There are 3 methods of data input:
- Manual Input Devices
- Direct Input Systems
Manual input devices are devices used by people to enter data. eg. Keyboards, pinting devices and microphones.
Direct input systems allow data to be entered without human intervention eg. optical mark readers. Used when large amounts of similar data needs to be entered.
Sensors collect data automatically.
KEYBOARDS are a common type of manual input used for writing anything from letters, to emails, to books.
- Adv: Simple and easy to use, People feel comfortable using them
- Disadv: Slow compared to more automated input devices eg. barcode reader
CONCEPT KEYBOARDS are used in places like fast-food restaurants. They allow the user to control what each key stands for. It involves a sheet with pressure pads with an overlay on top showing symbols which indicate what each key is for.
NUMERIC KEYBOARDS are used on mobile phones, at ATMs and in shops.
Adv: Small, easy to use, language independent
Disadv: When inputing anything other than digits they are slower than qwerty keyboards eg. when sending a text message.
Pointing Devices 1
A MOUSE is a pointing device, used commonly with a GUI, which you move to move an on screen pointer, clicking buttons on the mouse to make choices. There are 3 types:
- A mechanical mouse (with small ball underneath)
- Wired optical mice
- Wireless mice
- Adv: Fast method of input, intuitive to use as they involve pointing at things
- Disadv: Easily damaged, mice need a flat surface to work
A TOUCHPAD is used on laptops. It's a flat area by the keyboard. Move your finger on the pad and the pointer moves on screen. Tap the pad to click or use the buttons underneath.
TRACKERBALLS are like upside down mechanical mice. Ball is rolled by the user. It does not need a flat surface to work, but is harder to use than a mouse.
Pointing Devices 2
JOYSTICKS are used in gaming to move a character etc. Push forward the chartacter moves forward, left moves left and so on. They are also used to control wheel chairs and aircraft because of their simplicity.
TOUCH SCREENS are used in many places eg. buying tickets at railway stations. They are hard to vandalise, largely waterproof and you need no computer knowledge to operate them.
A GRAPHICS TABLET is a very large touch pad which senses movement of an object and sends this info to the computer. You use a stylus (very much like a pen) and press this against the screen.
A LIGHT PEN is used for 'drawing' directly onto a CRT monitor. They are rarely ever seen anymore because of the development of graphics tablets and touch screens.
SCANNERS shine light on a drawing/photograph and interpret the reflected light so the image can be stored on a computer system.
They are used for 3 types of input: images from hard copy material, OCR from hard-copy text, and OMR from specially prepared hard-copy forms.
- The hard-copy can be edited,
- saved and shared on the computer.
- Reduction of quality/distortion
DIGITAL CAMERAS are used to take pictures. They put areas of colour called pixels together to make a picture. The more pixels the better the quality of the photograph.
Images are stored in flash memory or a removable media card. This allows the images to be put onto a computer where they can be editied and shared like scanned images.
Adv over film cameras:
- Picture can be viewed immediately and deleted,
- photos are easier to edit
- the image can be used in other electronic documents.
- Battery must be charged and it runs out quickly.
Video Cameras and Webcams
VIDEO CAMERAS take a series of images which are run together to create the illusion of movement. Uses include: leisure & CCTV
WEBCAMS are a type of video camera wih no storage capacity. They are connected directly to a computer and are built in to some laptops. They are used to provide live video chat when using application such as skype or ichat.
Many businesses use webcams to hold VIDEO CONFERENCES over the internet. This allows company members to hold a meeting a short notice without having to travel to the venue.
Adv of video conferences:
- Can be held at short notice
- No need to pay for travel
- Take part from your own home
- You have to pay for equipment and internet connection
- Possible technical problems
Microphones and Music Keyboards
MICROPHONES are used to input sounds into a computer.
Speech is an analogue quantity, however computers can only process data in a digital format. Microphones convert sounds into a digital format.
They are commonly used to translate speech into text which can be used in word processors. These programs are called speech-to-text programs.
- Quicker than using a keyboard
- Useful for people with physical disabilities
- Can be unreliable
A music or MIDI KEYBOARD can also be used to input sounds. It is connected to a computer using a MIDI interface which translates the signal into digital data. It is commonly used for digital recording and requires little storage space but you must have musical ability to use it.
REMOTE CONTROLS are small hand-held devices used to control equipment such as TV's or radios.
When a button on the remote is pressed, it sends a signal containing a unique code to the equipent.
- You don't need to move around to use them
- The signal can interfere with other equipent
OCR and OMR
OCR stands for OPTICAL CHARACTER RECOGNITION. It is used to convert text from a scanned document into a format which can be used in a word processor.
- It is quicker tha re-typing a document
- It is useful for blind people scanned text can be read out loud by the computer.
- Not always reliable, particularly if the original copy is smudged
OMR stands for OPTICAL MARK RECOGNITION. This is where a scanner looks for marks on a sheet of paper eg. Answers on a multiple choice exam paper or marks on a school register.
- Very fast as there is only a small amount of data on the sheet.
- It will be unaccurate if the sheets are not lined up correctly or the sheets are dirty.
MICR stands for MAGNETIC INK CHARACTER RECOGNITION. It is used commonly for the account numbers on the bottom of bank cheques.
