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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

• 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.

(a) CPU & Main Memory

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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

• 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.

(b) Input 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:

Remember!! Hardware is made up of: (a) The CPU and Main Memory (b) Input Devices (c) Output Devices (d) Storage Devices

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Mouse Keyboard Bar Code/Wand Reader Point of Sale Terminal

Plotter Camera Tape Recorder Voice Data Entry

Optical Scanner Magnetic Ink Character Reader Optical Mark Reader

Touch Screen Stylus/Light Pen

Remember!! Hardware is made up of: (a) The CPU and Main Memory (b) Input Devices (c) Output Devices (d) Storage Devices

• these Accept information from the CPU and displays the results for the user.

• EG’s : Printer, Monitor.

(c) Output Devices

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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

Remember!! Hardware is made up of: (a) The CPU and Main Memory (b) Input Devices (c) Output Devices (d) Storage Devices

Monitor Flat Screen Monitor Thermal Printer Ink Jet printer Laser Printer Dot Matrix Printer Character Printer Plotter

Audio Response Microfilm Reader Speaker 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

• 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.

(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:

Remember!! Hardware is made up of: (a) The CPU and Main Memory (b) Input Devices (c) Output Devices (d) Storage Devices

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Magnetic Disk Disk Drive Floppy Disk Disk Cartridge Tape Drive CD-ROM

WORM CD Erasable CD USB Key USB Cable Hard Disk Memory Board

RAM ROM 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

Networks- Includes 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 (modulator-Demodulator) 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.