Grade 6 ICT Notes

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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IGCSE ICT - M anual Input Devices

The ICT Lounge

Section 2.1: Manual Input Devices In this section we will look at how input devices can be used to get data into a computer system.

Learning objectives of this section:

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

# Know the purpose of and be able to identify identify different manual input devices. # Understand the uses of each manual input device.

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

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

Input Devices Definition:

Key Words:

(what are they?)

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

Overview of Input Devices: #

Input, Data, Manual, Automatic

Examples:

Input devices are part of the 4 main hardware components of a computer system: Input Devices - these get data into the computer Processor - this does something with the data to make it useful information Output Devices - these show the results of processing Storage Devices - holds the data in the system.

#

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

This diagram shows where input

A mouse is an example of a commonly used

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input device.

devices fit into a computer system.

#

A keyboards is another example of a commonly used input device.

There are two different types of of input devices:

1. Manu Manual al Input Input Device Devices s 2. Direc Directt Input Input Device Devices s -

Data is input into the computer by hand hand (people have to do most of the work) Data is input into the computer directly by a machine/device machine/device (there is minimal input by people)

Manual Input Devices

NOTE: More examples will be shown further down this page.

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

(data entered by hand)

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 devices require humans to do most of the work needed to get data into the system.

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Joystick

Touch Screen

Scanner

Graphics Tablet

Light Pen

Microphone

Digital Camera

Web Camera

For example: If you are using a keyboard to input instructions into the computer, you have press the keys yourself. It is a manual job not automatic.

NOTE: Click the images to the left to move to more information about each one.

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 device Uses of the device Advantages of the device Disadvantages of the device

Keyboard Information:

Examples:

# Keyboards are one of the most commonly used manual input devices. # Key boards are used to input the following into the computer: Text Numbers Instructions # Most keyboards use a QWERTY key layout. The name 'QWERTY' comes from the first five lettered keys on on the top row of the keyboard - Q-W-E-R-T-Y.

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

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# Special keyboards called 'Ergonomic Keyboards' have been developed to help reduce health problems (such as repetitive strain injury)linked with typing. Ergonomic keyboards have a more natural shape to them with reduces stress on the wrist and hands. Ergonomic keyboards also come with a built-in hand-rest which further helps prevent health issues such as RSI (Repetitive Strain Injury). Ergonomic Keyboards have a natural shape and built‐in hand‐rest.

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: Inpung data into a computer using a keyboard.

CTRL + P to print CTRL + S to save CTRL + C to copy CTRL + V to paste PRT SC to take a screen shot of your work

NOTE: Command Line operating systems require a keyboard in order to be able to use the computer at all!

Advantages/Disadvantages of using a Keyboard: Advantages

Disadvantages

Enables fast entry of text into documents.

People with wrist and hand problems can find keyboards painful 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 is correct.

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 Information:

Examples:

# 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 withdraw from an ATM.

Telephones -

These use numeric keypads to allow us to enter phone numbers.

Chip and Pin devices -

These have numeric keypads to allow users to enter PIN numbers and payment amounts when we buy goods and products.

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

Mobile phones use numeric keypads to allow us to enter phone numbers.

Advantages/Disadvantages of using Numeric Keypads: Advantages

Disadvantages

Faster than QWERTY keyboards when used for entering numbers.

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

Numeric keypads are small so they can easily fit on smaller devices like mobile phones.

Difficult (but not impossible) to enter text information.

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Inpung data into a computer using a keyboard.

Pointing Devices

(mouse, touchpad, trackerball)

Overview of pointing devices:

Examples:

# Pointing devices are pieces of hardware that are used to control a pointer (curser) on a screen. # Pointing devices are frequently used with Graphical User Interface (GUI) operating systems where pointers are used to input commands by selecting icons.

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

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: Mouse Touchpad Trackerball Trackerballs also allow us to control a screen pointer.

Information about the Mouse: # There are two different types of mice - a ball mouse and an optical mouse.

Ball Mouse -

Uses a ball under the mouse to detect movement.

Optical Mouse -

Uses reflected light to detect movement.

Examples:

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# The ball (in a ball mouse) and the reflected light (in an optical mouse) allows the user to direct and control an on-screen pointer . # Mice have two buttons and a scroll wheel. These provide users with different functions: Left button is used to select icons and click options Right button is used to call up a drop-down menu of options Scroll wheel is used to move up and down through a document.

A ball mouse uses a ball to detect movement. These are prone to clogging which can affect accuracy.

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 wire plugged into the computer . They are powered by batteries instead of the computer.

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 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.

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 to communicate with the computer. They are powered by ba䘀eries.

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Advantages/Disadvantages of Mice: Advantages

Disadvantages

Faster to select icons and options when compared to a keyboard.

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

Very easy to move a pointer around a screen and to navigate through 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 you had a flat table to rest on.

Information about the Touchpad:

Examples:

# 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. 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.

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

Advantages/Disadvantages of Touchpads: Advantages

Disadvantages

Easier than QWERTY keyboards when used to select options and icons.

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

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

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

Can be used even when there is no flat surface available.

Some operations are more difficult to perform when compared to a mouse. Drag and Drop for example.

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

Information about the Trackerball:

Examples:

# Trackerball's are similar to mice but the ball is on the top of the device instead of the bottom. # 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 people with painful hand and wrist problems (like RSI) can use a trackerball.

Why are they more comfortable?

Trackerball's perform the same func伀ons as a mouse but they require less wrist movement and so are more comfortable to use.

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: Advantages

Disadvantages

People with hand/wrist problems can still use trackerball's

More expensive than mice.

Old arcade games machines o縂en used trackerball's to allow gamers to direct in‐game characters.

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More accurate than mice or touchpads.

More difficult to learn to use than a mouse.

Pointer can be positioned more exactly which makes trackerball's very using for image editing. Can be used even when there is no flat surface available. No limit on ball travel. A mouse sometimes runs out of room on a mouse mat. 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:

# 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.V Increasing/Decreasing the volume on a music player Selecting 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).

A satellite T.V remote control with bu䘀ons to control the channel, volume and many more.

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# Industry uses remote controls to operate machinery that might to too dangerous to get near to. Examples include: 1.

Cranes with heavy loads.

3.

Operating robot arms in hazardous chemical plants.

2.

Activating explosives in demolition.

Advantages/Disadvantages of Remote Controls: Advantages

Disadvantages

Devices can be operated without having to go to them. This is useful for people with disabilities.

People with limited hand movement can find them difficult to use.

They can operate devices that are in an unsafe environment.

The infra-red signal between the remote control and the device it operates can become blocked.

A man using a remote control to operate a crane.

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

Joysticks Information:

Examples:

# Joysticks have similar functions to that of mice and trackerballs...... to control a pointer on a 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 onscreen characters and the buttons are used for things like firing weapons.

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.

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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: Advantages

Disadvantages

Easier to control an on-screen curser or move an in-game character than it is when using a keyboard.

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

Very simple to get used to.

People with hand/wrist issues (like RSI) can find them painful to use.

Joys伀cks used to operate a crane.

Anyone can just pick one up and use it! Can be used by disabled people. Joysticks can be operated by hands or even feet.

Difficult (but not impossible) to enter text. For example: some games allow you to select individual letters using the joystick in order to spell out your name when entering a high score. Joys伀cks are also used to mimic real‐life flight condi伀ons on flight simulators.

Touch Screens Information: # Touch screens allow users to input commands into a computer by pressing or touching buttons/icons on the screen .

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

Examples:

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# 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 (a separate keyboard would make the devices quite large).

2.

Public information systems at airports or tourist information offices. A touch screen with 'pressable' op伀ons.

3.

Interactive whiteboards in schools.

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

Advantages/Disadvantages of Touch Screens: Advantages Very fast and easy to enter options (you just press them). No training needed in order for people to be able to use them. All people do is press the correct option.

Modern mobile phones use touch screens to reduce the size of the device.

Disadvantages Limited number of options available on the screen. Expensive compared to other input devices. Screen can become dirty and full of germs due to people touching it.

School classrooms use special touch screens called 'Interac伀ve Whiteboards'.

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Scanners Information:

Examples:

# Scanners are used to enter information on paper paper (hard copies) into a computer. computer . Scanners can convert hard copies copies (printed documents, photographs etc) into digital data. data. This digital data can then be stored and manipulated manipulated on your computer.

# Scanners reflect light off the hard copy in order to capture an analogue image image of the document. The scanner then converts the received analogue data into a digital format. format. # Once the hard copy has been converted to digital data, it can be stored on a computer and manipulated manipulated using Graphics Editing Software (such as Photoshop).

Earlier scanners, like the Sharp JX‐450, could only scan documents in low‐resolu伀on (image quality lost).

Uses of Scanners: # Used to scan hard copy / printed documents into a computer: # Old photos and important documents documents (like birth certificates) can be scanned into the computer. This means you still have a copy copy if the original is damaged or 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 convert analogue hard copies of documents and photos in digital data.

Advantages/Disadvantages of Scanners:

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Advantages

Disadvantages

Very fast to enter hard copies copies into the computer (compared to retyping with a keyboard).

Scanned images are usually of lesser quality quality than the original document.

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

Scanned images can take up a lot of disk space (especially if you scan them at a high resolution).

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.

Digital copies of the stored data can easily be duplicated duplicated and backed up. up . Old photo's that may be damaged can be scanned into the computer then repaired using Graphics Editing Software .

Graphics Tablet Information:

Examples:

# Graphics tablets are used by artists artists and designers designers to easily create and store digital graphics in a computer. # A graphics tablet can be drawn on with a special pen called a 'stylus'. '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. digital.

