Hardware & I/O Devices – Complete Notes for IBPS, SSC, RRB & Govt Exams

Introduction: Why Hardware & I/O Devices is a Must-Prepare Topic

Hardware forms the physical backbone of every computer system. Without hardware, software has nothing to run on. In government exams, Hardware & I/O Devices is consistently tested because it is directly relevant to banking operations, office environments, and government digital services — all of which use computers with specific input and output devices daily.

In exams like IBPS PO, IBPS Clerk, SBI PO, SBI Clerk, RRB NTPC, SSC CGL, and LIC AAO, questions from this chapter appear in multiple forms:

• "Which device is used to read bank cheques?" → MICR
• "Which device is used for OMR answer sheets?" → Optical Mark Reader
• "Which type of printer is used for multi-copy printing?" → Dot Matrix (impact printer)
• "What does VDU stand for?" → Visual Display Unit (Monitor)
• "Which port transmits 8 bits simultaneously?" → Parallel Port

This chapter also directly connects to questions about banking technology — ATMs use touch screens (dual I/O), bank cheques use MICR, answer sheets use OMR. Understanding these devices is not just exam preparation — it is practical knowledge for any banking or government office role.

What is Hardware?

Hardware refers to all the physical, tangible components of a computer system — the parts you can see, touch, and feel. Hardware is categorised into three functional groups:

Hardware is permanent — it does not change unless physically replaced. It works in conjunction with Software (programs/instructions) to perform useful tasks.

Input Devices - Feeding Data into the Computer

An input device is any hardware component that allows a user to feed data and instructions into the computer. The input device converts human-understandable data (text, images, sound) into machine-readable binary format.

Keyboard - The Most Common Input Device

The keyboard is the most widely used input device for computers. It allows users to enter text, numbers, commands, and special characters.

Key Layout Types:

Standard QWERTY keyboard has 104 keys (some variants have 101 or 108 keys)

Types of Keys on a Keyboard:

Mouse - The Pointing Device

The mouse is a pointing device that controls the cursor on the screen. It is the second most common input device after the keyboard.

Inventor: Douglas Engelbart at Stanford Research Center in 1963 Types of Mouse: Wired (Mechanical), Wireless (RF/Bluetooth), Optical (laser-based)

Mouse Actions:

Other Pointing Devices

Scanning and Reading Devices (OMR, OCR, MICR, BCR)

These are among the most frequently tested input devices in government exams because they are directly related to banking, examination systems, and retail:

MICR Deep Dive (Very Important for Banking Exams):

• Used exclusively by banks to process cheques
• The numbers printed at the bottom of a cheque are in MICR font using iron oxide (magnetic) ink
• MICR readers can process hundreds of cheques per minute with near-100% accuracy
• It is extremely difficult to forge — a major security advantage
• MICR numbers on a cheque include: Cheque number, Bank code, Account number, Transaction code

Other Important Input Devices

Output Devices - Getting Results from the Computer

An output device is any hardware component that receives processed data from the CPU and presents it to the user in a human-understandable form. Output can be temporary (soft copy) or permanent (hard copy).

Monitor (VDU - Visual Display Unit)

The monitor is the most common output device. It displays text, images, video, and graphical output from the computer in real time.

Monitor Types by Colour:

• Monochrome — displays only one colour (green/amber/white on black background)
• Colour Monitor — displays 256 to millions of colours

Image Quality is Determined by Three Factors:

Pixel = Picture Element — the smallest building block of any digital image. Every monitor image is composed of millions of tiny pixels.

Types of Monitors

Modern Display Terms:

• HDR (High Dynamic Range) — Wider brightness and colour range; more realistic visuals
• Gaming Refresh Rates — 144 Hz, 165 Hz, 240 Hz, 360 Hz — for smooth gameplay

Printers - Producing Hard Copy Output

A printer is a device that produces a permanent hard copy of data on paper (or other media).

Speed Measures:

• CPS — Characters Per Second (used for older impact printers)
• LPM — Lines Per Minute (line printers)
• PPM — Pages Per Minute (modern printers)
• DPI — Dots Per Inch (measures print quality/resolution)

Impact Printers

Impact printers work by physically striking a ribbon against paper — similar to a typewriter. They can print multiple copies simultaneously (using carbon paper), making them useful for invoices and receipts.

