grade 6 ict notes

8/19/2019 Grade 6 ICT Notes

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IGCSE ICT - Manual Input Devices 1

IGCSE ICT - Direct Input Devices 25

IGCSE ICT - Sensors 34

IGCSE ICT - Output Devices 39

IGCSE ICT - Control Devices 57

IGCSE ICT - Data Storage and Backing up Data 61

IGCSE ICT - Serial and Direct Data Access 65

IGCSE ICT - Storage Media 69

IGCSE ICT - Magnetic Storage Devices and Media 73

IGCSE ICT - Optical Storage Devices and Media 81

IGCSE ICT - Solid State Storage Devices and Media 92

IGCSE ICT - Comparison of Storage Media 98


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3/17/2016 IGCSE ICT - Manual Input Devices

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The ICT Lounge

Section 2.1:

Manual Input Devices

In this section we will look at how input devices can be used to get datainto a computer system.

In section 2.1 we will focus on manual input devices and then move ontodirect input devices in section 2.2.

For each input device you have to be able to identify it from an image,explain what it is used for and discuss advantages/disadvantages.

Learning objectives of this section:

# Know the purpose of and be able to identify differentmanual input devices.

# Understand the uses of each manual input device.

# Be able to discuss advantages and disadvantages of each manual input device.

Input Devices (what are they?) Key Words:Input, Data, Manual,Automatic

Definition: "Hardware devices that allow data to be entered into a computer."

Overview of Input Devices: Examples:

A mouse is an example of a commonly used

# Input devices are part of the 4 main hardware components of a computer system:

Input Devices - these get data into the computerProcessor - this does something with the data to make it useful informationOutput Devices - these show the results of processingStorage Devices - holds the data in the system.

# The image below shows where input devices fit into a computer system:

This diagramshows where input

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input device.

A keyboards is another example of a commonly used

input device.

NOTE:

More examples will be shownfurther down this page.

devices fit into acomputer system.

# There are two different types of input devices:

1. Manual Input Devices - Data is input into the computer by hand (people haveto do most of the work)

2. Direct Input Devices - Data is input into the computer directly by amachine/device (there is minimal input by people)

Manual Input Devices(data entered by hand)

Key Words:

Keyboard, Keypad, Pointing Device, Remote Control,Joystick, Touch Screen, Scanner, Digital Camera,Microphone, Graphic Tablet, Video Camera, Web Cam,Light Pen

Examples of Manual Input Devices:# The table below shows you some examples of manual input devices. Click each device to move to more information:

Keyboard Numeric Keypad Pointing Devices Remote Control

REMEMBER!

Manual input devicesrequire humans to domost of the work neededto get data into the

system.


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Joystick Touch Screen Scanner Graphics Tablet For example:If you are using akeyboard to inputinstructions into thecomputer, you have pressthe keys yourself. It is amanual job not automatic.

NOTE:

Click the images to the leftto move to more

information about eachone.

Light Pen Microphone Digital Camera Web Camera

Breakdown of each manual input device:

# The following sections will help summarise each of the manual input devices. For each one you will see:

Information about the deviceUses of the deviceAdvantages of the deviceDisadvantages of the device

Keyboard

Information:Examples:

The first five le䘀ered keys of a keyboard spell out

QWERTY.

# Keyboards are one of the most commonly used manual input devices.

# Key boards are used to input the following into the computer:

TextNumbersInstructions

# Most keyboards use a QWERTY key layout. The name 'QWERTY' comes from the first fivelettered keys on on the top row of the keyboard - Q-W-E-R-T-Y.


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Ergonomic Keyboards have a natural shape and built‐inhand‐rest.

Inpung data into a computer using a keyboard.

NOTE:

Command Line operating systemsrequire a keyboard in order to be

able to use the computer at all!

# Special keyboards called 'Ergonomic Keyboards' have been developed to help reducehealth problems (such as repetitive strain injury)linked with typing.

Ergonomic keyboards have a more natural shape to them with reduces stress on the wristand hands.

Ergonomic keyboards also come with a built-in hand-rest which further helps preventhealth issues such as RSI (Repetitive Strain Injury).

Uses of a Keyboard:

# Keyboards are used to input data into applications.

For Example - Entering text into word processing applications like Microsoft Word

Entering numbers into spreadsheet applications like Microsoft Excel

# Keyboards can also be used to enter commands into the computer.

For Example - Keyboard shortcuts:

CTRL + P to printCTRL + S to saveCTRL + C to copyCTRL + V to pastePRT SC to take a screen shot of your work

Advantages/Disadvantages of using a Keyboard:

Advantages Disadvantages

Enables fast entry of text into documents. People with wrist and hand problems can find keyboardspainful to use.

Very easy to use (you just press the keys). Keyboards are quite large and can take up a lot of desk space.

Information that you input instantly appears on the screen.This lets you quickly check that what you are entering iscorrect.

Entering data is slow when compared to automatic methods.

For example - a barcode code scanner will input data into the


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computer almost instantly.

Numeric Keypads


Bank ATM's use numeric keypads to let us enter PINnumbers and withdrawal amounts.

Mobile phones use numeric keypads to allow us to

enter phone numbers.

# Numeric keypads are used for entering numbers into a computer system ('Numeric'means number)

# Some numeric keypads also allow you to enter simple text and symbols.

Uses of Numeric Keypads:

# There are many day-to-day uses of numeric keypads. Here are some of them:

ATM (Automatic teller

machines) -

Entering personal identification numbers (PIN) into an

ATM to allow us to access our cash.

Withdrawing from ATM - Keying in how much money you would like to withdrawfrom an ATM.

Telephones - These use numeric keypads to allow us to enter phonenumbers.

Chip and Pin devices - These have numeric keypads to allow users to enter PINnumbers and payment amounts when we buy goods andproducts.

Advantages/Disadvantages of using Numeric Keypads:


Faster than QWERTY keyboards when usedfor entering numbers.

People with large hands can find themhard to use because of their small keys.

Numeric keypads are small so they caneasily fit on smaller devices like mobile

phones.

Difficult (but not impossible) to enter textinformation.


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Inpung data into a computer using a keyboard.

Pointing Devices (mouse, touchpad, trackerball)

Overview of pointing devices:Examples:

Mice are one of the devices that allow us to control a

screen pointer.

Trackerballs also allow us to control a screen pointer.

# Pointing devices are pieces of hardware that are used to control a pointer (curser) on ascreen.

# Pointing devices are frequently used with Graphical User Interface (GUI) operatingsystems where pointers are used to input commands by selecting icons.

Poin伀ng devices (like mice) are used to control pointers (curser's) and click icons and op伀ons on GUI opera伀ng systems.

# There are three main types of pointing device:

MouseTouchpad

Trackerball

Information about the Mouse:

# There are two different types of mice - a ball mouse and an optical mouse.Examples:

Ball Mouse - Uses a ball under the mouse to detect movement.

Optical Mouse - Uses reflected light to detect movement.


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# The ball (in a ball mouse) and the reflected light (in an optical mouse) allows the user todirect and control an on-screen pointer.

