15/05/2013
ICT THEORY
RE- CAP & REVISION
(SUMMARY OF THE THEORY HANDOUT)
4 MAIN AREAS
1. HARDWARE
2. SOFTWARE
3. NETWORKS, CONNECTIVITY,
COMMUNICATION & THE INTERNET.
4. USE/MISUSE AND CARE OF
COMPUTERS
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Hardware
Hardware: is any physical part of a computer
or the group of machines!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
Remember!!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
•
•
(a) CPU & Main Memory
Main Memory: Stores Programmes.
CPU: Controls all operations/jobs.
(So it reads data, changes it and
produces information for you to
use). It is like the Brain of the
Computer.
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Remember!!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
•
(b) Input Devices
These Devices read incoming Data
and pass it on to the CPU.
EG’s: Keyboard, Disk Drive,
Scanner, Bar Code Reader, Voice
Recognition, and Digital Camera.
Remember!!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
Input Devices
Mouse:
Keyboard:
Bar Code Reader/Wand Reader or Scanner:
Point of Sale Terminal:
Digitiser:
Camera/Tape Recorder:
VDE/Voice Data Entry:
OCR/Optical Character Reader (optical scanner):
MICR/Magnetic Ink Character Reader:
OMR/Optical Mark Recognition/Reader:
Touch screen:
Light Pen or Stylus:
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Mouse
Plotter
Keyboard
Camera
Optical Scanner
Touch Screen
•
Tape Recorder
Point of Sale Terminal
Voice Data Entry
Magnetic Ink Character Reader
Optical Mark Reader
Stylus/Light Pen
Remember!!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
•
Bar Code/Wand Reader
(c) Output Devices
these Accept information from the
CPU and displays the results for the
user.
EG’s : Printer, Monitor.
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Remember!!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
Output Devices
Monitor/VDU Or Visual Display Unit:
Flat Screen Technology’s:
Printer:
Non-Impact Printer:
Impact printer:
Plotter:
Audio response:
Microfiche/film:
Speaker
Digital Projector
Monitor
Laser Printer
Audio Response
Flat Screen Monitor
Dot Matrix Printer
Microfilm Reader
Thermal Printer
Character Printer
Speaker
Ink Jet printer
Plotter
Digital Projector
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Remember!!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
•
•
(d) Storage Devices
Storage Devices: these keep
information and instructions in the
Computer so that they can be used
again.
EG’s: CD’s, Floppy Disks, Hard Drive.
Remember!!
Hardware is made up of:
(a) The CPU and Main Memory
(b) Input Devices
(c) Output Devices
(d) Storage Devices
Storage Devices
STORAGE :
Magnetic Disks and Disk Drives:
Floppy Disk:
Disk cartridge:
Tape Drive:
CDROM: (Optical)
WORM CD’S (Optical)
ERASABLE CD’S:
(Optical)
USB key:
Hard Disk:
MEMORY :
Memory:
Byte:
Speed:
MIPS:
Volatile/Non-Volatile:
RAM/random Access Memory:
ROM/Read only Memory:
Storage Capacity:
Backup:
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Magnetic Disk
WORM CD
RAM
Disk Drive
Erasable CD
ROM
Floppy Disk
USB Key
Disk Cartridge
USB Cable
Tape Drive
Hard Disk
CD-ROM
Memory Board
Storage Capacity
Software
•
•
•
•
Software: Before a computer can actually
read data, change it, and produce
information for you, it needs a set of
instructions. These instructions are in the
Software and they help the computer
carry out different jobs.
EG’s: There are 3 main areas with
Software.
(a)Operating Systems Software
(b)Applications/Programme Software.
(c) Compatibility
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•
•
•
•
Software Types
Operating Systems Software or OS: This software
supervises the overall operations of a computer.
EG’s: IBM use DOS or Disk Operating Software, and
Apple, Macintosh, Dell, and Gateway use Windows
Operating Software.
Applications Software (Program Software): These
are programs that you can simply buy off the shelf
from a retailer/shop like PC world. In some cases a
company may want to use specific programs, in that
case they can get the programme specially designed;
EG’s Schools uses a Facility Programme to keep
school records, Accountants use a Payroll
Programme to do their accounts.
Software Programs
Operating Systems
ICONS
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Compatibility
• Compatible/incompatible Disks: A Disk
that is prepared for one OS may not work
on another OS.
• For Example: Word Perfect for Windows
may not work in Macintosh, you may have
to get the Macintosh version.
