Transcript Document

Unit 1B – Capabilities & limitations of ICT
Capabilities & limitation of ICT
ICT vs Manual methods of data processing
Case Study – the school reporting system
Your intermediate reports used to be done by hand, the
system has now been computerised.
What benefits are there of having a computerised reporting
system ?
Capabilities & limitation of ICT
ICT vs Manual methods of data processing
Case Study – the school reporting system
The old system was for subject teachers to transfer
levels and effort grades from their mark books into a grid
for pupils in each form.
Image of markbook & grid sheets in here
Capabilities & limitation of ICT
ICT vs Manual methods of data processing
Case Study – the school reporting system
These levels and grades were then copied onto pupil
report sheets by form teachers.
Image of report sheets in here
Capabilities & limitation of ICT
ICT vs Manual methods of data processing
Case Study – the school reporting system
The grids and duplicates of the reports were then stored
in a room.
Image of bundles of reports in here
Capabilities & limitation of ICT
ICT vs Manual methods of data processing
Case Study – the school reporting system
The new, computerised system requires teachers to
select the class they teach and then enter levels and
effort grades into the class list.
Image of class list page in here
Capabilities & limitation of ICT
ICT vs Manual methods of data processing
Case Study – the school reporting system
The data for each pupil is then processed and printed.
Image of final printout in here
Capabilities & limitation of ICT
ICT vs Manual methods of data processing
Case Study – the school reporting system
Consider the two systems and using a table (full page of
A4 with explanations) make a comparison of the two
systems :
Manual
Repetitive processing
Speed of processing
Data storage capacity
Speed of searching
Accuracy & speed of data
communications
Ability to produce
different output formats
Computerised
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Consider the effects of :
Hardware
Software
Suitability of operating system
Communication
GIGO
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Hardware :
Does the existing hardware meet minimum specifications for the
software? Ideally it should meet the recommended
specification.
System Requirements
Minimum System Requirements:
Intel® Pentium® or AMD® Athlon® 2 GHz
512 MB RAM
Windows® XP or Windows 2000 (XP recommended)
USB 2.0 port
Direct X® compatible graphics card (ATI® Radeon® or NVIDIA® GeForce" or higher
recommended)
Direct X compatible sound card
650 MB hard disk space
DVD burner, mouse, CD-ROM drive
Hardware specifications:
External Hi-Speed USB 2.0 video capture device
Composite video input (RCA connector)
S-Video input (mini-DIN connector)
Stereo audio input (2 x RCA connectors)
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Software : (object linking and embedding)
OLE allows information to be shared between different
programs
–For example, a spreadsheet created in Excel can be
included in a Word document either by embedding it in the
document, or by creating a link from the document.
An embedded object has no connection with its original source
file.
A linked object ensures that the information displayed in the
document will always be displayed – via the link – directly from
the source file.
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing
systems
Software :
Linked object
–original information remains in the source file
–destination file displays a representation of the linked
information but stores only the location of the original data
–linked information is updated automatically if you change
the original data in the source file
–Use if file size is a consideration
Embedded object
–becomes part of destination file.
–because an embedded object has no links to the source
file, the object is not updated if you change the original data
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Software :
Consider the data processing efficiency of a piece of software
in terms of :
Ease of data entry
Speed of processing
Compatibility
Memory requirements
Unnecessary features
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Suitability of operating system
Operating systems available are :
Windows – most common PC op sys
OSX (Panther) – most common apple mac op sys
Unix/Linux – GUI similar to windows but open source
MSDOS – command line driven op sys
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Suitability of operating system
Operating systems deal with
Memory management.
Resource allocation and scheduling
Backing store management
Interrupt handling
Allowing a user to communicate with the computer
Controlling peripheral devices
If the operating system does not run efficiently then the
application software will not run efficiently.
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Communication
If an application is being used on a network machine and the
processing is taking place over the network (grid processing)
then the efficiency & capability of the network becomes a factor
when considering efficiency of processing.
GIGO – garbage in = garbage out
If the data entry method is inefficient or input data is not valid
then the efficiency of processing is affected – errors will occur
during the data processing stage.
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Other factors affecting efficiency
Change in circumstance during software development
Software takes a long time to develop, if during this time
another product comes onto the market or a new system is
released (win 98 vs win XP) then the development of the
software is affected.
Speed of implementation
Once an organisation has acquired software it has to implement
it, this involves installing & training. This has a direct affect on
processing efficiency
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Other factors affecting efficiency
Compatibility
When windows XP was released, users who upgraded from win
98 suddenly found that their scanners / printers / applications
would not work – oops.
Insufficient testing
Software development is a very competitive field with pressure
to release products ahead of the field. As a result, software is
sometimes not fully tested.
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Other factors affecting efficiency
Poor communication with user
The user interface may not be very friendly (how ?)
