Know and understand characteristics of input and output devices

Published by Patrick Mutisya · 14 days ago

ICT 0417 – Types and Components of Computer Systems: Input and Output Devices

Types and Components of Computer Systems

Objective

Know and understand the characteristics of input and output devices.

1. Introduction

Computer systems consist of hardware that processes data and software that controls the hardware. The hardware can be grouped into three main categories:

  • Input devices – capture data from the user or environment.

  • Processing unit – CPU, memory and storage where data is manipulated.

  • Output devices – present processed information to the user or other systems.

2. Input Devices

Input devices convert physical or analog information into digital signals that the computer can understand. Key characteristics to consider are:

  • Type of data captured – text, graphics, sound, motion, etc.

  • Speed of input – measured in characters per second (cps), samples per second (Hz), or DPI for pointing devices.

  • Accuracy and precision – error rate, resolution, and repeatability.

  • Ergonomics – comfort, layout, and required user effort.

  • Connectivity – wired (USB, PS/2) or wireless (Bluetooth, RF).

Common Input Devices

DeviceData TypeTypical Speed/ResolutionKey AdvantagesTypical Uses
KeyboardAlphanumeric text, command keys\overline{10}–20 cps per handHigh accuracy, tactile feedbackWord processing, programming, data entry
Mouse / TouchpadPointer movement, clicks800–1600 DPI, 100–200 Hz pollingPrecise cursor controlGUI navigation, graphic design
ScannerStatic images, documents300–1200 DPIDigitises printed materialArchiving, OCR, photo editing
MicrophoneAudio (voice, music)44.1 kHz, 16‑bit depth (CD quality)Captures sound for speech recognition, recordingVoice commands, podcasts, video conferencing
Digital Camera / WebcamStill images, videoMegapixels (e.g., 12 MP), 30 fpsHigh‑resolution visual capturePhotography, video calls, image analysis
TouchscreenTouch position, gestures10–20 touch points, 100–200 HzDirect interaction, no peripheral neededMobile devices, kiosks, tablets

3. Output Devices

Output devices transform processed digital data into a form that can be perceived by the user or other equipment. Important characteristics include:

  • Type of output – visual, auditory, tactile, or printed.

  • Resolution / quality – pixels (display), DPI (printer), sample rate (audio).

  • Speed – refresh rate for displays, pages per minute (ppm) for printers.

  • Colour depth – number of colours that can be displayed or printed.

  • Connectivity – HDMI, DisplayPort, USB, network, wireless.

Common Output Devices

DeviceOutput TypeTypical Resolution / SpeedKey AdvantagesTypical Uses
Monitor (LCD/LED)Visual – images, video, text1920×1080 (Full HD) to 3840×2160 (4K); 60–144 Hz refreshHigh colour fidelity, real‑time displayGeneral computing, gaming, design
Printer (Inkjet/Laser)Printed hard copy600–2400 DPI; 10–30 ppm (colour)Portable (inkjet) or fast bulk output (laser)Documents, photos, labels
Speakers / HeadphonesAudio – music, speech44.1 kHz, 16‑bit (CD); up to 192 kHz, 24‑bit (Hi‑Res)Rich sound reproduction, personal listeningMedia playback, gaming, video calls
ProjectorLarge‑scale visual display720p–4K; brightness 2000–5000 lumensDisplays content on walls/screensPresentations, classrooms, home cinema
PlotterLarge‑format printed graphicsUp to 1200 DPI; width up to 36 inchesPrecision line drawing for CADEngineering drawings, architectural plans
Braille DisplayTactile – raised dots representing charactersRefresh rate \overline{10} cells/secAccessibility for visually impaired usersScreen reading, text editing

4. Comparison of Input and Output Devices

AspectInput DevicesOutput Devices
Primary FunctionCapture data from user/environmentPresent processed data to user/environment
Typical Data FlowAnalog → Digital conversionDigital → Analog (or visual) conversion
Key Performance MetricsSpeed (cps, Hz), resolution (DPI), accuracyResolution (pixels/DPI), refresh rate, colour depth
Ergonomic ConsiderationsHand/eye coordination, posture, fatigueViewing distance, sound level, tactile comfort
Common ConnectivityUSB, Bluetooth, PS/2, Wi‑FiHDMI, DisplayPort, USB, Ethernet, Wi‑Fi

5. Summary

  1. Input devices translate real‑world information into digital form; their quality is judged by speed, accuracy, and ergonomics.

  2. Output devices convert digital information back into a human‑readable form; key factors are resolution, speed, and suitability for the intended audience.

  3. Choosing the right combination of input and output devices enhances efficiency, user comfort, and the overall effectiveness of a computer system.

Suggested diagram: Flowchart showing data movement from input devices → CPU/Memory → output devices, with examples of each device type.