A ball mouse uses a ball to detect movement. These

are prone to clogging which can affect accuracy.

An op伀cal mouse uses light to detect movement. These

are more accurate than ball mice and are be䘀er for

edi伀ng images.

Cordless mice are used in exactly the same way as

regular mice but they do not use a wire plugged into

the computer. They use wireless technology in order tocommunicate with the computer. They are powered by

ba䘀eries.

# Mice have two buttons and a scroll wheel. These provide users with different functions:

Left button is used to select icons and click optionsRight button is used to call up a drop-down menu of optionsScroll wheel is used to move up and down through a document.

Mice use two bu䘀ons and a scroll wheel to allow us to ac伀vate different func伀ons.

# Cordless mice work in the same way as regular mice but they do not need a wireplugged into the computer. They are powered by batteries instead of the computer.

Cordless mice are an example of a wireless device.

Uses of Mice:

# Common uses of mice include:

1. Opening, closing, maximising and minimising programs and files.

2. Moving, grouping and deleting files.

3. Controlling a pointer on screen to select icons or move around the page.

4. Editing images in terms of size and position on the screen.


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Advantages/Disadvantages of Mice:


Faster to select icons and options when compared to akeyboard.

People with wrist and hand problems (like RSI) can find micepainful to use.

Very easy to move a pointer around a screen and to navigatethrough documents.

Ball mice can pick up dirt which will affect the accuracy of pointer movement.

Mice are small and do not take up much space. Mice need a flat surface in order to work properly

For example - they would be difficult to use on train unless youhad a flat table to rest on.

Information about the Touchpad:Examples:

Touchpads are built into laptops and perform the same

func伀ons as mice.

The touchpad allows us to control a screen pointer and

the bu䘀ons allow us to select icons and call up op伀ons.

# Used as a replacement to a mouse in many laptops.

# Users lightly brush their finger over the touchpad in order to control a pointer.

# Touchpads have two buttons which have the same purpose as mouse buttons:

Left Button - Used to select icons and activate options.

Right Button - Used to call up a drop-down list of menu options.

Uses of Touchpads:

# Touchpads have the same uses as mice. (click here to return to mouse uses)

Advantages/Disadvantages of Touchpads:


Easier than QWERTY keyboards when used to select optionsand icons.

More difficult to control a mouse pointer when compared to amouse.


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Touchpads are built into laptops so there is no need for aseparate mouse. This helps improve portability.

People with wrist and hand problems (like RSI) can findtouchpads painful to use.

Can be used even when there is no flat surface available. Some operations are more difficult to perform when compared toa mouse. Drag and Drop for example.

Won't get clogged with dirt (as can happen with ball mice) soperformance is never reduced.

Information about the Trackerball:Examples:

Trackerball's perform the same func伀ons as a mouse

but they require less wrist movement and so are more

comfortable to use.

Old arcade games machines o縂en used trackerball's to

allow gamers to direct in‐game characters.

# Trackerball's are similar to mice but the ball is on the top of the device instead of thebottom.

# Screen pointers are controlled by rotating the large ball with your hand.

# The buttons on trackerball's perform the same functions as those on mice and touchpads.

Uses of Trackerball's:

# Trackerball's have the same functions as mice. (click here to return to mouse uses)

# They are, however, much more comfortable to use than mice. This means that peoplewith painful hand and wrist problems (like RSI) can use a trackerball.

Why are they more

comfortable?

Trackerball's are more comfortable than mice because there is

less wrist movement required. They are more ergonomic.

# Some arcade gaming machines use trackerball's to control games characters on screen.

Because trackerball's are so durable (tough) they can deal with the wear and tear of gamers using them.

Advantages/Disadvantages of Touchpads:


People with hand/wrist problems can still usetrackerball's

More expensive than mice.


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More accurate than mice or touchpads.

Pointer can be positioned more exactly which makestrackerball's very using for image editing.

More difficult to learn to use than amouse.

Can be used even when there is no flat surfaceavailable.

No limit on ball travel.

A mouse sometimes runs out of room on a mousemat. With a trackerball you just keep rolling.

The world's first trackerball was developed in 1952 and

used a bowling ball.

Remote Control

Information:

Examples:

A satellite T.V remote control with bu䘀ons to

control the channel, volume and many more.

# Remote controls are used to control other devices using infra-red signals.

# Buttons on the remote control can be used to perform functions such as:

Changing the channel on a T.VIncreasing/Decreasing the volume on a music playerSelecting a different chapter on a DVD player

Uses of Remote Controls:

# Home entertainment systems use remote controls. Examples are:

1. Hi-Fi systems (music centers).

2. DVD / Blu-ray Players.

3. Satellite systems.

4. Some overhead projectors (like ours in the classroom).


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# Industry uses remote controls to operate machinery that might to too dangerous to getnear to. Examples include:

A man using a remote control to operate a crane.

1. Cranes with heavy loads. 2. Activating explosives in demolition.

3. Operating robot arms in hazardouschemical plants.

Advantages/Disadvantages of Remote Controls:


Devices can be operated without having togo to them. This is useful for people withdisabilities.

People with limited hand movement canfind them difficult to use.

They can operate devices that are in an

unsafe environment.

For example: Explosives to demolish abuilding can be set off at a safe distance.

The infra-red signal between the remote

control and the device it operates canbecome blocked.

Joysticks


A standard joys伀ck with a control s伀ck/handle, bu䘀ons

for selec伀ng op伀ons and a 'fire' bu䘀on

for gaming.

# Joysticks have similar functions to that of mice and trackerballs...... to control a pointer ona screen.

# There are two main parts to a joystick:

Handle /Stick -

Allows us to move a pointer in the direction we want.

Buttons - Allow us to select options or 'click stuff'.

# Joysticks are also popular devices for gaming. The handle allows gamers to control on-screen characters and the buttons are used for things like firing weapons.


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Joys伀cks used to operate a crane.

Joys伀cks are also used to mimic real‐life flight

condi伀ons on flight simulators.

Uses of Joysticks:

# They can control characters or objects in video games.

# Can control industrial machinery (cranes for example)

# They are used in simulators. For example flight simulators use joysticks in order for

trainee pilots to control the simulated plane.

Advantages/Disadvantages of Joysticks:


Easier to control an on-screen curser ormove an in-game character than it is whenusing a keyboard.

Not as easy to control an on-screencurser when compared to using a mouse.

Very simple to get used to.

Anyone can just pick one up and use it!

People with hand/wrist issues (like RSI)

can find them painful to use.

Can be used by disabled people. Joystickscan be operated by hands or even feet.

Difficult (but not impossible) to enter text.

For example: some games allow you toselect individual letters using the joystick inorder to spell out your name when enteringa high score.

Touch Screens


# Touch screens allow users to input commands into a computer by pressing ortouching buttons/icons on the screen.

# Giving users this ability to touch or press icons on the screen removes the need to use amouse.


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A touch screen with 'pressable' op伀ons.

Modern mobile phones use touch screens to

reduce the size of the device.

School classrooms use special touch screens called

'Interac伀ve Whiteboards'.