Validation rules may not have sensible error messages,
informing the user of their mistake
The instruction manual could be poor
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Ability of user
If the user is clueless then the efficiency of data entry /
processing is affected.
It has been postulated
that if a monkey
randomly hit keys on a
PC for 10,000 years
then at some point they
would type the entire
works of Shakespeare !
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Poor post implementation
Post implementation is the procedures / actions that are
carried out after the software has been installed. These
could be :
Training
Monitoring
Evaluation
Capabilities & limitation of ICT
Factors affecting the efficiency of data processing systems
Maintenance procedures
• Required
for a number of reasons
Errors may appear in the software
• Original requirements are modified
• Hardware developments may make it desirable to change
the software to take advantage
• New legislation may be introduced
•
Factors affecting the efficiency of data processing systems
Types of maintenance
•Perfective maintenance
system can be made better in some way without changing its
functionality.
•Adaptive maintenance
changing needs in a company may mean systems need to be
adapted – e.g. a single-user system may be adapted to a multiuser system.
•Corrective
maintenance
involves correction of previously undetected errors. e.g. the
millennium bug. Many major programs are released with ‘bugs’
that require maintenance releases – ‘patches’ or ‘service packs’ to
fix them (most of the Microsoft products)
Factors affecting the efficiency of data processing systems
Types of maintenance (cont)
• Process triggered by:
–
–
user or management requests
Further development by manufacturer
• Cost and impact on system are assessed for
feasibility
• New release has to be programmed and tested
• Software packages generally have release
numbers
–
–
Minor releases are indicated by a change in number
suffix e.g. 3.0 to 3.1 with Windows
Major releases are often indicated by a change like 4.0
to 5.0 or by a change in name
Factors affecting the efficiency of data processing systems
Types of maintenance (cont)
•Most
software developers would prefer to be working on exciting new
projects
•Maintenance
is very expensive
•Cost-effectiveness
depends upon
•A clearly-defined and well-documented original system
•Suitably qualified and informed analysts and programmers
•A clear
and uncomplicated dialogue path between user and developer
•A transparent structure that allows analysts and programmers to
fully the impact of any changes
•Limiting the amount of change at any one time
assess
Factors affecting the efficiency of data processing systems
Cost
Cost can be considered in terms of money, time and human
resources.
If a system has a high financial cost and takes a long time to be
implemented or process data then it would be considered
inefficient.
Factors affecting the efficiency of data processing systems
Hardware
(refer previous notes)
The hardware that is needed to run software efficiently is a factor to
be considered :
Is the hardware powerful enough to run the software ?
Is the hardware reliable enough ?
Is new hardware needed to run the software ?
Is the hardware compatible (mac vs PC)
Factors affecting the efficiency of data processing systems
Support
When you purchase software you often receive a form of support.
This may be in the form of :
-Help
files
-Online
(internet) help
-Technical
advice over the phone
-Engineer
callouts
-Updates
Nature & Capabilities of Software
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What is software?
Types of software
Generic software
Drivers, protocols and standards for interfacing with
peripherals and storage devices
Object linking and embedding
Functionality of internet software
Compatibility and portability
Features of software & evaluation/comparison
Upgrading - technical and human implications
Reliability - how do we make software reliable?
Nature & Capabilities of Software
What is software?
• Hardware is the physical
components that make up a
computer system.
• Software is the programs
and data that make the
hardware do something
useful.
• Software is NOT the CD or floppy disc that the program
comes on - usually you are just buying the licence to
use the software, and not the software itself.
Nature & Capabilities of Software
Firmware
• You may also come across the term Firmware - this
is software that is stored in hardware (i.e. on a chip)
and is usually found in embedded systems.
• Not all computers are multi-purpose desktop or
laptop PCs, mainframe or mini-computers, so are
designed for a specific purpose and are built into
machinery - these are called embedded systems.
• Embedded systems
are mostly used for
control, e.g. in
washing machines.
Nature & Capabilities of Software
Types of Software
There are three main categories of software:
• Operating systems
• Utility programs
• Applications
Applications come in different types :
•
•
•
•
Specific purpose - e.g. Encarta, POS, etc.
Generic - e.g. spreadsheets, databases, etc.
Off the shelf - i.e. a product such as Sage Accounts
Bespoke - i.e. custom-made for the user
Nature & Capabilities of Software
Operating Systems
• Control and manage the computer’s resources
– memory management
– resource allocation
– storage
– communication
– interrupt handling
• Examples include Windows (NT, 2000 and XP only, not
versions up to 98), Unix, Linux, CPM, Mac-OS.
• Heathcote says that they are installed on the hard disc,
but this is not always the case, e.g. RISC-OS, PDAs,
embedded systems and early home computers such as
Spectrums and VIC-20s!
