2. Input & Output Devices

• Numeric keypads:

  Advantages:

  • Faster than standard keyboards when entering numeric data.
  • Because many are small devices, they are very easy to carry around.

  Disadvantages:

  • Sometimes have small keys, which can make input more difficult.
  • Sometimes the order of the numbers on the keypad is not intuitive.
• Sensors

  Disadvantages:

  • Faulty sensors can give spurious results.
  • Most sensors are analogue; therefore, they require conversion using Analogue to Digital Convertors.
• Sensors

  Advantages:

  • Readings are more accurate as compared to human operators.
  • Readers are continuous, no breaks in the monitoring.
  • Because it is a continuous process, any action or warnings needed will be initiated immediately.
  • Automatic systems don’t need human intervention.
• Tracker ball:

  Disadvantages:

  • Not supplied with the computer as standard, therefore more costly.
  • Users may need training because it is not standard equipment
• Tracker ball:

  Uses:

  • Used in an industrial control room environment.
  • Used in some luxury cars to select functions such as radio.
• Tracker ball:

  Advantages:

  • Does not need the same fine control as a mouse.
  • Easier to use than a mouse if the operator has problems with their wrist.
  • More accurate positioning of the pointer on screen.
  • They are more robust than a mouse.
  • Needs less desk space than a mouse or keyboard.
• 1. Keyboards:

  Advantages:

  • Fast entry of new text into a document.
  • Well-known method.
  • Easy to use for most people.

  Disadvantages:

  • It can be difficult to use if the user has limited arm/wrist use.
  • Slow method when compared to direct data entry.
  • A fairly large device that uses up valuable desk space.
• 3. Mouse:

  Advantages:

  • Faster method for choosing an option rather than using a keyboard.
  • Very quick way of navigating through applications and the internet.
  • Does not need a large desk area when compared to a keyboard.

  Disadvantages:

  • It can be more difficult for people with restricted hand/wrist movement than using a keyboard for data entry.
  • Easy to damage, clogged up with dirt.
  • Difficult to use if no flat surface is readily available
• Touchpad:

  Advantages:

  • Faster than a keyboard for choosing options.
  • Used to navigate applications and the internet.
  • Because the touchpad is integrated into the laptop computer, no separate mouse, portability, and good if there are no flat surfaces available.

  Disadvantages:

  • People with limited hand/wrist movement find the device difficult to use.
  • Can be more difficult to control the pointer when compared to a normal mouse.
  • Drag and drop operations are more complicated using a touchpad.
• . Remote Control:

  • It can be operated from distance

  Disadvantages:

  • Difficult to use for people with limited hand/wrist movements.
  • Physical obstacles can easily block the signal
• Joysticks:

  Uses:

  • Used in video games.
  • Used in simulators, to mimic the actual controls.

  Advantages:

  • Easier than keyboards for screen navigation.
  • In some applications, the control is more realistic than using a mouse.

  Disadvantages:

  • The on-screen pointer is more difficult to use
• Driving wheel:

  Uses:

  • Used in video games

  Advantages:

  • More realistic experience than both mouse and joystick.
  • Easier than a keyboard or joystick to control steering movements.

  Disadvantages:

  • expensive than mouse or joystick.
  • Steering movements tend to be over-sensitive, which gives an unrealistic feel.
  • Unless it is an expensive simulator, feedback to steering wheel is non-existent
• Touch screen (as an input device):

  Uses:

  • Automatic teller machines

  Advantages:

  • Faster entry of options than using keyboard or mouse.
  • Very easy method for choosing options.
  • no training necessary in its use.

  Disadvantages:

  • The screen can get very dirty with constant touching.
• Scanners:

  Uses:

  • Scanning in documents and converting into different formats

  Advantages:

  • Images can be stored for editing at a later date.
  • When used with OCR, they are much faster and more accurate than typing the documents in.
  • Possible to recover damaged documents by scanning in and producing a copy.

  Disadvantages:

  • Limited quality, depending on how good the scanner’s resolution is.
  • Fairly slow input method, especially if color mode is selected.
• Digital Cameras:

  Uses:

  • Taking photographs, still better than smartphones and tablets.

