IGCSE1.3.2Paper 1 — Computer Systems

Input and Output Devices

The devices that get data in and results out, and where each is the right choice.

YOU SHOULD BE ABLE TO

Describe how common input devices work: barcode scanner, QR scanner, digital camera, keyboard, mouse, microphone, touch screen, 2D and 3D scanners.
Describe common output devices: monitors, printers (inkjet, laser, 3D), speakers, actuators.
Describe sensors and the data each collects.
Give suitable uses for each device.

Keyboard — an input deviceD-Kuru · CC BY-SA 3.0 at

Barcode reader — input, using a laser and a sensorNetwork.nt · Public domain

Inkjet printer — an output deviceSmartway777 · CC BY-SA 3.0

3D printer — builds an object layer by layerKristin Hardwick · CC0 1.0

SORT THEM

Sort each device by what it does for the computer.

PICK ONE, THEN PICK ITS GROUP

Input

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Output

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Storage

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//Sensors you must know

Each sensor measures one physical quantity and sends it as data to a system: temperature, moisture, humidity, light, infra-red, pressure, acoustic, gas, pH, magnetic field, proximity, level, motion. Be ready to pick the right one for a scenario — a greenhouse needs temperature, moisture and light; a burglar alarm needs infra-red and pressure.

//Touch screen types

Resistive: two layers pressed together — cheap, works with gloves, but poor durability and no multi-touch. Capacitive: senses the body's charge — good visibility and multi-touch, but needs bare skin or a special stylus. Infra-red: beams across the screen — works with any object, but is affected by strong light.

//Printer choice

Inkjet: excellent photo quality, cheap printer, expensive ink, slow for large jobs — good for home. Laser: fast, cheap per page, high volume — good for an office. 3D printer: builds an object in layers from a design file, used for prototypes and medical models.

CHECK YOURSELF

1.A greenhouse system must monitor the growing conditions. Which sensors fit best?

2.Which printer suits a busy office printing thousands of pages?