Computer Notes | JKSSB / JKPSC / FAA / SI
Input, Output & Peripheral Devices
Complete JKSSB Notes with All PYQs
Complete Theory · Classification · All Device Types · 50+ PYQs · New Statement-Based Pattern
📌 What You Will Learn
This post covers everything JKSSB asks about Input, Output and Peripheral Devices — definitions, classification, every device type with working principle, exam tips, and all PYQs mapped to each topic. Based on pattern analysis of Wildlife Guard (2025), Wildlife Inspector (2026), Junior Assistant, Finance Accounts Assistant, and all Graduate-level JKSSB papers.
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1. What Are Peripheral Devices? — The Basics
A peripheral device is any external hardware device connected to a computer to extend its functionality. The computer itself consists of the CPU + RAM + Motherboard. Everything else — keyboard, mouse, monitor, printer, scanner — is a peripheral.
Peripherals are classified into three broad categories based on their function:
📥 Input Devices
Send data/instructions into the computer. User → Computer. Examples: Keyboard, Mouse, Scanner, Microphone, Webcam, Joystick, Touchpad, OMR, OCR, MICR, Barcode Reader, Light Pen, Digitizer.
📤 Output Devices
Receive processed data from the computer and present it to the user. Computer → User. Examples: Monitor, Printer, Speaker, Projector, Plotter, Headphones.
↔️ Input-Output Devices
Perform both input and output functions. Examples: Touch Screen, Modem, Network Interface Card (NIC), USB Flash Drive, Hard Disk Drive (HDD), Fax Machine.
2. Input Devices — Complete Coverage
2.1 Keyboard
The keyboard is the most common input device. It converts keystrokes into digital signals sent to the CPU.
| Keyboard Type | Description |
|---|---|
| QWERTY | Standard layout — most widely used worldwide |
| AZERTY | French keyboard layout |
| DVORAK | Designed for speed/ergonomics — less common |
| Virtual Keyboard | On-screen keyboard, used in touchscreen devices |
| Ergonomic Keyboard | Curved design to reduce strain |
2.2 Mouse & Pointing Devices
A pointing device controls the cursor on screen. The mouse was invented by Douglas Engelbart in 1963.
| Device | Description |
|---|---|
| Mechanical Mouse | Uses a rubber ball underneath to detect movement — older technology |
| Optical Mouse | Uses LED light and optical sensor — most common today |
| Laser Mouse | Uses laser beam — more precise than optical |
| Wireless Mouse | Connects via Bluetooth or RF (radio frequency) dongle |
| Trackball | Stationary device — ball on top moved by thumb/fingers |
| Touchpad | Built into laptops — fingers slide on pressure-sensitive surface |
| Joystick | Used in gaming and aircraft simulators — moves in all 4 directions |
| Light Pen | Pen-shaped device for directly drawing on screen — used in CAD |
| Digitizer/Graphics Tablet | Used by designers — stylus draws on a flat pad |
2.3 Scanners
Scanners convert physical documents or images into digital form.
| Scanner Type | Description |
|---|---|
| Flatbed Scanner | Most common — document placed face-down on glass plate |
| Handheld Scanner | Portable — manually moved across document |
| Drum Scanner | High-quality — used in professional printing |
| Sheet-fed Scanner | Document fed through rollers — like a fax machine |
| 3D Scanner | Captures three-dimensional objects |
2.4 Webcam & Digital Camera
A webcam captures real-time video and images for video calling, streaming, and surveillance. A digital camera captures photographs stored as digital files (JPEG, RAW etc.).
2.5 Microphone
Converts sound (audio) into electrical signals for input into the computer. Used in voice recognition, recording, VoIP calls.
2.6 Touch Screen
A touch screen is both an input and output device. It displays output (like a monitor) and also accepts finger/stylus input. Used in smartphones, ATMs, kiosks, and tablets.
3. Output Devices — Complete Coverage
3.1 Monitor / Visual Display Unit (VDU)
The monitor is the primary output device — it displays text, graphics, and video. Screen size measured diagonally in inches. Resolution measured in pixels (e.g., 1920×1080 = Full HD).
| Monitor Type | Key Characteristics |
|---|---|
| CRT (Cathode Ray Tube) | Old technology — large, heavy, uses electron gun. Still asked in PYQs! |
| LCD (Liquid Crystal Display) | Flat, energy-efficient, uses liquid crystals and backlight |
| LED (Light Emitting Diode) | Type of LCD using LED backlight — thinner, brighter, more common today |
| OLED (Organic LED) | Each pixel emits its own light — deeper blacks, used in phones/TVs |
| Plasma | Uses plasma cells for each pixel — found in large TVs |
| TFT (Thin Film Transistor) | Type of LCD with improved image quality |
3.2 Speakers & Audio Output
Speakers convert digital electrical signals into sound. Audio output quality depends on the sound card inside the computer. Headphones provide personal audio output.