# Touch screens are more suitable for use with a limited amount of options.

Uses of Touch Screens:

# Common uses of touch screens include:

1. Mobile phones and PDA's use touch screens as a way of saving space (aseparate keyboard would make the devices quite large).

2. Public information systems at airports or tourist information offices.

3. Interactive whiteboards in schools.

4. On-screen multiple choice tests (like driving theory tests) sometimes use touchscreens.

Advantages/Disadvantages of Touch Screens:


Very fast and easy to enter options (you just press them).

Limited number of options available onthe screen.

No training needed in order for people tobe able to use them. All people do is pressthe correct option.

Expensive compared to other inputdevices.

Screen can become dirty and full of germs due to people touching it.


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Scanners


Earlier scanners, like the Sharp JX‐450, could only scan

documents in low‐resolu伀on (image quality lost).

Modern scanners are capable of scanning documents

and images in much higher resolu伀on. This means that

digital copies are closer to the original quality.

# Scanners are used to enter information on paper (hard copies) into a computer.

Scanners can convert hard copies (printed documents, photographs etc) into digital

data. This digital data can then be stored and manipulated on your computer.

# Scanners reflect light off the hard copy in order to capture an analogue image of thedocument. The scanner then converts the received analogue data into a digitalformat.

# Once the hard copy has been converted to digital data, it can be stored on a computerand manipulated using Graphics Editing Software (such as Photoshop).

Uses of Scanners:

# Used to scan hard copy / printed documents into a computer:

# Old photos and important documents (like birth certificates) can be scanned into thecomputer. This means you still have a copy if the original is damaged or lost.

Scanners are used to convert analogue hard copies of documents and photos in digital data.

Advantages/Disadvantages of Scanners:


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Very fast to enter hard copies into thecomputer (compared to retyping with akeyboard).

Scanned images are usually of lesserquality than the original document.

Very easy to scan and store documents andimages into the computer.

Digital copies of the stored data can easilybe duplicated and backed up.

Scanned images can take up a lot of diskspace (especially if you scan them at a highresolution).

Old photo's that may be damaged can bescanned into the computer then repairedusing Graphics Editing Software.

Some scanners are 'hand held' which means the user

physically moves the scanner across the image in order

to send a copy to a computer.

Graphics Tablet


A graphics tablet with a stylus pen .

Graphics tablets can be used to accurately 'draw'

illustra伀ons, symbols and diagrams.

# Graphics tablets are used by artists and designers to easily create and store digitalgraphics in a computer.

# A graphics tablet can be drawn on with a special pen called a 'stylus'.

# Whatever is drawn onto the tablet can be seen on a computer screen.

It is really just the same as drawing on paper but the final image is digital.

# Anything drawn onto the tablet can be saved into the computer as images.

Once images are saved into the computer, they can be edited using graphics editingsoftware.

Uses of Graphics Tablets:

# Allow designers to produce digital images much more accurately than if they were usinga mouse.


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A high‐end illustra伀on of a car produced using a

graphic tablet.

Advantages/Disadvantages of Graphic Tablets:


Much easier to draw images using a penthan it is to draw them using a mouse.

Very expensive when compared to amouse.

Very accurate drawings can be produced.

Stylus pens make it better for the artist tocapture fine detail than they could using amouse.

Not useful for some input needs.

For example - graphics tablets are notdesigned for entering data into the computerby clicking icons or menus.

Useful in countries where drawings andsymbols are used instead of text (like Chinaand Japan).

Light PensInformation:

Examples:

Light pens can replace mice and touch screen for

selec伀ng items on a CRT screen.

# Light pens are quite old technology and can be used as alternatives to mice, touchscreens or graphics tablets.

# Light pens are used by directly drawing or selecting icons on a computer screen.

Note: Currently light pens can currently only be used with CRT (cathode ray tube)monitors.

# They work by picking up light from the computer screen and then signaling to thecomputer exactly where the light was picked up. This allows the computer to 'draw' on thepart of the screen where the pen picked up the light.

Uses of Light Pens:

# Used for selecting objects on a CRT screen.

For example: replacing a mouse or touch screen clicking/touching icons.


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Light pens can be used to produce drawings directly on

a CRT screen.

Light pens only currently work with CRT Screens (the

fat ones) .

# Used for directly drawing onto a CRT screen.

For example: replacing a graphics tablet to produce hand-drawn designs.

Advantages/Disadvantages of Light Pens:


More accurate than touch screens.

(end of the pen is much thinner than afinger and so can accurately select smallicons)

Not as accurate as a graphics tablet whenused for producing drawings.

They are very small and so can be usedwhere there is no room for a mouse or

graphics tablet.

Can only be used with CRT (cathode raytube) screens.

(not usable with TFT or LCD screens)

Can be quite uncomfortable to use as youhave to hold your hand raised up to thecomputer screen for long periods.

MicrophonesInformation:

Examples:# Microphones are used to input analogue sounds into a digital computer.

1. Sounds exist in the form of sound waves (analogue signals that change slowly).

2.

Computers understand digital data and not

analogue.


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For example: computers understand combinationsof 0's and 1's.

3. The job of the microphone is to input analoguesound signals into the computer where the soundcard will convert analogue sound into digital (inother words the sound card will 'digitize' theanalogue sound into 1's and 0's)

Note: the sound card acts as an ADC (analogue todigital converter).

4. Once digitized, the sounds can be stored and usedby the computer.

Microphones are used to input sound into a computer.

Microphones can be used to hold voice conversa伀ons

over the Internet (like using Skype).

Microphones are used on hands‐free mobile phone kitsto make driving safer.

Uses of Microphones:

# Used to input sounds/speech for use in a range of applications. For example:

Narration (spoken words) in presentations or in web sitesVoice-over's in moviesSpeaking over the Internet using VoIP (Voice over Internet Protocol)An example of this would be using Skype to hold an online conversationConducting videoconferencing (e.g. business meetings online).

# Used in voice recognition software. For example:

Converting speech into text for use in word processors (useful for people who do

not have use of their hands)Issuing commands (e.g. some cars allow for speech to activate certain features like'starting the engine' or 'altering radio volume').

# Hands-Free mobile phones use a microphone to allow people to hold conversationswithout using their hands (this makes driving much safer).

# Used (along with headphones) in gaming so that gamers can talk to each other.

Advantages/Disadvantages of Microphones:



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Faster to read in text than to type it inusing a keyboard .

Sound files can take up a lot of computerstorage space.

Means that word processors can be used bypeople who cannot use their hands. Wordsare simply spoken into the softwareinstead of typed.

Speaking words into a word processor is notas accurate as typing. This means thatmistakes are common with words that soundthe same but have different meanings.

For example: 'see' and 'sea'.

Makes driving safer because people do notneed to take their hands off the steeringwheel in order to use their mobile phone.

Background noise can interfere withvoice recognition systems.

Microphones are very cheap to buy. Gamers use microphones to communicate instruc伀onsto each other in‐game .

Digital Cameras

Information: Examples:

An old film‐based camera .

# Have pretty much replaced the old style film-based cameras.

# Digital cameras store digital photographs on a memory card and these images caneasily be transferred onto a computer for viewing or editing.