A graphics tablet with a stylus pen .

# 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 editing software. software.

Uses of Graphics Tablets: # Allow designers to produce digital images much more accurately accurately than if they were using a mouse.

Graphics tablets can be used to accurately 'draw' illustra伀ons, symbols and diagrams.

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Advantages/Disadvantages of Graphic Tablets: Advantages

Disadvantages

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

Very expensive expensive when compared to a mouse.

Very accurate drawings drawings can be produced.

Not useful for some input needs.

Stylus pens make it better for the artist to capture capture fine detail detail than they could using a mouse.

For example - - graphics tablets are not designed for entering data into the computer by clicking icons or menus.

Useful in countries countries where drawings and symbols symbols are used instead of text (like China and Japan).

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

Light Pens Information:

Examples:

# Light pens are quite old technology and can be used as alternatives to mice, mice, touch screens or graphics tablets. tablets . # Light pens are used by directly drawing or selecting icons on a computer screen. screen .

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

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

Uses of Light Pens: # Used for selecting objects objects on a CRT screen. screen.

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

Light pens can replace mice and touch screen for selec伀ng items on a CRT screen.

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# Used for directly drawing onto a CRT screen.

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

Advantages/Disadvantages of Light Pens: Advantages

Disadvantages

More accurate than touch screens.

Not as accurate as a graphics tablet when used for producing drawings.

Light pens can be used to produce drawings directly on a CRT screen.

(end of the pen is much thinner than a finger and so can accurately select small icons) They are very small and so can be used where there is no room for a mouse or graphics tablet.

Can only be used with CRT (cathode ray tube) screens. (not usable with TFT or LCD screens) Can be quite uncomfortable to use as you have to hold your hand raised up to the computer screen for long periods. Light pens only currently work with CRT Screens (the fat ones) .

Microphones Information: # 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.

Examples:

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For example: computers understand combinations of 0's and 1's.

3. The job of the microphone is to input analogue sound signals into the computer where the sound card will convert analogue sound into digital (in other words the sound card will 'digitize' the analogue sound into 1's and 0's) Note: the sound card acts as an ADC (analogue to digital converter).

4. Once digitized, the sounds can be stored and used by the computer. Microphones are used to input sound into a computer.

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 sites Voice-over's in movies Speaking over the Internet using VoIP (Voice over Internet Protocol) An example of this would be using Skype to hold an online conversation Conducting 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').

Microphones can be used to hold voice conversa伀ons over the Internet (like using Skype).

# Hands-Free mobile phones use a microphone to allow people to hold conversations without 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: Advantages

Disadvantages

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

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

Sound files can take up a lot of computer storage space.

Means that word processors can be used by people who cannot use their hands. Words are simply spoken into the software instead of typed.

Speaking words into a word processor is not as accurate as typing. This means that mistakes are common with words that sound the same but have different meanings. For example: 'see' and 'sea'.

Makes driving safer because people do not need to take their hands off the steering wheel in order to use their mobile phone.

Background noise can interfere with voice recognition systems.

Microphones are very cheap to buy.

Gamers use microphones to communicate instruc伀ons to each other in‐game .

Digital Cameras Information:

Examples:

# Have pretty much replaced the old style film-based cameras. # Digital cameras store digital photographs on a memory card and these images can easily be transferred onto a computer for viewing or editing. # Most digital cameras have a built-in screen to allow for previewing the digital photograph. This is useful so that the photographer can decide which images to keep and which to delete. An old film‐based camera .

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

A modern digital camera with preview screen.

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. Tradi伀onal photographs were stored on reels of film .

Advantages/Disadvantages of Digital Cameras: Advantages

Disadvantages

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

Camera user needs to have computer skills to be able to transfer and print digital photographs.

Unwanted images can easily be deleted from the memory card.

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

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

Artistry of traditional photography is being lost.

No need to print at all because the images can be viewed a computer screen. This saves paper and is better for the environment.

Camera software can automatically correct 'bad images' making photography easier to master without as much skill.

Digital photographs are stored on memory cards.

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Memory cards can store thousands of digital photographs. Traditional photographs can take up a lot of physical storage space.

People using traditional 'film-cameras' had to take much more care to capture each image perfectly.

Digital images can easily be transferred using blutooth, email attachments and mobile phones. Digital images can be improved and edited easily using software (sharpening the 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)

Information:

Examples:

# Web cameras are similar to digital cameras in their function but they are directly connected 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 other publications. 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 is about. A web cam a䘀ached to a computer monitor.

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

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Uses of Web Cameras: # Used to conduct face-to-face conversations with friends and family online over VoIP applications such as Skype.

A similar use is to conduct face-to-face job interviews over the Internet. This removes 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 YouTube content.

Web cams allow long distance face‐to‐face interviews to take place.

# Web Cameras are sometimes used by parents to keep an eye on their children when they 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: Advantages

Disadvantages

Allow for long-distance face-to-face conversations. This removes the need for people to travel.

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

(especially useful for elderly and disabled people to keep in touch with family) Video conference business meetings and job interviews can be conducted very cheaply over long distances.

They do not have their own storage and so must be permanently fixed to the computing device.

Web cams allow elderly people to hold face‐to‐face conversa伀ons with rela伀ves.

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(no need for expensive travel or bookings of hotel rooms to attend the meeting or interview) Parents can keep an eye on their children from a different location.

Are usually in a fixed position and so cannot be easily moved around.

Web cams can be left running constantly which makes them useful as security devices 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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The ICT Lounge

Section 2.2: Direct Input Devices In section 2.1 we looked at manual input devices and talked about how these require a large amount of human interaction in order to get data into a computer. In this section we will focus on direct input devices. Direct input devices require 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 different direct 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 Stripe Reader

Optical Mark Reader (OMR)

Chip and PIN Reader

Optical Character Reader (OCR)

Barcode Reader

Magnetic Ink Character Recognition (MICR)

REMEMBER! Direct input devices do not require much human interaction to get their data into a computer system. For example: All a human has to do to use a Barcode Reader is point the reader at the barcode and pull the trigger. The reader will do the rest.

NOTE: Click the images to the left to move to more information about each one.

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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: Information about the device Uses of the device Advantages of the device Disadvantages of the device

Magnetic Stripe Reader Information:

Examples:

# Reads information from magnetic stripes found on Bank Cards, Membership Cards and Hotel Door Cards etc. # The strip on the cards holds information such as: Bank account number Name of card holder Expiry date of membership etc # Data contained on the card's stripe is read by pulling the card through the magnetic stripe reader. This is known as 'swiping'.

Informaon held on a card's 'magnec stripe' is read by swiping the card through a strip reader.

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

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's money 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 to open the door.

Details about bank accounts are stored on a magnec stripe .

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Advantages/Disadvantages of using a Magnetic Stripe Reader: Advantages

Disadvantages

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

The magnetic stripe on cards can only hold a 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 for example)

The stripes on cards are not affected by water and so quite robust (not easily damaged).

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

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

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

Hotel room cards contain data on the stripe that will unlock the door once inserted into the reader.

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

Chip and Pin Reader Information:

Examples:

# 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 entering a 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 the correct number. # If the correct PIN is entered, the cost of goods/services will be taken from the card holder'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: Supermarkets Restaurants Cafes Buying petrol etc

Chip and PIN Readers require the correct idenficaon number to be entered.

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Advantages/Disadvantages of using Chip and PIN Readers: Advantages

Disadvantages

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

It is possible to forget your PIN which means you cannot make payments with your card .

Information contained on the chip is harder to clone (copy) than it is to copy magnetic stripes .

People can look over your shoulder as you enter your PIN. This makes it possible to access your money if they ever stole your card.

Chips can hold more data than magnetic stripes can.

Informaon on a card's chip is more secure than on a magnec stripe .

Many goods and services can be purchased using Chip and PIN Readers .

Chip and PIN Readers are portable so they can be brought to you (waiter in a restaurant for example)

Barcode Scanner/Reader Information:

Examples:

# Used to read information that is stored on product's barcodes. # The barcode scanner reads the information stored on the barcode using a visible red light which is reflected and translated into digital information. # The barcode is present on products and holds information about each product including: Product Id number Manufacturer Country of origin The barcode does not store the price of the product . This information is held in a computer database and accessed using the product id.

Barcodes contain informaon about products and can be read with scanners.

Note: By storing the price in a database instead of on individual bar codes, it is easier to change (if you had a sale for example). All you would do is change the price in the database 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 the barcode 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 too large and heavy to move to the scanner).

A barcode on a package being scanned.

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Uses of Barcode Scanners/Readers: # Used in supermarkets, stores and warehouses where goods are marked with a barcode. Remember:

Barcodes hold information about the product which is linked to a computer database. This enables automatic very fast itemised billing to take place.

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

Barcodes are found on items that we buy in stores.

# They are used in keeping track of packages that are being delivered to different locations. # Also used in organising luggage in airports (helps ensure that luggage is loaded onto the correct plane).

Advantages/Disadvantages of Barcode Scanners/Readers: Advantages

Disadvantages

Quick and easy to change product prices.

Quite an expensive way to gather information. Each item needs a barcode and the scanners / computer technology / database needed is also expensive.

Only the price data in the database needs to updated. There is no need to change individual prices on each of the item's bar codes. Quick and easy way of getting information into a system.

POS terminals in supermarkets have built‐in barcode scanners.

Bar codes can be swapped on items which means people may pay less for more expensive items.

(all you do is scan the item's bar code) Very accurate as there is no manual typing involved.

Enables automatic stock control.

Rely on undamaged bar codes in order to function.

Hand held barcode scanners are used to read barcodes on large items.

