Hardware: output devices and their uses

What you'll learn

This revision guide covers output devices tested in the CIE IGCSE Computer Science specification. You'll learn how different output devices convert computer data into forms humans can perceive or that can control physical systems. Understanding the appropriate use cases, advantages and disadvantages of each device type is essential for exam success.

Key terms and definitions

Output device — hardware component that receives data from a computer and converts it into another form (visual, audio, physical movement or printed)

Resolution — the number of pixels that make up a display, expressed as width × height (e.g. 1920×1080), determining image sharpness and clarity

Actuator — an output device that converts electrical signals into physical movement, commonly used in control systems and robotics

Inkjet printer — a printer that produces output by spraying tiny droplets of liquid ink onto paper through microscopic nozzles

Laser printer — a printer that uses toner (powdered ink), static electricity and heat to fuse images onto paper

3D printer — a device that creates three-dimensional solid objects by building up successive layers of material based on digital models

Projector — an output device that displays enlarged computer images onto a screen or flat surface by projecting light

Pixel — the smallest controllable element of a digital image displayed on screen, consisting of red, green and blue sub-components

Core concepts

Monitors and display technologies

Monitors are the most common output devices, displaying visual information from computers. Several technologies exist, each with distinct characteristics suitable for different applications.

LCD (Liquid Crystal Display) monitors use liquid crystals sandwiched between two polarising filters. When electric current passes through, crystals align to allow light through, creating images. LED backlighting has largely replaced older CCFL technology.

Advantages of LCD monitors:

• Relatively inexpensive to manufacture
• Low power consumption compared to older CRT displays
• Thin and lightweight design
• Available in large sizes up to 40+ inches

Disadvantages of LCD monitors:

• Limited viewing angles (image quality degrades when viewed from the side)
• Slower response times can cause motion blur in fast-moving images
• Less accurate colour reproduction than some alternatives
• Backlight bleed can occur at screen edges

OLED (Organic Light Emitting Diode) displays use organic compounds that emit light when electricity passes through them. Each pixel produces its own light without requiring a backlight.

Advantages of OLED displays:

• Superior contrast ratios with true blacks (pixels can turn completely off)
• Wider viewing angles than LCD
• Faster response times eliminate motion blur
• More accurate colour reproduction
• Thinner construction possible

Disadvantages of OLED displays:

• Significantly more expensive than LCD
• Risk of screen burn-in with static images
• Generally shorter lifespan than LCD
• Lower peak brightness levels

Touchscreen monitors combine input and output functionality, detecting touch through capacitive or resistive technology while displaying visual information. Common in smartphones, tablets, point-of-sale systems and information kiosks.

Printers

Printers create permanent (hard copy) output on paper or other physical media. Three main types appear in IGCSE specifications.

Inkjet printers work by propelling tiny droplets of liquid ink from cartridges through microscopic nozzles onto paper. The print head moves horizontally across the page while paper advances vertically.

Advantages of inkjet printers:

• Lower initial purchase cost
• Excellent colour photo printing quality
• Quiet operation
• Can print on various media (photo paper, card, transparencies)
• Compact size suitable for home use

Disadvantages of inkjet printers:

• High running costs (expensive ink cartridges)
• Slow printing speeds, especially for colour documents
• Ink can smudge if paper gets wet
• Nozzles can clog if not used regularly
• Ink cartridges dry out over time

Laser printers use a complex process involving static electricity, toner (powdered ink), and heat. A laser beam draws the image on a photosensitive drum using static electricity to attract toner particles, which are then transferred and fused onto paper using heat and pressure.

Advantages of laser printers:

• Fast printing speeds (pages per minute)
• Low cost per page for high-volume printing
• Sharp, professional-quality text output
• Toner cartridges don't dry out
• Water-resistant output

Disadvantages of laser printers:

• Higher initial purchase cost
• Larger physical size
• Colour laser printers significantly more expensive
• Photo quality generally inferior to inkjet
• Higher power consumption (heating element required)

3D printers create three-dimensional physical objects from digital models using additive manufacturing. The most common type (FDM - Fused Deposition Modelling) melts plastic filament and deposits it layer by layer to build objects.

