Learning Objectives
By the end of this chapter, you will be able to:
- Differentiate between an input device and an output device.
- Classify and identify common types of input devices, including scanning and biometric devices.
- Classify and identify common types of output devices, including printer types.
- Recognize devices that perform both input and output.
- Choose suitable I/O devices for business tasks.
Interacting with Computers: Input and Output Devices
Input and output (I/O) devices are the peripherals that allow us to interact with a computer. Input devices are used to send data to the computer, and output devices are used to get feedback from the computer.
flowchart LR
User["User"] --> Input["Input Devices<br/>(Keyboard, Mouse, Scanner)"]
Input --> CPU["CPU Processing"]
CPU --> Output["Output Devices<br/>(Monitor, Printer, Speakers)"]
Output --> User
Figure 1: Input and Output Data Flow
Input Devices
Input devices translate our real-world actions into digital data that the computer can understand.
- Keyboard: The most common input device, used for typing text and commands.
- Mouse: A pointing device used to control the cursor on the screen and interact with graphical user interfaces (GUIs).
- Microphone: Captures audio and converts it into digital data.
- Scanner: Converts physical documents or images into digital files.
- Webcam: Captures video and still images.
Classification of input devices
| Category | Devices | Example use |
|---|---|---|
| Keyboard devices | Keyboard, numeric keypad | Typing letters, entering amounts |
| Pointing devices | Mouse, touchpad, trackball, joystick, stylus, light pen | Selecting, drawing, gaming |
| Touch devices | Touchscreen | Smartphones, ATMs, self-service kiosks |
| Scanning devices | Flatbed scanner, barcode reader, QR scanner | Digitizing documents, billing products |
| Recognition devices | OMR, OCR, MICR | Exam answer sheets, reading text, cheques |
| Biometric devices | Fingerprint reader, face and iris scanners | Attendance, phone unlocking, identity checks |
| Audio/video devices | Microphone, webcam, digital camera | Voice input, video meetings |
Recognition devices (common exam topic)
- OMR (Optical Mark Reader) — detects pencil or pen marks in fixed boxes; used for multiple-choice exam sheets and surveys.
- OCR (Optical Character Recognition) — converts printed or handwritten text in a scanned image into editable text.
- MICR (Magnetic Ink Character Recognition) — reads the special magnetic-ink numbers printed at the bottom of bank cheques; fast and hard to forge.
- Barcode / QR reader — reads product codes at billing counters or QR codes for payments.
Output Devices
Output devices translate the computer’s digital data back into a form that humans can understand.
- Monitor (Display Screen): The primary output device for a computer, which displays text and graphics.
- Printer: Produces a physical hard copy of digital documents.
- Speakers/Headphones: Produce audio output.
- Projector: Displays the computer’s screen output onto a larger surface.
- Plotter: Draws large, precise drawings such as engineering plans and maps.
Soft copy output is shown on a screen or played as sound and is temporary. Hard copy output is printed on paper and is permanent.
Types of monitors
- LCD/LED — flat, light, and energy-efficient; the most common today.
- OLED — each pixel produces its own light; deeper blacks and thinner screens, used in many smartphones.
- CRT — old, bulky tube monitors, now obsolete.
Types of printers
| Type | Category | How it works | Typical use |
|---|---|---|---|
| Dot-matrix | Impact | Pins strike an ink ribbon | Multi-part invoices and carbon copies |
| Inkjet | Non-impact | Sprays tiny ink droplets | Home and photo printing |
| Laser | Non-impact | Uses toner fused by heat | Fast, high-volume office printing |
| Thermal | Non-impact | Heats special paper | POS receipts, tickets, labels |
| 3D printer | Non-impact | Builds objects layer by layer | Prototypes and models |
Impact printers physically strike the paper and are noisy but can print carbon copies. Non-impact printers are quieter and faster.
Devices That Do Both
Some devices are both input and output devices:
- Touchscreen — shows output and accepts touch input.
- Headset with microphone — audio output and voice input.
- Modem / network card — sends and receives data.
- Multifunction printer — prints (output) and scans (input).
Business and Nepal Examples
- Supermarkets use barcode readers, POS touchscreens, and thermal receipt printers at billing counters.
- Banks use MICR to process cheques and fingerprint readers for staff login and customer verification.
- Offices and colleges use biometric attendance machines.
- Entrance and licence exams commonly use OMR answer sheets so results can be marked quickly by machine.
- Accounting offices still use dot-matrix printers where carbon-copy forms are needed.
Summary
Input and output devices are the essential bridge between humans and computers. Input devices—keyboards, pointing devices, touchscreens, scanners, OMR, OCR, MICR, barcode, and biometric readers—allow us to give commands and enter data, while output devices like monitors, printers, speakers, projectors, and plotters allow the computer to present us with the results of its processing. Some devices, such as touchscreens, do both. Together, they form the basis of the user interface and support many business processes.
Key Takeaways
- Input devices send data to the computer; output devices receive data from it.
- Input devices include keyboard, pointing, touch, scanning, recognition (OMR, OCR, MICR), biometric, and audio/video devices.
- Output can be soft copy (screen, sound) or hard copy (printed).
- Printers are impact (dot-matrix) or non-impact (inkjet, laser, thermal).
- Touchscreens and multifunction printers are both input and output devices.
Discussion Questions
- Is a touchscreen on a smartphone an input device, an output device, or both? Explain your answer.
- What are some specialized input or output devices you might find in a specific profession (e.g., a graphic designer, a doctor)?
- How have output devices changed over the last 20 years?
Exam-Style Questions
Short answer
- Differentiate between input and output devices with two examples each.
- Write short notes on OMR, OCR, and MICR.
- Differentiate between impact and non-impact printers.
Long answer
- Explain different types of input devices with their uses in business.
- Describe the major output devices. Which devices would you recommend for a supermarket billing counter, and why?