# Most digital cameras have a built-in screen to allow for previewing the digitalphotograph. This is useful so that the photographer can decide which images to keep andwhich to delete.

# Digital camera image quality is measured in 'Megapixels'. These are the number of dotsthat make up the image. Generally speaking, the higher the Megapixels, the higher thedetail quality of the image.

3 Megapixel cameras produce images made up of 3 Million pixels (dots).

24 Megapixel cameras produce images made up of 24 Million dots (8 times more detail)

# Most digital cameras can also capture video and sound as well as images.


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A modern digital camera with preview screen.

Tradi伀onal photographs were stored on reels of film .

Digital photographs are stored on memory cards.

# Almost all modern mobile phones have a built-in digital camera.

Uses of Digital Cameras:

# Used to capture digital images for uses such as:

Saving special moments (weddings, birthdays, family snaps etc)

Gathering images for use in presentations, web pages or publications(newspapers and magazines etc)

# Easy to transfer images to a computer for editing.

For example: using PhotoShop to alter brightness or contrast

# Images can be printed easily by:

Uploading to a computer and then printing

Connecting directly to a photo-printer and printing straight from the camera(no need to upload to a computer)

# Most digital cameras also allow for short, high-quality video clips to be produced.

Advantages/Disadvantages of Digital Cameras:


No film to develop. This means thatproducing the photo is much quicker.

Camera user needs to have computerskills to be able to transfer and print digitalphotographs.

Unwanted images can easily be deletedfrom the memory card.

Not all digital cameras produce images ashigh-quality as traditional cameras.

Because the images are digital it is easy tomake copies of them.

Artistry of traditional photography is beinglost.

Camera software can automaticallycorrect 'bad images' making photography

easier to master without as much skill.

No need to print at all because the imagescan be viewed a computer screen. This

saves paper and is better for theenvironment.


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Memory cards can store thousands of digital photographs. Traditionalphotographs can take up a lot of physicalstorage space.

People using traditional 'film-cameras' hadto take much more care to capture eachimage perfectly.

Digital images can easily be transferredusing blutooth, email attachments andmobile phones.

Digital images can be improved andedited easily using software (sharpeningthe image for example)

Tradi伀onal photography was much more difficult to

master. Much thought had to go into capturing quality

photographs.

Digital photographs are run‐through so縂ware which

does most of the hard work for us and makes it harder

to produce bad images.

Web Cameras (web cams)


A web cam a䘀ached to a computer monitor.

# Web cameras are similar to digital cameras in their function but they are directlyconnected to a computer and do not have memory storage.

# Web cameras can capture both digital images and video.

# Images / video are sent directly to the computer where they can be stored and used.

These digital images and video are often added to presentations, web sites and otherpublications.

YouTube channels sometimes use web cams to capture the content of the channel.This is usually a presenter giving out information about whatever topic the channel isabout.

# Many modern computing devices (such as laptops) come with built-in web cams.


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Uses of Web Cameras:

Web cams allow long distance face‐to‐face interviews

to take place.

Web cams allow elderly people to hold face‐to‐face

conversa伀ons with rela伀ves.

# Used to conduct face-to-face conversations with friends and family online over VoIPapplications such as Skype.

A similar use is to conduct face-to-face job interviews over the Internet. Thisremoves the need for job applicants to travel very large distances to attend the interview.

# Used to hold video-conferencing meetings over the Internet.

# Can capture image and video content for presentations, web sites and even YouTubecontent.

# Web Cameras are sometimes used by parents to keep an eye on their children whenthey are in another room.

# Some people use web cams as a cheap alternative to security cameras.

# Sometimes used to allow drivers to view the traffic conditions on roads.

This allows the driver to plan a different route if the traffic on a road is too congested.

Advantages/Disadvantages of Web Cameras:


Allow for long-distance face-to-faceconversations. This removes the need forpeople to travel.

(especially useful for elderly and disabledpeople to keep in touch with family)

The image/video quality can sometimesbe poor (low resolution).

Video conference business meetingsand job interviews can be conducted very

cheaply over long distances.

They do not have their own storage and somust be permanently fixed to the

computing device.

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(no need for expensive travel or bookings of hotel rooms to attend the meeting orinterview)

Parents can keep an eye on their childrenfrom a different location.

Are usually in a fixed position and socannot be easily moved around.

Web cams can be left running constantlywhich makes them useful as securitydevices on properties.

(as a form of security camera)

Traffic cams allow drivers to avoid heavy traffic.

Previous - Input/Output Devices

Main Menu

Next - Direct Input Devices

Links to Theory Units:

Section 1: Types and Components of Computer Systems Section 2: Input and Output Devices Section 3: Storage Devices and Media

Section 4: Computer Networks Section 5 : Data Types Secti on 6: The Effects of Using ICT

Section 7: The Ways in which ICT is used Section 7: Part 2 Section 8: Systems Analysis and Design

Links to Practical Units:

Section 9: Communication Section 10: Document Production Section 11: Data Manipulation

Section 12: Integration Section 13: Output Data Section 14: Data Analysis

Section 15: Web site Authoring Section 16: Presentation Authoring

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3/17/2016 IGCSE ICT - Direct Input Devices

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The ICT Lounge

Section 2.2:

Direct Input Devices

In section 2.1 we looked at manual input devices and talked about howthese require a large amount of human interaction in order to get datainto a computer.

In this section we will focus on direct input devices. Direct input devicesrequire less human interaction in order to get data into a computer.

Key Concepts of this section:

# Know the purpose of and be able to identify differentdirect input devices.

# Understand the uses of each direct input device.

# Be able to discuss advantages and disadvantages of each direct input device.

Direct Input Devices(no/little human interaction needed)

Key Words:

Magnetic Stripe Reader, Chip and Pin Reader,Barcode Reader, Magnetic Ink Character Recognition(MICR), Optical Mark Recognition (OMR),Optical Character Reader (OCR)

Examples of Direct Input Devices:

# The table below shows you some examples of direct input devices. Click each device to move to more information:

Magnetic StripeReader

Chip and PINReader

BarcodeReader REMEMBER!

Direct input devices do not

require much humaninteraction to get their datainto a computer system.

For example:All a human has to do touse a Barcode Reader ispoint the reader at thebarcode and pull thetrigger. The reader will dothe rest.

NOTE:

Click the images to the leftto move to more information

about each one.

Optical Mark Reader(OMR)

Optical CharacterReader (OCR)

Magnetic Ink CharacterRecognition (MICR)




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Breakdown of each direct input device:

# The following sections will help summarise each of the direct input devices. For each one you will see:


Magnetic Stripe Reader


Informaon held on a card's 'magnec stripe' is read by

swiping the card through a strip reader.

Details about bank accounts are stored on a

magnec stripe .

# Reads information from magnetic stripes found on Bank Cards, Membership Cardsand Hotel Door Cards etc.

# The strip on the cards holds information such as:

Bank account numberName of card holderExpiry date of membershipetc

# Data contained on the card's stripe is read by pulling the card through the magnetic stripereader.

This is known as 'swiping'.

