💻 Paper 1 · 1.3 Processor Fundamentals
1.3.4 Input, Output and Storage Devices
Cambridge 9618 · International A Level Computer Science · ~13 min read
Notes
Video
Slides
Quiz
Worksheet

Input Devices

Input devices convert real-world data into a form the computer can process. The key is to match the device to the task and justify the choice.

⌨️ Keyboard

Converts key presses into ASCII/Unicode character codes. Suitable for text entry and commands.

🖱️ Mouse / Trackpad

Detects movement and button clicks. Converts physical movement to cursor position. Suitable for GUI navigation and selection.

📱 Touchscreen

Detects finger/stylus pressure or capacitance at coordinates. Acts as both input and output. Used in smartphones, ATMs, kiosks.

🎙️ Microphone

Converts sound waves (analogue) to digital audio data. Used for voice recognition, VoIP, recording.

📷 Camera / Webcam

Captures light and converts to digital image/video data. Used for video calls, security, barcode reading.

📊 Barcode Reader / RFID

Barcode: scans reflected laser light pattern. RFID: reads electromagnetic signals from passive tags. Used in retail, logistics, access control.

🌡️ Sensors

Temperature, pressure, light, humidity, motion sensors. Convert physical quantities to digital signals. Used in embedded systems, control systems, IoT.

🖊️ Scanner / OMR / OCR

Scanner: captures document images. OMR (Optical Mark Recognition): detects marks on paper (exam papers, ballots). OCR: converts printed/handwritten text to digital characters.

Output Devices

🖥️ Monitor (LCD/OLED)

LCD: uses liquid crystals and backlight. OLED: each pixel emits its own light — better contrast, thinner. Measured in resolution, refresh rate, pixel density (PPI).

🖨️ Inkjet Printer

Sprays tiny droplets of ink. Suitable for home printing, photos, low-volume colour. Slow; ink cartridges expensive per page.

🖨️ Laser Printer

Uses toner (powder) and electrostatic charge. Fast, high-volume, cheaper per page. Better for text and office use.

🖨️ 3D Printer

Builds 3D objects layer by layer from filament or resin. Used in prototyping, manufacturing, medicine (prosthetics).

🔊 Speakers

Convert digital audio data to sound waves (analogue). Used with multimedia, music, alerts.

⚙️ Actuator

Converts a digital control signal into a physical movement. Used in robotics, control systems (e.g. motor, valve, servo).

Secondary Storage Devices

Secondary storage is non-volatile (data persists without power). The three main types are magnetic, optical, and solid-state.

TypeTechnologyExamplesProsCons
MagneticMagnetic domains on spinning platters; read/written by moving headHDD (Hard Disk Drive), magnetic tapeHigh capacity, low cost per GB; large drives (>10 TB)Slow (mechanical moving parts); vulnerable to shock; generates heat/noise
OpticalLaser burns/reads microscopic pits on a reflective discCD (~700 MB), DVD (~4.7 GB), Blu-ray (~25 GB)Cheap, portable, durable (no moving parts during storage), read-only formats are tamper-proofSlow access; low capacity vs HDD/SSD; easily scratched; optical drives becoming rare
Solid-StateFlash memory (NAND); no moving parts; electronic read/writeSSD, USB flash drive, SD card, NVMe driveVery fast; silent; shock resistant; compact and lightweightMore expensive per GB than HDD; limited write cycles (wear); lower max capacity than HDD

Key Storage Characteristics

When evaluating storage for a given scenario, consider:

  • Capacity — how much data can be stored (bytes, GB, TB)
  • Access speed — how fast data can be read/written (sequential access vs random access)
  • Cost per GB — magnetic < optical < solid-state (typically)
  • Portability — can the device be easily moved? (optical/USB flash = high; HDD = medium; magnetic tape = low)
  • Durability — resilience to physical damage (SSD = high; HDD = low; optical = medium)
  • Volatility — all secondary storage is non-volatile (data not lost on power off)

Analogue vs Digital

Many input devices capture analogue signals (continuous, infinite values) from the physical world. These must be converted to digital (discrete, binary) values using an Analogue-to-Digital Converter (ADC) before the CPU can process them. Examples: microphones (sound), temperature sensors, pressure sensors.

Similarly, digital outputs from the CPU may need converting to analogue signals for real-world use via a Digital-to-Analogue Converter (DAC) — e.g. audio output to speakers.

