion sensor /alarms– User’s might forget swipe

card to get in

• Anti virus software– Can detect viruses– Has to be kept up-to-date

to be effective.

• Regular backups– Lost data can be recovered

from copies– Copies should be kept off

site incase of fire– Need to be copied regularly

to be effective