# The magnetic stripe reader then sends data from the card into the computer forprocessing.

Uses of a Magnetic Stripe Reader:

# ATM's use these readers to process the information on bank cards.

# EFTPOS (Electronic Funds Transfer Point of Sale) use the readers to transfer customer'smoney from their bank accounts when they purchase goods in stores.

# Hotel rooms sometimes use magnetic stripe readers in place of door keys.

People who want to enter a room would swipe their card through the reader in order toopen the door.



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Hotel room cards contain data on the stripe that will

unlock the door once inserted into the reader.

Advantages/Disadvantages of using a Magnetic Stripe Reader:


Entering data is very fast. You just swipethe card through the machine.

The magnetic stripe on cards can only holda small amount of data.

No possibly of data entry errors as there

is no typing involved.

The cards need to be in contact with the

reader in order to be used.

(cannot be used over the internet forexample)

The stripes on cards are not affected bywater and so quite robust (not easilydamaged).

If the stripe does get damaged then thedata is lost (unreadable).

Data held on the card cannot be read byeye so bank details etc are safe.

Magnetic stripes on cards are easilyduplicated (known as card cloning).

(if this happens you are prone to theft of funds in your bank)

Chip and Pin Reader


Chip and PIN Readers require the correct

idenficaon number to be entered.

# Thes e allow people to pay for goods and services electronically at EFTPOS terminals(electronic funds transfer point of sale).

# The chip and pin reader works by inserting a bank/credit card into a slot and then enteringa PIN (personal identification number).

The PIN ensures that the person with the bank card is the genuine owner. Only the

owner of the card should know the PIN and money can only be transferred with thecorrect number.

# If the correct PIN is entered, the cost of goods/services will be taken from the cardholder's bank and transferred to the companies (restaurant, store etc)

Uses of Chip and Pin Readers:

# Used to make secure payments for goods/services in places such as:

SupermarketsRestaurantsCafes

Buying petroletc



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Informaon on a card's chip is more secure than

on a magnec stripe .

Many goods and services can be purchased using

Chip and PIN Readers .

Advantages/Disadvantages of using Chip and PIN Readers:


More secure than magnetic stripe readersas the user needs to know the correct PIN.

It is possible to forget your PIN whichmeans you cannot make payments withyour card .

Information contained on the chip is harderto clone (copy) than it is to copy magneticstripes .

People can look over your shoulder asyou enter your PIN. This makes it possibleto access your money if they ever stole yourcard.

Chips can hold more data than magneticstripes can.

Chip and PIN Readers are portable sothey can be brought to you (waiter in arestaurant for example)

Barcode Scanner/ReaderInformation:

Examples:

Barcodes contain informaon about products and can

be read with scanners.

A barcode on a package being scanned.

# Used to read information that is stored on product's barcodes.

# The barcode scanner reads the information stored on the barcode using a visible redlight which is reflected and translated into digital information.

# The barcode is present on products and holds information about each product including:

Product Id numberManufacturerCountry of origin

The barcode does not store the price of the product . This information is held in acomputer database and accessed using the product id.

Note: By storing the price in a database instead of on individual bar codes, it is easier tochange (if you had a sale for example). All you would do is change the price in thedatabase instead of having to replace the barcodes on each of the items.

# Once a barcode has been scanned, a computer can read the information stored on thebarcode and access details about the product that are stored in a database.

# Barcode scanners are usually built into POS (point of sale) terminals in supermarkets.

# Handheld scanners are also commonly used to read bar codes (usually if items are toolarge and heavy to move to the scanner).



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Barcodes are found on items that we buy in stores.

POS terminals in supermarkets have built‐in

barcode scanners.

Hand held barcode scanners are used to read barcodes

on large items.

Uses of Barcode Scanners/Readers:

# Used in supermarkets, stores and warehouses where goods are marked with abarcode.

Remember: Barcodes hold information about the product which is linked to acomputer database. This enables automatic very fast itemised billing totake place.

# They are used in libraries to scan in library cards and read ISBN numbers on booksto find out which ones are on loan.

# They are used in keeping track of packages that are being delivered to differentlocations.

# Also used in organising luggage in airports (helps ensure that luggage is loaded ontothe correct plane).

Advantages/Disadvantages of Barcode Scanners/Readers:


Quick and easy to change productprices.

Only the price data in the database needsto updated. There is no need to changeindividual prices on each of the item's barcodes.

Quite an expensive way to gatherinformation. Each item needs a barcodeand the scanners / computer technology /database needed is also expensive.

Quick and easy way of getting informationinto a system.

(all you do is scan the item's bar code)

Bar codes can be swapped on itemswhich means people may pay less for moreexpensive items.

Very accurate as there is no manual

typing involved.

Rely on undamaged bar codes in order to

function.

(if a bar code is damaged, item numbershave to be typed into the system by hand)

Enables automatic stock control.

Optical Mark R eader (OMR)


# System which automatically readsmarks made in pen or pencil.

# Typically used to read multiple choice examinations where students shade in (mark)answers that they think are correct.



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Opcal Mark Reader automacally inpung the

answers given on a mulple choice form.

OMR devices can read the shaded areas on

mulple choice tests.

They can also read shaded areas on loo ckets.

# The OMR reader shines a light onto the form and less light is reflected where a pencilmark has been made.

# This allows the reader to tell which options have been chosen and sends the resultsback to a computer.

Once the data is on a computer it can be quickly analysed.

For example: the computer will work out the grade of a multiple choice test.

# Optimal Mark Readers can input the data held on forms (such as multiple choice exams)very fast.

Up to 4000 sheets per hour can be processed this way.

Imagine how long it would take to mark 4000 multiple choice tests by eye!!

Uses of OMR's:

# Used to read the shaded areas on documents such as:

Multiple choice examinationsMultiple choice questionnairesLottery tickets

But are typically used on any document that has multiple choice responses that areshaded in.

Advantages/Disadvantages of OMR's:


Extremely fast way of inputting information into a computer.

(around 4000 forms can be read per hour)

Forms need to be accurately designed to make sure that themarks/shading are in correct position to be read by the device.

Very accurate as document's data is fed into the computerautomatically with no manual typing.

(accuracy relies on the forms being filled in correctly)

If forms have been incorrectly filled in they cannot be readproperly.

(In this case documents would have to be read manually, by eye,which would take a long time)

Can save money as there is no need to employ workers toenter form information into a computer.

Can only read shaded areas (Cannot input or read text).

Forms can jam in the machine as they are fed through.



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Optical Character R eader (OCR)


Printed text on a document being scanned as part of

the 'digizing' process.

Regular scanners can also be used for inpung

scanned text into a computer ready for digizing.

Image of text being converted to digital.

(click image to zoom)

# Optical character readers consist of a scanner along with special software.

# OCR's allow us to scan text on paper (hardcopy) into a computer.

# Once into the computer, OCR softwareconverts the scanned text into a digital format.

The digital version of the text can be edited and formatted.