3.3 Projector
Projects computer output onto a large screen. Used in classrooms, conference rooms, cinema halls. Types: DLP (Digital Light Processing), LCD Projector, LED Projector.
3.4 Plotter
A plotter is a special output device used to print large-scale vector graphics — architectural drawings, engineering blueprints, maps. Unlike printers (which print dots), plotters draw continuous lines using pens.
| Plotter Type | Description |
|---|---|
| Drum Plotter | Paper wrapped around a drum — pen moves horizontally while drum rotates |
| Flatbed Plotter | Paper is flat — pen moves in X and Y directions over the paper |
| Inkjet Plotter | Uses inkjet technology for large-format printing |
4. Printers — Most Frequently Asked in JKSSB
Printers are the most-tested output device topic in JKSSB Computer section. They are classified into two main categories based on whether the print head physically touches the paper.
Impact Printers (Physical Contact)
The print head physically strikes a ribbon against paper to form characters. Works like a typewriter. Louder, slower, but can print on multi-copy carbon paper.
- Dot Matrix Printer
- Daisy Wheel Printer
- Chain/Band Printer
- Drum Printer
- Line Printer
Non-Impact Printers (No Contact)
Print head does NOT touch the paper. Use ink, laser, or heat to form images. Quieter, faster, better quality. Cannot print multi-copy carbon paper.
- Inkjet Printer
- Laser Printer
- Thermal Printer
- Electrostatic Printer
- 3D Printer
| Printer | Type | Working & Key Facts |
|---|---|---|
| Dot Matrix | Impact | Pins on print head strike ribbon → forms dots → characters. Cheapest. Used for bills/receipts. Speed: 30–600 CPS (characters per second) |
| Daisy Wheel | Impact | Wheel with characters embossed on petals. High-quality text but slow. Cannot print graphics. Speed: 25–55 CPS |
| Line Printer | Impact | Prints one full line at a time. Very fast. Used in large mainframe computers. Speed: 600–1200 LPM |
| Drum Printer | Impact | Characters on a rotating drum. Fast — used in mainframes |
| Inkjet | Non-Impact | Sprays tiny ink droplets onto paper. Good for photos. Home use. Resolution: 300–1200 DPI |
| Laser | Non-Impact | Uses laser beam + electrostatic charge + toner powder. Fastest, best quality text. Office standard. Speed: 4–20+ PPM |
| Thermal | Non-Impact | Uses heat to create image on special heat-sensitive paper. Used in ATMs, POS billing, fax machines. No ink needed |
| 3D Printer | Non-Impact | Creates 3D physical objects layer by layer from digital designs using plastic/resin/metal |
• Dot Matrix = Impact, cheapest, used for multi-copy billing
• Daisy Wheel = Impact, high quality text, cannot print graphics
• Laser = Fastest, best quality, most common in offices
• Thermal = No ink, used in ATMs and billing machines
• Inkjet = Best for colour photos at home
• Speed measured in: CPS (Character Per Second) for impact, PPM (Pages Per Minute) for laser/inkjet, LPM (Lines Per Minute) for line printers
• Quality measured in: DPI (Dots Per Inch)
5. Special Input Devices — OMR, OCR, MICR, BCR
These are specialised input devices used to read specific types of data — marks, text, magnetic ink, and barcodes. JKSSB asks at least 2–3 questions from this category in every exam.
| Device | Full Name | Working & Uses | Exam Status |
|---|---|---|---|
| OMR | Optical Mark Recognition/Reader | Detects and reads pencil/pen marks in predefined positions. Used for: Exam answer sheets (MCQ checking), voting forms, surveys. Cannot read handwriting — only marks in boxes. | JKSSB PYQ Favourite ⭐ |
| OCR | Optical Character Recognition | Reads and converts printed/handwritten text into editable digital text. Used for: Converting scanned documents to Word/PDF, reading book pages. ABBYY FineReader, Adobe Acrobat — OCR software. | Asked in PYQs |
| MICR | Magnetic Ink Character Recognition | Reads characters printed with magnetic ink. Used in: Banking — reading cheque numbers, account numbers, bank codes at bottom of cheques. Characters look like blocky fonts. | Bank/Cheque context ⭐ |
| BCR (Barcode Reader) | Barcode Reader | Uses laser to read barcodes (series of vertical black/white lines). Used for: Supermarket billing, inventory management, library books, product tracking. | Common in PYQs |
| QR Code Reader | Quick Response Code | Reads 2D QR codes using camera. Stores more data than barcode. Used for: Payments, URLs, tickets, menus. | Newer format |
| Magnetic Stripe Reader | Magstripe Reader | Reads magnetic stripe on back of debit/credit cards. The stripe contains iron-based particles in plastic tape. | Card swiping machines |
• OMR = Only reads MARKS (pen/pencil circles) — used for answer sheets
• OCR = Reads actual TEXT (letters, numbers) — converts to editable format
• MICR = Reads MAGNETIC INK — only used in banking/cheques
• Barcode Reader = Reads 1D barcodes (lines) — used in shopping/inventory
• QR Code = 2D version of barcode — stores more data
• OMR cannot read handwriting. MICR uses special magnetic ink not regular ink.