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

Optical Mark R eader (OMR) Information: # 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.

Examples:

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# The OMR reader shines a light onto the form and less light is reflected where a pencil mark has been made. # This allows the reader to tell which options have been chosen and sends the results back 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.

Opcal Mark Reader automacally inpung the answers given on a mulple choice form.

# 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!!

OMR devices can read the shaded areas on mulple choice tests.

Uses of OMR's: # Used to read the shaded areas on documents such as: Multiple choice examinations Multiple choice questionnaires Lottery tickets

But are typically used on any document that has multiple choice responses that are shaded in. They can also read shaded areas on loo ckets.

Advantages/Disadvantages of OMR's: Advantages

Disadvantages

Extremely fast way of inputting information into a computer.

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

(around 4000 forms can be read per hour) Very accurate as document's data is fed into the computer automatically with no manual typing.

If forms have been incorrectly filled in they cannot be read properly.

(accuracy relies on the forms being filled in correctly)

(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 to enter 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) Information:

Examples:

# 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 convert scanned text into digital (digitizes)

3.

Digital text can be used in digital devices and applications

Printed text on a document being scanned as part of the 'digizing' process.

Regular scanners can also be used for inpung scanned text into a computer ready for digizing.

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 digital format for use on E-book readers such as Amazon's Kindle.

Advantages/Disadvantages of OCR's: Advantages

Disadvantages

Very fast way of entering hard-copy text

The system can have difficulty reading

Image of text being converted to digital. (click image to zoom)

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into a computer.

handwriting (especially if it is messy).

Cheaper than paying an employee to manually re-type printed text into a computer.

Not 100% accurate.

Avoids typing errors as the process is automatic (no typing involved)

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

(relies on being able to read the original text)

It is also possible to digize handwring.

Magnetic Ink Character R ecognition (MICR) Information:

Examples:

# MICR is a system which can read information printed in a special ink (the ink contains iron particles). # This special ink is used to write customer account numbers on the bottom of cheques. # The MICR device reads the account numbers then converts it to a form the computer can understand. # The converted information is then sent to the computer so the cheque can be processed.

Uses of MICR: # MICR devices are mainly used to process cheques. Below there is a summary of the process: 1.

Every day millions of cheques. are sent to banks for processing. To process the information 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. with 100% accuracy (They can handle 300 per minute).

3.

MICR can be used to read the following information: Customer account number Bank sort-code/branch number Cheque number.

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

Advantages/Disadvantages of MICR:

A MICR device reading the magnec ink on a cheque.

Magnec ink is used to write various account numbers on cheques. (click image to zoom)

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Advantages

Disadvantages

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

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

Greater security than OCR because the special ink characters cannot be changed.

Both the MICR device Magnetic Ink are more expensive than other 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 the magnetic ink characters. For example: if someone tries to manually alter an account number by hand the device will still read only the original data.

Pre vio us - Manua l Input Dev ic es

Next - Sens ors





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


Section 7: Part 2










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3/17/2016

IGCSE ICT - Sensors

The ICT Lounge

Section 2.3: Sensors In the last section we looked at how data can be input into a computer system (both manually and directly). In this section we will discuss how sensors can be used to automatically detect changes in the environment around and then directly feed this data into a computer for processing.

Sensors Definition:

Key Concepts of this section: # Know the definition of the term 'sensor'. # Understand the different types of sensors and what uses they perform. # Be able to discuss advantages and disadvantages of sensors.

(what are they?)

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

Overview of Sensors:

Key Words: Data, Automatic, Measured, Analogue, Digital, Analogue to Digital Converter, ADC

Examples:

# Used to detect data in the surrounding environment that constantly changes. For example: Temperature - measuring heat in a room Light - setting off a burglar alarm Humidity - detecting when plants become too dry. # This information is ‘physical’ and ‘analogue’. Analogue data is constantly changing and it changes very smoothly. Thermometers are examples of temperature sensors.

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IGCSE ICT - Sensors

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

Computers don’t understand analogue data and therefore it needs to be converted to digital (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 in order to achieve this. Infrared burglar alarms are examples of light sensors.

Examples of Sensors # The table below shows you some examples of sensors: Temperature

Pressure

Key Words: Temperature, Pressure, Light, Sound, Humidity, pH, Monitoring, Data Collection

Light

REMEMBER! Sensors are used to AUTOMATICALLY get data into a computer system.

NOTE: We will look at each sensor in greater detail further down this page.

Sound

Humidity/Moisture

pH

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IGCSE ICT - Sensors

Uses of Sensors

Examples:

# Sensors are used in monitoring and control applications. # When monitoring, the data is sent directly to some sort of a computer and is then processed and used.

For example:

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

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

For example:

Sensors in burglar alarms can automacally detect intruders.

Taking measurements in scientific experiments Measuring pollution in the atmosphere Sensing the temperature in a room and using this to either turn a heating 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.

Automac doors open when people are detected nearby.

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IGCSE ICT - Sensors

Pressure

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

Light

Automatic greenhouses, Automatic doors, Burglar alarm systems, Street lighting control.

Sound

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

Humidity/Moisture

Automatic greenhouses, Environmental monitoring, Agriculture, Factories that manufacture items that can be ruined by too much air moisture (microchips etc).

pH

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

A variety of sensors are used on automac greenhouses to keep plants in perfect condions.

Advantages/Disadvantages of Sensors # The table below highlights some of the main advantages and disadvantages of using sensors:

Advantages Readings taken using sensors are more accurate than those taken by a human. 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 is detected). No need for humans to operate the sensor. This can be useful if gathering the information is hazardous like in detecting radiation levels for example.

Disadvantages

pH sensors are used to monitor the acidity and alkalinity level of aquariums (wrong levels can kill fish).

Faulty sensors can give incorrect results. For example: if the sensors on a car that help with reverse parking become dirty they may not identify an obstacle and cause you to crash into it.

Malfunconing sensors used on cars to assist in 'reverse parking' can cause crashes.

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IGCSE ICT - Sensors

Previous - Direct Input Devices

Next - Output Devices








Section 7: Part 2










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3/17/2016


The ICT Lounge

Section 2.4: Output Devices Once data has been input into a computer system and processed, it is now 'useful information'. This information is ready to be output (sent out). In this section you will learn about the different types of output devices that 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.

Output Devices Definition:

Key objectives of this section: # Know the purpose of and be able to identify different output devices. # Understand the uses of each output device. # Be able to discuss advantages and disadvantages of each output device.

(what are they?)

"Hardware devices that allow information to be sent out of a computer system."

Overview of Output Devices: #

Output devices are part of the 4 main hardware components of a computer system: Input Devices - these get data into the computer Processor - this does something with the data to make it useful information Output Devices - these show the results of processing Storage Devices - holds the data in the system

#

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

Key Words: Input, Processor, Output, Storage, Hardware, Data, Information

Examples:

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This diagram shows where output devices fit into a computer system.

A computer monitor (screen) is an example of a commonly used output device.

#

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).

Printers are another example of a commonly used output device.

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

Examples of Output Devices

NOTE: More examples will be shown further down this page.

Key Words: CRT Monitor , TFT Monitor, Laser Printer, Inkjet Printer, Dot matrix Printer, Plotter, Speakers, Multimedia Projector

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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 send processed information OUT of a computer.

NOTE:

Dot Matrix Printer

Plotter

Speakers

Multimedia Projector

Click the images to the left to move to more information about each one.

Breakdown of each output device: # The following sections will help summarise each of the manual i nput devices. For each one you will see: Information about the device Uses of the device Advantages of the device Disadvantages of the device

CRT Monitor (cathode ray tube) Information: # CRT stands for 'cathode ray tube'.

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

Examples:

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# 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 quality screen image and take up far less space.

CRT's produce an image (Made up of tiny dots) by firing Electron Beams against a Phosphor Screen Each dot is coloured Red, Green or Blue of different intensities which produces a vast amount of different colours.

CRT monitors are very bulky and take up a lot of desk space.

Note: These dots combine to create millions of different colour shades. (just like when you mix colours in art)

Light pens can be used with CRT's to produce drawings and designs directly onto the screen.

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

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

Advantages/Disadvantages of CRT Monitors: Advantages

Disadvantages

Can be used with light pens to create drawings on screen.

They are very large and bulky which means they take up large amounts of desk space.

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

Screen glare can be a problem with CRT's.

Note: their large size and weight also make them 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.

Screen glare when in direct light makes viewing difficult.

(you do not have to stand directly in front of the CRT screen in order to see what is on it) Note: they are also prone to 'screen flicker' which can cause headaches and eye strain. Cheaper to buy than TFT screens.

They also need more power than TFT's to operate (more expensive to run).

CRT monitors can get very hot.

TFT Monitors (thin film transistor) Information: # 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

Examples:

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computer screens.

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

#

TFT screens are made up of thousands of tiny pixels. Each pixel has 3 transistors red, green and blue and each transistor can produce different intensities. This allows huge amounts of colours to be produced (16.7 million).

TFT monitors are much thinner than CRT's.

A back light is used to shine light onto these pixels 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 light to pass through and onto the pixel.

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)

TFT screens are light and are perfect as displays for portable devices such as laptops.

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Advantages/Disadvantages of TFT Monitors: Advantages

Disadvantages

Lightweight so they are perfect for portable laptops and wall mounting.

Images can appear unclear when viewed from an angle.

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

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

They produce much less glare than CRT’s and 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.

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

(Computer Aided Drawings are not yet possible on TFT monitors) They emit less radiation than CRT monitors. They produce less heat than CRT's.

Their lightweight makes TFT's easy to mount on walls.

Laser Printer Information: # These produce high quality hard copy outputs (on paper) .