  Advantages:

  • better-quality photographs than with a traditional camera.
  • Faster to upload photographs to a computer than scanning in hard copies.
  • Memory cards can store many thousands of photographs.
  • No need to develop film, saves money
  • Unwanted images can be deleted from memory card.

  Disadvantages:

  • Images need to be compressed to reduce amount of memory used.
• Microphones:

  Uses:

  • To input speech
  • Input in voice recognition software for authentication.
  • As a sensor, to pick up sound
  • Used in audio conferencing

  Advantages:

  • Faster to read in text than it is to type it in.
  • Improves security, if used as an authentication system.

  Disadvantages:

  • Sound files use up a lot of computer memory.
  • Reading in data is more error prone than typing in.
• Light pens:

  Uses:

  • Selecting object on CRT screens
  • Drawing on screens

  Advantages:

  • Greater accuracy than touch screens
  • Small, makes them portable as well as capable of being used in small spaces.
  • Easy-to-use technology.

  Disadvantages:

  • Lagging problems while drawing on screen.
  • Only works with CRT monitors.
  • Rather dated technology
• Magnetic Stripe Readers:

  Uses:

  • On credit card for use at ATMs
  • Security device to allow entry to buildings

  Advantages:

  • Faster than keying in data manually.
  • Error-free
  • readable form.
  • Robust, there are no moving parts.

  Disadvantages:

  • If the card is damaged, the data is lost.
  • Doesn’t work at a distance.
  • As the information isn’t human-readable, this can be a disadvantage in some cases
• Chip and PIN reader:

  Uses:

  • Where payments are made using cards

  Advantages:

  • It is more secure than contactless cards as the PIN acts as a second security layer.
  • More robust system than Magnetic Stripe Cards

  Disadvantages:

  • Be very careful so the PIN isn’t seen by anyone while being typed in
• Radio Frequency Identification (RFID) reader:

  Uses:

  • Livestock tracking
  • Retail, instead of barcodes, as they don’t need to be scanned in.
  • Admission passes.
  • Library books, to acknowledge the books which have been borrowed.

  Advantages:

  • No line-of-sight contact is needed.
  • Very robust and reliable technology.
  • Very fast read rate.

  Disadvantages:

  • As they use radio waves, they are easy to jam/interrupt.
  • Easy to hack into the signal.
  • RFID is more expensive than a comparable barcode system.
• Optical Mark Reader/Recognition (OMR):

  Uses:

  • Used in MCQs checking.
  • Used in voting papers.

  Advantages:

  • fast way input survey results.
  • accurate because, no human intervention.
  • More accurate than OCR .

  Disadvantages:

  • Designing the forms can be complicated to ensure the marks are correctly positioned.
  • If there are problems, they need to be manually checked, time consuming
• Optical Character Recognition/Reader:

  Uses:

  • Processing passports and identity cards.
  • Converting hard copy documents into electronic form

  Advantages:

  • It is a much faster data entry system than manual typing.
  • No human intervention, its error free.

  Disadvantages:

  • System has difficulty in reading different handwritings.
  • Still not a very accurate technique.
• Barcode readers:

  Uses:

  • supermarkets for stock control.
  • libraries, to keep track of books.
  • safety function to ensure of electrical equipment on a daily basis.

  Advantages:

  • Much faster than manually keying in data.
  • Allow automatic stock control.
  • They are a tried and trusted technology.

  Disadvantages:

  • Relatively expensive system to administer.
  • barcodes can be swapped between items.
  • Can be more easily damaged than RFID tags or magnetic stripes
• Quick response (QR) code scanner:

  Uses:

  • used in advertising
  • Wi-Fi authentication
  • Used in restaurants, see the menu by scanning.

  Advantages:

  • hold more information than normal barcode.
  • fewer errors than with barcodes.
  • QR codes are easier to read because can read them on a smartphone.
  • It is possible to encrypt QR codes.

