Hardware, Memory & Number Systems
🔒 Log in to trackInput and output devices
🔒 Log in to trackInput devices feed data to the CPU: keyboard, mouse, trackball, joystick, light pen, touch screen, scanner, digital camera, webcam, microphone, barcode/QR reader, biometric (fingerprint/retina) scanner, stylus, and the classic readers:
| Device | Reads | Used in |
|---|---|---|
| OMR (Optical Mark Recognition) | Pencil/ink marks (bubbles) | OMR answer sheets, surveys |
| OCR (Optical Character Recognition) | Printed/written characters into editable text | Digitising documents |
| MICR (Magnetic Ink Character Recognition) | Iron-oxide ink characters | Cheque processing (9-digit code) |
| Barcode reader | Parallel black-white bars | Shops, libraries |
Output devices: monitor/VDU (CRT -> LCD/LED/OLED), printer, plotter, speaker, projector, headphone.
Printers: Impact (physical strike - Dot Matrix, Daisy Wheel; noisy, carbon-copy possible) vs Non-impact (no strike - Inkjet (sprays ink), Laser (electrophotographic, fast, office standard), Thermal (bills, ATMs)). Plotter draws large precise hard copies (engineering drawings).
Both input & output: touch screen, modem, network card, headsets with mic, and storage devices generally.
Input devices — data goes IN
Anything that feeds data or commands to the computer is an input device.
| Group | Devices |
|---|---|
| Typing / pointing | Keyboard, mouse, trackball, touchpad, joystick, light pen, stylus |
| Capture | Scanner, digital camera, webcam, microphone |
| Readers | Barcode/QR reader (shops), OMR (answer sheets), OCR (scanned text), MICR (bank cheques), biometric scanner (fingerprint, iris) |
The reader trio by one word each: OMR = Marks (pencil bubbles), OCR = Characters (printed text becomes editable text), MICR = Ink (magnetic characters on cheques).
Output devices — results come OUT
| Device | Gives |
|---|---|
| Monitor | Soft copy — output you can see but not touch |
| Printer | Hard copy — output on paper |
| Speaker / headphones | Sound |
| Plotter | Hard copy of large drawings and maps (engineering, architecture) |
| Projector | A big soft copy on a screen |
Printers: impact vs non-impact
| Type | How it works | Examples |
|---|---|---|
| Impact | Physically strikes the paper through a ribbon | Dot matrix, daisy wheel — noisy, cheap, multi-copy forms |
| Non-impact | No hitting — sprays ink, fuses toner, or heats paper | Laser (toner, fast, office), inkjet (liquid ink, home), thermal (bills) |
Devices that do BOTH
A touch screen takes your finger's input and displays output. A headset has a mic (in) and speakers (out). Exams ask 'which is both input and output?' — touch screen is the standard answer.
Pointing devices in one line each
- Mouse — the standard pointing device; a ball or optical sensor tracks movement.
- Trackball — an upside-down mouse: you roll the ball, the device stays put.
- Touchpad — the laptop's flat mouse replacement.
- Joystick — direction control for games and flight simulators.
- Light pen / stylus — draw or point directly on the screen.
- Touchpad + pointers all feed position data IN — every one is an input device.
Pairing questions (device ↔ use)
| Device | Classic use in exams |
|---|---|
| Barcode reader | Supermarket billing |
| OMR | Evaluating pencil-bubble answer sheets |
| MICR | Reading the cheque code line in banks |
| OCR | Converting a scanned page into editable text |
| Biometric scanner | Attendance, Aadhaar-style identity checks |
| Plotter | Engineering drawings, maps, posters |
| Webcam + mic | Video calls |
Modern extras
- 3D printer — builds a physical solid object layer by layer (an output device).
- Webcam + microphone — the video-call input pair.
Question types you will see
Each type: how to recognise it, the method step by step, and one question to try.
Input device identification
'Which is an input device?', 'a barcode reader is used to…', 'joystick is used in…' — pick the device that feeds data in.
Test each option: does data flow INTO the computer (input) or OUT (output)?
Scanner, microphone and camera are input even though they feel like 'media' devices.
Monitor, printer, speaker, plotter, projector are always output.
Which of the following is an input device?
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Scanner — it feeds a paper document into the computer as an image. Monitor, speaker and plotter all send data out.
Output device identification; soft vs hard copy
'Which is an output device?', 'printed output is called a … copy', 'monitor output is called a … copy'.
Soft copy = on screen (monitor, projector); hard copy = on paper (printer, plotter).
Speaker and headphones are output (sound).
'Touch screen' is the planted trap in output-only questions — it is both.
Output shown on paper (a printout) is called a —
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Hard copy — permanent, touchable output. Output on a monitor is a soft copy.
Both input and output / odd one out
'Which device works as both input and output?', 'which is NOT an input device?' — one option breaks the family.
Both-direction devices: touch screen, headset (mic + speaker), fax machine (classic), smart TV with voice remote.
For 'not an input', look for the printer, monitor or speaker hiding in the list.
Classify each option before reading the stem twice — speed comes from the table.
Which device acts as both an input and an output device?
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Touch screen — your touch is input and the display is output. A mouse is input-only; a monitor is output-only.
Printer technology and reader classification
'Which is an impact printer?', 'laser printer is non-impact because…', 'OCR converts…', 'plotter is used for…', '3D printer makes…'.
Impact = physical strike (dot matrix, daisy wheel); non-impact = laser, inkjet, thermal.
Readers by one word: OMR marks, OCR characters, MICR magnetic ink.
Plotter = large-format drawings; 3D printer = solid objects layer by layer.
Which of the following is an impact printer?
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Dot matrix — its pins physically strike the ribbon against the paper. Laser, inkjet and thermal printers never touch the paper with force.
Shortcuts that save time
OMR = Marks (bubbles), OCR = Characters (text), MICR = Ink on cheques (banks). Marks, Characters, Ink - match the noun in the question.
Bank cheque reading uses?
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MICR - magnetic ink characters.
If the printer physically hits paper (dot matrix, daisy wheel) it is impact - noisy but makes carbon copies. Inkjet/Laser/Thermal never touch with force: non-impact.
Which is a non-impact printer - Dot Matrix or Laser?
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Laser (dot matrix strikes the ribbon).
Mistakes to avoid
Where most students lose marks on this subtopic.
Marking a touch screen as input-only - it is both input and output.
Calling MICR an optical technology - it reads magnetic ink.
Saying plotters are for office documents - plotters are for large-format drawings/graphs.
Quick revision
Read this the night before the exam.
Input: keyboard, mouse, scanner, mic, camera, barcode/OMR/OCR/MICR readers, biometrics.
OMR = Marks, OCR = Characters, MICR = magnetic Ink (cheques).
Output: monitor (soft copy), printer/plotter (hard copy), speaker, projector.
Impact = hits paper (dot matrix); non-impact = laser, inkjet, thermal.
Touch screen = both input and output. 3D printer = solid object output.
Practice: 17 questions
Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.
Topic test · 10 questions
Suggested time 4 min · wrong answers go to your mistake notebook automatically.