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

Examples:

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# 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 before the 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 the memory when it is ready to do so.

Laser printers are popular for environments that require fast high‐quality printouts.

Think of the Buffer Memory as a kind of waiting room

#

Laser printers work by using a laser beam to 'draw' onto a drum. The laser leaves a positive electric charge on the drum in the places where it drew.

A special power known as 'toner' is sprayed onto the drum and it sticks to the parts that contain the positive electric charge. The drum is then pressed onto a sheet of paper and the paper is heated (fused) so that the toner is bound to the paper.

Uses of Laser Printers: # Very useful for printing where noise levels need to be kept low (Like in an office where people need to concentrate or use telephones etc).

Laser printers can handle very large print jobs.

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# 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 printing demands of many computers. Popular with:

Colour laser printers are expensive to buy and run.

Schools Businesses Offices.

Toner cartridge (these contain toner power).

Advantages/Disadvantages of Laser Printers: Advantages

Disadvantages

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 replaced often.

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.

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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 Information:

Examples:

# 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 better than 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 so printing is done a bit at a time.

Inkjets can produce photo‐quality colour printouts.

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

#

Inkjet printers work by spraying ink onto a page of paper. The ink is held in 'ink cartridges' and there are 4 different colours - black, cyan, magenta and yellow. These mix to form a vast amount of other colours. Motors are used to position the ink cartridges over the correct position of the page and to drag the paper through the

Inkjets require 4 separate ink cartridges ‐ Black, Cyan, Magenta, Yellow.

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printer.

Click image to zoom

Uses of Inkjet Printers: # Good where few printouts are needed (low volume). # Ideal for single-page, very high quality printing. (Photo quality images). Inkjet printouts will smudge if not le to dry before handling.

# Often used to print photographs.

Advantages/Disadvantages of Inkjet Printers: Advantages

Disadvantages

Output is very high quality (Especially good for colour photograph 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 large print jobs.

Smaller th an l aser printers so take up less space.

They can be expensive to run as new ink cartridges are not cheap to buy.

Do not produce ozone or other harmful compounds.

Printouts can easily smudge if document is not left to dry properly.

Very quiet whilst printing.

Dot Matrix Printer Information: # Often called an ‘Impact Printer’ where pins are pressed against an inked ribbon which produces an imprint on paper.

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

Examples:

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

Continuous paper is the name given to hundreds of sheets of paper that are joined together and 'continuously' fed through the printer. The paper sheets can be separated after printing is complete. Dot matrix printers are noisy and slow.

# Dot matrix printers are still used in environments where print speed and noise is not an issue (like in car garages and factories).

#

These printers work by using a set of pins to press an inked ribbon against paper. When the pin/ribbon hits the paper a printed dot is left behind. The dots can be arranged to form basic text and images. Different coloured ink ribbons can be used to produce colour printouts.

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

Dot matrix printers use ink ribbons.

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# Can make ‘Carbon Copies’ of a document using special ‘Carbon Paper’ underneath normal printer paper.

Advantages/Disadvantages of Dot Matrix Printers: Advantages

Disadvantages

Work just fine in dusty and dirty environments where laser or inkjet printers could easily be damaged.

Very noisy so not suitable for an office environment

Carbon copies can be produced using carbonated paper.

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

Very cheap to buy and maintain.

Very poor print quality. Dot matrix printout quality is very low.

(Inked ribbons are very cheap) Good for continuous printing. (e.g. long print jobs like wage slips)

Dot matrix printouts are made up of arranged dots.

Plotter Information: # 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. 3 foot wide by 10 foot long).

Examples:

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# 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 the paper by a computer.

Uses of Plotters: # Used to produce large, accurate drawings. Some examples are listed below: Blueprints of buildings (plans/designs) Maps Giant posters and adverts (like those we see on billboards).

A drum ploer.

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

Advantages/Disadvantages of Plotters: Advantages

Disadvantages

They can produce much larger printouts than other printers.

Their print times are very slow.

The print quality is extremely high.

They are very expensive to buy and maintain.

A flatbed ploer.

Plotters can also 'cut out' designs for use in sign making.

Ploers can produce very large printouts like those seen on adversing boards.

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Speakers Information:

Examples:

# Many everyday uses of a computer require the user to listen to different types of sounds. For example: Listening to a music album Watching a movie. Browsing videos on YouTube Multimedia encyclopedias. In order for the computer to output these sounds it requires some sort of 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 do something wrong but these can only produce very basic sounds like 'beeps'.

Speakers allow us to listen to sound coming out of a computer system.

Speakers are analogue and cannot output digital 'computerised' sounds. Digital data from the computer must first be converted into analogue sound using a sound card. The analogue sound can then be output via the speakers and we can listen to it.

E‐Book readers (like the Amazon Kindle) have special soware called 'screen readers' that can narrate the words on the screen.

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

Uses of Speakers: # Used to output sound from multimedia presentations (like famous speeches etc). # Used in home entertainment (surround sound etc). Speakers are an important part of home entertainment

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IGCSE ICT - Output Devices systems.

# Can be used by blind people to listen to words on the screen instead of reading . Note:

Special software called 'screen readers' are also needed in order to convert the printed words into sound.

# Can be used to play downloaded music files.

Advantages/Disadvantages of Speakers: Advantages

Disadvantages

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 be High quality speakers can be expensive. turned into sound.

Multimedia Projectors Information:

Examples:

# These project whatever appears on a computer monitor onto a very large screen so that large numbers of people can view it.

# Multimedia Projectors are usually controlled using a remote control. # The remote control makes it possible to direct the presentations without the need to be at the computer.

# Multimedia projectors are often hung from the roof on special brackets.

Uses of Multimedia Projectors: # Can be used for training presentations to allow the whole audience to see images from a single computer.

A mulmedia projector.

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# Also used for large scale advertising of new products.

For example: the famous Apple Technology Innovations presentations with Steve Jobs (click here to watch)

# Home cinema systems where images from DVD’s or televisions are projected to a large screen.

Mulmedia projectors can be used to project images onto a very large screen.

Advantages/Disadvantages of Multimedia Projectors: Advantages

Disadvantages

Many people to clearly view the same presentation.

Lower image quality compared to a computer screen.

Enhance the viewers experience.

Very expensive to buy.

For example: watching movies on a large screen is better than a small TV screen.

Cooling fans in the projector are noisy.

Previous - Sensors

Next - Control Devices

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Section 2.5: Control Devices In this unit we have discussed both input and output devices, including the different ways data is put into computers and how the resulting information is sent out.

Key Concepts of this section:

The last topic covered in this unit is 'control devices'. You will see how these are used in conjunction with sensors to 'make something happen'.

Control Devices Definition:

# Know what the main control devices are. # Understand the role of sensors and actuators within control devices. # Be able to discuss uses of different types of control devices.

(what are they?)

"Output devices that work in conjunction with sensor input devices and commands from computers in order to control a process."

Overview of Control Devices: #

Key Words: Input, Process, Output, Sensor, Control Device, Actuator

Examples:

Control devices are output devices which work together with sensors.

Remember -

Sensors gather 'measurable' data from the environment and input it into a computer. They do not need any human involvement. Sensors typically gather data such as temperature, pressure, pH etc.

#

Data gathered by a sensor is input into a computer which then decides what to do with the data (processes it).

#

Once the computer has decided what to do with the data it sends instructions to the control device.

#

The control device then physically changes something in response to commands received from the computer.

INPUT ‐ Burglar breaks light sensor and this data is

Consider this example:

sent to the computer.

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INPUT PROCESS -

A burglar breaks the infrared light sensor on a security system. This data is sent to a small computer inside a security light. The computer sends instructions to an 'actuator' telling it to switch on the security light.

OUTPUT -

The actuator switches on the security light.

Note: See below for a description of what an actuator is.

PROCESS ‐ Computer looks at the data and instructs an actuator to switch on the security light.

Actuators ---- what are they? # Actuators take instructions from the computer and then make the 'physical' part of the process happen. For example - In our security system example above, the computer has decided that it is necessary to switch on the security light but it cannot do this by itself. Instead the computer instructs the actuator to switch the light on. OUTPUT ‐ The actuator switches on the security light

# Think of actuators as kind of like muscles.

and the burglar is scared away.

We cannot move our limbs without using our muscles in much the same way as a light in a control device cannot turn on without an actuator.

NOTE: Sensors and control devices are discussed in more detail in a later unit (link here).

Actuators respond to instructions sent by a computer. Our muscles respond to instructions sent by our brain. # Actuators can also physically operate devices such as motors, pumps, switches and valves.

Examples of Control Devices

Key Words: Motor, Buzzer, Heater, Lights

# The table below shows you some examples of control devices: Motor

Buzzer

Heater

Light / Lamp

REMEMBER! Control devices require inputs from sensors and instructions from a computer in order to produce the correct output.

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Uses of Control Devices # The table below summarises the main uses of different control devices: Remember -

Type of Sensor: Motor

Examples:

each of these control devices are switched on and off by an actuator

Used In:

Households: Automatic washing machines (to make drum spin) DVD player (to make disc spin) Air conditioners (to make fans spin) Industry: Controlling robot arms Computer systems:

Motors in washing machines make the drum spin.

Spinning disks in hard disk drives Spinning cooling fans

Buzzer

Heater

Light / Lamp

Microwave ovens (to signal that the food is cooked) Alarm systems (loud siren to warn of intruders)

Central heating systems (to keep rooms correct temperature) Washing machines (To keep water the correct temperature) Automatic greenhouses (ensures air is correct temperature for plants)

Image of a hard disk drive showing the actuator that makes the disk spin (click to zoom).