Applications of 3D printing:

• Rapid prototyping in product design and engineering
• Manufacturing custom medical prosthetics and dental implants
• Creating architectural scale models
• Producing spare parts for machinery
• Educational demonstrations of complex structures

Advantages of 3D printers:

• Create complex geometric shapes impossible with traditional manufacturing
• Produce custom one-off items economically
• Reduce material waste (only uses material needed)
• Enable rapid iteration in design process

Disadvantages of 3D printers:

• Very slow production speeds (hours for single objects)
• Limited material choices compared to traditional manufacturing
• Lower strength and durability than injection-moulded parts
• Relatively expensive for consumer models
• Require technical expertise to operate effectively

Speakers and audio output

Speakers convert digital audio data into sound waves humans can hear. The computer's sound card converts digital signals to analogue, which drives electromagnets that vibrate speaker cones, producing pressure waves in air.

Applications requiring speakers:

• Multimedia presentations and video conferencing
• Accessibility features (screen readers for visually impaired users)
• Gaming and entertainment systems
• Audio editing and music production
• Alert sounds and system notifications

Headphones work on the same principle as speakers but deliver sound directly to ears, providing privacy and preventing disturbance to others.

Actuators and control systems

Actuators are output devices that create physical movement or mechanical action in response to electrical signals from a computer. They bridge the digital and physical worlds in control and automation systems.

Types of actuators:

• Motors — produce rotational movement (e.g. opening automated doors, moving robot arms)
• Solenoids — create linear push/pull motion (e.g. electronic locks, valve control)
• Hydraulic/Pneumatic actuators — use fluid or air pressure for powerful movement (e.g. industrial machinery)
• Servos — motors with position feedback for precise angular control (e.g. robotics, RC vehicles)

Applications of actuators in control systems:

• Automated manufacturing — robotic arms positioning and assembling components
• Climate control — opening/closing vents, adjusting thermostats
• Transportation — controlling traffic lights based on sensor input
• Smart homes — automated blinds, door locks, heating systems
• Agriculture — greenhouse temperature control, automated irrigation
• Healthcare — precise positioning in surgical robots, automated drug dispensing

Projectors

Projectors enlarge and display computer output onto large screens or walls, making them visible to audiences. Modern projectors use DLP (Digital Light Processing) or LCD technology.

Advantages of projectors:

• Display very large images (80+ inches) economically
• Portable models available for mobile presentations
• Suitable for business presentations and educational settings
• Image size easily adjustable by changing projection distance

Disadvantages of projectors:

• Require darkened rooms for optimal visibility
• Lamp replacement expensive (traditional bulb projectors)
• Image quality affected by ambient light
• Setup required (positioning, focusing, screen needed)

Other output devices

Plotters are specialised printers that use pens to draw continuous lines, ideal for technical drawings, architectural plans and engineering diagrams. Modern inkjet plotters have largely replaced older pen plotters.

Buzzer/Beeper produces simple warning sounds in control systems and embedded devices (e.g. alarm systems, microwave completion alert, reversing vehicles).

LED indicators provide simple visual status feedback (power on/off, activity indicators, warning lights) using light-emitting diodes that consume minimal power.

Worked examples

Example 1: Output device selection

Question: A graphic design company needs to purchase output devices for their new office. They produce high-quality marketing materials including brochures and posters.

(a) Recommend a suitable printer for producing draft colour documents for internal review. Justify your choice. [3 marks]

(b) Recommend a different printer for producing final high-quality posters. Justify your choice. [3 marks]

Model answer:

(a) Inkjet printer [1 mark]

• Produces good quality colour output suitable for reviewing designs [1 mark]
• Lower initial cost than laser printers / suitable for moderate printing volumes [1 mark]

(b) Large format inkjet printer / plotter [1 mark]

• Can produce large poster-size output [1 mark]
• Excellent colour reproduction and photo quality needed for marketing materials [1 mark]

Example 2: Actuators in control systems

Question: A museum uses a computer-controlled climate system to protect valuable artifacts.

