Computer Revision1 [Input & Output & Sensors]

• It is a peripheral / hardware used to enter data and instruction into a computer.

• It is used to transmit the data electronically to the computer.

1. It is an input device

2. Most commonly used input device

3. It is used to enter data into a computer by typing

It is used to enter the barcode number if the barcode is damaged.

1. To enter data manually in word processor

2. To type a report

1. Very easy to use (just have to press keys)

2. Most computers come with a keyboard

3. Specialist keyboards are available (ergonomic, gaming)

4. Information that you input appears instantly on the screen, this let you to quickly check what you are entering is correct

1. Very slow to enter data

2. Easy to make mistake when typing in data

3. Keyboards are not suitable for creating diagrams

4. Easily collects dust and dirt, so not suitable for dirty environments

5. Excessive use can lead to health problems such as RSI (Repetitive Strain Injury)

1. Fewer typing errors may be made because one button is pressed

2. Speed up the time to enter data because fewer buttons are pressed

3. May require less training because it is easier to identify item from its image

4. Can stop dirt / food damage as there are no keys for food / dirt to get into

1. Poor for text or numeric input

2. Limited options are available

1. It is used to read data from QR code (Quick Response code)

2. It can identify a standard QR code based on the 3 large squares

3. Once it has identified these 3 squares, it knows everything contained inside the squares is a QR code

4. QR code scanner analyses the QR code by breaking the whole thing down to a grid

5. It looks at the individual grid squares and assigns each one a value based on whether it is black or white

6. It then groups grid squares to create larger patterns

• The barcode is captured / scanned by a camera / QR scanner

• It is read using a laser

• Light is reflected back

• It is processed by an app

• The 3 large squares are used to define the alignment

• Squares / Data are decoded and converted to binary value

1. It is the only device which works both as an input and output device

2. It allows users to input commands into a computer by pressing or touching icons on a screen

3. It is suitable for use with a limited amount of options

4. Touchscreen works particularly well with a menu-driven interface (ATM at banks)

1. Mobile phone / Tablet - easy to input data; use of icons for apps selection; to save space

2. Public information systems at airports - easy method for public to enter data into system; fewer chance of error since number of choices are limited

3. Interactive whiteboards in schools - Easier method to input data into system; limited number of options

1. Resistive

2. Capacitive

3. Infra-red

1. Uses multiple layers (2) of materials that transmit electric current

2. When the top layer / screen is touched into the bottom layer, the current changes

3. The location of the touch is found

1. Cheap to manufacture

2. Can use stylus / finger / gloved finger / pen

1. Poor visibility in sunlight

2. Vulnerable to scratch

3. Does not allow multitouch facility

4. Wears through time

1. Uses a conductive layer

2. Current flows from all 4 corners of the screen (an electrostatic field is created)

3. Sensors around the screen monitor the electrostatic field

4. When finger / stylus touches the screen, the current changes and the location of the touch is calculated

1. Good visibility in sunlight

2. Very durable surface

3. Allows multitouch facility

1. Screen will break / crack on impact

2. cannot be used when wearing gloves

1. Infra-red rays are sent across the screen

2. Has sensors around the edge / Sensors capture beams

3. Infra-red rays form a grid across the screen

4. Sensors detect where the screen has been touched through a break in an infra-red beam

5. The position where the screen is touched is calculated

1. Good durability

2. Allows multitouch facility

3. Can use stylus / finger / pen / gloved finger

1. Expensive to manufacture

2. Screen will break / crack on impact

3. Sensitive to dust / dirt

It is a series of black and white parallel lines of different varying thickness

• It is used to read barcodes

• It shines light / red laser at the barcode

• Light is reflected back (White lines reflect more light, while black lines reflect less light)