  Disadvantages:

  • More than one QR format is available.
  • QR codes can be used to transmit malicious data
• Cathode ray tube (CRT) monitors:

  Uses:

  • Their large screens allow complex diagrams to be created
  • Used with light pens to allow designs to be created.

  Advantages:

  • Can be seen at a wider range of angles, unlike LCDs.
  • Allow the use of light pens.

  Disadvantages:

  • heavy and bulky.
  • run very hot and can cause fires if left unattended.
  • They use a lot more power than LCDs.
  • Their flickering can lead to headaches
• Liquid Crystal Display (LCD) screens:

  Uses:

  • Main output device for modern computers.
  • phones, laptops use LCD screens.

  Advantages:

  • Very efficient, low power consumption.
  • Lightweight devices.
  • Screens can made in various sizes.
  • No flickering images.
  • Very sharp image resolution.

  Disadvantages:

  • Colour and contrast from different angles are inconsistent.
  • Motion blur is a common issue.
  • Lower contrast than CRT monitors.
• Touch screen (as an output devices):

  Uses:

  • ATMs

  Advantages:

  • Don’t need additional input devices.
  • They are very interactive, many functions like swiping
  • They add a high-tech feel to devices and interfaces.

  Disadvantages:

  • They tend to get dirty
  • Frequent use results in straining of arm muscles
  • If large amounts of data are input/output, they aren’t very accurate
• Multimedia projectors:

  Uses:

  • allow the whole audience to see images.
  • Advertising presentations.
  • Home cinema systems.

  Advantages:

  • More people can watch, don’t have to crowd around a laptop.
  • Avoids the need for several networked computers.

  Disadvantages:

  • Images can be fuzzy.
  • Expensive
  • Set-up can be complicated
• Laser printers:

  Uses:

  • low noise is required.
  • If fast, high quality, printing is required.

  Advantages:

  • Printing is fast.
  • handle very large print jobs.
  • Quality high.
  • Toner cartridges last for a long time.

  Disadvantages:

  • fast if several copies are being made.
  • Color laser printers are expensive to run.
• Inkjet printers:

  Advantages:

  • High-quality output
  • Cheaper than laser printers.
  • Very lightweight

  Disadvantages:

  • Slow output if many copies are needed.
  • Can’t do large print jobs.
  • Printing can smudge if user isn’t careful.
  • Can be expensive if used a lot.
• Dot matrix printers:

  Uses:

  • where noise isn’t a major issue.

  Advantages:

  • Can be used in varying environments
  • Very cheap to run and maintain.
  • Good for continuous printing.

  Disadvantages:

  • noisy
  • Initial cost is more than an inkjet printer.
  • slow and low quality
• (Graph) Plotters:

  Uses:

  • architectural drawings
  • engineering drawings
  • Drawing animation characters.

  Advantages:

  • Very high-quality output.
  • can produce large, monochrome and color drawings very accurately.
  • Can print on a variety on materials.

  Disadvantages:

  • slow printing.
  • Expensive equipment
  • Have a very large physical footprint compared to a printer.
• 3D printers:

  Uses:

  • parts of the aircraft are made using 3d printers they can be very lightweight.

  Advantages:

  • Manufacturing become much easier.
  • initial cost is high, it is still cheaper than the more conventional way
  • Parts for machinery that aren’t available can be made.

  Disadvantages:

  • Could lead to manufacture of dangerous items by almost anyone.
  • job loss
• Speaker:

  Uses:

  • Used in phones, computers.
  • Plays downloaded sound files.

  Advantages:

  • Amplified sounds, louder than the original sound.
  • enough to be heard by a huge crowd.
  • Very simple technology.
  • They are especially useful for blind people, for instance, reading e-books.

  Disadvantages:

  • Speaker output can disturb irrelevant people in the same area
  • Sound quality is high only expensive speakers.
  • take a lot of desk space
• Actuators:

  Uses:

  • Used to turn on motors, buzzers, and switches.
  • Allow a computer to control physical devices,

  Advantages:

  • Allow remote operation of many devices.
  • Relatively inexpensive devices.

  Disadvantages:

  • could go wrong.
  • As analogue devices, signals need to be converted using a DAC.