IGCSE ICT: Input and Output Devices — Revision Notes

Condensed for the final weeks. For the full explanation, use the Input and Output Devices study guide.

The three sub-topics as a data journey

2.1 Input devices — a person actively enters data: keyboard, numeric keypad, pointing devices, remote control, joystick/driving wheel, touch screen (as input), scanner, camera, microphone, sensors, light pen.

2.2 Direct data entry devices — data is captured automatically, without a person typing or clicking it: magnetic stripe reader, chip and PIN reader, RFID reader, OMR, OCR, bar code reader, QR scanner.

2.3 Output devices — processed data becomes something a person can see, hear or physically use: monitor, touch screen (as output), multimedia projector, laser printer, inkjet printer, dot matrix printer, plotter, 3D printer, speaker, actuator.

Device-by-scenario, not device-by-definition

Build a device / advantage / disadvantage table for every device in 2.1–2.3, then practise applying it:

• Supermarket till: bar code reader (speed, accuracy) + chip and PIN reader (secure payment).
• School register: RFID reader beats a keyboard — removes manual entry, faster.
• Parcel delivery: bar code/QR scanner, not OCR — OCR reads printed/handwritten text, not codes.
• Hospital wristband: RFID over bar code — no line of sight needed, works while patient moves.
• Large-format poster proof: plotter, not inkjet — built for large-format, high-precision line work.

Devices that belong in more than one category

Touch screen is both input (making a selection) and output (displaying an image) — a directly-tested distinction. Actuator is the output device most often forgotten: it converts an electrical signal into physical movement (opening a valve, moving a robot arm, triggering a motor) — the correct answer whenever a scenario describes a system causing physical movement, not display/print/sound.

Worked example: justifying a device choice

Scenario: A library wants to speed up book returns and reduce manual data-entry errors. Answer: Use a bar code reader rather than a keyboard — it reads each book’s ID directly from its bar code, removing manual transcription and the typing errors that come with it, and is faster per item than typing an ID number in by hand.

Why direct data entry (2.2) is a distinct group

Direct data entry devices are worth learning as a separate group from 2.1, because exam questions often ask why a direct entry method is preferred over manual input — the answer is consistently some combination of: greater speed, lower error rate, and no need for a person to read or interpret the data before entry. A chip and PIN reader is preferred to typing a card number by hand for exactly this combination of speed and reduced transcription error, alongside the security benefit of not exposing the full card number to be copied down.

Comparing devices within the same category

Cambridge also expects comparisons within 2.3’s printer group, not just across the wider device list. A laser printer is fast and cheap per page for high-volume black-and-white office printing, but has a higher upfront cost than an inkjet. An inkjet printer produces high-quality colour output at low upfront cost, but is slower and more expensive per page for high-volume printing. A dot matrix printer is noisy and low-resolution, but remains useful specifically where multi-part carbon forms need to be printed in one pass (e.g. a delivery note with a customer copy and a warehouse copy) or where a very harsh, dusty environment would damage a laser or inkjet mechanism. Selecting between these three should always be justified against the scenario’s actual requirement — volume, quality, multi-part forms, or environment — rather than by naming whichever printer sounds most modern.

Exam traps

• Forgetting a touch screen can be both input and output, depending on how it is used in the scenario.
• Confusing OCR (reads printed/handwritten text) with OMR (reads marks in predefined positions, e.g. a multiple-choice answer sheet) or a bar code reader (reads printed codes).
• Naming “printer” generically instead of specifying laser, inkjet, dot matrix or plotter, when the scenario’s requirements (speed, cost, large-format, multi-part carbon forms) point to a specific type.
• Forgetting the actuator when a scenario describes physical movement rather than a visible/audible/printed output.
• Giving a single-word justification (“faster”) instead of naming the specific device property that makes it faster or more suitable for the described scenario.

Self-test

1. Name a direct data entry device suited to reading a printed multiple-choice answer sheet, and name the device suited to reading printed or handwritten free text.
2. Why is RFID often preferred over a bar code reader for tracking a moving object?
3. Give one input use and one output use of a touch screen.
4. Which output device is correct for a scenario describing a robot arm moving to pick up an object?
5. State two reasons a chip and PIN reader is preferred over typing a card number by hand.
6. Why would a graphic designer choose a plotter over an inkjet printer for a large poster proof?

Answers: 1. OMR reads a predefined-position mark sheet; OCR reads printed or handwritten text. 2. RFID does not need a direct line of sight and can be read while the object is moving or the tag is concealed, unlike a bar code reader. 3. Input: making a selection on screen; output: displaying an image or interface. 4. Actuator — it converts an electrical signal into the physical movement described. 5. Faster than typing a full card number, and reduces transcription error; also more secure since the full number is not manually copied down. 6. A plotter is built for large-format, high-precision line work, which an inkjet printer is not designed to match at that scale and precision.