6. Computer Ports & Interfaces
A port is a physical connection point on a computer that allows peripheral devices to be connected. Ports are essential connectors between the CPU and external devices.
| Port | Description | Used For |
|---|---|---|
| USB (Universal Serial Bus) | Most common port. USB 2.0 (480 Mbps), USB 3.0 (5 Gbps — blue), USB 3.1 (10 Gbps), USB-C (reversible). Supports hot-plugging (connect/disconnect without restart). | Keyboard, Mouse, Pen Drive, Printer |
| HDMI (High-Definition Multimedia Interface) | Transmits both audio and video digitally in high definition. Standard for TVs, monitors, projectors. | Monitor, TV, Projector |
| VGA (Video Graphics Array) | Older analog video port (15-pin D-sub connector). No audio. Being replaced by HDMI/DisplayPort. | Older Monitors, Projectors |
| DisplayPort | Digital video and audio — higher bandwidth than HDMI. Used in high-refresh-rate gaming monitors. | High-end Monitors |
| PS/2 | Circular 6-pin port. Purple = Keyboard, Green = Mouse. Older technology, replaced by USB. | Old Keyboards, Old Mice |
| Serial Port (COM Port) | Transmits data one bit at a time. Older 9-pin or 25-pin connector. Used for modems and old printers. | Old Modems, Printers |
| Parallel Port (LPT Port) | Transmits data 8 bits simultaneously. 25-pin female connector. Used for printers — called 'printer port'. | Old Printers |
| Audio Jack (3.5mm) | Analog audio connection. Green = Speaker/Headphone output, Pink = Microphone input, Blue = Line in. | Speakers, Headphones, Mic |
| Ethernet (RJ-45) | Network port for wired LAN connection. Also called RJ-45 port. | LAN Cable, Network |
| Thunderbolt | High-speed data + video + power. Thunderbolt 3 = USB-C shape. Intel + Apple standard. | Laptops, External Drives |
• USB 3.0 = Blue coloured port
• PS/2 Purple = Keyboard | PS/2 Green = Mouse
• Parallel port = Printer port (25-pin)
• Serial port = COM port (9 or 25 pin)
• HDMI = Audio + Video together
• VGA = Video only, analog, no audio
• RJ-45 = Ethernet/LAN port (network)
7. All JKSSB PYQs — Input/Output & Peripheral Devices
These are actual questions asked in JKSSB examinations across various posts — Junior Assistant, Finance Accounts Assistant (FAA), Wildlife Guard/Inspector, Panchayat Secretary, Accounts Assistant, SI (Finance), and Graduate-level exams.
8. New Statement-Based Pattern Practice MCQs
Based on the new JKSSB 2026 exam pattern (Wildlife Inspector, Wildlife Guard, FAA expected format), these are statement-based questions that require evaluating multiple facts simultaneously — exactly as asked in recent exams.
⚡ Quick Revision — Most Exam-Tested Facts
Input vs Output vs Both
- Input: Keyboard, Mouse, Scanner, Mic, Webcam, Joystick, OMR, OCR, MICR
- Output: Monitor, Printer, Speaker, Projector, Plotter
- Both: Touch Screen, Modem, HDD, NIC, USB Drive, Fax
Printers Summary
- Impact: Dot Matrix, Daisy Wheel, Line, Drum, Chain
- Non-Impact: Laser, Inkjet, Thermal, 3D
- Fastest: Laser | Cheapest: Dot Matrix
- ATM/Bills: Thermal | Photos: Inkjet
- No graphics: Daisy Wheel
Special Readers
- OMR → Answer sheets (marks only)
- OCR → Text to editable digital
- MICR → Banking, cheques
- Barcode → Supermarkets, inventory
- QR Code → Payments, URLs
Ports
- USB 3.0 = Blue
- Parallel = Printer port (25-pin)
- PS/2 Purple = Keyboard, Green = Mouse
- HDMI = Audio + Video
- VGA = Video only, analog
- RJ-45 = Ethernet/LAN
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