Security lights Automatic greenhouse (to give plants correct amount of light)

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Next - Storage Devices and Media

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Section 3.1: Data Storage and Backing up Data In this section you will see what is meant by the terms 'data storage' and 'backing up data'. We also discuss why it is very important that data is backed up and briefly look at some circumstanses that can destroy our data.

Data Storage Definition:

Key Concepts of this section: # Know what is meant by 'Data Storage'. # Understand the difference between temporary storage and permanent storage. # Be able to discuss why it is important to back up data.

(what is it?)

"Data Storage is where we put data in a ‘known’ place (Save) which we can come back to later and get the data back again (Read)"

Overview of Data Storage: #

There are some terms that you need to be aware of when we talk about data storage:

Writing of data = Reading data =

#

Storing data (also known as saving) Getting our data back (also known as opening)

Data can either be stored temporary or permanent. RAM (computer memory) is used to store data temporarily Backing Storage Devices are used to store data permanently.

Key Words: Data, Storage, Save/Write, Open/Read, RAM, Permanent, Volatile, Non-Volatile

Examples:

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The difference between these are explained below:

RAM (computer memory)

Backing Storage Device

Data is temporarily stored.

Data is permanently stored.

Volatile - data is erased when computer is switch off.

Non-Volatile - data is not erased when computer loses power.

Used to only store data that is currently in use.

Used to store data long term. (data is only erased when we manually choose to delete it)

(e.g. open programs and unsaved files) Very fast reading/writing of data.

Storage devices can be saved on and read from.

Slower reading/writing of data. Examples of permanent storage devices include hard disk drives, DVD's and flash memory sticks.

#

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

RAM can only store data whilst computer has power. USB scks store data permanently.

This diagram shows where storage devices fit into a computer system.

Without storage devices we could not run operang systems, programs or save our work. Our computers would be be completely useless!

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Backing up Data Definition:

Key Words: Backup, Copy, Medium

"Backing up is the process of using a storage device to copy files and data to a different storage medium in case of a problem with the original copy"

Overview of Data Backups:

Examples:

# Backing up of data is simply the process of making copies of your files. # To back up data you need 2 pieces of equipment: Storage Device - The hardware that saves (writes) or reads the data from the storage medium. (DVD Player for example) Storage Medium - The hardware that actually holds the data (Memory Sticks, Hard Disk Drives, DVD Disks etc) # Backing up is considered 'good practice' and helps prevent us from losing our work and files.

Note:

There are many ways we can lose computer files. We could accidentally delete them, files could be infected with a virus or someone could even deliberately erase our files! Backing up data just means to 'make copies' of files.

# Backups of files should be stored in a different location to the original.

This is to ensure we have safe copies in the event that the originals are destroyed by fire or floods etc. If the backups were in the same location as the originals then the fire would destroy the backups as well!

DVD drives are 'Storage Devices' that are used to read/write data onto DVD discs.

Why Backup Data? # There are many reasons why backups are made. Some of the common reasons are summarised below:

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1.

Original data could be accidentally copied over or deleted.

2.

Data could be lost due to damage to the original storage device. For example: You hard disk drive could stop spinning.

3.

You could lose your original storage device. For example: Your laptop could get stolen or you could misplace a memory stick.

4. Hackers could access our data and delete it (or change it) 5.

Original storage device could be destroyed in a fire.

Note: Backups don't help prevent data loss in the event of viruses. if the original file had a virus BEFORE the it was backed up then the copy will also be infected.

Previous - Storage Devices and Media Main Menu

DVD discs are example of 'Storage Medium' and these hold the data.

Next - Ways in which Data is Stored and Read








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Section 3.2: Ways in which Data is Stored and Read In this section we will look at the 2 main ways in which data is accessed, stored and read: Serial Access (also known as 'sequential access) Direct Access (also known as 'random access)

Key Concepts of this section: # Know the difference between 'Serial' and 'Direct' data access. # Understand how both serial and direct access work. # Be able to state the different uses of serial and direct data access storage methods.

Serial Access Overview: #

This method is also sometimes called 'Sequential Access'.

#

Data is accessed by starting at the beginning and then searched through, in order/sequence, until the required information is found.

Key Words: Serial, Sequential, Sequence, Magnetic Tape

Examples:

Kind of like an old film reel where the movie starts at the beginning and data is read in order until the movie is finished

#

The need to search from the beginning of the storage medium makes this type of data access very slow. Serial data access reads data in 'sequence'.

Where Serial Access is used:

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#

Serial access is used on old magnetic tapes. These are used where it is necessary to store a lot of data but where speed of access is unimportant. Magnetic Tapes are still used for backing up large amounts of data in organisations like schools and business.

#

Serial access medium (like magnetic tapes) are also used in batch processing systems like payroll and in the preparation of utility bills. The way that serial access works means that all of the data has to be read and there is no danger of missing out someone's wage payment or bill invoice.

Remember:

Old film reels access the movie's scenes in 'sequence'. E.g. from start to finish.

Serial access works by accessing the data at the beginning and then working through it bit-by-bit until the end. This is why there is no danger of missing anything out during the batch processing examples above.

#

Examples of storage medium that use serial access are: Video cassettes Music cassettes Backup tape cartridges(hold lots of tape for backing up large amounts of data).

Direct Access

Magne㔧c tape can store a lot of data but it is slow to access it.

Key Words: Direct, Random

Overview: # This method is also sometimes called 'Random Access'. # The computer can calculate exactly where the data has been stored and can go straight to it directly (instant access). The computer knows where all of the data on the storage medium is and so it can access it very quickly.

Examples:

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It is not forced to start accessing the data at the beginning and then working through bit-by-bit like with serial access. A good comparison as to how direct access differs to serial access is to think of how DVD movies work compared to old film-reel movies. In a DVD movie you can 'jump' directly to any scene you want but in a film-reel you have to move through every scene until you come to one you want. # This 'direct' method of accessing data is much faster than serial access.

Direct access can go straight to the required data 'directly'.

Where Direct Access is used: #

This method is used with storage medium such as: Hard Disk Drives CD's and DVD's Direct access is used on most modern storage devices where speed of access is important. DVD movies allow you to jump to scenes. This is possible through direct access.

Note: The large size of modern files makes direct access even more useful.

# Direct access medium are used in situations where fast access to data is important like in online booking systems and point-of-sale (POS) terminals in shops.

For example:

You wouldn't want to wait around at a shop checkout while the system was trying to access the price of beans!

# Other examples of storage medium that use direct access are: USB memory sticks Flash memory (like in digital cameras and mobile phones) Blu-ray discs

Previous - Data Storage and Backing

Flash memory cards are an example of storage medium that use direct access.

Next - Storage Media Introduction

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Section 3.3: Storage Media Introduction In this section you will be introduced to the 3 main types of storage media:


Magnetic storage media Optical storage media Solid state storage media We also discuss storage media capacity, including kilobytes, megabytes, gigabytes and terabytes.

Storage Media #

# Know the difference between storage devices and storage media. # Be able to name the different storage capacity units (from smallest to largest).

(a quick introduction)

Storage media is the term given to the devices that are used to hold data.

Note:

Storage media is NOT the same thing as a storage device.

Key Words: Storage device , Storage media, Internal, External, Magnetic, Optical, Solid-State

Examples:

Storage media = the part that holds the data Storage device = the machine that reads/writes data to and from the media

# Stor age media is 'permanent storage' and will hold data even when the computer is powered off . Remember:

Permanent storage devices: Devices that hold data without power and are known as 'non-volatile' Temporary storage devices: Devices that lose data without power and are known as 'volatile'.

# St orage media can either be: Internal - inside the computer External - plugged into the computer from outside (e.g. usb stick) #

There are 3 different types of storage media and they all store data in different ways. These are summarised below:

The CD is the 'media' (where data is held) The CD Drive is the 'device' (reads data on media).

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Storage Media

Summary

1. Magnetic media

2. Optical media

3. Solid-state media

Holds data magnetically Surface area of the media are magnetised so that they can hold 'bits' of data The device that reads the media can also read the bits held on the surface area.

Holds data by burning 'dots' onto the surface with a high powered laser The device that reads the media can read the data by shining a lower powered laser over the dots .

There are 2 types of computer storage ‐ Permanent and Temporary.

NOTE: Holds data on devices that have no moving parts.

Storage Capacity # Storage capacity is the term given to the maximum amount of data that can be stored on the media. # Storage amounts are measured in 'bytes' and there are 8 bits in 1 byte.

All 3 types of media are covered in more detail in the next 3 sections of this unit.

Key Words: Bit, Byte, Kilobyte, Megabyte, Gigabyte, Terabyte

Examples:

Bits are short for 'binary digits'. This is the smallest unit of data that can be stored. Each 'bit' is represented as a binary number, either 1 or 0. A single letter on a keyboard takes up 1 byte of storage (8 bits). Computers read and process everything in the form of binary numbers. Each binary number takes up 1 bit of storage. For example: The letter C looks like 01000011 to a computer. There are 8 binary numbers.... so 'C' takes up 8 bits or 1 byte of storage.

There are 8 bits (binary digits) in 1 byte of data. (click to zoom)

# Click here for a text to binary converter to see what other keyboard characters look like in binary.

Storage Capacity Units: # We refer to the storage capacities of different media in the following units:

There are 16 bits in 2 bytes of data. (click to zoom)

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Unit

Abbreviation

Information

Bit

Smallest unit of data (either a 1 or a 0)

Byte

1 byte = 8 bits

Kilobyte

KB

1 KB = 1024 bytes

Megabyte

MB

1 MB = 1024 Kilobytes

Gigabyte

GB

1 GB = 1024 Megabytes

Terabyte

TB

1 TB = 1024 Gigabytes

Floppy disks can't store very much data (about 1.44 MB).