Nature & Capabilities of Software
Kernel
Shell
Operating Systems
• The kernel is hardware
specific and controls primary
and secondary storage,
input and output.
• The shell provides the user
interface - this could be a
command line or a
Graphical User Interface.
• It is possible that an operating system, e.g. Windows NT
or Linux, could run on several platforms (e.g. Intel, Power
PC, DEC Alpha) by having the same shell with different
kernels
Nature & Capabilities of Software
Memory Management
• System resources and hardware
often require memory which
must be allocated by the OS
• Most modern operating systems
are capable of multi-tasking
(running several programs at
once) - each program will require
its own area of memory to store
data.
• Some types of OS can use multiple processors, so they
must also decide where a process takes places, as well
as which memory it will use!
Nature & Capabilities of Software
Memory Management
Primary storage (e.g. RAM):
• Volatile - i.e. contents are lost without power
• Fast - access time of around 7ns for PC RAM
• Relatively expensive - 1Gb DDR RAM costs £140
Secondary storage (e.g. hard disc):
• Non-volatile, usually magnetic
media - stored without power
• Slower - access time of around
8ms
• Cheaper, e.g. 40Gb for £35
Nature & Capabilities of Software
Virtual Memory
• Sometimes the operating system can use secondary
storage to supplement primary storage in a way that is
transparent to the application - this is called virtual
memory
• RAM
overflows
onto the
disc - e.g.
in the
Windows
paging/
swap-file
Nature & Capabilities of Software
Disc Storage
Sect
or
Constant angular
Constant linear
velocity
velocity
• CLV discs (e.g. Compact Discs) slow down as sectors
nearer the edge are read - the sectors are the same
physical length so that capacity is increased
Nature & Capabilities of Software
File Allocation and Fragmentation
• File A is written
A
A
• File B is written
A
B
A
B
B
B
B
A
B
• File A is edited
• Disc is fragmented
• The disc is now
defragmented - the
sectors are contiguous
and so quicker to read
• Location of file is stored
in the File Allocation
Table (FAT)
Nature & Capabilities of Software
User Interface
• Manages multi-tasking – e.g. each application in
a separate window
• Allocates events to the appropriate application:
– Mouse movement
– Mouse click/double-click
– Key presses
– Timers
Keystrokes
Mouse
movements or
clicks
Shell
GUI
WIMP
Menu
Command
Nature & Capabilities of Software
User Interface
• Provides the ability to transfer information between
applications – e.g. the clipboard in Windows
Application
Clipboard
Copy
A
Past
e
• Provides a consistent
appearance to
applications, e.g.
menus, help, printing
and error messages
Application
B
Nature & Capabilities of Software
Peripherals
• Peripherals can be connected to a computer either
internally - e.g. video or sound cards - or externally,
through USB, serial or parallel ports.
• Internal devices are serviced through interrupts - the
OS polls each device in turn to see whether it requires
any processing time.
• The operating system communicates with the device
through a driver.
• A driver is a piece of software that translates the
user’s instructions - e.g. that they want a particular
piece of text to be bold - into the device-specific control
codes that the particular hardware uses.
Nature & Capabilities of Software
Utility Programs
• A utility is a small program, usually with a technical
function - they often come with an operating system.
• Examples of utilities are:
– Virus checkers
– Windows Explorer/File Manager/Xtree
– Printer Manager
– Scandisk & Defrag
– Winzip (or other compression software)
– Norton Utilities/PC Tools
– Compilers and interpreters
– Performance monitoring
– Backup and restore
Nature & Capabilities of Software
Applications
• Written for a specific purpose - inflexible
• Such systems may be bespoke or off-the-shelf
• Bespoke systems are those written specifically for a
particular customer, usually in a language such as
C++, Visual BASIC or Java, e.g.
– Point of Sale (POS) systems
– Insurance quotation systems
– Management Information Systems (MIS)
• Off-the-shelf software is the boxed products you
might see in PC World:
– Sage Accounting
– AutoRoute
Nature & Capabilities of Software
Bespoke Software
• Purpose-designed for
task - it does exactly
what you want (or
what you asked for,
anyway!)
• Purpose-designed for
hardware
• Extra features can be
integrated more easily
• More likely to be bugridden
• Tied into one suppliers,
e.g. for:
– documentation (no
books!)
– training
– support
• Portability of data is less
likely
• Much more expensive
Nature & Capabilities of Software
General Purpose/Generic Software
• Some software wasn’t designed for a specific purpose they are known as generic or content-free applications
• Examples of generic software include:
– word processors and DTP applications
– database management systems
– spreadsheets
• Integrated packages contain several of these functions
in one application - e.g. Microsoft Works or Lotus
Symphony
• Software suites contain these functions in separate
applications, e.g. Microsoft Office or Lotus SmartSuite