# Once converted to digital, the text can be be used in programs such as word-processors,presentations, web sites etc. See diagram below:

Diagram shows how OCR works:

1. Hard copy scanned into computer

2. OCR software used to convertscanned text into digital (digitizes)

3. Digital text can be used in digitaldevices and applications

Uses of OCR's:

# Used in the processing of Passports and Identity Cards.

# OCR is also used in the process of digitizing books.

Note: book digitizing is where hard copy printed books are converted into digitalformat for use on E-book readers such as Amazon's Kindle.

Advantages/Disadvantages of OCR's:


Very fast way of entering hard-copy text The system can have difficulty reading


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It is also possible to digize handwring.

into a computer. handwriting (especially if it is messy).

Cheaper than paying an employee tomanually re-type printed text into acomputer.

Not 100% accurate.

(relies on being able to read the originaltext)

Avoids typing errors as the process isautomatic (no typing involved)

As it is not 100% accurate, informationneeds to be manually checked for errors.This is time consuming.

Magnetic Ink Character R ecognition (MICR)


A MICR device reading the magnec ink on a cheque.

Magnec ink is used to write various account numbers

on cheques. (click image to zoom)

# MICR is a system which can read information printed in a special ink(the ink contains iron particles).

# This special ink is used to writecustomer account numbers on the bottom of cheques.

# The MICR device reads the account numbers then converts it to a form the computer canunderstand.

# The converted information is then sent to the computer so the cheque can beprocessed.

Uses of MICR:

# MICR devices are mainly used to process cheques. Below there is a summary of theprocess:

1. Every day millions of cheques. are sent to banks for processing. To process theinformation on these cheques. would take far too long if it were done by hand.

2. MICR automatically (and quickly) processes the information on these cheques. with100% accuracy (They can handle 300 per minute).

3. MICR can be used to read the following information:

Customer account numberBank sort-code/branch numberCheque number.

# Some countries also use MICR devices to read the passport number on passports.

Advantages/Disadvantages of MICR:


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Cheques. can be processed very quickly (up to 300 perminute.)

Only a very limited number of different characters can be read.

Greater security than OCR because the special ink characterscannot be changed.

Both the MICR device Magnetic Ink are more expensive thanother methods of direct data entry.

No manual input… therefore less errors.

(user just swipes information through the reader)

Information can still be read even if someone writes over themagnetic ink characters.

For example: if someone tries to manually alter an accountnumber by hand the device will still read only the original data.

Pre vio us - Manua l Input Dev ic es Next - Sens ors

Links to Theory Units:Section 1: Types and Components of Computer Systems Section 2: Input and Output Devices Section 3: Storage Devices and Media

Section 4: Computer Networks Sec ti on 5 : Da ta Ty pes S ec ti on 6 : Th e Ef fe ct s o f Us ing I CT






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3/17/2016 IGCSE ICT - Sensors

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Section 2.3:

Sensors

In the last section we looked at how data can be input into a computersystem (both manually and directly).

In this section we will discuss how sensors can be used to automaticallydetect changes in the environment around and then directly feed thisdata into a computer for processing.

Key Concepts of this section:

# Know the definition of the term 'sensor'.

# Understand the different types of sensors and whatuses they perform.

# Be able to discuss advantages and disadvantages of sensors.

Sensors (what are they?) Key Words:Data, Automatic, Measured,Analogue, Digital, Analogue toDigital Converter, ADC

Definition: "A device which automatically inputs data into a computer system,where the data is constantly changing and can be measured."

Overview of Sensors: Examples:

Thermometers are examples of temperature sensors.

# Used to detect data in the surrounding environment that constantly changes. Forexample:

Temperature - measuring heat in a roomLight - setting off a burglar alarmHumidity - detecting when plants become too dry.

# This information is ‘physical’ and ‘analogue’.

Analogue data is constantly changing and it changes very smoothly.




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For example: Outside temperature changes all of the time but it does so very graduallyand smoothly. It doesn't suddenly jump from 10°C to 20°C.

Infrared burglar alarms are examples of light sensors.

# Computers don’t understand analogue data and therefore it needs to be converted todigital (e.g. 1’s and 0’s).

The computer can then read the data.

A special device called an Analogue to Digital Converter (ADC) is used inorder to achieve this.

Examples of SensorsKey Words:

Temperature, Pressure, Light, Sound, Humidity, pH,Monitoring, Data Collection

# The table below shows you some examples of sensors:

Temperature Pressure Light REMEMBER! Sensors are used toAUTOMATICALLY getdata into a computersystem.

NOTE:We will look at each

sensor in greater detailfurther down this page.

Sound Humidity/Moisture pH



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Uses of Sensors Examples:

Sensors in burglar alarms can

automacally detect intruders.

Automac doors open when people are

detected nearby.

# Sensors are used in monitoring and control applications.

# When monitoring, the data is sent directly to some sort of a computer and is thenprocessed and used.

Forexample:

A burglar climbs through a window and walks through an alarm’s lightsensor. The computer inside the alarm will pick up on the broken light signaland use this information to sound the alarm

# Sensors can also be used for a wide range of data collection and everydayapplications.

Forexample: Taking measurements in scientific experiments

Measuring pollution in the atmosphereSensing the temperature in a room and using this to either turn aheating system on or off Automatic doors open themselves when they detect a person nearby.

# The table below specifies the uses of different types of sensors:

Type of Sensor: Used For:

Temperature Automatic washing machines, Central heating systems,Automatic greenhouses, Cookers.



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Pressure Burglar alarm systems, Washing machines, Robotics,Environmental monitoring.

Light Automatic greenhouses, Automatic doors, Burglar alarmsystems, Street lighting control.

Sound Burglar alarm systems, Voice recognition systems (like using avoice command to start a car).

Humidity/Moisture Automatic greenhouses, Environmental monitoring, Agriculture,Factories that manufacture items that can be ruined by toomuch air moisture (microchips etc).

pH Automatic greenhouses, Chemical manufacturing,Environmental monitoring, Aquariums (wrong pH can kill fish).

A variety of sensors are used on automac

greenhouses to keep plants in perfect condions.

pH sensors are used to monitor the acidity and

alkalinity level of aquariums (wrong levels can kill fish).

Malfunconing sensors used on cars to assist in

'reverse parking' can cause crashes.

Advantages/Disadvantages of

Sensors# The table below highlights some of the main advantages and disadvantages of using

sensors:


Readings taken using sensors are more accuratethan those taken by a human. Faulty sensors can give incorrect

results.

For example: if the sensors on acar that help with reverse parkingbecome dirty they may not identifyan obstacle and cause you to crashinto it.

Sensors can monitor information constantly

(They don’t get tired like humans can).

Sensors can respond to information immediately(Burglar alarms goes off as soon as an intruder isdetected).

No need for humans to operate the sensor. Thiscan be useful if gathering the information ishazardous like in detecting radiation levels forexample.



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Previous - Direct Input Devices Next - Output Devices

Links to Theory Units:

Section 1: Types and Components of Computer Systems Section 2: Input and Output Devices Section 3: Storage Devices and Media

Section 4: Computer Networks Section 5 : Data Types Secti on 6: The Effects of Using ICT






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3/17/2016 IGCSE ICT - Output Devices

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The ICT Lounge

Section 2.4:

Output Devices

Once data has been input into a computer system and processed, it isnow 'useful information'. This information is ready to be output (sentout).