# Storage media all have different storage capacities. For example:

Hard disk drives have capacities in the terabytes. Floppy disk drives can only hold 1.44MB of data.

Storage Capacity Examples: # The table below gives you some real-world examples of approximately how much data we could store on storage media with different capacities: CD's can hold about 800 MB of data.

Storage Media Capacity

How much Data could be Stored

1 kilobyte

1 thousand characters (half a page of text)

1 megabyte

1 million characters (500 pages of text)

1 Gigabyte

1 billion characters (500,000 pages of text)

1 Terabyte

1 trillion characters (1,000,000 thick books)

Hard disk drives can store terabytes of data. This is the equivalent of many libraries full of books.

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Section 3.4: Magnetic Storage Media In this section you will see the 4 different types of magnetic storage media. Fixed hard disk drive Portable hard disk drive Floppy disk Magnetic tape

Key Concepts of this section: # Know the 4 different types of magnetic storage media. # Understand the uses of each magnetic media.

For each we will discuss features, uses, advantages/disadvantages.

Examples of Magnetic Storage Media

# Be able to discuss advantages and disadvantages of each magnetic media.

Key Words: Fixed Hard Disk Drive , Portable Hard Disk Drive, Floppy Disk, Magnetic Tape

# The table below shows you some examples of magnetic storage media. Click each of the media to move to more information: Fixed Hard Disk Drive

Portable Hard Disk Drive

Floppy Disk

Magnetic Tape

REMEMBER! Magnetic storage media uses a magnatised surface area in order to hold bits of information.

NOTE: (Direct Access)

(Direct Access)

(Direct Access)

(Serial Access)


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Breakdown of each output device: # The following sections will help summarise each of the 4 different magnetic storage media. For each one you will see: Information about the media Uses of the media Advantages of the media Disadvantages of the media

Fixed Hard Disk Drive Information:

Examples:

# Used on all computers and are the main method of storing data. This is because they are capable of very fast direct access of files and have very large storage capacities. # The disc surface (Platter) is coated in a magnetic film which is where the data is stored. These have read/write heads which allow data to be written to (saved) or read (used) from the disc. The read/write heads (along with direct data access) allow for very fast data access speeds. A summary of a fixed hard disk drive. (Click to zoom)

# Hard Discs are used to store operating systems, software applications and all other files. # Typical storage spaces are 250 gigabytes up to 4 terabytes (4,096 gigabytes).

Uses of Fixed Hard Disk Drives: # Used to store the operating system and applications software (Windows, Word, Excel etc). # Used for storing files and documents (music and homework for example). # Real-time systems (robots, chemical plant control systems) and online systems (booking airline tickets etc) use hard disc drives to store data. Fixed hard disk drives are designed to be 'fixed' into

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This is because real-time / online systems require data to be processed very quickly. Fixed hard disk drives have very fast data access speeds and so can handle this.

the computer and not removed.

# Used in file-servers on computer networks to store files (Like the student: drive in your school is used to store your work).

Advantages/Disadvantages of Fixed Hard Disk Drives: Advantages

Disadvantages

Fast read/write times (Saves data to disk and reads back from it quickly).

Can be damaged easily when computer is not shut down properly (Disc crash!).

Huge capacities (Can store thousands of movies and music files).

Not portable as they are designed to be ‘fixed’ into computer and not removed

Fixed hard disk drives store data on magne娀cally coated disks (known as plaers).

Very easy to update/delete files

Portable Hard Disk Drive Information:

Examples:

# Works in a similar way to fixed hard discs but are connected to the computer externally via a Universal Serial Bus (USB) port. # They use direct data access methods which makes reading/writing of data very fast. # Portable Disc Drives are designed to be transportable. # They come with a USB Cable to allow for easy attachment to other computers which allows for easy backing up / sharing of files. A summary of a portable hard disk drive. (Click to zoom)

# Because they are used outside of the computer they come with protective casing to avoid physical damage to the disc drive. # Typical storage spaces are 250 gigabytes up to 3 terabytes (3,072 gigabytes).

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Uses of Portable Hard Disk Drives: # Like fixed hard drives, they are used to store large files (such as video). # Can be used as portable back-up systems to avoid loss of data. # Used to transfer data, files and software between computers via USB connectivity.

Their protective casing makes them harder to damage whilst in transport.

Portable hard disk drives are protected from damage by a tough outer casing.

Advantages/Disadvantages of Portable Hard Disk Drives: Advantages

Disadvantages

Fast read/write times (direct data access).

Small size makes them easy to misplace or have stolen.

Huge capacities. (Thousands of movies and music files)

More expensive than other forms of storage

Small and light with protective casing. (Makes them very portable)

Protective casing will only protect against minor bumps. If the device is dropped it can still become damaged.

Designed to plug into almost any computer via USB ports.

Note: This is always a risk when transporting data externally!

Portable hard disk drives are small and light.

Portable hard disk drives connect to almost any other computer via usb..

Floppy Disk Information: # Old method of portable data storage where information is held on a thin plastic disc.

Examples:

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# Data on a floppy disk is read/written by a floppy disk drive which rotates the disk. # As the disc rotates, a read/write head is used to add or read data. The data is read/written using direct data access methods.

Even though floppy disks use direct data access, their data transfer rates are very slow. Good job they can only store 1.44MB!!

A summary of a floppy disk. (Click to zoom)

# The disc of plastic is protected by a retractable metal sleeve and hard plastic casing. A small notch provides write protection (prevents accidentally copying over work).

# Maximum storage on a floppy disc is only about 1.44 MB (700 pages of text).

Floppy disks do not have high enough capacities to store large modern files. This has made them obsolete (useless) and computers no longer have floppy disk drives installed. The magne娀c plas娀c disk is protected by plas娀c casing and a metal sleeve.

Uses of Floppy Disks: # Can still be used where very small files need to be transferred/stored (e.g. small word processed documents).

# Write protect facility is useful to prevent accidental overwriting of data. Floppy disks are read/wrien to using floppy disk drives.

Advantages/Disadvantages of Floppy Disks: Advantages

Disadvantages

Cost very little to buy.

Very low storage capacity when compared to other media (1.44 Mb).

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Can be write protected easily which protects against accidentally copying over files.

Very few modern computers have floppy disc drives (device used to read the disk).

Very small, light and easy to carry (portable).

Floppy discs are very delicate and easy to damage (Not robust). Slow data transfer rate (Takes a long time to save/read from the disk).

Floppy disks are now doomed!

Magnetic Tape Information:

Examples:

# This is one of the oldest forms of computer data storage. # Magnetic tape is a thin strip of magnetic coated plastic which is wrapped onto a reel. # Data is stored on the magnetic plastic in the form of 1’s and 0’s (binary numbers). # Data is written to and read from in sequence (i.e. in order) which is also known as 'serial access'. Remember:

Serial Access works a bit like a video tape. To access something in the middle of the tape you need to start at the beginning then fast-forward until you get to the part you need.

A summary of magne娀c tape. (Click to zoom)

# This type of storage media has a very slow data access rate. Because it is so slow, It is useless for real-time applications (where what is stored is constantly being updated). The slow access speeds makes it useless for holding data during real-time applications (e.g. alarm systems). This is because in real-time applications, stored data needs to be constantly and quickly updated. Magne娀c tape is a magne娀c coated plas娀c

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wrapped onto a reel.

# Sony have developed magnetic tape capable of storing a huge 185TB of data.

Uses of Magnetic Tape: # Used where extremely large amounts of data need to be backed up. # Used where speed of reading/writing of data is NOT a priority. For Example:

Magnetic tape is used to hold data in batch processing applications such as clearing bank cheques and producing payslips. It can be used here because speed is not important. These jobs are usually left running at night when everyone has gone home.

# Used for backups of computer networks in schools and business.

For Example:

Magne娀c tape uses serial (sequen娀al) access to read/write data. It works much like a movie film reel.

Your school files are frequently backed up on the school's network.

Advantages/Disadvantages of Magnetic Tape: Advantages

Disadvantages

Less expensive than the equivalent capacity hard disk drive.

Very slow data access/transfer (Reading data back from the tape is slow).

Very robust (Not easily damaged). Very large storage capacities (Up to 185 terabytes or 185 trillion characters).

Needs another tape to update data

Magne娀c tape is one of the oldest forms of computer data storage media and it can store vast amounts of data.

For example: original tape + tape with the changes = updated tape.

Previous - Storage Media Introduction

Next - Optical Storage Devices

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Section 3.5: Optical Storage Media In this section you will see the 8 different types of optical stora ge media. CD-ROM DVD-ROM CD-R DVD-R

CD-RW DVD-RW Blu-Ray Disc DVD-RAM

Key Concepts of this section: # Know the different types of optical storage media. # Understand the uses of each optical media. # Be able to discuss advantages and disadvantages of each optical media.


Optical Storage Media Definition:

(an overview)

"All the mediums that use a light source to read/write data onto a disc."

Overview of Optical Storage Media: #

Key Words: Data Dots, Disc, Laser, Burn, Disc Drive

Examples:

Optical storage media stores data on a disc as a number of data dots that can be read using light (usually a laser beam). Each dot represents 1’s and 0’s (Bits of information).

#

Data is read by shining the laser beam onto the surface of the disc.