• Sensors detect the reflected light

• Different reflections will give different binary values

• A microprocessor interprets the data

1. Supermarket checkout - read barcodes to find prices description

- allows automatic stock control

2. Library systems - can track book on loan

- can link books to borrowers using barcoded cards

3. Airport check-ins - barcodes on luggage to track whereabouts

• Barcodes identifies a product

• The barcode is used to look up the products in the database

• Stock can be automatically deducted from the system

• Can check if stock level is below certain level

• Automatic reorder is done

• Automatically update new stock level

1. Much easier and faster to change prices on stock items

2. Allows automatic stock control

3. Much better and more up-to-date sales information

4. No need to price every stock item on the shelf

1. Faster checkout queues (staff don't need to remember price)

2. Error in charging customers are reduced

3. Customer is given an itemised bill

At the airport to produce an electric version of the passenger's face

1. Direct transfer to a computer

2. No processing is needed / No need to print

3. Extra copies can be made any time

4. Unwanted images can be detected

5. Images can be viewed immediately

It is used to input sound for use

1. Narration in presentation or in websites

2. Speaking over the internet using VoIP (Voice Over Internet Protocol) using skype

3. Conducting videoconferencing

4. Hand free mobile phones use a microphone to allow people to hold conversations without using their hands

1. It is faster to provide voice as input than to type text using keyboard

2. Help in improving safety and security of drivers

3. Sound waves can be manipulated in real time

1. Sound files require a large memory for storage

2. Voice recognition software is not accurate as manual typing

3. Sound signals are required to be amplified for paper reconstruction

4. Can be affected by background noise

• The microphone has a diaphragm

• The incoming sound waves cause vibrations, causing a coil to move past a magnet

• An electric signal is produced

It is used to make digital copies of documents or pictures to create a 2D image

1. Scanner shines light onto the surface of a document

2. It uses mirrors and lenses

3. The captured image is converted into a digital file

4. Produces a 2D image

1. Used at airports

2. At the airport, the 2D photograph in the passport is scanned and stored as a JPEG image

3. The passengers' face is photographed using a digital camera

4. The two digital images are compared using face recognition software

5. Key parts of the face are compared (data such as - distance between the eyes; - width of the nose; - shape of cheek bones

1. It shines a laser over the surface of a 3D object

2. It records the measurements and the dimensions of the object

3. Measurements are converted to digital file

4. Produces a 3D digital model

1. Entertainment industry, in the production of movies and video games

2. Industrial design

3. Quality control

4. Medical field

5. Documentation of cultural artefacts

1. Save time in design work

2. Quickly capture all the physical measurement of any physical object

3. ensure parts will fit together on the first try

4. Utilize modern manufacturing on parts that were originally manufactured before CAD (Computer Aided Design)

1. It is impossible to measure any surface that is out of the scanner's line of sight

2. Ambient light may blend with the laser and interfere with the scan's accuracy

3. Initial cost can be quite expensive

• An input device

• A pointing device - controls the movement of the cursor / pointer on the screen

1. Their sealed bottom surfaces do not absorb dust and dirt

2. It works on any surface, even on glass

3. Require little training to use

4. Usually supplied as part of a new computer system

1. Need a flat surface close to the computer

2. Excessive use can lead to RSI

• A peripheral device that sends results of processing to the user

• Translates signals from the computer into human-readable form

1. Monitor

2. Printer

3. Projector

4. Speaker

5. Actuator

1. Most common output device

2. Also known as VDU (Visual Display Unit)

3. Used to produce soft copy (information stored electronically) of the stored information

• The number of pixels that can be represented horizontally and vertically on a screen

