Hardware devices (Cambridge (CIE) AS Computer Science): Revision Note

Microphone

• Converts sound waves into electrical signals

• Allows users to record voice or send audio into a computer

• Dynamic microphones – good for loud environments (e.g. concerts)

• Condenser microphones – more sensitive and accurate, used in studios

Touchscreen

• Detects a user's touch and converts it into an input command

• Capacitive – responds to electrical charge from your finger (used in smartphones, tablets)

• Resistive – responds to pressure (used in ATMs, tills)

• First used in ATMs and information kiosks, now used in smartphones, tablets, laptops, smart displays

• Popular for direct, easy interaction and improved accessibility

Laser printer

• Laser beam draws the image of the page onto a photosensitive drum, changing its electric charge

• Toner is transferred from drum to paper

• Toner sticks to the drum – toner powder is attracted to charged areas matching text/image shape

• Fusing – paper passes through hot rollers, melting toner onto paper so it doesn't smudge

3D printer

• Builds objects layer by layer from the bottom up

• Uses various materials such as thermoplastics, resins, and metals

• Allows high customisation and rapid prototyping

• Handles complex shapes traditional methods can’t make easily

• FDM – melts plastic and builds in layers, SLA – uses light to harden liquid resin

• Used in healthcare (prosthetics), automotive/aerospace (custom parts)

• Can be slow for large/detailed objects, some methods need costly specialist materials

Speakers

• Convert electrical signals into sound waves

• Range from basic laptop speakers to high-end multi-driver home theatre systems

• Found in phones, laptops, studios, smart devices, home theatres

• Improved with digital sound processing and miniaturised components

• Support voice commands, calls, and multimedia playback

Virtual reality headset

• Creates a fully immersive 360° digital environment

• Lets users look around and interact with the virtual world

• Uses head tracking, motion sensors, and stereoscopic displays for 3D vision

• Uses – gaming, education/training, architecture/design, medical/therapy

• Challenges – expensive hardware, possible eye strain or motion sickness, time-intensive content creation

Magnetic hard disk

• Multiple metal platters coated with magnetic material store data as magnetised iron particles (0s and 1s)

• Platters spin at high speed (typically 5400–7200 RPM)

• Data read/written using electromagnets

• Platters divided into concentric tracks and wedge-shaped sectors, forming track sectors

• Read/write arm, controlled by an actuator, positions the head over the correct track sector

• Reliable but mechanical – can be slower and more prone to damage than SSDs

Solid state (flash) memory

• Stores data in cells using transistors that act as switches

• Uses NAND or NOR gates to control flow of electrons

• Writing: high voltage pushes electrons onto floating gate

• Faster and more durable than magnetic drives

• Common examples: SSDs, USB flash drives

• Each cell contains a control gate (controls current) and a floating gate (stores charge)

• Erasing: reverse high voltage pulls electrons off floating gate

• No moving parts – better shock resistance

Optical disc reader/writer

• Uses a laser to read and/or write data on optical discs

• Writing: laser burns pits and lands onto the disc surface

• Arm moves the laser across the disc

• Blu-rays store the most, CDs the least

• Examples: CD, DVD, Blu-ray

• Reading: laser scans surface; changes in reflection indicate 0s and 1s

• CD-R = write once, CD-RW/DVD-RW = rewriteable

• Slower than magnetic/solid-state storage but good for archival