In this section you will learn about the different types of output devicesthat are commonly in use.

For each out device you have to be able to identify it from an image,explain what it is used for and discuss advantages/disadvantages.

Key objectives of this section:

# Know the purpose of and be able to identify differentoutput devices.

# Understand the uses of each output device.

# Be able to discuss advantages and disadvantages of each output device.

Output Devices (what are they?) Key Words:Input, Processor, Output,Storage, Hardware, Data,Information

Definition: "Hardware devices that allow information to be sent out of acomputer system."

Overview of Output Devices:Examples:

# Output devices are part of the 4 main hardware components of a computer system:

Input Devices - these get data into the computerProcessor - this does something with the data to make it useful informationOutput Devices - these show the results of processingStorage Devices - holds the data in the system

# The image below shows where output devices fit into a computer system:




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A computer monitor (screen) is an example of a

commonly used output device.

Printers are another example of a commonly used

output device.

NOTE:

More examples will be shownfurther down this page.

This diagramshows whereoutput devices fitinto a computersystem.

# Some devices produce a temporary output.

For example: a computer monitor produces images on the screen that constantly refresh

and change.

# Some devices produce a permanent output.

For example: a printer produces outputs as hard copies on paper(these cannot be changed once printed).

The information below discusses some examples of output devices including their uses,advantages and disadvantages.

Examples of Output

Devices

Key Words:

CRT Monitor , TFT Monitor, Laser Printer, Inkjet Printer,Dot matrix Printer, Plotter, Speakers, MultimediaProjector



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# The table below shows you some examples of output devices. Click each device to move to more information:

CRT Monitor TFT Monitor Laser Printer Inkjet Printer REMEMBER! Output devices sendprocessed information OUTof a computer.

NOTE:

Click the images to the leftto move to more

information about each one.

Dot Matrix Printer Plotter Speakers Multimedia Projector

Breakdown of each output device:

# The following sections will help summarise each of the manual i nput devices. For each one you will see:


CRT Monitor (cathode ray tube)


# CRT stands for 'cathode ray tube'.

# These are the old, bulky, heavy monitors that are still in use today (although being usedless and less).



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Note:

These dots combine to create millions of different colour shades.

(just like when you mix colours in art)

CRT's produce an image (Made up of tiny dots) byfiring Electron Beams against a Phosphor Screen

Each dot is coloured Red, Green or Blue of differentintensities which produces a vast amount of differentcolours.

CRT monitors are very bulky and take up

a lot of desk space.

Light pens can be used with CRT's to produce drawings

and designs directly onto the screen.

# These are the least expensive types of monitor.

# CRT’s are becoming rare as TFT monitors are replacing them.

Note: TFT's are replacing CRT's largely because they produce a higher qualityscreen image and take up far less space.

#

Uses of a CRT Monitors:

# CRT Monitors allow users to instantly see outputs from the computer.

For example - Users would be able to see words they are typing into word processors.


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Screen glare can be a problem with CRT's.

CRT monitors can get very hot.

Users could also see changes that they are making to an image ingraphics editors (like Photoshop)

# CRT's are also used with light pens to allow drawings to be created on screen.

Advantages/Disadvantages of CRT Monitors:


Can be used with light pens to createdrawings on screen.

Note: light pens and CRT's are also usedwith CAD software (computer aided design).

They are very large and bulky whichmeans they take up large amounts of deskspace.

Note: their large size and weight also makethem difficult (and dangerous) to move.

Produce a larger range of colours than

TFT monitors.

They create a lot of heat and have been

known to cause fires.

The screen angle is better than with TFT's.

(you do not have to stand directly in front of the CRT screen in order to see what is on it)

Screen glare when in direct light makesviewing difficult.

Note: they are also prone to 'screenflicker' which can cause headaches and eyestrain.

Cheaper to buy than TFT screens. They also need more power than TFT's tooperate (more expensive to run).

TFT Monitors (thin film transistor)


# TFT stands for 'thin film resistor'.

# These are thin flat screened monitors that are commonly seen today.

# As they become cheaper, these have taken over from CRT monitors as the most popular


t


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This allows huge amounts of colours tobe produced (16.7 million).

TFT screens are made up of thousands of tiny pixels. Each pixel has 3 transistors -

red, green and blue and each transistor canproduce different intensities.

A back light is used to shine light onto thesepixels in order for the colours to be produced.

In order to light a single pixel, tiny windows

can be opened and closed to allow the lightto pass through and onto the pixel.

TFT monitors are much thinner than CRT's.

TFT screens are light and are perfect as displays for

portable devices such as laptops.

computer screens.

# TFT's are used with the newer desktop PC's, laptops and mobile phones.

#

Uses of TFT Monitors:

# TFT Monitors allow users to instantly see outputs from the computer.

# They are used as screens in laptops and also mobile phones.

Their thin and light design helps the laptop remain portable (light and easy to transport)


Ad t /Di d t f TFT M it


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TFT's are also used as displays in mobile phones.

Their lightweight makes TFT's easy to

mount on walls.

Advantages/Disadvantages of TFT Monitors:


Lightweight so they are perfect forportable laptops and wall mounting.

Images can appear unclear when viewedfrom an angle.

(you need to look straight at the screen forthe best image)

They are very thin and do not take up asmuch desk space as a CRT monitor.

They produce much less glare than CRT’sand so are friendly to the eye.

Lower picture quality (definition)compared to a CRT monitor.

They use less power than CRT monitors(cheaper to run).

Cannot be used with Light Pens yet.

(Computer Aided Drawings are not yetpossible on TFT monitors)

They emit less radiation than CRTmonitors.

They produce less heat than CRT's.

Laser Printer


# These produce high quality hard copy outputs (on paper) .

# Laser printers use Toner pressed on a page to produce printed documents.


# They can print large amounts of pages at a very quick rate


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The laser leaves a positive electriccharge on the drum in the places where it

drew.

Laser printers work by using a laser beam to'draw' onto a drum.

A special power known as 'toner' is sprayedonto the drum and it sticks to the parts thatcontain the positive electric charge.

The drum is then pressed onto a sheet of paper and the paper is heated (fused) so thatthe toner is bound to the paper.

Laser printers are popular for environments that

require fast high‐quality printouts.

Laser printers can handle very large

print jobs.

# They can print large amounts of pages at a very quick rate.

# You can buy both black and white and colour laser printers.

# They use a buffer memory which stores the information for the whole document beforethe pages can be printed out.

For example: Once you press print, the document is sent to the printers memory(RAM) and stored there. The printer will then output whatever is in thememory when it is ready to do so.

Think of the Buffer Memory as a kind of waiting room

#

Uses of Laser Printers:

# Very useful for printing where noise levels need to be kept low (Like in an office wherepeople need to concentrate or use telephones etc).



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Colour laser printers are expensive to buy and run.

Toner cartridge (these contain toner power).

# Good at producing high quality printouts very fast.

# Good for environments where high volume of printing is required (lots of printouts).

This is because they have a low printing cost per page.