• In this case they are incompatible or, they
cannot be used together. If you can use a
disk in two different Operating Systems,
then they are compatible
NetworksIncludes Connectivity, Communciation, & Internet
•
•
Network: this is the idea that computer resources in
an area can be shared by linking them. It is shared by
an Integrated Computer System
(integrated/interconnected).
For Example: Your computer room in school may have
20 computers but only 1 printer, if for example 10 of
these computers can send documents to the 1 printer
to print, then they are sharing the resource or sharing
the 1 printer. Files can also be shared using a network.
A large computer called a server is used to help share
files and information on the network for many people
to use.
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•
•
•
Networks
There are 2 types of Networks: LAN and
WAN.
WAN: This network is used to transfer and
share information over a great distance,
for example, from one country to another
country.
LAN: A Local Area Network is used to
transfer and share information and
resources when computers are close to one
another. For Example, in a LAN the
network may connect devices within a room
or building.
Networks
RING
STAR
BUS
Commonly used and they use a
Server/Host. All
computers/Node are connected
in a loop.
All devices use a computer/Node and
Server/Host, but not necessarily
each other.
Computers/Nodes share the same bus
or channel for transmitting to
other computers/nodes or
Servers/hosts.
Messages pass from Node to Node
before it reaches its destination.
If one node is down, it is just by
passed.
Nodes can access a Host as well as
each other.
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Ring Network
Star Network
Bus Network
Connectivity
•
Connectivity: Telephone lines move
wave signals called analogue signals.
However if a Modem (modulatorDemodulator) is used, it can change
digital signals (from a computer)
into wave/analogue signals so that
information can be sent over phone
lines.
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Communication
• Communication: in order for this
information to be sent, it needs to go
through a suitable communication
channel, or a cable.
• EG’s:Twisted pair Cable, Coaxial Cable, Fibre
Optic
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Internet
• The Internet: allows you to connect with 1000’s of
Networks worldwide.
• For example: you can access thousands of databases
including, newspapers, journals, magazines,
Universities, government agencies, businesses.
• An ISP or and Internet Service Provider will provide
the customer with access to the internet, e.g. Eircom
or NTL.
• ISDN: Some use a dial up connection called an ISDN
Line or Integrated Systems Digital Network. Dial up
lines are becoming less common, as they are slower.
The Internet
• The World Wide Web or WWW helps you to connect with any web
page; you can type in an address in the top address bar called the
URL or Universal Resource Locator.
•
HTTP or Hyper Text Transfer Protocol will help you to search in
this address bar. HTML or Hyper Text Mark up Language is the
Language the internet often uses to carry out commands.
• A hyperlink is a blue link that connects you to another page.
• A search engine e.g. Google or Yahoo will help you to search for
something by typing in words instead of a full address.
• Video Conferencing: this allows full motion video and sound to be
transmitted over telephone lines. The sound is captured by
microphones, it is sent to the listener at a high speed.
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Computer Care
• Ergonomics: This refers to any Health and Safety issues relating to
PC Use. For Example: In your work area: To Reduce Screen Glare,
place a screen over your monitor. To reduce sound pollution in your
office, place sound absorbing materials on furniture, walls, ceilings
and floors.
• To prevent discomfort and permanent injury, create an
ergonomically designed workstation/Desk Area, for Example:
(a) Your arm angle in keyboarding should be 15-30 Degrees below your
line of sight
(b) The Screen should be 3-4 times brighter than the room, to avoid
eye strain.
(c) Your forearms should be horizontal, your lower back should have
support, you should have an adjustable chair, and your feet should
be flat on the floor.
(d) You should have a wrist rest to prevent Repetitive Strain Injury.
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Computer Care
Care of Floppy Diskettes:
• Any disk can become ‘corrupt’ and will not
work if not looked after properly, so you
should always keep a back up, or a second
copy of the information somewhere else.
• Keep the Disk safe in a box or container.
• When writing on the Label, do so, before you
place the label on the disk, as it could damage
it.
Computers V’s People
ADVANTAGES OF COMPUTING
DISADVANTAGES OF COMPUTING
1.
Fast: high Speed of getting Information.
1.
Cost: may be Expensive to start with.
1.
Accurate: It is almost 100% accurate/correct.
1.
Errors: There may be Mistakes inside the
programme.
1.
Compact Storage: No filing Cabinets needed all info on
PC.
1.
Training Costs: Training Staff may be time
consuming and expensive.
1.
Presentation: Clear, Neat Work.
1.
Virus: If a computer gets a Virus, you may loose
everything.
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