Input and Output Devices
Input devices
| Device | Use |
|---|---|
| Keyboard | Text entry. QWERTY layout. |
| Mouse | Pointing device. Invented by Douglas Engelbart (1964). |
| Scanner | Converts paper into a digital image. |
| OCR | Optical Character Recognition: reads printed text. |
| OMR | Optical Mark Recognition: reads marked bubbles, as in OMR answer sheets. |
| MICR | Magnetic Ink Character Recognition: reads the ink on the bottom of bank cheques. |
| Barcode reader | Reads product codes. QR code reader reads two-dimensional codes. |
| Touch screen, light pen, joystick, trackball, stylus | Pointing and drawing. |
| Microphone, webcam | Audio and video input. |
| Biometric devices | Fingerprint, iris and face scanners (Aadhaar enrolment). |
Output devices
| Device | Facts |
|---|---|
| Monitor | CRT (old), LCD, LED, OLED. Sharpness depends on resolution (pixels) and PPI. |
| Printer: impact | Strikes the paper. Dot-matrix, daisy-wheel, line printer. Can make carbon copies. Noisy. |
| Printer: non-impact | Inkjet, laser, thermal. Quiet and sharper. |
| Plotter | Draws large engineering drawings (maps, blueprints). |
| Projector, speakers, headphones | Display and sound output. |
Printer speed: dot-matrix in CPS (characters per second), line printers in LPM (lines per minute), laser and inkjet in PPM (pages per minute). Print quality is in DPI (dots per inch).
Ports and connectors
| Port | Use |
|---|---|
| USB (Type-A, Type-C) | Universal Serial Bus. Keyboards, drives, charging. Hot-swappable. |
| HDMI | Digital video and audio to a TV or monitor. |
| VGA | Older analogue video. DVI: digital video. |
| Ethernet (RJ-45) | Wired network. |
| Thunderbolt | Very fast data, video and power in one port. |
| PS/2 | Old keyboard and mouse port. |
Keep practising
Notes are only half the work. Test yourself with questions and discuss doubts with other aspirants.
Prepared for exam revision from standard computer textbooks, Microsoft documentation and official sources. Features differ between Excel and Word versions (2016, 2019, 2021, 365) so check which version your exam follows. Found a mistake? Tell us.