Input/Output — Set 1

Correct Answer: A. Keyboard

• **Keyboard** = a primary input device that lets users type letters, numbers, symbols, and function commands directly into a computer — it remains the most universal text-entry tool across desktops, laptops, and servers because every keystroke is instantly transmitted as a digital signal. • **Design origin** — the keyboard layout derives from the 19th-century typewriter, but adds dedicated rows of function keys (F1–F12), a numeric keypad, and navigation keys not present on typewriters. • Modern keyboards connect via USB or Bluetooth and some include backlit keys for low-light use. • 💡 Option B (Mouse) is wrong because a mouse is a pointing device used for navigating the screen, not for entering text; Option C (Scanner) is wrong because a scanner converts physical documents into digital images, not typed input; Option D (Monitor) is wrong because a monitor is an output device that displays information, it cannot accept typed input.

Correct Answer: C. Output

• **Monitor (Output device)** = a screen that receives processed signals from the graphics card and renders them as visible text, images, and video — it is classified as output because information flows FROM the computer TO the user, not the other way. • **Display technology** — modern monitors use LCD (Liquid Crystal Display) or LED panels, replacing older bulky CRT (Cathode Ray Tube) monitors that used electron beams. • Monitor quality is judged by resolution (pixel count), refresh rate (Hz), and colour accuracy (measured in sRGB or DCI-P3). • 💡 Option A (Input) is wrong because monitors do not send any data into the computer; Option B (Storage) is wrong because a monitor holds no data permanently; Option D (Processing) is wrong because processing is done by the CPU, not the display screen.

Correct Answer: D. Laser or LED

• **Laser or LED** = an optical mouse shines a Laser or LED light onto the surface beneath it, and a tiny CMOS image sensor photographs that surface thousands of times per second to calculate direction and speed of movement — this is why it requires no moving mechanical parts. • **Advantage over mechanical mice** — the older rubber-ball mouse trapped dust inside the ball casing, causing erratic movement; the optical design eliminated that mechanical wear point entirely. • Laser-based optical mice offer higher DPI (dots per inch) sensitivity than standard LED models, making them popular for precision gaming. • 💡 Option A (Mechanical Ball) is wrong because that describes the older generation mice, not optical ones; Option B (Radio Waves) is wrong because radio waves are used for wireless communication, not surface movement detection; Option C (Magnetic Sensor) is wrong because mice do not use magnetic fields to detect motion.

Correct Answer: A. To convert physical images into digital format

• **Convert physical images into digital format** = a document scanner uses a bright light bar and CCD sensors to capture reflected light from paper and encode it as a digital image file — this is its defining purpose as an input device. • **Resolution matters** — scanner resolution is measured in DPI; archival-quality scanning for historical documents typically requires 600 DPI or higher to preserve fine detail. • Flatbed scanners handle books and photos, while ADF (Automatic Document Feeder) scanners process multi-page documents automatically. • 💡 Option B (To print digital files) is wrong because printing is the function of a printer, not a scanner; Option C (To display text on a screen) is wrong because displaying is what a monitor does; Option D (To store permanent backup) is wrong because scanners do not store data — they capture and send it to the computer.

Correct Answer: C. Plotter

• **Plotter** = a specialised output device that draws precise vector graphics on large-format paper sheets using ink pens or cutting blades — unlike standard printers it moves the drawing instrument along both X and Y axes to produce continuous lines rather than dot patterns. • **Professional use** — plotters are the standard tool for engineering CAD drawings, architectural blueprints, GIS maps, and vinyl sign-cutting because the output can be several metres wide. • Modern pen plotters have largely been replaced by large-format inkjet plotters that spray ink but still produce the same oversized precision output. • 💡 Option A (Laser Printer) is wrong because laser printers use toner on A4/A3 sheets and cannot handle large-format technical drawings; Option B (Inkjet Printer) is wrong because standard inkjet printers are limited in paper size and precision for engineering blueprints; Option D (Dot Matrix Printer) is wrong because dot matrix printers use impact pins on ribbons and are not designed for vector graphics or large formats.

