GCSE ICT

1
GCSE ICT

• LESSON 6
• Booklet Sections 8, 9 10
• Data storage, Operation Transfer.

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How is data stored?

• Data can be stored in paper-based systems
  including
• Reference books
• Dictionaries
• Encyclopaedias
• Directories
• Index Files
• Filing systems

3
What do all paper-based data systems have in
common?

• The data is stored systematically (e.g.
  alphabetically dictionaries, encyclopaedias,
  telephone directories date order year books,
  almanacs).
• The data has a key piece of information that
  helps users to find what they are looking for
  (e.g. surname in a telephone directory, date in a
  year book).

4
How is data stored?

• It can also be stored in computerised databases.

5
Computerised data systems

• Computerised data systems also known as
  databases are organised in similar ways to
  paper-based data systems.
• However because computerised data systems can
  handle data faster and in more flexible ways than
  paper-based systems, they have begun to replace
  many paper-based systems.

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What is a computerised database?

• A database is a large store of information.
• It should set out so that it can be kept
  up-to-date easily.
• It should be easy to find the information that
  you need.

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What does a computerised database contain?

• The information contained in a database is held
  in RECORDS.
• Each record is made up of one or more FIELDS.
• A FIELD contains a separate piece of information
  within each RECORD.
• A group of related RECORDS is a FILE.

8
Types of field

• There are several types of FIELD.
• The most common are
• ALPHANUMERIC or CHARACTER TEXT - these contain
  letters and numbers, but the numbers can not be
  manipulated.
• NUMERIC - these numbers that can be manipulated.
• LOGIC these have Yes/No or True/False answers.

9
How can a database be used?

• Once the database has been set up, the
  information for each record can be added.
• This information can then be INTERROGATED
  (questions can be asked) to produce REPORTS
  (answers).

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Examples of computerised databases

• Medical records held at hospitals and doctors
  surgeries.
• The Police National Computer.
• School records held on a school SIMS (School
  Information Management System) system.

11
The advantages of computerised databases

• Information usually only needs to be entered
  once.
• Files can be linked together so that when one is
  up-dated all linked files are also up-dated (N.B.
  This is only true of RELATIONAL databases).

• The record structure can be altered after data
  has been entered.
• Access to data is rapid.
• It is difficult to lose data.
• Data can be validated as it is entered.

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The disadvantages of computerised databases

• If the computer system is not working or is
  off-line, the database can not be accessed.
• Because databases contain confidential
  information, they must be kept secure

• People have to be trained to use a database if
  its advantages are to be exploited to the full,
  and this takes time and money.

13
Database Management System

• A data base management system (DBMS) is a group
  of programs that
• Allow data files to be created
• Allow data held in files to be altered
• Allow data held in files to be extracted

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Database Management System

• A DBMS also allows
• Datafiles (or tables held within data files) to
  be linked together.
• Queries (or questions) to be asked of the data.
• Data to be added (or appended).
• Data to be deleted or altered.
• The structure to datafiles (or tables) to be
  altered.

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Database Management System

• A DBMS also allows
• Levels of security by only allowing particular
  users access to each of the datafiles (or
  tables).
• Data to be imported from other computer packages
  (e.g. spreadsheets).
• Data to be exported to other computer packages
  (e.g. mail merge).

16
Methods of computer operation

• There a several different methods of operation.
• Most computers can undertake each of these
  simultaneously.
• These methods of operation are

• Batch mode
• Single program mode
• Multitasking mode
• Multi-user mode
• Multiprocessor mode
• Real time mode

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Batch mode

• In larger computer systems it is sometimes more
  efficient to group together programs (in a BATCH)
  before they are run through the computer system
  (e.g. a company payroll).
• Whilst the computer system is operating in batch
  mode, no user input can take place.

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Batch mode
19
Single program mode
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Multitasking mode
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Multiuser mode
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Multiprocessor mode
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Real time mode
24
Data transfer

• Users often need to transfer data between
  software packages or computers.
• Until relatively recently this was difficult to
  achieve, but the increasing use of computers and
  the growth of ICT has forced software designers
  to make this much easier.
• File conversion from older to newer versions of
  the software.

25
ASCII

• ASCII is the acronym for American Standard Code
  for Information Interchange.
• ASCII is a world-wide standard code for
  representing characters (letters, numbers etc.)
  as binary code.

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ASCII

• Before its introduction, it was almost impossible
  to transfer data between software packages or
  computers.
• For example the letter A has the ASCII code 0100
  0001 and B is 0100 0010.

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An example of ASCII

• HELLO! Is represented by the following ASCII
  code
• H 0100 1000
• E 0100 0101
• L 0100 1100
• L 0100 1100
• O 0100 1111
• ! 0010 0001