(a) State what is meant by an actuator. [2 marks]

(b) Describe how actuators would be used in this climate control system. [4 marks]

Model answer:

(a) An output device [1 mark] that converts electrical signals into physical movement / mechanical action [1 mark]

(b)

• Temperature sensors send data to the computer / microprocessor [1 mark]
• If temperature exceeds threshold, computer sends signal to actuators [1 mark]
• Motors/actuators open or close air conditioning vents / adjust heating valves [1 mark]
• Motors control fan speeds to circulate air / maintain even temperature [1 mark]

[Accept any sensible description showing sensors → computer/processor → actuators → physical action]

Example 3: Display technology comparison

Question: A hospital is choosing between LCD and OLED displays for operating theatre equipment.

Compare LCD and OLED display technologies, recommending which would be more suitable for this application. [6 marks]

Model answer:

LCD advantages:

• Lower cost to purchase / more economical [1 mark]
• Longer lifespan / no risk of burn-in [1 mark]

OLED advantages:

• Better viewing angles allow multiple surgeons to view clearly from different positions [1 mark]
• Superior contrast and colour accuracy important for medical imaging [1 mark]
• Faster response time for viewing real-time surgical imaging / video [1 mark]

Recommendation: OLED would be more suitable [1 mark] because image accuracy and viewing angles are critical for patient safety / justify expense in medical setting [accept reasonable justification]

Common mistakes and how to avoid them

• Confusing input and output devices. Remember: output devices receive data FROM the computer and convert it to another form. Touchscreens have BOTH input and output functions — state both if asked about their purpose.

• Describing features instead of advantages. When asked for advantages, explain the benefit to users. "High resolution" is a feature; "Produces sharper, clearer images allowing detailed work" is an advantage.

• Vague comparisons without context. Avoid statements like "laser printers are better" — always specify the context. Laser printers are better for high-volume office printing; inkjet printers are better for photo printing at home.

• Mixing up 3D printer advantages with general printing. 3D printers create physical objects and enable rapid prototyping — don't discuss text/document printing quality, which is irrelevant.

• Using incorrect terminology. Learn the precise terms: it's "toner" in laser printers (not ink), "resolution" not "quality", "actuator" not "motor" (actuator is the broader category).

• Not providing examples in "describe" questions. When describing how actuators work in control systems, include a specific example showing the complete sequence: sensor → processor → actuator → physical action.

Exam technique for "Hardware: output devices and their uses"

• "State" commands (1-2 marks): Write brief, factual answers. "State an output device" requires just "Monitor" or "Printer" — no explanation needed. Don't waste time over-explaining.

• "Describe" commands (2-4 marks per point): Provide enough detail to earn marks. For "Describe how a laser printer works", cover multiple stages (laser, drum, toner, fusing). Each distinct point earns a mark.

• "Compare" commands require both sides. Always discuss both items being compared. For "Compare LCD and OLED displays", you must mention advantages/disadvantages of both — discussing only one loses marks.

• Justification earns marks. Questions asking you to "recommend" or "justify" require reasoning. "Inkjet printer because it produces good quality colour" scores marks; "Inkjet printer" alone does not.

Quick revision summary

Output devices convert computer data into perceivable or physical forms. Key devices include monitors (LCD, OLED), printers (inkjet, laser, 3D), speakers, projectors and actuators. LCD monitors offer economical general-purpose displays while OLED provides superior image quality at higher cost. Inkjet printers excel at photo printing but have high running costs; laser printers deliver fast, economical document printing. 3D printers create physical prototypes through additive manufacturing. Actuators enable control systems by converting signals to physical movement. Choose devices based on specific application requirements, balancing cost, quality and functionality.