If the light hits one of the dots it is reflected back differently than it would be if there was no dot. This difference is read as data by the computer. Data is stored on op퀄cal media in the form of 퀄ny

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bumps known as 'data dots'. (Click to zoom)

#

Some Optical Disks (such as CD-R’s) allow you to write data to the disc as well as read it. This works by using the laser beam to ‘burn’ dots onto the surface of the disk (creating the data) and then reading them back again. This process is known as ‘burning’.

#

In order to read/write data on a disc you need a 'disc drive'. For example:

CD Drive, DVD Drive, Blu-Ray Drive A DVD disc drive is used to read and add data to DVD op퀄cal disc.

The drive contains the following: A mount for the disc A laser (to read/write the data bumps) A motor (to spin the disc across the laser)

Anima퀄on showing how Disc‐Drives work.

Examples of Optical Media # The table below shows you some examples of optical storage media. Click each of the media to move to more information: CD-ROM

DVD-ROM

NOTE: All the examples of optical storage media on this page use direct data access.

CD-R

Key Words: CD-ROM, DVD-ROM, CD-R, DVD-R, CD-RWR, DVD-RW, DVD-RAM, Blu-Ray Disc

DVD-R

REMEMBER! Optical storage media stores data on tiny bumps called data dots. (Direct Access)

(Direct Access)

(Direct Access)

(Direct Access)

NOTE: CD-RW

DVD-RW

DVD-RAM

Blu-ray Disc

Click the images to the left to move to more information

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about each one.

(Direct Access)

(Direct Access)

(Direct Access)

(Direct Access)

Breakdown of each output device: # The following sections will help summarise each of the optical storage media. For each one you wil l see: Information about the media Uses of the media Advantages of the media Disadvantages of the media

CD-ROM and DVD-ROM Information:

Examples:

# ROM stands for 'read only memory'. This means that the data cannot be written over (added to) and can only be read. # CD-ROM's and DVD-ROM's are bought with pre-loaded data already on them.

Usually pre-loaded with software, music, movies and games.

# Whatever is already loaded onto the ROM cannot be removed or changed . Remember:

This is because ROM discs are 'read only'. So if you purchase a music CD, you can listen to the tracks on the disc but you can't can't add more songs of your own.

# CD-ROMs have a maximum capacity of about 800MB (about 400,000 pages of text) DVD-ROMs have a maximum capacity of about 4.7GB (about 2.4 million pages of text)

CD‐ROMs store up to 800MB and were used to distribute pre‐loaded so샿ware, music etc.

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IGCSE ICT - Optical Stor age Devices and M edi a

Uses of CD-ROMs and DVD-ROMs: # CD-ROMS CD-ROMS are used by manufacturers to store smaller files files (up to 800MB) such as: Music tracks Software (such as word processors, spreadsheets etc) Audibooks etc # DVD-ROMS DVD-ROMS have much larger storage capacities capacities (up to 4.7 GB) than CD-ROMS and are used to store bigger files such as: Movies Modern games games (like grand theft auto, call of duty etc) Multimedia enclyclopedias etc

DVD‐ROMs are used to distribute larger files such as movies.

Advantages/Disadvantages of CD-ROMs and DVD-ROMs: Advantages

Disadvantages

Hold Hold far more data than Floppy Discs.

Hold far less data data than hard disk drives or memory sticks.

Less expensive than Hard Disc Drives.

Very slow data transfer and access rates rates when compared to hard drisk drives. (Reading back from the dics is slow)

Data stored on them is 'read only' only' which means you cannot accidentally erase erase the files.

You cannot add your own files files to the discs because they are both read only.

Very portable portable as they are small and light.

CD-R and DVD-R Information: # The letter ‘R’ ‘R’ means that the disc is recordable once once only.

Examples:

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# Once the disc has data recorded recorded on it becomes a CD/DVD ROM ROM (read only). # Data can be added to the disc (once) (once) but NOT erased erased when it is on there. # Data is ‘burnt’ ‘burnt’ onto the discs using a disc burner. burner .

Note:

A disc burner works in the same way as a regular disc drive but is uses a more powerful laser laser to burn data onto a CD/DVD-R disc. A disc burner can also read the data data held on the disc using a less powerful laser laser that is not strong enough to burn. CD‐R's can have about 700MB of data burnt onto a special metallic dye.

#

Thin layer of metallic dye dye is used to record the data onto. When CD-R’s and DVD-R’s are burnt, the laser makes permanent marks marks (dots of data which represent 1’s and 0’s) onto the metallic dye. These marks cannot be erased erased (which is why what you add to the disc is permanent). DVD-R's DVD-R's use a dye that allows for more dots dots to be burnt onto the disc's surface.

A disc has data 'burnt' onto it's surface using a more powerful laser.

This is why DVD-R's can hold more data that CD-R's

DVD‐R's use a different type of metallic dye that allows for more data to be held on the disc.

# CD-R have a maximum capacity capacity of about 700MB 700MB (about 80 minutes of audio) DVD-R have a maximum capacity capacity of about 4.7GB 4.7GB (over 2 hours of video)

Note:

DVD-R's are also available in 'dual-layer'. 'dual-layer'. This means they have have two layers layers of recordable surfaces which means they can store more data (about 8.5GB) than a regular DVD-R.

Uses of CD-R and DVD-R:

A DVD burner add data onto a disc and read it back off.

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# CD-R's used to create personalised playlists of music. music. # DVD-R's used to store home recordings of video video shot on digital cameras. # They can be used to backup important data data so that there are copies in case the originals get erased or deleted. # They can be used to transfer data data from one computer to another.

Advantages/Disadvantages of CD-R and DVD-R: Advantages

Disadvantages

Once burned, data is impossible to accidentally delete delete because the disc becomes read only.

Only recordable once. This means updating updating the disc is impossible. impossible.

Cheaper Cheaper than RW discs and Hard Disk Drives .

If an error occurs during burning the disc is damaged damaged and must be thrown away (wasted)

Easy to transport transport information from one computer to another

Very slow slow data transfer rate.

(Can take the disc out of one machine and use in another)

Dual Layer DVD's allow for more data to be held on the disc.

(Burning data onto a disc can take up to 15 minutes) Not all all CD/DVD players can read CD-R and DVD-R discs

Data is burnt onto CD‐R/DVD‐R discs using a laser. Once the data is on the disc it cannot be removed.

CD-RW and DVD-RW Information: # The letters ‘RW’ ‘RW’ stand for Re-Writeable. Re-Writeable. This means that the disc can be recorded on over and over over again. # Unlike CD/DVD-R’s these discs DO NOT become ROMS ROMS (not read only) once burned. # RW drives drives are used to burn data onto dye on the RW disc (and also read from it).

Examples:

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# The dye used to record data is called 'phase changing dye' and it allows the bumps of data to be ‘undone’.

The bumps of data are really just flattened again which effectively erases any stored data.

# Data can be added to the disc and can also be erased.

CD-RW's and DVD-RW's can be reused around 1000 times.

# CD-RW have a maximum capacity of about 700MB

CD‐RW can store up to 700MB of data and be reused over and over.

DVD-RW have a maximum capacity of about 4.7GB

Uses of CD-RW and DVD-RW: # CD-RW's are used to create personalised playlists of music and then add/remove songs as you wish. # DVD-RW's are used to record television programmes and can be recorded over many times.

DVD-RW's are also used to record video content of closed circuit television (CCTV) to allow security to keep an eye on businesses and what is happening on the streets

# They can both also be used to make backups of computer files.

DVD‐RW can store up to 4.7GB of data and be reused over and over.

Advantages/Disadvantages of CD-RW and DVD-RW: Advantages

Disadvantages

Can be re-used many times .

More expensive to buy than CD/DVD-R discs

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Data stored on the discs can be updated.

It is possible to accidentally overwrite data (since RW discs can be updated) .

Not as wasteful as the –R format.

Data transfer to the discs is very slow compared to a hard disk drive.

(Even if burning fails, the disk can still be recorded on later and not thrown away)

(Depending on the speed of your disc burner it can take up to 15 minutes to burn an entire DVD-RW)

DVD-RAM (DVD-Random Access Memory) Information:

Examples:

# With DVD-RAM writing and reading of data can happen at the same time. This means that you could watch a programme at the same time that another one is being recorded – (Read and write at the same time) # They use a similar Phase Changing Recording Dye to CD/DVD-RW’s which allows DVD-RAM discs to be recorded over many times. Note:

DVD-RAM is much faster and easier than CD/DVD-RW at overwriting data.

# DVD-RAM discs can be rewritten over many many times (over 100,000). # Data can be reliably stored on DVD-RAM for many years due to their high quality. # DVD-RAM has a capacity of 4.7GB (or 9.4GB with with double sided discs).

Uses of DVD-RAM:

DVD‐RAM is a very high quality method of storing data. Discs can last for years and years.

# Because DVD-RAM discs last so long they are used in video and data archiving (Safe store for important files and records). # Used in DVD recorders to record TV programmes (on digital and sattelite) to allow simultaneous recording and playback. # Used in camcorders to store video (Reliably and for many years).

DVD‐RAM is used in DVD recorders to record TV programmes.

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Advantages/Disadvantages of DVD -RAM: Advantages

Disadvantages

Long life - last at least 30 years.

Can be written over 100,000 times (RW Disks only allow 1,000 re-writes).

Expensive compared to DVD and CD recordable discs. Don’t work in as many devices as the –R or –RW discs.

Very fast access to stored files .

Offer very large storage capacity compared to CD’s (Up to 9.4Gb with double sided discs). Can read data at the same time it is being written.

Blu-ray Disc Information:

Examples:

# Work in a similar way to DVD ROMS but the laser used to read the data is blue rather than red (Red lasers used to read the other disc types).