Non-Impact Printers

Non-impact printers do not touch the paper mechanically — they use heat, ink jets, or laser beams. They are quieter, higher quality, and faster than impact printers, but cannot make multiple copies simultaneously.

Key Difference — Impact vs. Non-Impact:

Plotter - Vector Graphics Output

A plotter is a specialised output device that uses pens, pencils, or markers to draw high-quality vector graphics and technical drawings on paper. Unlike printers that print by dots, plotters draw continuous lines.

Used for: Architectural blueprints, engineering designs, CAD/CAM drawings, maps, banners

Other Output Devices

Both Input and Output Devices (Dual I/O Devices)

Some devices serve as both input and output simultaneously:

I/O Ports - Connecting External Devices

Ports are the physical interfaces through which external devices connect to the computer. Each port type has specific data transfer speeds and uses.

Key Port Facts for Exams:

• Parallel port → 8 bits at once → Faster per transfer but obsolete
• Serial port → 1 bit at a time → Slower but longer cable runs
• USB → "Universal" → Works with almost everything → Plug and Play
• USB-C → Same connector both sides → Now mandatory in EU for phones

Memory Tricks

🔑 Scanning Devices — "BOMB":

Barcode Reader | OMR | MICR | Biometric Remember which is used where: Banks use MICR; Objective tests use OMR

🔑 MICR vs OCR vs OMR:

MICR = Magnetic → Banks → Cheques OCR = Characters → Scanned text → Documents OMR = Marks → Answer sheets → Exams

🔑 Impact vs Non-Impact Printers:

Impact = "It hits the paper" → Dot Matrix, Daisy Wheel → Noisy, multi-copy Non-Impact = "No touch" → Laser, Inkjet, Thermal → Quiet, high quality

🔑 Monitor Image Quality — "RDR":

Resolution (higher = better) | Dot Pitch (smaller = better) | Refresh Rate (higher = better)

🔑 Types of Ports — Speed Order (Slow to Fast):

Serial → Parallel → USB 2.0 → USB 3.0 → USB 4.0 → Thunderbolt 5

🔑 Douglas Engelbart = Mouse inventor (1963):

"Doug Engelbart Enabled the Mouse" = DEM = Douglas Engelbart Mouse

One-Liner Recap (Quick Revision)

1. An input device accepts data and instructions from the user and converts them into machine-readable binary format for the computer to process.
2. The keyboard is the most common input device; a standard QWERTY keyboard has 104 keys and is named after its first six letter keys.
3. The mouse was invented by Douglas Engelbart at Stanford Research Center in 1963 and is a pointing device that controls the cursor on screen.
4. MICR (Magnetic Ink Character Recognition) reads magnetic-ink characters at the bottom of bank cheques and is used exclusively in banking for cheque processing.
5. OMR (Optical Mark Reader) detects pencil/pen marks on specially designed paper sheets and is used for processing objective test answer sheets.
6. OCR (Optical Character Recognition) scans printed text and converts it into editable digital text, used for telephone bills and scanned document conversion.
7. A monitor (VDU - Visual Display Unit) is the most common output device; image quality depends on Resolution, Dot Pitch, and Refresh Rate.
8. LCD monitors use liquid crystals, LED monitors emit their own light, OLED monitors offer superior contrast and blacks, and AMOLED is the fastest refreshing type used in smartphones.
9. Impact printers physically strike a ribbon to print and can produce multiple copies (Dot Matrix, Daisy Wheel), while Non-Impact printers use heat, laser, or ink jets and are quieter and higher quality.
10. A Laser printer uses a laser beam on a photo-sensitive drum and produces the highest quality print output at the highest speed among all printer types.
11. A Dot Matrix printer is an impact printer with 9 to 24 pins that prints patterns of dots and is used for multi-copy forms in banking and retail.
12. A Thermal printer applies heat to chemically treated paper and is used in fax machines and receipt printers without requiring any ink.
13. A Plotter is a specialised output device that draws continuous vector graphics using pens, used for architectural blueprints and engineering drawings.
14. Touch screens, modems, FAX machines, headsets, and network cards are examples of devices that serve as both input and output simultaneously.
15. USB (Universal Serial Bus) is the most widely used port standard; USB 4.0 supports up to 40 Gbps, while Thunderbolt 5 reaches up to 120 Gbps.

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