What are input, output and storage devices, and how do they fit the input-process-output model?
Classify peripherals as input, output or storage devices, and explain the input-process-output model of a computer system
A focused answer to the O-Level Computing point on peripherals. Classifying devices as input, output or storage, the input-process-output model with feedback, and choosing suitable devices for a task.
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What this dot point is asking
SEAB wants you to classify peripheral devices as input, output or storage, and to explain the input-process-output (IPO) model of a computer system. The central idea is that a computer takes in data, processes it, and produces output, and that the devices attached to it each play one of these roles.
The answer
What a peripheral is
A peripheral is a device attached to the computer that is not part of the core processor and memory. Peripherals fall into three groups by their role: input, output and storage.
Input devices
An input device sends data into the computer. The user (or the environment) provides data, and the device turns it into a form the computer can process.
Examples: keyboard, mouse, microphone, scanner, touchscreen (as input), camera, and sensors (such as a temperature sensor).
Output devices
An output device takes data out of the computer and presents it to the user.
Examples: monitor (screen), printer, speakers, and a touchscreen (as output).
Storage devices
A storage device keeps data so it can be saved or moved.
Examples: hard disk drive, solid state drive, USB flash drive, and memory card.
The input-process-output model
The input-process-output (IPO) model describes how a computer system works:
INPUT -> PROCESS -> OUTPUT
- Input: data is taken in (for example from a keyboard or sensor).
- Process: the CPU works on the data following the program's instructions.
- Output: the result is produced (shown on screen, printed, played).
Storage can hold data before or after processing, and feedback can loop output back to affect the next input (for example a thermostat turning on heating, which then changes the temperature it senses).
Choosing a suitable device
The right device depends on the task: a microphone suits voice input, a scanner suits copying documents, a printer suits a paper copy, and a sensor suits automatic readings. Matching device to task is a common exam skill.
Examples in context
Example 1. A self-checkout till. A barcode scanner (input) reads items, the computer processes the prices and total (process), and a screen and receipt printer show and print the total (output). A card reader inputs payment, completing the IPO cycle for the shopper.
Example 2. A games console. A controller is the input device, the console's processor handles the game logic (process), and the television and speakers are the output devices. The game saves to storage so progress is kept, and the player's actions provide continuous feedback into input.
Try this
Q1. Classify a scanner and a pair of speakers as input or output devices. [2 marks]
- Cue. A scanner is an input device; speakers are an output device.
Q2. State the three stages of the input-process-output model. [3 marks]
- Cue. Input, process, output.
Q3. Give a suitable input device for measuring temperature automatically. [1 mark]
- Cue. A temperature sensor.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original4 marksClassify each device as input, output or storage, and state what it does: microphone, monitor, USB flash drive, printer.Show worked answer →
Classification and purpose:
- Microphone: an input device; it captures sound and sends it into the computer.
- Monitor: an output device; it displays visual output to the user.
- USB flash drive: a storage device; it stores data so it can be kept or moved.
- Printer: an output device; it produces a physical (paper) copy of output.
Markers reward the microphone as input, the monitor and printer as output, and the USB flash drive as storage, each with a correct purpose.
Original5 marks(a) Describe the input-process-output model of a computer system. (b) Using a digital weather station as an example, give a device or step for each of input, process and output.Show worked answer →
(a) The input-process-output (IPO) model describes how a computer system works: it takes in data (input), the CPU works on that data following instructions (process), and it gives a result (output). Storage may hold data before or after processing, and feedback can loop output back to influence input.
(b) For a digital weather station:
- Input: a temperature sensor reads the air temperature and sends the data in.
- Process: the computer processes the readings, for example calculating an average or comparing to a threshold.
- Output: the result is shown on a display (or triggers an alert).
Markers reward input then process then output described in order, and a sensible input device, processing step and output device for the weather station.
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