Input and Output Devices

• Keyboard (QWERTY), mouse, trackball, joystick, light pen, touch screen, stylus.

• Scanner: converts paper documents or images into digital form.

• OMR (Optical Mark Reader): detects marks made in bubbles, used for checking MCQ answer sheets, such as NET and entrance exams.

• OCR (Optical Character Recognition): converts printed or handwritten text to editable text.

• MICR (Magnetic Ink Character Reader): reads magnetic ink characters on bank cheques.

• Barcode reader: reads product codes in retail and libraries. QR code scanner is a 2-D variant.

• Microphone, webcam, digital camera, biometric devices (fingerprint, iris, face).

Trap pairs: OMR is marks and exams, OCR is text, MICR is cheques and banks, barcode is retail.

• Monitors: CRT, LCD, LED, OLED. Quality depends on resolution (pixels) and refresh rate.

• Printers: impact (dot-matrix, line printer, daisy wheel, with a physical strike, noisy, can make carbon copies) and non-impact (inkjet, laser, thermal, quiet, higher quality). Laser printers are fast and give high-quality text. Print speed is in PPM (pages per minute), and resolution in DPI.

• Plotter: large engineering drawings and maps.

• Speakers, headphones, projector.

Touch screen, modem, headset with microphone, multifunction printer (print and scan). Some are classed as input-output devices. Hard disks and pen drives are storage devices, not typical I/O in exam logic.

A monitor, printer, speaker and plotter are output. Keyboard, mouse, scanner and light pen are input. Resolution is described in pixels (monitor) and DPI (printer).