Their fast printing speed /low printing cost per page makes them the printer of choice on networks. This is because they need to be able to keep up with the printingdemands of many computers.

Popular with:

SchoolsBusinessesOffices.

Advantages/Disadvantages of Laser Printers:


Very fast at printing documents. Environmentally unfriendly (produce ozone).

They also use more power than inkjets.

Toner cartridges last a long time and don't need to be replacedoften.

Laser printers are more expensive to buy (but cheap to run).

Laser printers can handle high volumes of printing. Colour laser printers are much more expensive to buy and run

than inkjets.


Very quiet when printing They are larger in size compared to other types of printers

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These mix to form a vast amount of other colours.

Inkjet printers work by spraying ink onto apage of paper.

The ink is held in 'ink cartridges' and thereare 4 different colours - black, cyan,magenta and yellow.

Motors are used to position the ink

cartridges over the correct position of thepage and to drag the paper through the

Very quiet when printing. They are larger in size compared to other types of printers.

Very high quality printouts.

Reliable - don't breakdown as easily as inkjet printers.

Cheaper to run than inkjets (low cost per page).

Inkjet Printer


Inkjets can produce photo‐quality

colour printouts.

Inkjets require 4 separate ink cartridges ‐

Black, Cyan, Magenta, Yellow.

# These are used to produce high quality hard copies (on paper).

# Although the quality of Inkjet printouts is not as good as Laser printers, it is far betterthan Dot Matrix printers.

# Ink is stored in and delivered to the paper via an ink cartridge.

# Inkjet's can print in both black and white and colour.

# Inkjet printers have small amounts of internal memory (RAM) to store print jobs soprinting is done a bit at a time.

The whole document cannot be stored in printer’s RAM so there is often a pause whilethe computer sends the rest of the data

#


printer Click image to zoom

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printer. Click image to zoom

Inkjet printouts will smudge if not le to dry

before handling.

Uses of Inkjet Printers:

# Good where few printouts are needed (low volume).

# Ideal for single-page, very high quality printing. (Photo quality images).

# Often used to print photographs.

Advantages/Disadvantages of Inkjet Printers:


Output is very high quality (Especially good for colourphotograph printing).

Slow printing rates, especially if several copies are needed.

Much cheaper to buy than laser printers. Ink cartridges don’t last long and so are not suitable for largeprint jobs.

Smaller th an l aser printers so take up less space. They can be expensive to run as new ink cartridges are notcheap to buy.

Do not produce ozone or other harmful compounds. Printouts can easily smudge if document is not left to dryproperly.

Very quiet whilst printing.

Dot Matrix Printer


# Often called an ‘Impact Printer’ where pins are pressed against an inked ribbon whichproduces an imprint on paper.

# They are very slow, noisy and produce poor quality outputs (click here for video).


http://www.ictlounge.com/work/inputandoutputdevices/part3-output_devices/videos/working_dot_matrix.mp4


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Different coloured ink ribbons can be used toproduce colour printouts.

These printers work by using a set of pins to pressan inked ribbon against paper.

When the pin/ribbon hits the paper a printed dotis left behind.

The dots can be arranged to form basic text andimages.

Dot matrix printers are noisy and slow.

Dot matrix printers use ink ribbons.

# Are still useful where ‘Continuous Paper’ needs to be used. For example, printing off allof a business's employee payslips.

Continuous paper is the name given to hundreds of sheets of paper that are joinedtogether and 'continuously' fed through the printer.

The paper sheets can be separated after printing is complete.

# Dot matrix printers are still used in environments where print speed and noise is notan issue (like in car garages and factories).

#

Uses of Dot Matrix Printers:

# Dot matrix printers are very robust and can be used in noisy and dirty environments(like garages and warehouses).


# Can make ‘Carbon Copies’ of a document using special ‘Carbon Paper’ underneath


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Dot matrix printout quality is very low.

Dot matrix printouts are made up of arranged dots.

# Can make Carbon Copies of a document using special Carbon Paper underneathnormal printer paper.

Advantages/Disadvantages of Dot Matrix Printers:


Work just fine in dusty and dirtyenvironments where laser or inkjetprinters could easily be damaged.

Very noisy so not suitable for an officeenvironment

Carbon copies can be produced usingcarbonated paper.

Very slow to print (slowest of all the typesof printers)

Very cheap to buy and maintain.

(Inked ribbons are very cheap)

Very poor print quality.

Good for continuous printing.

(e.g. long print jobs like wage slips)

Plotter


# There are 2 different types of plotters --- drum and flatbed.

# Produce hard copies but are capable of printing on very large pieces of paper (e.g. 3foot wide by 10 foot long).


# The print quality of plotters in very high


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A drum ploer.

A flatbed ploer.

Ploers can produce very large printouts like those

seen on adversing boards.

# The print quality of plotters in very high.

# Plotters can also produce very large and accurate documents such as blueprints(plans) for buildings

# Plotters draw images on the page using coloured pens which are moved around thepaper by a computer.

Uses of Plotters:

# Used to produce large, accurate drawings. Some examples are listed below:

Blueprints of buildings (plans/designs)MapsGiant posters and adverts (like those we see on billboards).

# Pens can be replaced with cutting tools to produce large signs.

Advantages/Disadvantages of Plotters:


They can produce much larger printoutsthan other printers.

Their print times are very slow.

The print quality is extremely high. They are very expensive to buy andmaintain.

Plotters can also 'cut out' designs for use insign making.


S k


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Speakers can also be used to alter thevolume of the sounds.

Speakers are analogue and cannot output digital'computerised' sounds.

Digital data from the computer must first beconverted into analogue sound using a soundcard.

The analogue sound can then be output via thespeakers and we can listen to it.

Speakers


Speakers allow us to listen to sound coming out

of a computer system.

E‐Book readers (like the Amazon Kindle) have special

soware called 'screen readers' that can narrate the

words on the screen.

Speakers are an important part of home entertainment

# Many everyday uses of a computer require the user to listen to different types of sounds.For example:

Listening to a music albumWatching a movie.

Browsing videos on YouTubeMultimedia encyclopedias.

In order for the computer to output these sounds it requires some sortof speaker system!

# Speakers can be connected directly to a computer or are built into the monitor or casing.

Note: Most computers have small built in speakers to alert users when they dosomething wrong but these can only produce very basic sounds like 'beeps'.

#

Uses of Speakers:

# Used to output sound from multimedia presentations (like famous speeches etc).

# Used in home entertainment (surround sound etc).


systems.# Can be used byblind people to listen to words on the screen instead of reading


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# Can be used byblind people to listen to words on the screen instead of reading .

Note: Special software called 'screen readers' are also needed in order to convertthe printed words into sound.

# Can be used to play downloaded music files.

Advantages/Disadvantages of Speakers:


Everyone in the room can hear the sound. Output from speakers can disturb people trying to work.

They can help blind people use a computer because text can beturned into sound.

High quality speakers can be expensive.

Multimedia Projectors


A mulmedia projector.

# These project whatever a

grade 6 ict notes

Documents