Information: G061 - Systems and Communication

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ICT Theory Revision Guide

3.1.1 Data, Information, Knowledge and Processing

a)

Data is the raw facts and figures (alphanumeric characters), without meaning. For example, 211210 is the data entered in when entering the date 21/12/2010.

b)

Information is processed data with a meaning (and sometimes context and structure):

Information = Data + [Context] + [Structure] + Meaning

c)

d)

Information is processed data with a meaning, structure and context.

Knowledge is the application of that information to a situation.

e)

f)

Direct (primary) data is data collected from an original source. It is data that has been physically collected by you.

Indirect (secondary) data has two interpretations:

- Data that has been used for a purpose different to that for which it was originally collected.

- The people/companies involved in collecting the data are different to those using the data. For example, market research companies.

g)

A static information source is one where the data, once created, does not change. For example, books and CDs.

A dynamic information source is one where the data can change and be updated. For example, pages on the World Wide Web and CD-RW.

h)

To understand what the quality of information produced will be like, we must determine how good the data entered is. This depends on six factors:

i)

Encoding data is taking the original data and storing it in a different representation.

j)

Validation ensures that the data value entered is sensible and reasonable (doesn’t check if it’s accurate).

  • Range Check - to check that the value entered is within a pre-determined range.
  • Type Check - makes sure that the data is of the correct data type.
  • Check Digit - allows a number to be self checking – the computer applies a set of rules which determines of the numbers entered are valid. (ISBN)
  • Field Length Check - checks the number of characters entered (minimum and maximum)
  • Field Presence Check - makes sure data has been entered into a field
  • Lookup Check – takes the value entered and compares it against a list of values in a separate table
  • Picture/Format Check – makes sure the location of the numbers and letters in the data is the same every time (differs from a type check, which checks the overall type)

k)

Verification ensures that the data entered is entered correctly (reducing errors), but not that it is correct itself.

  • Computer verification (double entry) - you enter the data in twice and the computer checks the entries.
  • Manual verification (proof reading) - you enter the data in and check manually from the screen against the source.
  • Lookup verification - having part of the data and retrieving the rest/checking the rest by looking up the data on a list (e.g. postcode)

l)

Back-up is keeping a copy of the current data. It is important so that data is not lost, so is written at short intervals.

There are many different back-up devices, including:

  • external memory: floppy disk, memory card, etc.
  • external hard drive
  • tape
  • making a second copy on a different disk, storing it off site.

Archiving is for long-term storage of data that is not required immediately, often at all. Archiving is written to large capacity storage devices at long intervals.

The procedure for archiving files is:

  1. Copy the file onto the archival media (disk or tape).
  2. Verify the copied files (make sure the two copies are exactly the same and the copy has worked).
  3. Delete the original files.

m)

Information costs time and money to be produced. Costs are incurred in four main areas – hardware, software, consumables and personnel.

Hardware can be used to collect the information, process it and output it. The initial costs of the hardware are expensive. Ongoing costs include repair, maintenance, network management, etc.

Software licenses need to be purchased, including operating systems, utilities, etc. There may also be training costs to train users how to use the software.

Consumables are items that get used, including paper and printer ink/toner.

Personnel costs are the costs related to people working in the organisation.

n)

 

Feedback is where the output from the system forms part of the input to the system.


3.1.2 Software and Hardware Components of an Information System

a)

Hardware is the physical components that make up a computer (e.g. graphics cards and speakers).

Software is the programming code that makes the computer work (e.g. applications and operating systems).

Standardisation is the imposition of a set of standards on manufacturers. It affects web pages (page may be displayed differently), company takeovers (lack of global standards means the two systems can’t work together), and ICT manufacturers (allows them to release new hardware and make more money).

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Disadvantages:

b)

Input devices needed for different situations include:

  • Touch screen
  • OMR (optical mark reader)
  • OCR (optical character recognition)
  • Bar code reader
  • Magnetic strip
  • Chip and pin
  • Biometrics
  • Keyboard
  • Mouse
  • Microphone
  • Sensors

Output devices needed for different situations include:

  • Monitor
  • Laser printer
  • Inkjet printer
  • Impact printer
  • Plotter
  • Speakers
  • Motors

Storage devices needed for different situations include:

  • Hard disk
  • Floppy disc
  • Zip disc
  • CD-R
  • CD-RW
  • DVD
  • Magnetic tape
  • Flash drive

c)

Visually impaired specialist hardware:

  • a Braille keyboard
  • a microphone (used with voice recognition software)
  • a loudspeaker (text read ...

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