Exam tip: Cambridge 9618 questions often give a scenario and ask you to recommend a suitable device AND justify your choice. Always link the device's characteristics to the specific requirements — e.g. "A laser printer is suitable for the office because it has a fast print speed and low cost per page for high-volume printing." Avoid vague justifications like "it's better."
⚠️ Common Mistakes
  • Saying HDDs are faster than SSDs — SSDs have no moving parts and are significantly faster for random access
  • Saying optical storage is volatile — all secondary storage is non-volatile (data persists without power)
  • Confusing OMR and OCR — OMR detects the presence of marks (ticks/crosses); OCR reads actual characters/letters
  • Saying inkjet is cheaper per page than laser — laser printers have lower cost per page for high-volume printing; inkjet cartridges are expensive relative to output
✅ Notes completed!
▶
Video coming soon
Click slide or press arrow keys to navigate

Worksheet — 1.3.4 Input, Output & Storage

8 questions · instantly marked · Cambridge 9618 standard

Q1Compare magnetic and solid-state secondary storage in terms of speed, cost per GB, and durability.[6]
✅ Mark scheme
Mark scheme
Speed: SSD much faster than HDD due to no moving parts; HDD is slower due to mechanical read/write head movement [2]; Cost per GB: HDD cheaper per GB than SSD; SSD more expensive [2]; Durability: SSD more durable — no moving parts so resistant to shock; HDD has spinning platters vulnerable to physical shock [2].
Q2A supermarket uses RFID tags on products. Explain how RFID works and give one advantage over traditional barcodes.[3]
✅ Mark scheme
Mark scheme
RFID uses electromagnetic/radio waves to read data stored on a passive tag without needing line-of-sight contact [1]; the tag is powered by the reader's radio signal — no battery needed [1]; advantage: multiple items can be scanned simultaneously without having to individually align each barcode with a scanner [1]. (Accept other valid advantages.)
Q3Explain the difference between OMR and OCR, giving an appropriate use case for each.[4]
✅ Mark scheme
Mark scheme
OMR (Optical Mark Recognition) detects the presence or absence of marks (e.g. filled circles/ticks) in predefined positions on a form [1]; use case: marking exam multiple-choice answer sheets, lottery tickets [1]; OCR (Optical Character Recognition) identifies and converts printed or handwritten characters into machine-readable text [1]; use case: digitising printed documents, reading passports [1].
Q4A weather station collects temperature and humidity data. Explain why an ADC is needed and what it does.[3]
✅ Mark scheme
Mark scheme
The sensors produce analogue signals (continuously varying voltages representing temperature/humidity) [1]; a CPU can only process digital (binary) data [1]; the ADC (Analogue-to-Digital Converter) samples the analogue signal at regular intervals and converts each sample to a binary value [1].
Q5A hospital wants to archive patient records long-term. Recommend a suitable storage type and justify your choice with two reasons.[3]
✅ Mark scheme
Mark scheme
Magnetic (HDD) or Optical (Blu-ray/DVD) recommended [1]; two valid reasons from: high capacity for large amounts of data [1]; non-volatile so data persists without power [1]; optical is read-only once written (CD-R/DVD-R) so data cannot be accidentally modified [1]; HDDs offer very large capacity at low cost per GB for bulk archiving [1].
Q6Compare inkjet and laser printers. In which situation would a laser printer be more appropriate?[4]
✅ Mark scheme
Mark scheme
Inkjet: sprays ink droplets; slower; higher cost per page; better for high-quality colour photos [1]; Laser: uses toner powder; faster print speed; lower cost per page; better text quality [1]; Laser is more appropriate for: high-volume office printing [1] because its faster speed and lower cost per page makes it more economical for large quantities [1].
Q7State three characteristics to consider when choosing secondary storage for a given application.[3]
✅ Mark scheme
Mark scheme
Any three from: capacity [1]; access speed [1]; cost per GB [1]; portability [1]; durability [1]. Award 1 mark each, max 3.
Q8Explain what an actuator is and give one example of its use in a real-world control system.[2]
✅ Mark scheme
Mark scheme
An actuator converts a digital control signal (from the CPU or controller) into a physical action/movement [1]; example: a motor turning a fan when the temperature sensor signals the temperature is too high; a valve opening to allow water flow in an irrigation system [1].
Topic Quiz
Question 1 of 15
You scored
out of 15
Card 1 of 10
Click to reveal definition
🎉
All cards reviewed!
TermDefinition
🎯

Mini Test — 1.3.4 Devices & Storage

10 questions · 10 marks · 10 minutes

← 1.3.3 Assembly Language
21 of 82 · Cambridge 9618
1.3.5 Memory Types →
🔒
Pro lesson
Upgrade to CSZone Pro to access all Cambridge 9618 A Level lessons.
Upgrade to Pro →