Correct Answer: C. Escape (Esc)

• **Escape (Esc)** = a keyboard key specifically designed to cancel, interrupt, or exit the current operation in most software — pressing Esc closes dialog boxes, stops a web page from loading, exits full-screen mode, or cancels a command mid-execution. • **Historical origin** — the Esc key was introduced in 1960 by IBM engineer Bob Bemer to send an escape sequence to teletype terminals, signalling the end of a control string. • On a standard QWERTY keyboard it sits at the top-left corner, making it easy to reach quickly during any operation. • 💡 Option A (Enter) is wrong because the Enter key confirms or executes a command rather than cancelling it; Option B (Shift) is wrong because Shift is a modifier key that temporarily changes character case; Option D (Backspace) is wrong because Backspace deletes the character to the left of the cursor, it does not cancel an operation.

Correct Answer: D. Computer Gaming

• **Computer Gaming** = a joystick is a multi-directional lever input device that pivots on a base and sends its tilt angle to the computer — this makes it ideal for gaming, especially flight simulators, where the player must control movement across multiple axes simultaneously. • **Aviation origin** — joysticks were first developed for real aircraft controls; computer joysticks mimic that feel and are standard equipment in professional flight-simulator training rigs. • Modern gaming joysticks include programmable buttons, throttle controls, and force-feedback motors that vibrate to simulate turbulence or impact. • 💡 Option A (Word Processing) is wrong because word processing requires text input via keyboard, not directional lever control; Option B (Slide Presentation) is wrong because presentations are navigated with a mouse or wireless clicker; Option C (Data Entry) is wrong because joysticks have no character keys and cannot enter alphanumeric data.

Correct Answer: A. Dot Matrix

• **Dot Matrix** = an impact printer that fires a column of tiny metal pins against an ink ribbon onto paper, forming characters from a grid of dots — the physical contact between pins, ribbon, and paper is what defines it as an impact printer. • **Carbon copy advantage** — because the pins physically strike through multiple layers, dot matrix printers can print on carbon or NCR paper simultaneously, making them still used today for railway tickets, bank passbooks, and multi-part invoices. • They are significantly noisier than laser or inkjet printers, and print speed is measured in characters per second (CPS) rather than pages per minute. • 💡 Option B (Laser) is wrong because laser printers use toner powder fused by heat with no pins or ribbon; Option C (Thermal) is wrong because thermal printers use heat-sensitive paper and require no ink ribbon; Option D (Inkjet) is wrong because inkjet printers spray liquid ink through nozzles without any physical impact on paper.

Correct Answer: C. Microphone

• **Microphone** = an input device that converts sound waves (air pressure variations) into electrical signals using a thin vibrating diaphragm — these electrical signals are then digitised by the sound card into a digital audio format such as WAV or MP3. • **Condenser vs dynamic** — computer microphones are typically condenser type (high sensitivity, requires power) used in studios, or dynamic type (robust, suits loud environments) used in live settings. • Microphones are essential for voice calls, speech-to-text dictation, podcasting, and video conferencing in modern computing. • 💡 Option A (Speaker) is wrong because a speaker is an output device that converts electrical signals back into sound, the reverse of a microphone; Option B (Sound Card) is wrong because the sound card processes audio signals internally but cannot capture sound from the environment on its own; Option D (Headphones) is wrong because headphones are output devices for listening, not for capturing audio.

Correct Answer: D. Monitor

• **Monitor** = the output device that produces a soft copy — a soft copy is a digital, on-screen version of information that exists only while the device is powered and disappears when the display is switched off or the file is closed. • **Hard copy vs soft copy** — a hard copy (produced by printers and plotters) is a permanent physical output on paper or film; a soft copy on a monitor can be scrolled, edited, and transmitted electronically without consuming any material. • Soft copies are environmentally efficient and are standard for emails, PDFs on screen, and office documents viewed without printing. • 💡 Option A (Printer) is wrong because a printer produces hard copies on physical paper, the opposite of a soft copy; Option B (Typewriter) is wrong because a typewriter mechanically imprints characters directly onto paper, always producing a hard copy; Option C (Plotter) is wrong because plotters draw on large paper sheets, producing hard copies used in engineering and architecture.