The account number is printed in special magnetic ink. When the cheque is passed through an MICR reader the magnetised patterns of the numbers can be identified as charcters.
It is much quicker than human sorting and you pay less wages as you don't have to hire anyone for this job.
Bar Codes and Bar Code Readers
A BAR CODE is a collection of short black and white parallel lines of different thicknesses.
These lines can stand for the digits 0 to 9 and can then be read as a code number.
They are read by BARCODE READERS which shine an infra-red laser at the lines and read the reflection to tell how thick the lines are.
- Faster than using a keyboard.
- More accurate than using a keyboard as humans can make mistakes
- Can be difficult to change product details quickly. Eg. if the price changed.
Magnetic Stripe Readers
MAGNETIC STRIPES are used on credit cards, library cards and hotel room key cards. Data is stored on the magnetic stripe and read when required.
Eg. In a hotel each card will have a unique code for each room. When the card is put into the reader on the door, the code is read and checked, then the door is unlocked.
- If the card is lost/stolen, thieves can't identify which room it is for as all the cards look the same, unlike with a key.
- Information on the card can be easily read/altered using a small device bought over the internet.
Chip and Pin Readers
CHIP AND PIN technology was introduced to replace the use of magnetic stripes on credit/debit cards because of the availability of devices which could read/alter the data on a magentic stripe.
Now, credit/debit cards include a chip which stores data such as a person's PIN (Personal Identification Number), card number and card expiry date.
When making payments the card is inserted into a CHIP AND PIN READER which reads the PIN on the chip and matches it to the PIN entered on the number pad by the customer. It would also check the card is in date and that there is enough money in the account to complete the transaction.
- Secure, as the chip is difficult to read
- People are careless with their PIN.
A SENSOR is an device which collects data and inputs it to a computer system. Sensors collect data continuously.
Sensors detect analogue data which is continuously varying, such as temperature.
A computer can only process digital data, so an analogue-to-digital converter is essential and placed between the sensor and the computer.
- Sensors can work 24/7 without needing a break
- More reliable & accurate than humans
- Sensors can go in places humans can't go. Eg. Somewhere radioactive.
- If there is a powercut or their battery dies they will stop working.
Sensors can detect temperature (eg. in greenhouses), pressure (eg. a burglar alarm system), light (eg. street lamps) and humidity (eg. greenhouses) as well as other things.
Output Devices: Monitors
A MONITOR is a device which displays information from the computer on a screen. There are two main types of monitors:
CRT (CATHODE RAY TUBE) and TFT (THIN FILM TRANSISTOR.)
CRT monitors are old and not as common any more.
- Displays a HUGE range of colours
- You don't have to be directly in front of the screen to see whats on it clearly
- Very bulky, difficult to move and mount on walls.
TFT monitors are the modern alternative to CRT monitors.
- They are smaller, lighter and thinner than CRT monitors so can be wall mounted and used in laptops and phones.
- The picture is sharper,
- They can not display the range of colours that a CRT monitor can.
- You also have to be directly infront of the screen for a clear picture.
Output Devices: Projectors
MULTIMEDIA PROJECTORS are output devices which can project an image onto a large surface as required such as: a white board or a wall.
They can also be linked to DVD players or use television signals as their input making them useful in public places to show things like football matches.
- Lots of uses. Eg. In schools, presentations, films, sports matches etc.
- Portable or can be mounted to roof
- Uses a fragile and expensive bulb which is a major recurring expense
Output Devices: Printers
There are three main types of printer used at the current time: Laser, inkjet & dot-matrix.
Laser printers are the fastest and have the best quality. They are cheaper in the long-run.
However, they are the most expensive to buy, the toner (the ink used) is toxic and the reproduction of colour is not as precise as with an inkjet printer.
Inkjet printers are cheaper than laser printers, they are lighter and smaller.
However, they are slower that laser printers and the ink will run if printouts get wet.
Dot matrix printers are the cheapest and the most robust. More than one copy can be printed at a time. (Useful for reciepts, customer copy and shop copy.)
However they are the slowest and are very loud.
For these reasons, Laser printers would be used in schools and businesses, inkjet printers would be used in the home and dot matrix printers would be used for reciepts/cheques in shops etc.
Output Devices: Plotters
PLOTTERS are line-drwawing output devices.
FLAT BED PLOTTERS involve a motor which drives a pen across the page at any angle/distance. The paper is flat underneath the pen.
DRUM PLOTTERS involve a drum which the papern lies on. The drum spins to drive the paper under the pen.
Uses of plotters include:
- architects for plans
- civil engineers for road planning/maps
- CAD (Computer aided design) engineers for plane parts
- vinyl sign cutting.
Output Devices: Speakers
SPEAKERS allow the user to hear music or sound from a computer.
HEADPHONES are personal speakers, which can be used so no one else can hear what you are listening to.
Speakers can be useful for blind people as they allow special software (a screen-reader) which describes what is on the screen.
Control Devices (Actuators)
Output devices used in control systems are called ACTUATORS.
Actuators include: switches, motors, heaters, buzzers and LED's.
Sensors work with Actuators to form a control system.
A control system could be in washing machine. A temperature is used to see if the temperature is hot enough. It is not a heater (the actuator) will turn on.
Another example would be the buzzer on a microwave which makes a noise when the timer runs down.