This blue laser colour is why the name ‘Blu-ray’ was used

# Blue lasers are capable of reading data dots that are positioned closer together on the disk surface. As a result, more data dots (1's and 0's) can be stored and read.

Remember:

More data dots = higher capacity. (up to 50 million pages of text)

# Blu-ray-RW discs can be rewritten to in much the same way as RW disks.

A Blu‐ray disc and drive.

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#


Blu-ray's have capacities of 25GB, 50Gb and 100GB (depending on the disc).

Uses of Blu-ray Discs: # Used to store high definition video (Like high quality movies).

One 25GB Blu-ray disc can store 2 hours of HDTV.

# Used in some home video consoles (Like Playstation 3). # Used to back up hard disk drives in PC’s.

Blu‐ray discs have huge storage capaci퀄es.

Advantages/Disadvantages of Blu-ray: Advantages

Disadvantages

Huge storage capacity. Perfect for high definition movies .

Very expensive compared to other optical media.

Data can be read/transferred very fast when compared to other optical media.

Only work in Blu-Ray drives/players which are expensive. (Not everyone has these drives which limits the use of the disks)

Previous - Magnetic Storage Media

Blu‐ray discs are read with a blue laser. This laser can read data dots that are closer together..

Next - Solid State Storage Media







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Section 7: Part 2










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The ICT Lounge

Section 3.6: Solid State Storage Media In this section you will see the 4 different ty pes of solid state storage media.

Key Concepts of this section: # Know the different types of solid state storage media. # Understand the uses of each solid state media.

Solid State Hard Drive Memory stick Flash memory Micro flash memory

# Be able to discuss advantages and disadvantages of each solid state media.


Solid State Media Definition:

(an overview)

"Any memory device with no moving parts and are based on electronic circuits."

Overview of Solid State Media: #

Key Words: Flash memory, No moving parts, Electronic circuits

Examples:

Solid State Drives have no moving parts.

No reels of tape, no spinning disks, no moving laser beams etc.

#

SSD technology is known as'flash memory' and this is the smallest form of data storage. Summary of solid state drives. (Click to zoom)

Examples include memory sticks, memory cards etc.

#

They store data as 1’s and 0’s within millions of electrical transistors instead of on films of magnetic substance or as dots on discs.

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If the transistor conducts an electric current, this equates a 1. If it does not conduct a current, this equates a 0 Animaᰁon showing how flash memory works.

#

They hold several advantages over Magnetic Disc Drives:

Solid state hard drives are much smaller than magneᰁc hard disks.

Much smaller Use less power (no moving parts means less power needed) Faster data access and transfer times Much more robust (harder to damage)

Examples of Solid State Media

NOTE: All the examples of solid state storage media on this page use direct data access.

Key Words: Solid state hard drive , Memory stick, Pen drive, Flash memory, Micro flash memory, SD card, Micro SD card

# The table below shows you some examples of solid state storage media. Click each of the media to move to more information: Solid State Hard Drives

Memory Stick / Pen Drive

Flash Memory Cards

Micro Flash Memory Cards

REMEMBER! Solid state media have no moving parts.

NOTE:

( Dir ec t Ac ce ss )

( Di rec t Ac ces s)

(Di re ct A cc es s)

( Dir ec t Ac ce ss )


Breakdown of each output device: # The following sections will help summarise each of the manual input devices. For each one you will see: Information about the media Uses of the media Advantages of the media Disadvantages of the media

Solid State Hard Drives

(SSD's)

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Information:

Examples:

# Used in desktop PC's and laptops in place of magnetic hard disk drives. # They are also known as 'SSD's'. # They offer advantages over magnetic hard drives such as: Run silently (magnetic hard disk drives spin producing whirring sound) Longer life span Faster data access and transfer times Use less power Produce less heat # They use solid state technology based on electrical circuits which means they have no moving parts. No moving parts = less chance of them breaking down.

SSD's are used in place of magneᰁc hard disks in laptops and PC's .

Magnetic hard disks have moving parts such as spinning disks and read/write heads. Eventually these parts stop functioning.

# These store files permanently (non-volatile storage). # They have a current capacity of about 1TB (approx 1 million thick books worth of text)

Uses of Solid State Hard Drives: # Used in desktop PC's and laptops to permanently store data such as: Operating systems Software applications (such as word processors, spreadsheets etc) Music/Video files School work, photos

SSD's compared to magneᰁc hard disk drives. (Click to zoom)

Advantages/Disadvantages of Solid State Hard Drives: Advantages

Disadvantages

Last longer than magnetic hard disks (no moving parts).

Smaller storage capacity than magnetic hard disks.

Faster data access/transfer times.

More expensive than magnetic hard disks.

Note: Computers even boot up faster using solid state hard drives. Use less power and produce less heat. Run silently.

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Memory Sticks / Pen Drives Information:

Examples:

# Memory sticks are small, portable external storage devices. # They are used to easily transfer data between computers. # Memory sticks use solid state technology and are usually connected to the computer via USB ports. Note:

Memory sticks are making other forms of portable storage (like CD’s and DVD’s) redundant as they are much easier and quicker to transfer data. Summary of memory sᰁcks. (Click to zoom)

# Data access and transfer is very fast. # Memory sticks are very cheap to buy. You can currently get 32GB of storage for less than £10! # Current capacities of memory sticks are up to 512GB (about 500,000 thick books)

Uses of Memory Sticks: # Used for easily transporting files/data between computers.

Memory sᰁcks are very small and connect to computers via USB.

# Used for backing up data quickly and easily.

Advantages/Disadvantages of Memory Sticks: Advantages

Disadvantages

Very small and lightweight (portable).

No write-protect feature . This means that it is possible to accidentally copy over data

Robust - no moving parts means they are less likely to become damaged.

Small physical size means that they are easy to misplace or lose

For example: CD's and DVD's can get scratched. Compatible with almost any computer. (most computers have USB ports) Large storage capacities (up to 512 GB)

More expensive per GB than magnetic hard disks.

Memory sᰁcks have large capaciᰁes.

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Flash Memory Cards

(and Micro Flash Memory Cards)

Information:

Examples:

# Flash memory cards are also known as 'Secure Digital Cards' (or SD Cards). # SD cards are small and rectangular in shape. # These are a form of Electronically Erasable Programmable Read Only Memory (EEPROM). # SD cards use solid state technology (they have no moving parts).

Note:

Micro flash memory cards are just smaller versions of the regular flash memory cards.

Summary of memory sᰁcks. (Click to zoom)

Micro flash memory cards are sometimes also called 'Micro SD Cards'.

# A wide range of devices have slots to read flash memory cards including laptops, mobile phones, tablets and mp3 players. # SD card readers can be used to transfer data from the cards onto a desktop PC. # SD Cards have a maximum capacity of about 256GB Micro SD Cards have a maximum capacity of about 128GB

SD cards and Micro SD cards are really the same thing except for the size.

Uses of Flash Memory Cards: # SD cards are used to store photos on digital cameras.

Note: Many stores that offer printing services have SD card readers that access data on your cards. This means you can get your photographs printed without even having to take your digital camera with you to the store.

# SD cards are used in hand held devices (like PDA’s and palmtop's) to store files and data. # Micro SD cards are used in mobile phones as memory cards to store photos and

Micro SD cards have a very small physical size.

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music etc. # Micro SD cards can be used by MP3 players to store music files

Advantages/Disadvantages of Flash Memory Cards: Advantages

Disadvantages

Very small so they are easy to transport files from one device to another (Camera to Camera for example).

More expensive per GB than magnetic hard disk drives.

Robust and not easily damaged (No moving parts). Easy to connect to mobile devices through SD Slots

Flash memory is used as storage in devices such as mp3 players.

Lower storage capacity than magnetic hard disks.

Small size makes them easy to have stolen or lose. Desktop PC's don't usually come with built-in memory card readers. To connect to a desktop PC you need to buy an SD card reader.

Flash card readers can connect flash cards to PC's

Previous - Optical Storage Media

Next - Comparison of Storage Media








Section 7: Part 2










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The ICT Lounge

Section 3.7: Comparison of Storage Media In this section we will compare the storage media in terms of:


Amount of data stored (capacity) Speed of data access Poratability Cost

# Know that storage media can be compared. # Be able to compare each of the storage media in terms of the 4 areas highlighted.

Note: The data on this page could change.

Solid State Media Comparison Tables Comparing the amount of data stored (storage capacity) Low storage capacity

# Floppy disk # CD-ROM, CD-R, CD-RW

1.44MB - 800MB Medium Storage Capacity 4.7GB - 512GB

High storage capacity

# DVD-ROM, DVD-R, DVD-RW # DVD-RAM # Blu-ray discs # Micro SD card, SD card # Memory stick # Solid state hard drives # Fixed hard disk, Portable hard disk # Magnetic tape

1TB - 185TB

Comparing the speed to access data

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Slow access speed

# Magnetic tape # Floppy disk

Medium access speed

# CD-ROM, CD-R, CD-RW # DVD-ROM, DVD-R, DVD-RW # DVD-RAM # Blu-ray # Fixed hard disks, Portable hard disk

Fast access speed

# Memory stick # Solid state hard drive # Micro SD card, SD card

Comparing how portable each storage media is Not portable at all

# Fixed hard disk

Quite portable

# Solid state hard drive # Magnetic tape # Portable hard disk

Very portable

# CD-ROM, CD-R. CD-RW # DVD-ROM, DVD-R, DVD-RW, DVD-RAM # Floppy disk # Micro SD card, SD card # Memory stick

Comparing the cost Very cheap £4 - £10 - for packs

# Floppy disks # CD-R, CD-RW # DVD-R, DVD-RW, DVD-RAM

Grade 6 ICT Notes

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