• The higher the resolution of a monitor, the more pixel is used

• Picture element

• Smallest addressable area on the screen

1. Light and takes less desk space

2. Consumes less power

3. Produces less radiation

1. The display is made up of pixels that are arranged together as a matrix(2)

2. Each pixel has three filters -Red -Blue -Green

3. Shader of colour is achieved by mixing Red, Blue, and Green

4. The screen is backlit with CCFL (Cold Cathode Fluorescent Lamp) / LED

5. Uses a flat panel display

1. Smartphones

2. PDA's

1. Low power consumption

2. Runs at low temperature

3. Do not suffer image burn

4. Do not suffer flicker issues

5. Higher resolution image

6. Cheaper to purchase than LED

7. Bright colours / image

1. Do not use CCFL

2. Light is emitted by diodes

3. It is a flat panel display

4. Used in mobile devices such as smartphones and tables

1. Good colour definition

2. Consume less energy

3. More reliable as LED's are long-lasting

4. Colours are vivid

5. Reaches maximum brightness quality immediately

6. Screens can be thinner

• Produces hardcopy

1. Uses liquid ink

2. Uses either thermal bubble or piezoelectric technology

1. Print head which consists of nozzles

2. Stepper motor

3. Belt

4. Ink cartridge

1. A crystal is located at the back of the ink reservoir for each nozzle

2. The crystal is given a tiny electric charge which makes it vibrate

3. This vibration forces ink to be ejected onto paper

1. Tiny resistors create localised heat which makes the ink to vaporise

2. This causes the ink to form a tiny bubble

3. As the bubble expands, some of the ink is ejected from print head onto the paper

1. Inexpensive / Cheap to manufacture

2. High quality printouts

3. can use colours

4. Quiet

1. Inks are expensive

2. Runs out of ink quickly

3. Not suitable for dirty / dusty / damp atmospheres

1. To produce one-off photographs

2. To print a project at home

1. It uses powdered ink / toner

2. It uses negative and positive charges drums / rotary drums

3. It uses a static electric charge on a rotating drum to generate output

4. Produces high volume of colour printing of advertising flyers / leaflets

5. Faster at printing

1. Produces high quality printing

2. Faster at printing

3. Produces high volume output

• Toner is expensive

• Producing flyers / leaflets / magazines

1. Production of an object which is built up layer by layer (additive) / removal of material (subtractive)

2. Used in CAD applications

3. Uses plastic, resin or powdered metal to generate a physical ouput

1. To make prosthetic limbs

2. In fashion and art

3. Making parts for items no longer in production (suspension parts for a vintage car)

• Show enlarged computer output

• Uses a high intensity beam of light shone through three layers of changing pixels

1. Uses millions of micro mirrors to reflect light through a lens

2. Uses a colour wheel

1. Give / Produce audio / Sounds instructions

2. An output device

1. Everyone in the room can hear the sound

2. Help the blind to hear the text that can be turned into sound

Output from speaker can disturb people working

1. An output device

2. Converts the computer signals into movement

1. Light bulb (creates light)

2. Heater (increases temperature)

3. Buzzer / Bell (creates noise)

4. Motor (spins things around)

5. Pump (pushes water / air through pipes)

1. An input device

2. Measures / Takes physical readings of the surrounding environments

1. To measure the level of infra-red / microwaves to detect the break in the beam of light

2. To alert any intruders

1. Automatic doors

2. Burglar alarm system

1. To measure the temperature of the environment

2. To alert when it is too hot / cold

1. Chemical process

2. Control heating / Air conditioning system

3. Greenhouse environment

4. Oven

1. To detect sound / vibration

2. To alert if sound is too loud

1. Burglar alarm system

2. Leak detection system (detecting liquids moving in pipes)

3. Disco lighting

1. To measure the amount of CO₂ / oxygen is present

2. To alert when too much CO₂ / oxygen is present

1. Greenhouse environment

2. Confined area (spacecraft)

3. Fish tank / Aquarium

4. Pollution monitoring in a river

1. To measure the brightness of the environment

2. To alert when there is too much / too little light

1. Street lighting

2. Growth control in greenhouse

1. To measure how acidic / alkaline the soil is

2. To alert when there may be something polluting the soil

1. Measure acidity of river

2. Used in greenhouse to monitor soil acidity

3. Chemical process

1. To measure the water content of the soil

2. To alert when it is too dry / too wet

1. Clothes dryer

2. Greenhouse

1. To measure the water content in the air

2. To alert when the air is too dry

1. Clothes dryer

2. Greenhouse

3. Refrigerators

4. Air conditioning system

• Regulates the flow of liquids and gases within pipes and tubes

• Detects leaks, blockages and changes in liquid concentration due to contamination or pollution

1. To detect the presence of nearby objects without any physical contact

2. Sends data to microprocessor

1. Automated production lines for object detection

2. Used in smartphones to detect if a user is holding their phone

3. Collision detection on robots

4. Used in public washrooms to control water flow

1. To detect a change in pressure

2. To alert if there is an intruder